//! Helpers and objects for building Goose load tests.
//!
//! Goose manages load tests with a series of objects:
//!
//! - [`Scenario`] each user is assigned a scenario, which is a collection of transactions.
//! - [`Transaction`] transactions define one or more web requests and are assigned to scenarios.
//! - [`GooseUser`] a user state responsible for repeatedly running all transactions in the assigned scenario.
//! - [`GooseRequestMetric`] optional metrics collected for each URL/method pair.
//!
//! ## Creating Scenarios
//!
//! A [`Scenario`](./struct.Scenario.html) is created by passing in a `&str` name to the `new` function, for example:
//!
//! ```rust
//! use goose::prelude::*;
//!
//! let mut loadtest_transactions = scenario!("LoadtestTransactions");
//! ```
//!
//! ### Scenario Weight
//!
//! A weight can be applied to a scenario, controlling how often it is assigned to
//! [`GooseUser`](../goose/struct.GooseUser.html) threads. The larger the integer value
//! of weight, the more the scenario will be assigned to user threads. In the following
//! example, `FooTransactions` will be assigned to users twice as often as `Bar`
//! Transactions. We could have just added a weight of `2` to `FooTransactions` and left
//! the default weight of `1` assigned to `BarTransactions` for the same weighting:
//!
//! ```rust
//! use goose::prelude::*;
//!
//! #[tokio::main]
//! async fn main() -> Result<(), GooseError> {
//!     let mut foo_transactions = scenario!("FooTransactions").set_weight(10)?;
//!     let mut bar_transactions = scenario!("BarTransactions").set_weight(5)?;
//!
//!     Ok(())
//! }
//! ```
//!
//! ### Scenario Host
//!
//! A default host can be assigned to a scenario, which will be used only if the `--host`
//! CLI option is not set at run-time. For example, this can configure your load test to
//! run against your local development environment by default, allowing the `--host` option
//! to override host when you want to load test production. You can also assign different
//! hosts to different scenario if this is desirable:
//!
//! ```rust
//! use goose::prelude::*;
//!
//! let mut foo_transactions = scenario!("FooTransactions").set_host("http://www.local");
//! let mut bar_transactions = scenario!("BarTransactions").set_host("http://www2.local");
//! ```
//!
//! ### Scenario Wait Time
//!
//! Wait time is specified as a low-high Duration range. Each time a transaction completes in the
//! scenario, the user will pause for a random number of milliseconds inclusively between
//! the low and high wait times. In the following example, users loading `foo` transactions will
//! sleep 0 to 2.5 seconds after each transaction completes, and users loading `bar` transactions will
//! always sleep 5 seconds after each transaction completes.
//!
//! ```rust
//! use goose::prelude::*;
//! use std::time::Duration;
//!
//! let mut foo_transactions = scenario!("FooTransactions").set_wait_time(Duration::from_secs(0), Duration::from_millis(2500)).unwrap();
//! let mut bar_transactions = scenario!("BarTransactions").set_wait_time(Duration::from_secs(5), Duration::from_secs(5)).unwrap();
//! ```
//! ## Creating Transactions
//!
//! A [`Transaction`](./struct.Transaction.html) must include a pointer to a function which
//! will be executed each time the transaction is run.
//!
//! ```rust
//! use goose::prelude::*;
//!
//! let mut a_transaction = transaction!(transaction_function);
//!
//! /// A very simple transaction that loads the front page.
//! async fn transaction_function(user: &mut GooseUser) -> TransactionResult {
//!     let _goose = user.get("").await?;
//!
//!     Ok(())
//! }
//! ```
//!
//! ### Transaction Name
//!
//! A name can be assigned to a transaction, and will be displayed in metrics about all requests
//! made by the transaction.
//!
//! ```rust
//! use goose::prelude::*;
//!
//! let mut a_transaction = transaction!(transaction_function).set_name("a");
//!
//! /// A very simple transaction that loads the front page.
//! async fn transaction_function(user: &mut GooseUser) -> TransactionResult {
//!     let _goose = user.get("").await?;
//!
//!     Ok(())
//! }
//! ```
//!
//! ### Transaction Weight
//!
//! Individual transactions can be assigned a weight, controlling how often the transaction runs. The
//! larger the value of weight, the more it will run. In the following example, `a_transaction`
//! runs 3 times as often as `b_transaction`:
//!
//! ```rust
//! use goose::prelude::*;
//!
//! #[tokio::main]
//! async fn main() -> Result<(), GooseError> {
//!     let mut a_transaction = transaction!(a_transaction_function).set_weight(9)?;
//!     let mut b_transaction = transaction!(b_transaction_function).set_weight(3)?;
//!
//!     Ok(())
//! }
//!
//! /// A very simple transaction that loads the "a" page.
//! async fn a_transaction_function(user: &mut GooseUser) -> TransactionResult {
//!     let _goose = user.get("a/").await?;
//!
//!     Ok(())
//! }
//!
//! /// Another very simple transaction that loads the "b" page.
//! async fn b_transaction_function(user: &mut GooseUser) -> TransactionResult {
//!     let _goose = user.get("b/").await?;
//!
//!     Ok(())
//! }
//! ```
//!
//! ### Transaction Sequence
//!
//! Transactions can also be configured to run in a sequence. For example, a transaction with a
//! sequence value of `1` will always run before a transaction with a sequence value of `2`. Weight can
//! be applied to sequenced transactions, so for example a transaction with a weight of `2` and a sequence
//! of `1` will run two times before a transaction with a sequence of `2`. Scenarios can contain
//! transactions with sequence values and without sequence values, and in this case all transactions with
//! a sequence value will run before transactions without a sequence value. In the following example,
//! `a_transaction` runs before `b_transaction`, which runs before `c_transaction`:
//!
//! ```rust
//! use goose::prelude::*;
//!
//! let mut a_transaction = transaction!(a_transaction_function).set_sequence(1);
//! let mut b_transaction = transaction!(b_transaction_function).set_sequence(2);
//! let mut c_transaction = transaction!(c_transaction_function);
//!
//! /// A very simple transaction that loads the "a" page.
//! async fn a_transaction_function(user: &mut GooseUser) -> TransactionResult {
//!     let _goose = user.get("a/").await?;
//!
//!     Ok(())
//! }
//!
//! /// Another very simple transaction that loads the "b" page.
//! async fn b_transaction_function(user: &mut GooseUser) -> TransactionResult {
//!     let _goose = user.get("b/").await?;
//!
//!     Ok(())
//! }
//!
//! /// Another very simple transaction that loads the "c" page.
//! async fn c_transaction_function(user: &mut GooseUser) -> TransactionResult {
//!     let _goose = user.get("c/").await?;
//!
//!     Ok(())
//! }
//! ```
//!
//! ### Transaction On Start
//!
//! Transactions can be flagged to only run when a user first starts. This can be useful if you'd
//! like your load test to use a logged-in user. It is possible to assign sequences and weights
//! to [`on_start`](./struct.Transaction.html#method.set_on_start) functions if you want to have
//! multiple transactions run in a specific order at start time, and/or the transactions to run multiple times.
//! A transaction can be flagged to run both on start and on stop.
//!
//! ```rust
//! use goose::prelude::*;
//!
//! let mut a_transaction = transaction!(a_transaction_function).set_sequence(1).set_on_start();
//!
//! /// A very simple transaction that loads the "a" page.
//! async fn a_transaction_function(user: &mut GooseUser) -> TransactionResult {
//!     let _goose = user.get("a/").await?;
//!
//!     Ok(())
//! }
//! ```
//!
//! ### Transaction On Stop
//!
//! Transactions can be flagged to only run when a user stops. This can be useful if you'd like your
//! load test to simulate a user logging out when it finishes. It is possible to assign sequences
//! and weights to [`on_stop`](./struct.Transaction.html#method.set_on_stop) functions if you want to
//! have multiple transactions run in a specific order at stop time, and/or the transactions to run multiple
//! times. A transaction can be flagged to run both on start and on stop.
//!
//! ```rust
//! use goose::prelude::*;
//!
//! let mut b_transaction = transaction!(b_transaction_function).set_sequence(2).set_on_stop();
//!
//! /// Another very simple transaction that loads the "b" page.
//! async fn b_transaction_function(user: &mut GooseUser) -> TransactionResult {
//!     let _goose = user.get("b/").await?;
//!
//!     Ok(())
//! }
//! ```
//!
//! ## Controlling User
//!
//! When Goose starts, it creates one or more [`GooseUser`](./struct.GooseUser.html)s,
//! assigning a single [`Scenario`](./struct.Scenario.html) to each. This user is
//! then used to generate load. Behind the scenes, Goose is leveraging the
//! [`reqwest::client`](https://docs.rs/reqwest/*/reqwest/struct.Client.html)
//! to load web pages, and Goose can therefor do anything [`reqwest`](https://docs.rs/reqwest/)
//! can do.
//!
//! The most common request types are [`GET`](./struct.GooseUser.html#method.get) and
//! [`POST`](./struct.GooseUser.html#method.post), but [`HEAD`](./struct.GooseUser.html#method.head),
//! PUT, PATCH and [`DELETE`](./struct.GooseUser.html#method.delete) are also supported.
//!
//! ### GET
//!
//! A helper to make a `GET` request of a path and collect relevant metrics.
//! Automatically prepends the correct host.
//!
//! ```rust
//! use goose::prelude::*;
//!
//! let mut transaction = transaction!(get_function);
//!
//! /// A very simple transaction that makes a GET request.
//! async fn get_function(user: &mut GooseUser) -> TransactionResult {
//!     let _goose = user.get("path/to/foo/").await?;
//!
//!     Ok(())
//! }
//! ```
//!
//! The returned response is a [`reqwest::Response`](https://docs.rs/reqwest/*/reqwest/struct.Response.html)
//! struct. You can use it as you would any Reqwest Response.
//!
//!
//! ### POST
//!
//! A helper to make a `POST` request of a string value to the path and collect relevant
//! metrics. Automatically prepends the correct host. The returned response is a
//! [`reqwest::Response`](https://docs.rs/reqwest/*/reqwest/struct.Response.html)
//!
//! ```rust
//! use goose::prelude::*;
//!
//! let mut transaction = transaction!(post_function);
//!
//! /// A very simple transaction that makes a POST request.
//! async fn post_function(user: &mut GooseUser) -> TransactionResult {
//!     let _goose = user.post("path/to/foo/", "string value to post").await?;
//!
//!     Ok(())
//! }
//! ```
//!
//! ## License
//!
//! Copyright 2020-2022 Jeremy Andrews
//!
//! Licensed under the Apache License, Version 2.0 (the "License");
//! you may not use this file except in compliance with the License.
//! You may obtain a copy of the License at
//!
//! <http://www.apache.org/licenses/LICENSE-2.0>
//!
//! Unless required by applicable law or agreed to in writing, software
//! distributed under the License is distributed on an "AS IS" BASIS,
//! WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//! See the License for the specific language governing permissions and
//! limitations under the License.

use downcast_rs::{impl_downcast, Downcast};
use http::method::Method;
use regex::Regex;
use reqwest::{header, Client, ClientBuilder, RequestBuilder, Response};
use serde::{Deserialize, Serialize};
use std::hash::{Hash, Hasher};
use std::sync::Arc;
use std::time::Duration;
use std::{fmt, str};
use std::{future::Future, pin::Pin, time::Instant};
use url::Url;

use crate::logger::GooseLog;
use crate::metrics::{
    GooseCoordinatedOmissionMitigation, GooseMetric, GooseRawRequest, GooseRequestMetric,
};
use crate::{GooseConfiguration, GooseError, WeightedTransactions};

/// By default Goose sets the following User-Agent header when making requests.
static APP_USER_AGENT: &str = concat!(env!("CARGO_PKG_NAME"), "/", env!("CARGO_PKG_VERSION"));

/// By default Goose times out requests after 60,000 milliseconds.
static GOOSE_REQUEST_TIMEOUT: u64 = 60_000;

/// `transaction!(foo)` expands to `Transaction::new(foo)`, but also does some boxing to work around a limitation in the compiler.
#[macro_export]
macro_rules! transaction {
    ($transaction_func:ident) => {
        Transaction::new(std::sync::Arc::new(move |s| {
            std::boxed::Box::pin($transaction_func(s))
        }))
    };
}

/// `scenario!("foo")` expands to `Scenario::new("foo")`.
#[macro_export]
macro_rules! scenario {
    ($name:tt) => {
        Scenario::new($name)
    };
}

/// Goose transactions return a result, which is empty on success, or contains a boxed
/// [`TransactionError`](./enum.TransactionError.html) on error.
pub type TransactionResult = Result<(), Box<TransactionError>>;

/// An enumeration of all errors a [`Transaction`](./struct.Transaction.html) can return.
#[derive(Debug)]
pub enum TransactionError {
    /// Wraps a [`reqwest::Error`](https://docs.rs/reqwest/*/reqwest/struct.Error.html).
    Reqwest(reqwest::Error),
    /// Wraps a [`url::ParseError`](https://docs.rs/url/*/url/enum.ParseError.html).
    Url(url::ParseError),
    /// The request failed.
    RequestFailed {
        /// The [`GooseRequestMetric`](./struct.GooseRequestMetric.html) that failed.
        raw_request: GooseRequestMetric,
    },
    /// The request was canceled. This happens when the throttle is enabled and the load
    /// test finishes.
    RequestCanceled {
        /// Wraps a [`flume::SendError`](https://docs.rs/flume/*/flume/struct.SendError.html),
        /// a [`GooseRequestMetric`](./struct.GooseRequestMetric.html) has not yet been constructed.
        source: flume::SendError<bool>,
    },
    /// There was an error sending the metrics for a request to the parent thread.
    MetricsFailed {
        /// Wraps a [`flume::SendError`](https://docs.rs/flume/*/flume/struct.SendError.html),
        /// which contains the [`GooseMetric`](../metrics/enum.GooseMetric.html) that wasn't sent.
        source: flume::SendError<GooseMetric>,
    },
    /// There was an error sending debug information to the logger thread.
    LoggerFailed {
        /// Wraps a [`flume::SendError`](https://docs.rs/flume/*/flume/struct.SendError.html),
        /// which contains the [`GooseDebug`](./struct.GooseDebug.html) that wasn't sent.
        source: flume::SendError<Option<GooseLog>>,
    },
    /// Attempted an unrecognized HTTP request method.
    InvalidMethod {
        /// The unrecognized HTTP request method.
        method: Method,
    },
}
/// Implement a helper to provide a text description of all possible types of errors.
impl TransactionError {
    fn describe(&self) -> &str {
        match *self {
            TransactionError::Reqwest(_) => "reqwest::Error",
            TransactionError::Url(_) => "url::ParseError",
            TransactionError::RequestFailed { .. } => "request failed",
            TransactionError::RequestCanceled { .. } => {
                "request canceled because throttled load test ended"
            }
            TransactionError::MetricsFailed { .. } => "failed to send metrics to parent thread",
            TransactionError::LoggerFailed { .. } => "failed to send log message to logger thread",
            TransactionError::InvalidMethod { .. } => "unrecognized HTTP request method",
        }
    }
}

/// Implement format trait to allow displaying errors.
impl fmt::Display for TransactionError {
    // Implement display of error with `{}` marker.
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            TransactionError::Reqwest(ref source) => {
                write!(f, "TransactionError: {} ({})", self.describe(), source)
            }
            TransactionError::Url(ref source) => {
                write!(f, "TransactionError: {} ({})", self.describe(), source)
            }
            TransactionError::RequestCanceled { ref source } => {
                write!(f, "TransactionError: {} ({})", self.describe(), source)
            }
            TransactionError::MetricsFailed { ref source } => {
                write!(f, "TransactionError: {} ({})", self.describe(), source)
            }
            TransactionError::LoggerFailed { ref source } => {
                write!(f, "TransactionError: {} ({})", self.describe(), source)
            }
            _ => write!(f, "TransactionError: {}", self.describe()),
        }
    }
}

// Define the lower level source of this error, if any.
impl std::error::Error for TransactionError {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match *self {
            TransactionError::Reqwest(ref source) => Some(source),
            TransactionError::Url(ref source) => Some(source),
            TransactionError::RequestCanceled { ref source } => Some(source),
            TransactionError::MetricsFailed { ref source } => Some(source),
            TransactionError::LoggerFailed { ref source } => Some(source),
            _ => None,
        }
    }
}

/// Auto-convert Reqwest errors.
impl From<reqwest::Error> for TransactionError {
    fn from(err: reqwest::Error) -> TransactionError {
        TransactionError::Reqwest(err)
    }
}

/// Auto-convert Url errors.
impl From<url::ParseError> for TransactionError {
    fn from(err: url::ParseError) -> TransactionError {
        TransactionError::Url(err)
    }
}

/// When the throttle is enabled and the load test ends, the throttle channel is
/// shut down. This causes a
/// [`flume::SendError`](https://docs.rs/flume/*/flume/struct.SendError.html),
/// which gets automatically converted to `RequestCanceled`.
/// [`RequestCanceled`](./enum.TransactionError.html#variant.RequestCanceled)
impl From<flume::SendError<bool>> for TransactionError {
    fn from(source: flume::SendError<bool>) -> TransactionError {
        TransactionError::RequestCanceled { source }
    }
}

/// Attempt to send metrics to the parent thread failed.
impl From<flume::SendError<GooseMetric>> for TransactionError {
    fn from(source: flume::SendError<GooseMetric>) -> TransactionError {
        TransactionError::MetricsFailed { source }
    }
}

/// Attempt to send logs to the logger thread failed.
impl From<flume::SendError<Option<GooseLog>>> for TransactionError {
    fn from(source: flume::SendError<Option<GooseLog>>) -> TransactionError {
        TransactionError::LoggerFailed { source }
    }
}

/// An individual scenario.
#[derive(Clone, Hash)]
pub struct Scenario {
    /// The name of the scenario.
    pub name: String,
    /// Auto-generated machine name of the scenario.
    pub machine_name: String,
    /// An integer reflecting where this scenario lives in the internal
    /// [`GooseAttack`](../struct.GooseAttack.html)`.scenarios` vector.
    pub scenarios_index: usize,
    /// An integer value that controls the frequency that this scenario will be assigned to a user.
    pub weight: usize,
    /// A [`Duration`](https://doc.rust-lang.org/std/time/struct.Duration.html) range defining the
    /// minimum and maximum time a [`GooseUser`] should sleep after running a transaction.
    pub transaction_wait: Option<(Duration, Duration)>,
    /// A vector containing one copy of each [`Transaction`](./struct.Transaction.html) that will
    /// run by users running this scenario.
    pub transactions: Vec<Transaction>,
    /// A fully scheduled and weighted vector of integers (pointing to
    /// [`Transaction`](./struct.Transaction.html)s and [`Transaction`](./struct.Transaction.html) names.
    pub weighted_transactions: WeightedTransactions,
    /// A vector of vectors of integers, controlling the sequence and order
    /// [`on_start`](./struct.Transaction.html#method.set_on_start)
    /// [`Transaction`](./struct.Transaction.html)s are run when the user first starts.
    pub weighted_on_start_transactions: WeightedTransactions,
    /// A vector of vectors of integers, controlling the sequence and order
    /// [`on_stop`](./struct.Transaction.html#method.set_on_stop)
    /// [`Transaction`](./struct.Transaction.html)s are run when the user first starts.
    pub weighted_on_stop_transactions: WeightedTransactions,
    /// An optional default host to run this `Scenario` against.
    pub host: Option<String>,
}
impl Scenario {
    /// Creates a new [`Scenario`](./struct.Scenario.html). Once created, a
    /// [`Transaction`](./struct.Transaction.html) must be assigned to it, and finally it must
    /// be registered with the [`GooseAttack`](../struct.GooseAttack.html) object. The
    /// returned object must be stored in a mutable value.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut example_transactions = scenario!("ExampleTransactions");
    /// ```
    pub fn new(name: &str) -> Self {
        trace!("new scenario: name: {}", &name);
        Scenario {
            name: name.to_string(),
            machine_name: Scenario::get_machine_name(name),
            scenarios_index: usize::max_value(),
            weight: 1,
            transaction_wait: None,
            transactions: Vec::new(),
            weighted_transactions: Vec::new(),
            weighted_on_start_transactions: Vec::new(),
            weighted_on_stop_transactions: Vec::new(),
            host: None,
        }
    }

    /// An internal helper to convert a Scenario name to a machine name which is only
    /// alphanumerics.
    fn get_machine_name(name: &str) -> String {
        // Remove all non-alphanumeric characters.
        let re = Regex::new("[^a-zA-Z0-9]+").unwrap();
        let alphanumeric = re.replace_all(name, "");
        // Convert to lower case.
        alphanumeric.to_lowercase()
    }

    /// Registers a [`Transaction`](./struct.Transaction.html) with a
    /// [`Scenario`](./struct.Scenario.html), where it is stored in the
    /// [`Scenario`](./struct.Scenario.html)`.transactions` vector. The function
    /// associated with the transaction will be run during the load test.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut example_transactions = scenario!("ExampleTransactions");
    /// example_transactions.register_transaction(transaction!(a_transaction_function));
    ///
    /// /// A very simple transaction that loads the "a" page.
    /// async fn a_transaction_function(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.get("a/").await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn register_transaction(mut self, mut transaction: Transaction) -> Self {
        trace!("{} register_transaction: {}", self.name, transaction.name);
        transaction.transactions_index = self.transactions.len();
        self.transactions.push(transaction);
        self
    }

    /// Sets a weight on a scenario. The larger the value of weight, the more often the scenario will
    /// be assigned to users. For example, if you have scenario foo with a weight of 3, and scenario
    /// bar with a weight of 1, and you spin up a load test with 8 users, 6 of them will be running
    /// the foo scenario, and 2 will be running the bar scenario.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// #[tokio::main]
    /// async fn main() -> Result<(), GooseError> {
    ///     let mut example_transactions = scenario!("ExampleTransactions").set_weight(3)?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn set_weight(mut self, weight: usize) -> Result<Self, GooseError> {
        trace!("{} set_weight: {}", self.name, weight);
        if weight == 0 {
            return Err(GooseError::InvalidWeight {
                weight,
                detail: ("Weight must be set to at least 1.".to_string()),
            });
        }
        self.weight = weight;

        Ok(self)
    }

    /// Set a default host for the scenario. If no `--host` flag is set when running the load test, this
    /// host will be pre-pended on all requests. For example, this can configure your load test to run
    /// against your local development environment by default, and the `--host` option could be used to
    /// override host when running the load test against production.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut example_transactions = scenario!("ExampleTransactions").set_host("http://10.1.1.42");
    /// ```
    pub fn set_host(mut self, host: &str) -> Self {
        trace!("{} set_host: {}", self.name, host);
        // Host validation happens in main() at startup.
        self.host = Some(host.to_string());
        self
    }

    /// Configure a senario to to pause after running each transaction. The length of the pause will be randomly
    /// selected from `min_wait` to `max_wait` inclusively.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    /// use std::time::Duration;
    ///
    /// #[tokio::main]
    /// async fn main() -> Result<(), GooseError> {
    ///     scenario!("ExampleTransactions").set_wait_time(Duration::from_secs(0), Duration::from_secs(1))?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn set_wait_time(
        mut self,
        min_wait: Duration,
        max_wait: Duration,
    ) -> Result<Self, GooseError> {
        trace!(
            "{} set_wait time: min: {:?} max: {:?}",
            self.name,
            min_wait,
            max_wait
        );
        if min_wait.as_millis() > max_wait.as_millis() {
            return Err(GooseError::InvalidWaitTime {
                min_wait,
                max_wait,
                detail:
                    "The min_wait option can not be set to a larger value than the max_wait option."
                        .to_string(),
            });
        }
        self.transaction_wait = Some((min_wait, max_wait));

        Ok(self)
    }
}

/// Commands sent from the parent thread to the user threads, and from the manager to the
/// worker processes.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum GooseUserCommand {
    /// Tell worker process to pause load test.
    Wait,
    /// Tell worker process to start load test.
    Run,
    /// Tell user thread or worker process to exit.
    Exit,
}

/// Supported HTTP methods.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Ord, PartialOrd)]
pub enum GooseMethod {
    Delete,
    Get,
    Head,
    Patch,
    Post,
    Put,
}
/// Display method in upper case.
impl fmt::Display for GooseMethod {
    // Implement display of `GooseMethod` with `{}` marker.
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            GooseMethod::Delete => write!(f, "DELETE"),
            GooseMethod::Get => write!(f, "GET"),
            GooseMethod::Head => write!(f, "HEAD"),
            GooseMethod::Patch => write!(f, "PATCH"),
            GooseMethod::Post => write!(f, "POST"),
            GooseMethod::Put => write!(f, "PUT"),
        }
    }
}

/// Convert [`http::method::Method`](https://docs.rs/http/*/http/method/struct.Method.html)
/// to [`GooseMethod`](./enum.GooseMethod.html).
pub fn goose_method_from_method(method: Method) -> Result<GooseMethod, Box<TransactionError>> {
    Ok(match method {
        Method::DELETE => GooseMethod::Delete,
        Method::GET => GooseMethod::Get,
        Method::HEAD => GooseMethod::Head,
        Method::PATCH => GooseMethod::Patch,
        Method::POST => GooseMethod::Post,
        Method::PUT => GooseMethod::Put,
        _ => {
            return Err(Box::new(TransactionError::InvalidMethod { method }));
        }
    })
}

/// The response to a [`GooseRequestMetric`].
#[derive(Debug)]
pub struct GooseResponse {
    /// The request that this is a response to.
    pub request: GooseRequestMetric,
    /// The response.
    pub response: Result<Response, reqwest::Error>,
}
impl GooseResponse {
    pub fn new(request: GooseRequestMetric, response: Result<Response, reqwest::Error>) -> Self {
        GooseResponse { request, response }
    }
}

/// Object created by [`log_debug()`](struct.GooseUser.html#method.log_debug) and written
/// to log to assist in debugging.
#[derive(Debug, Deserialize, Serialize)]
pub struct GooseDebug {
    /// String to identify the source of the log message.
    pub tag: String,
    /// Optional request made.
    pub request: Option<GooseRequestMetric>,
    /// Optional headers returned by server.
    pub header: Option<String>,
    /// Optional body text returned by server.
    pub body: Option<String>,
}
impl GooseDebug {
    fn new(
        tag: &str,
        request: Option<&GooseRequestMetric>,
        header: Option<&header::HeaderMap>,
        body: Option<&str>,
    ) -> Self {
        GooseDebug {
            // Convert tag from &str to string.
            tag: tag.to_string(),
            // If request is defined, clone it.
            request: request.cloned(),
            // If header is defined, convert it to a string.
            header: header.map(|h| format!("{:?}", h)),
            // If header is defined, convert from &str to string.
            body: body.map(|b| b.to_string()),
        }
    }
}

/// Used internally by Coordinated Omission Mitigation, tracks the cadence between when the same request
/// is made as Goose loops through a Scenario.
#[derive(Debug, Clone)]
struct GooseRequestCadence {
    /// The last time this GooseUser lopped through its Transactions.
    last_time: std::time::Instant,
    /// Total milliseconds of delays followed each Transaction. This has to be substracted out as it's
    /// not impacted by the upstream server and it can change randomly affecting the cadence.
    delays_since_last_time: u64,
    /// How many times this GooseUser has looped through all of its Transactions.
    counter: u64,
    /// The minimum time taken to loop through all Transactions.
    minimum_cadence: u64,
    /// The maximum time taken to loop through all Transactions.
    maximum_cadence: u64,
    /// Average amount of time taken to loop through all Transactions.
    average_cadence: u64,
    /// Total amount of time spent processing Transactions.
    total_elapsed: u64,
    /// If non-zero, the length of the server slowdown detected by the Goose Coordinated
    /// Omission Mitigation in milliseconds.
    coordinated_omission_mitigation: u64,
    /// The expected cadence to loop through all Transactions.
    user_cadence: u64,
    /// If -1 coordinated_omission_mitigation was never enabled. Otherwise is a counter of how
    /// many times the mitigation triggered.
    coordinated_omission_counter: isize,
}
impl GooseRequestCadence {
    // Return a new, empty RequestCadence object.
    fn new() -> GooseRequestCadence {
        GooseRequestCadence {
            last_time: std::time::Instant::now(),
            delays_since_last_time: 0,
            counter: 0,
            minimum_cadence: 0,
            maximum_cadence: 0,
            average_cadence: 0,
            total_elapsed: 0,
            coordinated_omission_mitigation: 0,
            user_cadence: 0,
            coordinated_omission_counter: -1,
        }
    }
}

/// A marker trait representing user data of any type
/// ([generic](https://doc.rust-lang.org/rust-by-example/generics.html)) that can
/// be added to any [`GooseUser`](../goose/struct.GooseUser.html). The format of
/// the data stored in `GooseUserData` must be defined in your load test, and by
/// default supports any type that supports
/// [`Send`](https://doc.rust-lang.org/std/marker/trait.Send.html) and
/// [`Sync`](https://doc.rust-lang.org/std/marker/trait.Sync.html).
///
/// Stored in the [`GooseUser`] object in a private `session_data` field. Per-user
/// session data is stored by invoking [`GooseUser::set_session_data`]. The session
/// data can be accessed by invoking [`GooseUser::get_session_data`],
/// [`GooseUser::get_session_data_mut`], [`GooseUser::get_session_data_unchecked`],
/// or [`GooseUser::get_session_data_unchecked_mut`].
///
/// For an example, see
/// [`examples/simple_with_session`](https://github.com/tag1consulting/goose/blob/main/examples/simple_with_session.rs).
pub trait GooseUserData: Downcast + Send + Sync + 'static {}
impl_downcast!(GooseUserData);
impl<T: Send + Sync + 'static> GooseUserData for T {}

/// An individual user state, repeatedly running all [`Transaction`](./struct.Transaction.html)s
/// in a specific [`Scenario`](./struct.Scenario.html).
pub struct GooseUser {
    /// The Instant when this `GooseUser` client started.
    pub started: Instant,
    /// How many iterations of the scenario this GooseUser has run.
    pub(crate) iterations: usize,
    /// An index into the internal [`GooseAttack`](../struct.GooseAttack.html)`.scenarios`
    /// vector, indicating which [`Scenario`](./struct.Scenario.html) is running.
    pub scenarios_index: usize,
    /// Client used to make requests, managing sessions and cookies.
    pub client: Client,
    /// The base URL to prepend to all relative paths.
    pub base_url: Url,
    /// A local copy of the global [`GooseConfiguration`](../struct.GooseConfiguration.html).
    pub config: GooseConfiguration,
    /// Channel to logger.
    pub logger: Option<flume::Sender<Option<GooseLog>>>,
    /// Channel to throttle.
    pub throttle: Option<flume::Sender<bool>>,
    /// Normal transactions are optionally throttled,
    /// [`test_start`](../struct.GooseAttack.html#method.test_start) and
    /// [`test_stop`](../struct.GooseAttack.html#method.test_stop) transactions are not.
    pub is_throttled: bool,
    /// Channel for sending metrics to the parent for aggregation.
    pub metrics_channel: Option<flume::Sender<GooseMetric>>,
    /// Channel for notifying the parent when thread shuts down.
    pub shutdown_channel: Option<flume::Sender<usize>>,
    /// An index into the internal [`GooseAttack`](../struct.GooseAttack.html)`.weighted_users`
    /// vector, indicating which weighted `GooseUser` is running.
    pub weighted_users_index: usize,
    /// Load test hash.
    pub load_test_hash: u64,
    /// Tracks the cadence that this user is looping through all Transactions, used by Coordinated
    /// Omission Mitigation.
    request_cadence: GooseRequestCadence,
    /// Tracks how much time is spent sleeping during a loop through all transactions.
    pub(crate) slept: u64,
    /// Current transaction name.
    pub(crate) transaction_name: Option<String>,
    /// Optional per-user session data of a generic type implementing the
    /// [`GooseUserData`] trait.
    session_data: Option<Box<dyn GooseUserData>>,
}
impl GooseUser {
    /// Create a new user state.
    pub fn new(
        scenarios_index: usize,
        base_url: Url,
        configuration: &GooseConfiguration,
        load_test_hash: u64,
    ) -> Result<Self, GooseError> {
        trace!("new GooseUser");

        // Either use manually configured timeout, or default.
        let timeout = if configuration.timeout.is_some() {
            match crate::util::get_float_from_string(configuration.timeout.clone()) {
                Some(f) => f as u64 * 1_000,
                None => GOOSE_REQUEST_TIMEOUT,
            }
        } else {
            GOOSE_REQUEST_TIMEOUT
        };

        let client = Client::builder()
            .user_agent(APP_USER_AGENT)
            .cookie_store(true)
            .timeout(Duration::from_millis(timeout))
            // Enable gzip unless `--no-gzip` flag is enabled.
            .gzip(!configuration.no_gzip)
            .build()?;

        Ok(GooseUser {
            started: Instant::now(),
            iterations: 0,
            scenarios_index,
            client,
            base_url,
            config: configuration.clone(),
            logger: None,
            throttle: None,
            is_throttled: true,
            metrics_channel: None,
            shutdown_channel: None,
            // A value of max_value() indicates this user isn't fully initialized yet.
            weighted_users_index: usize::max_value(),
            load_test_hash,
            request_cadence: GooseRequestCadence::new(),
            slept: 0,
            transaction_name: None,
            session_data: None,
        })
    }

    /// Create a new single-use user.
    pub fn single(base_url: Url, configuration: &GooseConfiguration) -> Result<Self, GooseError> {
        let mut single_user = GooseUser::new(0, base_url, configuration, 0)?;
        // Only one user, so index is 0.
        single_user.weighted_users_index = 0;
        // Do not throttle [`test_start`](../struct.GooseAttack.html#method.test_start) (setup) and
        // [`test_stop`](../struct.GooseAttack.html#method.test_stop) (teardown) transactions.
        single_user.is_throttled = false;

        Ok(single_user)
    }

    /// Returns the number of iterations this GooseUser has run through it's
    /// assigned [`Scenario`].
    pub fn get_iterations(&self) -> usize {
        self.iterations
    }

    /// Returns an optional reference to per-[`GooseUser`] session data.
    ///
    /// Leaves the session data in-place, returning an optional reference to the
    /// original session data if existing and of the correct type. Returns [`None`]
    /// if no session data has been set or the session data set is not of type `T`.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// struct Foo(String);
    ///
    /// let mut transaction = transaction!(get_session_data_function);
    ///
    /// /// A very simple transaction that makes a GET request.
    /// async fn get_session_data_function(user: &mut GooseUser) -> TransactionResult {
    ///     let foo = user.get_session_data::<Foo>().expect("Missing session data!");
    ///     println!("Session data: {}", foo.0);
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn get_session_data<T: GooseUserData>(&self) -> Option<&T> {
        match &self.session_data {
            Some(data) => data.downcast_ref::<T>(),
            None => None,
        }
    }

    /// Returns a reference to per-[`GooseUser`] session data, without doing any
    /// validation that the session data exists and is of the correct type.
    ///
    /// Leaves the session data in-place, returning a reference to the original
    /// session data. Calling this method on a [`GooseUser`] object without
    /// session data or with a different type `T` will panic.
    ///
    /// For a safe alternative see [`GooseUser::get_session_data`].
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// struct Foo(String);
    ///
    /// let mut transaction = transaction!(get_session_data_unchecked_function);
    ///
    /// /// A very simple transaction that makes a GET request.
    /// async fn get_session_data_unchecked_function(user: &mut GooseUser) -> TransactionResult {
    ///     let foo = user.get_session_data_unchecked::<Foo>();
    ///     println!("Session data: {}", foo.0);
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn get_session_data_unchecked<T: GooseUserData>(&self) -> &T {
        let session_data = self.session_data.as_deref().expect("Missing session data!");

        session_data
            .downcast_ref::<T>()
            .expect("Invalid session data!")
    }

    /// Returns an optional mutable reference to per-[`GooseUser`] session data.
    ///
    /// Leaves the session data in-place, returning an optional mutable reference
    /// to the original session data if existing and of the correct type. Returns
    /// [`None`] if no session data has been set or the session data set is not of
    /// type `T`.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// struct Foo(String);
    ///
    /// let mut transaction = transaction!(get_session_data_mut_function);
    ///
    /// /// A very simple transaction that makes a GET request.
    /// async fn get_session_data_mut_function(user: &mut GooseUser) -> TransactionResult {
    ///     let foo = user.get_session_data_mut::<Foo>().expect("Missing session data!");
    ///     foo.0 = "Bar".to_owned();
    ///     Ok(())
    /// }
    /// ```
    pub fn get_session_data_mut<T: GooseUserData>(&mut self) -> Option<&mut T> {
        match &mut self.session_data {
            Some(data) => data.downcast_mut::<T>(),
            None => None,
        }
    }

    /// Returns a mutable reference to per-[`GooseUser`] session data, without
    /// doing any validation that the session data exists and is of the correct
    /// type.
    ///
    /// Leaves the session data in-place, returning a mutable reference to the
    /// original session data. Calling this method on a [`GooseUser`] object
    /// without session data or with a different type `T` will panic.
    ///
    /// For a safe alternative see [`GooseUser::get_session_data_mut`].
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// struct Foo(String);
    ///
    /// let mut transaction = transaction!(get_session_data_unchecked_mut_function);
    ///
    /// /// A very simple transaction that makes a GET request.
    /// async fn get_session_data_unchecked_mut_function(user: &mut GooseUser) -> TransactionResult {
    ///     let foo = user.get_session_data_unchecked_mut::<Foo>();
    ///     foo.0 = "Bar".to_owned();
    ///     Ok(())
    /// }
    /// ```
    pub fn get_session_data_unchecked_mut<T: GooseUserData>(&mut self) -> &mut T {
        let session_data = self
            .session_data
            .as_deref_mut()
            .expect("Missing session data!");
        session_data
            .downcast_mut::<T>()
            .expect("Invalid session data!")
    }

    /// Sets session data for the current [`GooseUser`].
    ///
    /// If session data already exists for the current [`GooseUser`], it will be
    /// replaced. Session data must be of a type implementing the
    /// [`GooseUserData`] trait.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// struct Foo(String);
    ///
    /// let mut transaction = transaction!(set_session_data_function);
    ///
    /// /// A very simple transaction that makes a GET request.
    /// async fn set_session_data_function(user: &mut GooseUser) -> TransactionResult {
    ///     user.set_session_data(Foo("Foo".to_string()));
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn set_session_data<T: GooseUserData>(&mut self, data: T) {
        self.session_data.replace(Box::new(data));
    }

    /// A helper that prepends a `base_url` to all relative paths.
    ///
    /// A `base_url` is determined per user thread, using the following order
    /// of precedence:
    ///  1. `--host` (host specified on the command line when running load test)
    ///  2. [`Scenario`](./struct.Scenario.html)`.host` (default host defined for the
    /// current scenario)
    ///  3. [`GooseDefault::Host`](../config/enum.GooseDefault.html#variant.Host) (default host
    /// defined for the current load test)
    pub fn build_url(&self, path: &str) -> Result<String, Box<TransactionError>> {
        // If URL includes a host, simply use it.
        if let Ok(parsed_path) = Url::parse(path) {
            if let Some(_host) = parsed_path.host() {
                return Ok(path.to_string());
            }
        }

        // Otherwise use the `base_url`.
        match self.base_url.join(path) {
            Ok(u) => Ok(u.to_string()),
            Err(e) => Err(Box::new(e.into())),
        }
    }

    /// A helper to make a `GET` request of a path and collect relevant metrics.
    /// Automatically prepends the correct host.
    ///
    /// Calls to `get()` return a [`GooseResponse`](./struct.GooseResponse.html) object which
    /// contains a copy of the request you made ([`GooseRequestMetric`](./struct.GooseRequestMetric.html)),
    /// and the response ([`reqwest::Response`](https://docs.rs/reqwest/*/reqwest/struct.Response.html)).
    ///
    /// If you need to set headers, change timeouts, or otherwise make use of the
    /// [`reqwest::RequestBuilder`](https://docs.rs/reqwest/*/reqwest/struct.RequestBuilder.html)
    /// object, refer to [`GooseUser::get_request_builder`].
    ///
    /// # Example
    /// GET a URL.
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut transaction = transaction!(get_function);
    ///
    /// /// A very simple transaction that makes a GET request.
    /// async fn get_function(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.get("path/to/foo/").await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn get(&mut self, path: &str) -> Result<GooseResponse, Box<TransactionError>> {
        // GET path.
        let goose_request = GooseRequest::builder()
            .method(GooseMethod::Get)
            .path(path)
            .build();

        // Make the request and return the GooseResponse.
        self.request(goose_request).await
    }

    /// A helper to make a named `GET` request of a path and collect relevant metrics.
    /// Automatically prepends the correct host.
    ///
    /// Calls to `get_named()` return a [`GooseResponse`](./struct.GooseResponse.html) object which
    /// contains a copy of the request you made ([`GooseRequestMetric`](./struct.GooseRequestMetric.html)),
    /// and the response ([`reqwest::Response`](https://docs.rs/reqwest/*/reqwest/struct.Response.html)).
    ///
    /// If you need to set headers, change timeouts, or otherwise make use of the
    /// [`reqwest::RequestBuilder`](https://docs.rs/reqwest/*/reqwest/struct.RequestBuilder.html)
    /// object, refer to [`GooseUser::get_request_builder`].
    ///
    /// # Example
    /// GET a URL and name the request in collected metrics.
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut transaction = transaction!(get_function);
    ///
    /// /// A very simple transaction that makes a GET request, naming it for metrics.
    /// async fn get_function(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.get_named("path/to/foo/", "foo").await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn get_named(
        &mut self,
        path: &str,
        name: &str,
    ) -> Result<GooseResponse, Box<TransactionError>> {
        // GET path named.
        let goose_request = GooseRequest::builder()
            .method(GooseMethod::Get)
            .path(path)
            .name(name)
            .build();

        // Make the request and return the GooseResponse.
        self.request(goose_request).await
    }

    /// A helper to make a `POST` request of a path and collect relevant metrics.
    /// Automatically prepends the correct host.
    ///
    /// Calls to `post()` return a [`GooseResponse`](./struct.GooseResponse.html) object which
    /// contains a copy of the request you made ([`GooseRequestMetric`](./struct.GooseRequestMetric.html)),
    /// and the response ([`reqwest::Response`](https://docs.rs/reqwest/*/reqwest/struct.Response.html)).
    ///
    /// If you need to set headers, change timeouts, or otherwise make use of the
    /// [`reqwest::RequestBuilder`](https://docs.rs/reqwest/*/reqwest/struct.RequestBuilder.html)
    /// object, refer to [`GooseUser::get_request_builder`].
    ///
    /// # Example
    /// POST an arbitrary body.
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut transaction = transaction!(post_function);
    ///
    /// /// A very simple transaction that makes a POST request.
    /// async fn post_function(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.post("path/to/foo/", "BODY BEING POSTED").await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn post<T: Into<reqwest::Body>>(
        &mut self,
        path: &str,
        body: T,
    ) -> Result<GooseResponse, Box<TransactionError>> {
        // Build a Reqwest RequestBuilder object.
        let url = self.build_url(path)?;
        let reqwest_request_builder = self.client.post(url);

        // POST request.
        let goose_request = GooseRequest::builder()
            .method(GooseMethod::Post)
            .path(path)
            .set_request_builder(reqwest_request_builder.body(body))
            .build();

        // Make the request and return the GooseResponse.
        self.request(goose_request).await
    }

    /// A helper to make a `POST` request of a form on a path and collect relevant metrics.
    /// Automatically prepends the correct host.
    ///
    /// Calls to `post_form()` return a [`GooseResponse`](./struct.GooseResponse.html) object which
    /// contains a copy of the request you made ([`GooseRequestMetric`](./struct.GooseRequestMetric.html)),
    /// and the response ([`reqwest::Response`](https://docs.rs/reqwest/*/reqwest/struct.Response.html)).
    ///
    /// If you need to set headers, change timeouts, or otherwise make use of the
    /// [`reqwest::RequestBuilder`](https://docs.rs/reqwest/*/reqwest/struct.RequestBuilder.html)
    /// object, refer to [`GooseUser::get_request_builder`].
    ///
    /// # Example
    /// POST a form.
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut transaction = transaction!(post_function);
    ///
    /// /// A very simple transaction that POSTs form parameters.
    /// async fn post_function(user: &mut GooseUser) -> TransactionResult {
    ///     let params = [("foo", "bar"), ("foo2", "bar2")];
    ///     let _goose = user.post_form("path/to/foo/", &params).await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn post_form<T: Serialize + ?Sized>(
        &mut self,
        path: &str,
        form: &T,
    ) -> Result<GooseResponse, Box<TransactionError>> {
        // Build a Reqwest RequestBuilder object.
        let url = self.build_url(path)?;
        let reqwest_request_builder = self.client.post(url);

        // POST form request.
        let goose_request = GooseRequest::builder()
            .method(GooseMethod::Post)
            .path(path)
            .set_request_builder(reqwest_request_builder.form(&form))
            .build();

        // Make the request and return the GooseResponse.
        self.request(goose_request).await
    }

    /// A helper to make a `POST` request of json on a path and collect relevant metrics.
    /// Automatically prepends the correct host.
    ///
    /// Calls to `post_json()` return a [`GooseResponse`](./struct.GooseResponse.html) object which
    /// contains a copy of the request you made ([`GooseRequestMetric`](./struct.GooseRequestMetric.html)),
    /// and the response ([`reqwest::Response`](https://docs.rs/reqwest/*/reqwest/struct.Response.html)).
    ///
    /// If you need to set headers, change timeouts, or otherwise make use of the
    /// [`reqwest::RequestBuilder`](https://docs.rs/reqwest/*/reqwest/struct.RequestBuilder.html)
    /// object, refer to [`GooseUser::get_request_builder`].
    ///
    /// # Example
    /// POST an arbitrary JSON object.
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut transaction = transaction!(post_function);
    ///
    /// /// A very simple transaction that POSTs an arbitrary json object.
    /// async fn post_function(user: &mut GooseUser) -> TransactionResult {
    ///     let json = &serde_json::json!({
    ///         "foo": "bar",
    ///         "foo2": "bar2"
    ///     });
    ///     let _goose = user.post_json("path/to/foo/", &json).await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn post_json<T: Serialize + ?Sized>(
        &mut self,
        path: &str,
        json: &T,
    ) -> Result<GooseResponse, Box<TransactionError>> {
        // Build a Reqwest RequestBuilder object.
        let url = self.build_url(path)?;
        let reqwest_request_builder = self.client.post(url);

        // POST json request.
        let goose_request = GooseRequest::builder()
            .method(GooseMethod::Post)
            .path(path)
            .set_request_builder(reqwest_request_builder.json(&json))
            .build();

        // Make the request and return the GooseResponse.
        self.request(goose_request).await
    }

    /// A helper to make a `HEAD` request of a path and collect relevant metrics.
    /// Automatically prepends the correct host.
    ///
    /// Calls to `head()` return a [`GooseResponse`](./struct.GooseResponse.html) object which
    /// contains a copy of the request you made ([`GooseRequestMetric`](./struct.GooseRequestMetric.html)),
    /// and the response ([`reqwest::Response`](https://docs.rs/reqwest/*/reqwest/struct.Response.html)).
    ///
    /// If you need to set headers, change timeouts, or otherwise make use of the
    /// [`reqwest::RequestBuilder`](https://docs.rs/reqwest/*/reqwest/struct.RequestBuilder.html)
    /// object, refer to [`GooseUser::get_request_builder`].
    ///
    /// # Example
    /// Make a HEAD request.
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut transaction = transaction!(head_function);
    ///
    /// /// A very simple transaction that makes a HEAD request.
    /// async fn head_function(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.head("path/to/foo/").await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn head(&mut self, path: &str) -> Result<GooseResponse, Box<TransactionError>> {
        // HEAD request.
        let goose_request = GooseRequest::builder()
            .method(GooseMethod::Head)
            .path(path)
            .build();

        // Make the request and return the GooseResponse.
        self.request(goose_request).await
    }

    /// A helper to make a `DELETE` request of a path and collect relevant metrics.
    /// Automatically prepends the correct host.
    ///
    /// Calls to `delete()` return a [`GooseResponse`](./struct.GooseResponse.html) object which
    /// contains a copy of the request you made ([`GooseRequestMetric`](./struct.GooseRequestMetric.html)),
    /// and the response ([`reqwest::Response`](https://docs.rs/reqwest/*/reqwest/struct.Response.html)).
    ///
    /// If you need to set headers, change timeouts, or otherwise make use of the
    /// [`reqwest::RequestBuilder`](https://docs.rs/reqwest/*/reqwest/struct.RequestBuilder.html)
    /// object, refer to [`GooseUser::get_request_builder`].
    ///
    /// # Example
    /// Make a DELETE request.
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut transaction = transaction!(delete_function);
    ///
    /// /// A very simple transaction that makes a DELETE request.
    /// async fn delete_function(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.delete("path/to/foo/").await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn delete(&mut self, path: &str) -> Result<GooseResponse, Box<TransactionError>> {
        // DELETE request.
        let goose_request = GooseRequest::builder()
            .method(GooseMethod::Delete)
            .path(path)
            .build();

        // Make the request and return the GooseResponse.
        self.request(goose_request).await
    }

    /// Used to get a [`reqwest::RequestBuilder`] object. If no [`reqwest::RequestBuilder`] is
    /// already defined in the [`GooseRequest`] passed to [`GooseUser::request`] it will automatically
    /// invoke this function.
    ///
    /// The HTTP request method must be defined as a [`GooseMethod`], and the path that will be requested
    /// must be defined as a [`&str`].
    ///
    /// It is possible to use this function to directly interact with the [`reqwest::RequestBuilder`]
    /// object and the [`GooseRequest`] object during load tests. In the following example, we set a
    /// timeout on the Request, and tell Goose to expect a 404 HTTP response status code.
    ///
    /// # Example
    /// Request a non-existent page, timing out after 500 milliseconds.
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut transaction = transaction!(test_404);
    ///
    /// async fn test_404(user: &mut GooseUser) -> TransactionResult {
    ///     use std::time::Duration;
    ///
    ///     // Manually interact with the Reqwest RequestBuilder object.
    ///     let request_builder = user.get_request_builder(&GooseMethod::Get, "no/such/path")?
    ///         // Configure the request to timeout if it takes longer than 500 milliseconds.
    ///         .timeout(Duration::from_millis(500));
    ///
    ///     // Manually build a GooseRequest.
    ///     let goose_request = GooseRequest::builder()
    ///         // Manually add our custom RequestBuilder object.
    ///         .set_request_builder(request_builder)
    ///         // Tell Goose to expect a 404 status code.
    ///         .expect_status_code(404)
    ///         // Turn the GooseRequestBuilder object into a GooseRequest.
    ///         .build();
    ///
    ///     // Finally make the actual request with our custom GooseRequest object.
    ///     let _goose = user.request(goose_request).await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn get_request_builder(
        &self,
        method: &GooseMethod,
        path: &str,
    ) -> Result<RequestBuilder, Box<TransactionError>> {
        // Prepend the `base_url` to all relative paths.
        let url = self.build_url(path)?;

        // Invoke appropriate Reqwest convenience function to generate an
        // appropriate RequestBuilder.
        Ok(match method {
            GooseMethod::Delete => self.client.delete(&url),
            GooseMethod::Get => self.client.get(&url),
            GooseMethod::Head => self.client.head(&url),
            GooseMethod::Patch => self.client.patch(&url),
            GooseMethod::Post => self.client.post(&url),
            GooseMethod::Put => self.client.put(&url),
        })
    }

    /// Makes a request for the provided [`GooseRequest`] object, and if metrics are enabled
    /// captures relevant metrics.
    ///
    /// Calls to `request()` return a [`Result`] containing a [`GooseResponse`] on success, and a
    /// [`flume::SendError`](https://docs.rs/flume/*/flume/struct.SendError.html)`<bool>`,
    /// on failure. Failure only happens when `--throttle-requests` is enabled and the load test
    /// completes. The [`GooseResponse`](./struct.GooseResponse.html) object contains a copy of
    /// the request you made ([`GooseRequestMetric`](./struct.GooseRequestMetric.html)), and the
    /// response ([`reqwest::Response`](https://docs.rs/reqwest/*/reqwest/struct.Response.html)).
    ///
    /// # Example
    /// Make a GET request.
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut transaction = transaction!(get_function);
    ///
    /// /// A simple transaction that makes a GET request.
    /// async fn get_function(user: &mut GooseUser) -> TransactionResult {
    ///     let goose_request = GooseRequest::builder()
    ///       // Goose will prepend a host name to this path.
    ///       .path("path/to/loadtest")
    ///       // GET is the default method, this is not necessary.
    ///       .method(GooseMethod::Get)
    ///       // Assemble the `GooseRequestBuilder` into a `GooseRequest.
    ///       .build();
    ///     let goose = user.request(goose_request).await?;
    ///
    ///     // Do stuff with goose.request and/or goose.response here.
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn request<'a>(
        &mut self,
        mut request: GooseRequest<'_>,
    ) -> Result<GooseResponse, Box<TransactionError>> {
        // If the RequestBuilder is already defined in the GooseRequest use it.
        let request_builder = if request.request_builder.is_some() {
            request.request_builder.take().unwrap()
        // Otherwise get a new RequestBuilder.
        } else {
            self.get_request_builder(&request.method, request.path)?
        };

        // Determine the name for this request.
        let request_name = self.get_request_name(&request);

        // If throttle-requests is enabled...
        if self.is_throttled && self.throttle.is_some() {
            // ...wait until there's room to add a token to the throttle channel before proceeding.
            debug!("GooseUser: waiting on throttle");
            // Will result in TransactionError::RequestCanceled if this fails.
            if let Err(e) = self.throttle.clone().unwrap().send_async(true).await {
                return Err(Box::new(e.into()));
            }
        };

        // Once past the throttle, the request is officially started.
        let started = Instant::now();

        // Create a Reqwest Request object from the RequestBuilder.
        let built_request = match request_builder.build() {
            Ok(r) => r,
            Err(e) => return Err(Box::new(e.into())),
        };

        // Get a string version of request path for logging.
        let path = match Url::parse(built_request.url().as_ref()) {
            Ok(u) => u.path().to_string(),
            Err(e) => {
                error!("failed to parse url: {}", e);
                "".to_string()
            }
        };

        // Grab a copy of any headers set by this request, included in the request log
        // and the debug log.
        let mut headers: Vec<String> = Vec::new();
        for header in built_request.headers() {
            headers.push(format!("{:?}", header));
        }

        // If enabled, grab a copy of the request body, included in the request log and
        // the debug log.
        let body = if self.config.request_body {
            // Get a bytes representation of the body, if any.
            let body_bytes = match built_request.body() {
                Some(b) => b.as_bytes().unwrap_or(b""),
                None => b"",
            };
            // Convert the bytes into a &str if valid utf8.
            str::from_utf8(body_bytes).unwrap_or("")
        } else {
            ""
        };

        // Record the complete client request, included in the request log and the debug log.
        let raw_request = GooseRawRequest::new(
            goose_method_from_method(built_request.method().clone())?,
            built_request.url().as_str(),
            headers,
            body,
        );

        // Record information about the request.
        let mut request_metric = GooseRequestMetric::new(
            raw_request,
            request_name,
            self.started.elapsed().as_millis(),
            self.weighted_users_index,
        );

        // Make the actual request.
        let response = self.client.execute(built_request).await;
        request_metric.set_response_time(started.elapsed().as_millis());

        // Determine if the request suceeded or failed.
        match &response {
            Ok(r) => {
                let status_code = r.status();
                debug!("{:?}: status_code {}", &path, status_code);

                // Update the request_metric object.
                request_metric.set_status_code(Some(status_code));
                request_metric.set_final_url(r.url().as_str());

                // Check if we were expecting a specific status code.
                if let Some(expect_status_code) = request.expect_status_code {
                    // Record a failure if the expected status code was not returned.
                    if status_code != expect_status_code {
                        request_metric.success = false;
                        request_metric.error = format!("{}: {}", status_code, request_name);
                    }
                // Otherwise record a failure if the returned status code was not a success.
                } else if !status_code.is_success() {
                    request_metric.success = false;
                    request_metric.error = format!("{}: {}", status_code, request_name);
                }

                // Load test user was redirected.
                if self.config.sticky_follow && request_metric.raw.url != request_metric.final_url {
                    let base_url = self.base_url.to_string();
                    // Check if the URL redirected started with the load test base_url.
                    if !request_metric.final_url.starts_with(&base_url) {
                        let redirected_url = match Url::parse(&request_metric.final_url) {
                            Ok(u) => u,
                            Err(e) => return Err(Box::new(e.into())),
                        };
                        let redirected_base_url =
                            redirected_url[..url::Position::BeforePath].to_string();
                        info!(
                            "base_url for user {} redirected from {} to {}",
                            self.weighted_users_index + 1,
                            &base_url,
                            &redirected_base_url
                        );
                        let _ = self.set_base_url(&redirected_base_url);
                    }
                }
            }
            Err(e) => {
                // @TODO: what can we learn from a reqwest error?
                warn!("{:?}: {}", &path, e);
                request_metric.success = false;
                request_metric.set_status_code(None);
                request_metric.error = clean_reqwest_error(e, request_name);
            }
        };

        // If enabled, track the cadence between each time the same request is made while
        // this GooseUser is running. If requests are blocked by the upstream server, this
        // allows Goose to backfill the requests that should have been made based on
        // cadence statistics.
        request_metric.user_cadence = self
            .coordinated_omission_mitigation(&request_metric)
            .await?;

        // Send a copy of the raw request object to the parent process if
        // we're tracking metrics.
        if !self.config.no_metrics {
            self.send_request_metric_to_parent(request_metric.clone())?;
        }

        if request.error_on_fail && !request_metric.success {
            error!("{:?} {}", &path, &request_metric.error);
            return Err(Box::new(TransactionError::RequestFailed {
                raw_request: request_metric,
            }));
        }

        Ok(GooseResponse::new(request_metric, response))
    }

    /// Tracks the time it takes for the current GooseUser to loop through all Transactions
    /// if Coordinated Omission Mitigation is enabled.
    pub(crate) async fn update_request_cadence(&mut self, thread_number: usize) {
        if let Some(co_mitigation) = self.config.co_mitigation.as_ref() {
            // Return immediately if coordinated omission mitigation is disabled.
            if co_mitigation == &GooseCoordinatedOmissionMitigation::Disabled {
                return;
            }

            // Grab the current timestamp to calculate the difference since the last
            // time through the loop.
            let now = std::time::Instant::now();

            // Swap out the `slept` counter, which is the total time the GooseUser slept
            // between transactions, a potentially randomly changing value. Reset to 0 for the
            // next loop through all Transactions.
            self.request_cadence.delays_since_last_time = self.slept;
            self.slept = 0;

            // How much time passed since the last time this GooseUser looped through all
            // transactions, accounting for time waiting between Transactions due to `set_wait_time`.
            let elapsed = (now - self.request_cadence.last_time).as_millis() as u64
                - self.request_cadence.delays_since_last_time;

            // Update `minimum_cadence` if this was the fastest seen.
            if elapsed < self.request_cadence.minimum_cadence
                || self.request_cadence.minimum_cadence == 0
            {
                self.request_cadence.minimum_cadence = elapsed;
            // Update `maximum_cadence` if this was the slowest seen.
            } else if elapsed > self.request_cadence.maximum_cadence {
                self.request_cadence.maximum_cadence = elapsed;
            }

            // Update request_cadence metrics based on the timing of the current request.
            self.request_cadence.counter += 1;
            self.request_cadence.total_elapsed += elapsed;
            self.request_cadence.last_time = now;
            self.request_cadence.average_cadence =
                self.request_cadence.total_elapsed / self.request_cadence.counter;

            if self.request_cadence.counter > 3 {
                if self.request_cadence.coordinated_omission_counter < 0 {
                    debug!(
                        "user {} enabled coordinated omission mitigation",
                        thread_number
                    );
                    self.request_cadence.coordinated_omission_counter += 1;
                }
                // Calculate the expected cadence for this Transaction request.
                let cadence = match co_mitigation {
                    // Expected cadence is the average time between requests.
                    GooseCoordinatedOmissionMitigation::Average => {
                        self.request_cadence.average_cadence
                    }
                    // Expected cadence is the maximum time between requests.
                    GooseCoordinatedOmissionMitigation::Maximum => {
                        self.request_cadence.maximum_cadence
                    }
                    // Expected cadence is the minimum time between requests.
                    GooseCoordinatedOmissionMitigation::Minimum => {
                        self.request_cadence.minimum_cadence
                    }
                    // This is not possible as we would have exited already if coordinated
                    // omission mitigation was disabled.
                    GooseCoordinatedOmissionMitigation::Disabled => unreachable!(),
                };
                if elapsed > (cadence * 2) {
                    debug!(
                        "user {}: coordinated_omission_mitigation: elapsed({}) > cadence({})",
                        thread_number, elapsed, cadence
                    );
                    self.request_cadence.coordinated_omission_counter += 1;
                    self.request_cadence.coordinated_omission_mitigation = elapsed;
                } else {
                    self.request_cadence.coordinated_omission_mitigation = 0;
                }
                // Always track the expected cadence.
                self.request_cadence.user_cadence = cadence;
            }
        } else {
            // Coordinated Omission Mitigation defaults to average.
            unreachable!();
        }
    }

    /// If Coordinated Omission Mitigation is enabled, compares how long has passed since the last
    /// loop through all Transactions by the current GooseUser. Through this mechanism, Goose is
    /// able to detect stalls on the upstream server being load tested, backfilling requests based
    /// on what statistically should have happened. Can be disabled with `--co-mitigation disabled`.
    async fn coordinated_omission_mitigation(
        &self,
        request_metric: &GooseRequestMetric,
    ) -> Result<u64, Box<TransactionError>> {
        if let Some(co_mitigation) = self.config.co_mitigation.as_ref() {
            // Return immediately if coordinated omission mitigation is disabled.
            if co_mitigation == &GooseCoordinatedOmissionMitigation::Disabled {
                return Ok(0);
            }

            // Generate an info level alert if this specific request took longer than the normal
            // cadence, as that means this specific request will likely trigger Coordinated
            // Omission Mitigation.
            if self.request_cadence.counter > 3
                && request_metric.response_time > self.request_cadence.user_cadence
            {
                let transaction_name = if let Some(transaction_name) = &self.transaction_name {
                    format!(", transaction name: \"{}\"", transaction_name)
                } else {
                    "".to_string()
                };
                info!(
                    "{:.3}s into goose attack: \"{} {}\" [{}] took abnormally long ({} ms){}",
                    request_metric.elapsed as f64 / 1_000.0,
                    request_metric.raw.method,
                    request_metric.raw.url,
                    request_metric.status_code,
                    request_metric.response_time,
                    transaction_name,
                );
            }

            // Check if Coordinated Omission Mitigation has been triggered.
            if self.request_cadence.coordinated_omission_mitigation > 0 {
                // Base our coordinated omission generated request metric on the actual
                // metric that triggered this logic.
                let mut coordinated_omission_request_metric = request_metric.clone();
                // Record data points specific to coordinated_omission.
                coordinated_omission_request_metric.coordinated_omission_elapsed =
                    self.request_cadence.coordinated_omission_mitigation;
                // Record data points specific to coordinated_omission.
                coordinated_omission_request_metric.user_cadence =
                    self.request_cadence.user_cadence;
                // Send the coordinated omission mitigation generated metrics to the parent.
                self.send_request_metric_to_parent(coordinated_omission_request_metric)?;
            }
            Ok(self.request_cadence.user_cadence)
        } else {
            // A setting for coordinated omission mitigation is required, defaults to Average.
            unreachable!();
        }
    }

    fn send_request_metric_to_parent(
        &self,
        request_metric: GooseRequestMetric,
    ) -> TransactionResult {
        // If requests-file is enabled, send a copy of the raw request to the logger thread.
        if !self.config.request_log.is_empty() {
            if let Some(logger) = self.logger.as_ref() {
                if let Err(e) = logger.send(Some(GooseLog::Request(request_metric.clone()))) {
                    return Err(Box::new(e.into()));
                }
            }
        }

        // Parent is not defined when running
        // [`test_start`](../struct.GooseAttack.html#method.test_start),
        // [`test_stop`](../struct.GooseAttack.html#method.test_stop), and during testing.
        if let Some(metrics_channel) = self.metrics_channel.clone() {
            if let Err(e) = metrics_channel.send(GooseMetric::Request(request_metric)) {
                return Err(Box::new(e.into()));
            }
        }

        Ok(())
    }

    /// If `request_name` is set, unwrap and use this. Otherwise, if the Transaction has a name
    /// set use it. Otherwise use the path.
    fn get_request_name<'a>(&'a self, request: &'a GooseRequest) -> &'a str {
        match request.name {
            // If a request.name is set, unwrap and return it.
            Some(rn) => rn,
            None => {
                // Otherwise determine if the current Transaction is named, and if so return it.
                if let Some(transaction_name) = &self.transaction_name {
                    transaction_name
                } else {
                    // Otherwise return a copy of the the path.
                    request.path
                }
            }
        }
    }

    /// Manually mark a request as a success.
    ///
    /// Goose determines if a request was successful based on the the HTTP response status
    /// code. By default, it uses [`reqwest::StatusCode::is_success`]. If an alternative
    /// HTTP response code is expected, use [`GooseRequestBuilder::expect_status_code`]. If
    /// validation requires additional logic, you can use set_success().
    ///
    /// A copy of your original request is returned with the response, and a mutable copy
    /// must be included when setting a request as a success.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut transaction = transaction!(get_function);
    ///
    /// /// A simple transaction that makes a GET request.
    /// async fn get_function(user: &mut GooseUser) -> TransactionResult {
    ///     let mut goose = user.get("404").await?;
    ///
    ///     if let Ok(response) = &goose.response {
    ///         // We expect a 404 here.
    ///         if response.status() == 404 {
    ///             return user.set_success(&mut goose.request);
    ///         }
    ///     }
    ///
    ///     Err(Box::new(TransactionError::RequestFailed {
    ///         raw_request: goose.request.clone(),
    ///     }))
    /// }
    /// ````
    pub fn set_success(&self, request: &mut GooseRequestMetric) -> TransactionResult {
        // Only send update if this was previously not a success.
        if !request.success {
            request.success = true;
            request.update = true;
            self.send_request_metric_to_parent(request.clone())?;
        }

        Ok(())
    }

    /// Manually mark a request as a failure.
    ///
    /// By default, Goose will consider any response with a 2xx status code as a success.
    /// You may require more advanced logic, in which a 2xx status code is actually a
    /// failure. A copy of your original request is returned with the response, and a
    /// mutable copy must be included when setting a request as a failure.
    ///
    /// Calls to `set_failure` must include four parameters. The first, `tag`, is an
    /// arbitrary string identifying the reason for the failure, used when logging. The
    /// second, `request`, is a mutable reference to the
    /// ([`GooseRequestMetric`](./struct.GooseRequestMetric.html)) object of the request being
    /// identified as a failure (the contained `success` field will be set to `false`,
    /// and the `update` field will be set to `true`). The last two parameters, `header`
    /// and `body`, are optional and used to provide more detail in logs.
    ///
    /// The value of `tag` will normally be collected into the errors summary table if
    /// metrics are being displayed. However, if `set_failure` is called multiple times,
    /// or is called on a request that was already an error, only the first error will
    /// be collected.
    ///
    /// This also calls [`GooseUser::log_debug`].
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut transaction = transaction!(loadtest_index_page);
    ///
    /// async fn loadtest_index_page(user: &mut GooseUser) -> TransactionResult {
    ///     let mut goose = user.get("").await?;
    ///
    ///     if let Ok(response) = goose.response {
    ///         // We only need to check pages that returned a success status code.
    ///         if response.status().is_success() {
    ///             match response.text().await {
    ///                 Ok(text) => {
    ///                     // If the expected string doesn't exist, this page load
    ///                     // was a failure.
    ///                     if !text.contains("this string must exist") {
    ///                         // As this is a named request, pass in the name not the URL
    ///                         return user.set_failure("string missing", &mut goose.request, None, None);
    ///                     }
    ///                 }
    ///                 // Empty page, this is a failure.
    ///                 Err(_) => {
    ///                     return user.set_failure("empty page", &mut goose.request, None, None);
    ///                 }
    ///             }
    ///         }
    ///     };
    ///
    ///     Ok(())
    /// }
    /// ````
    pub fn set_failure(
        &self,
        tag: &str,
        request: &mut GooseRequestMetric,
        headers: Option<&header::HeaderMap>,
        body: Option<&str>,
    ) -> TransactionResult {
        // Only send update if this was previously a success.
        if request.success {
            request.success = false;
            request.update = true;
            request.error = tag.to_string();
            self.send_request_metric_to_parent(request.clone())?;
        }
        // Write failure to log, converting `&mut request` to `&request` as needed by `log_debug()`.
        self.log_debug(tag, Some(&*request), headers, body)?;

        // Print log to stdout.
        info!("set_failure: {}", tag);

        Err(Box::new(TransactionError::RequestFailed {
            raw_request: request.clone(),
        }))
    }

    /// Write to [`debug_file`](../struct.GooseConfiguration.html#structfield.debug_file)
    /// if enabled.
    ///
    /// This function provides a mechanism for optional debug logging when a load test
    /// is running. This can be especially helpful when writing a load test. Each entry
    /// must include a tag, which is an arbitrary string identifying the debug message.
    /// It may also optionally include references to the GooseRequestMetric made, the headers
    /// returned by the server, and the response body returned by the server,
    ///
    /// As the response body can be large, the `--no-debug-body` option (or
    /// [`GooseDefault::NoDebugBody`](../config/enum.GooseDefault.html#variant.NoDebugBody) default)
    /// can be set to prevent the debug log from including the response body. When this option
    /// is enabled, the body will always show up as `null` in the debug log.
    ///
    /// Calls to [`GooseUser::set_failure`] automatically invoke `log_debug`.
    ///
    /// To enable the debug log, a load test must be run with the `--debug-log-file=foo`
    /// option set, where `foo` is either a relative or an absolute path of the log file
    /// to create. Any existing file will be overwritten.
    ///
    /// In the following example, we are logging debug messages whenever there are errors.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut transaction = transaction!(loadtest_index_page);
    ///
    /// async fn loadtest_index_page(user: &mut GooseUser) -> TransactionResult {
    ///     let mut goose = user.get("").await?;
    ///
    ///     match goose.response {
    ///         Ok(response) => {
    ///             // Grab a copy of the headers so we can include them when logging errors.
    ///             let headers = &response.headers().clone();
    ///             // We only need to check pages that returned a success status code.
    ///             if !response.status().is_success() {
    ///                 match response.text().await {
    ///                     Ok(html) => {
    ///                         // Server returned an error code, log everything.
    ///                         user.log_debug(
    ///                             "error loading /",
    ///                             Some(&goose.request),
    ///                             Some(headers),
    ///                             Some(&html),
    ///                         );
    ///                     },
    ///                     Err(e) => {
    ///                         // No body was returned, log everything else.
    ///                         user.log_debug(
    ///                             &format!("error loading /: {}", e),
    ///                             Some(&goose.request),
    ///                             Some(headers),
    ///                             None,
    ///                         );
    ///                     }
    ///                 }
    ///             }
    ///         },
    ///         // No response from server.
    ///         Err(e) => {
    ///             user.log_debug(
    ///                 "no response from server when loading /",
    ///                 Some(&goose.request),
    ///                 None,
    ///                 None,
    ///             );
    ///         }
    ///     }
    ///
    ///     Ok(())
    /// }
    /// ````
    pub fn log_debug(
        &self,
        tag: &str,
        request: Option<&GooseRequestMetric>,
        headers: Option<&header::HeaderMap>,
        body: Option<&str>,
    ) -> TransactionResult {
        if !self.config.debug_log.is_empty() {
            // Logger is not defined when running
            // [`test_start`](../struct.GooseAttack.html#method.test_start),
            // [`test_stop`](../struct.GooseAttack.html#method.test_stop), and during testing.
            if let Some(logger) = self.logger.clone() {
                if self.config.no_debug_body {
                    if let Err(e) = logger.send(Some(GooseLog::Debug(GooseDebug::new(
                        tag, request, headers, None,
                    )))) {
                        return Err(Box::new(e.into()));
                    }
                } else if let Err(e) = logger.send(Some(GooseLog::Debug(GooseDebug::new(
                    tag, request, headers, body,
                )))) {
                    return Err(Box::new(e.into()));
                }
            }
        }

        Ok(())
    }

    /// Manually build a
    /// [`reqwest::Client`](https://docs.rs/reqwest/*/reqwest/struct.Client.html).
    ///
    /// By default, Goose configures the following options when building a
    /// [`reqwest::Client`](https://docs.rs/reqwest/*/reqwest/struct.Client.html):
    ///  - reports itself as the
    ///    [`user_agent`](https://docs.rs/reqwest/*/reqwest/struct.ClientBuilder.html#method.user_agent)
    ///    requesting web pages (ie `goose/0.15.2`);
    ///  - [stores cookies](https://docs.rs/reqwest/*/reqwest/struct.ClientBuilder.html#method.cookie_store),
    ///    generally necessary if you aim to simulate logged in users;
    ///  - enables
    ///    [`gzip`](https://docs.rs/reqwest/*/reqwest/struct.ClientBuilder.html#method.gzip) compression;
    ///  - sets a 60 second [`timeout`](https://docs.rs/reqwest/*/reqwest/struct.ClientBuilder.html#method.timeout) all
    ///    on all requests.
    ///
    /// # Default configuration:
    ///
    /// ```rust
    /// use reqwest::Client;
    /// use core::time::Duration;
    ///
    /// static APP_USER_AGENT: &str = concat!(env!("CARGO_PKG_NAME"), "/", env!("CARGO_PKG_VERSION"));
    ///
    /// let builder = Client::builder()
    ///   .user_agent(APP_USER_AGENT)
    ///   .cookie_store(true)
    ///   .gzip(true)
    ///   .timeout(Duration::from_secs(60));
    /// ```
    ///
    /// Alternatively, you can use this function to manually build a
    /// [`reqwest::Client`](https://docs.rs/reqwest/*/reqwest/struct.Client.html).
    /// with custom configuration. Available options are found in the
    /// [`reqwest::ClientBuilder`](https://docs.rs/reqwest/*/reqwest/struct.ClientBuilder.html)
    /// documentation.
    ///
    /// When manually building a
    /// [`reqwest::Client`](https://docs.rs/reqwest/*/reqwest/struct.Client.html),
    /// there are a few things to be aware of:
    ///  - Manually building a client in [`test_start`](../struct.GooseAttack.html#method.test_start)
    ///    will only affect requests made during test setup;
    ///  - Manually building a client in [`test_stop`](../struct.GooseAttack.html#method.test_stop)
    ///    will only affect requests made during test teardown;
    ///  - A manually built client is specific to a single Goose thread -- if you are
    ///    generating a large load test with many users, each will need to manually build their
    ///    own client (typically you'd do this in a Transaction that is registered with
    ///   [`Transaction::set_on_start()`] in each Scenario requiring a custom client;
    ///  - Manually building a client will completely replace the automatically built client
    ///    with a brand new one, so any configuration, cookies or headers set in the previously
    ///    built client will be gone;
    ///  - You must include all desired configuration, as you are completely replacing Goose
    ///    defaults. For example, if you want Goose clients to store cookies, you will have to
    ///    include
    ///    [`.cookie_store(true)`](https://docs.rs/reqwest/*/reqwest/struct.ClientBuilder.html#method.cookie_store).
    ///
    /// In the following example, the Goose client is configured with a different user agent,
    /// sets a default header on every request, stores cookies, supports gzip compression, and
    /// times out requests after 30 seconds.
    ///
    /// ## Example
    /// ```rust
    /// use goose::prelude::*;
    /// use core::time::Duration;
    ///
    /// transaction!(setup_custom_client).set_on_start();
    ///
    /// async fn setup_custom_client(user: &mut GooseUser) -> TransactionResult {
    ///     use reqwest::{Client, header};
    ///
    ///     // Build a custom HeaderMap to include with all requests made by this client.
    ///     let mut headers = header::HeaderMap::new();
    ///     headers.insert("X-Custom-Header", header::HeaderValue::from_str("custom value").unwrap());
    ///
    ///     // Build a custom client.
    ///     let builder = Client::builder()
    ///         .default_headers(headers)
    ///         .user_agent("custom user agent")
    ///         .cookie_store(true)
    ///         .gzip(true)
    ///         .timeout(Duration::from_secs(30));
    ///
    ///     // Assign the custom client to this GooseUser.
    ///     user.set_client_builder(builder).await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    ///
    /// # Alternative Compression Algorithms
    /// Reqwest also supports
    /// [`brotli`](https://docs.rs/reqwest/*/reqwest/struct.ClientBuilder.html#method.brotli) and
    /// [`deflate`](https://docs.rs/reqwest/*/reqwest/struct.ClientBuilder.html#method.deflate) compression.
    ///
    /// To enable either, you must enable the features in your load test's `Cargo.toml`, for example:
    /// ```text
    /// reqwest = { version = "^0.11.4",  default-features = false, features = [
    ///     "brotli",
    ///     "cookies",
    ///     "deflate",
    ///     "gzip",
    ///     "json",
    /// ] }
    /// ```
    ///
    /// Once enabled, you can add `.brotli(true)` and/or `.deflate(true)` to your custom
    /// [`reqwest::Client::builder()`], following the documentation above.
    ///
    /// # Custom Cookies
    /// Custom cookies can also be manually set when building a custom [`reqwest::Client`]. This requires
    /// loading the [`GooseUser::base_url`] being load tested in order to properly build the cookie. Then
    /// a custom [`reqwest::cookie::Jar`] is created and the custom cookie is added with
    /// [`reqwest::cookie::Jar::add_cookie_str`]. Finally, the new cookie jar must be specified as the
    /// [`reqwest::ClientBuilder::cookie_provider`] for the custom client.
    ///
    /// ## Example
    /// ```rust
    /// use reqwest::{cookie::Jar, Client};
    /// use std::sync::Arc;
    ///
    /// use goose::prelude::*;
    ///
    /// transaction!(custom_cookie_with_custom_client).set_on_start();
    ///
    /// async fn custom_cookie_with_custom_client(user: &mut GooseUser) -> TransactionResult {
    ///     // Prepare the contents of a custom cookie.
    ///     let cookie = "my-custom-cookie=custom-value";
    ///
    ///     // Pre-load one or more cookies into a custom cookie jar to use with this client.
    ///     let jar = Jar::default();
    ///     jar.add_cookie_str(
    ///         cookie,
    ///         &user.base_url,
    ///     );
    ///
    ///     // Build a custom client.
    ///     let builder = Client::builder()
    ///         .user_agent("example-loadtest")
    ///         .cookie_store(true)
    ///         .cookie_provider(Arc::new(jar))
    ///         .gzip(true);
    ///
    ///     // Assign the custom client to this GooseUser.
    ///     user.set_client_builder(builder).await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub async fn set_client_builder(
        &mut self,
        builder: ClientBuilder,
    ) -> Result<(), TransactionError> {
        self.client = builder.build()?;

        Ok(())
    }

    /// Some websites use multiple domains to serve traffic, redirecting depending on
    /// the user's roll. For this reason, Goose needs to respect a redirect of the
    /// `base_url` and subsequent paths should be built from the redirect domain.
    ///
    /// For example, if the `base_url` (ie `--host`) is set to `foo.example.com` and the
    /// load test requests `/login`, thereby loading `http://foo.example.com/login` and
    /// this request gets redirected by the server to `http://foo-secure.example.com/`,
    /// subsequent requests made by this user need to be against the new
    /// `foo-secure.example.com domain`. (Further, if the `base_url` is again redirected,
    /// such as when loading `http://foo-secure.example.com/logout`, the user should
    /// again follow for subsequent requests, perhaps in this case back to
    /// `foo.example.com`.)
    ///
    /// Load tests can also request absolute URLs, and if these URLs are redirected
    /// it does not affect the `base_url` of the load test. For example, if
    /// `foo.example.com` is the base url, and the load test requests
    /// `http://bar.example.com` (a different domain) and this request gets redirected
    /// to `http://other.example.com`, subsequent relative requests would still be made
    /// against `foo.example.com`.
    ///
    /// This functionality is used internally by Goose to follow redirects of the
    /// `base_url` when `--sticky-follow` is specified at run time, or
    /// [`set_default`](../struct.GooseAttack.html#method.set_default)
    /// `(`[`GooseDefault::StickyFollow`](../config/enum.GooseDefault.html#variant.StickyFollow)
    /// `, true)` is enabled. It is also
    /// available to be manually invoked from a load test such as in the following
    /// example.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    /// use std::time::Duration;
    ///
    /// #[tokio::main]
    /// async fn main() -> Result<(), GooseError> {
    ///     let _goose_metrics = GooseAttack::initialize()?
    ///         .register_scenario(scenario!("LoadtestTransactions")
    ///             .set_host("http://foo.example.com/")
    ///             .set_wait_time(Duration::from_secs(0), Duration::from_secs(3))?
    ///             .register_transaction(transaction!(transaction_foo).set_weight(10)?)
    ///             .register_transaction(transaction!(transaction_bar))
    ///         )
    ///         // Set a default run time so this test runs to completion.
    ///         .set_default(GooseDefault::RunTime, 1)?
    ///         .execute()
    ///         .await?;
    ///
    ///     Ok(())
    /// }
    ///
    /// async fn transaction_foo(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.get("").await?;
    ///
    ///     Ok(())
    /// }
    ///
    /// async fn transaction_bar(user: &mut GooseUser) -> TransactionResult {
    ///     // Before this transaction runs, all requests are being made against
    ///     // http://foo.example.com, after this transaction runs all subsequent
    ///     // requests are made against http://bar.example.com/.
    ///     user.set_base_url("http://bar.example.com/");
    ///     let _goose = user.get("").await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn set_base_url(&mut self, host: &str) -> Result<(), Box<TransactionError>> {
        self.base_url = match Url::parse(host) {
            Ok(u) => u,
            Err(e) => return Err(Box::new(e.into())),
        };
        Ok(())
    }
}

/// Defines the HTTP requests that Goose makes.
///
/// Can be manually created and configured with [`GooseRequest::builder`], but it's typically
/// more convenient to use the [`GooseUser::get`], [`GooseUser::get_named`], [`GooseUser::post`],
/// [`GooseUser::post_form`], [`GooseUser::post_json`], [`GooseUser::head`] and
/// [`GooseUser::delete`] helpers.
///
/// For complete instructions review [`GooseRequestBuilder`].
#[derive(Debug)]
pub struct GooseRequest<'a> {
    // Defaults to `""`.
    path: &'a str,
    // Defaults to [`GooseMethod::Get`].
    method: GooseMethod,
    // Defaults to [`None`].
    name: Option<&'a str>,
    // Defaults to [`None`].
    expect_status_code: Option<u16>,
    // Defaults to [`false`].
    error_on_fail: bool,
    // Defaults to [`None`].
    request_builder: Option<RequestBuilder>,
}
impl<'a> GooseRequest<'a> {
    /// Convenience function to bring [`GooseRequestBuilder`] into scope.
    pub fn builder() -> GooseRequestBuilder<'a> {
        GooseRequestBuilder::new()
    }
}

/// Used to build a [`GooseRequest`] object, necessary to make a request with Goose.
///
/// It's only necessary to build manually if the [`GooseUser::get`], [`GooseUser::get_named`],
/// [`GooseUser::post`], [`GooseUser::post_form`], [`GooseUser::post_json`], [`GooseUser::head`]
/// and [`GooseUser::delete`] helpers don't provide you with enough flexibility.
///
/// # Example
/// ```rust
/// use goose::prelude::*;
///
/// let mut a_transaction = transaction!(transaction_function);
///
/// // A simple transaction that loads a relative path.
/// async fn transaction_function(user: &mut GooseUser) -> TransactionResult {
///     // Manually create a GooseRequestBuilder object.
///     let goose_request = GooseRequest::builder()
///         // Set a relative path to request.
///         .path("about")
///         // Name the request in the metircs.
///         .name("About page")
///         // Build the GooseRequest object.
///         .build();
///
///     // Make the configured request.
///     let _goose = user.request(goose_request).await?;
///
///     Ok(())
/// }
/// ```
pub struct GooseRequestBuilder<'a> {
    path: &'a str,
    method: GooseMethod,
    name: Option<&'a str>,
    expect_status_code: Option<u16>,
    error_on_fail: bool,
    request_builder: Option<RequestBuilder>,
}
impl<'a> GooseRequestBuilder<'a> {
    // Internal method to build a [`GooseRequest`] from a [`GooseRequestBuilder`].
    fn new() -> Self {
        Self {
            path: "",
            method: GooseMethod::Get,
            name: None,
            expect_status_code: None,
            error_on_fail: false,
            request_builder: None,
        }
    }

    /// Set the path to request.
    ///
    /// Typically is a relative path allowing Goose to append a configurable base_url.
    ///
    /// Defaults to `""` (the main index).
    ///
    /// # Example
    /// This can be implemented in a simpler way using the [`GooseUser::get`] helper function.
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut a_transaction = transaction!(transaction_function);
    ///
    /// // A simple transaction that loads a relative path.
    /// async fn transaction_function(user: &mut GooseUser) -> TransactionResult {
    ///     // Manually create a GooseRequestBuilder object.
    ///     let goose_request = GooseRequest::builder()
    ///         // Set a relative path to request.
    ///         .path("a/relative/path")
    ///         // Build the GooseRequest object.
    ///         .build();
    ///
    ///     // Make the configured request.
    ///     let _goose = user.request(goose_request).await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn path(mut self, path: impl Into<&'a str>) -> Self {
        self.path = path.into();
        self
    }

    /// Set the method of the request.
    ///
    /// Must be set to a [`GooseMethod`].
    ///
    /// Defaults to [`GooseMethod::Get`].
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut a_transaction = transaction!(transaction_function);
    ///
    /// // Make a DELETE request.
    /// async fn transaction_function(user: &mut GooseUser) -> TransactionResult {
    ///     // Manually create a GooseRequestBuilder object.
    ///     let goose_request = GooseRequest::builder()
    ///         // Set a relative path to request.
    ///         .path("path/to/delete")
    ///         // Set the method to DELETE.
    ///         .method(GooseMethod::Delete)
    ///         // Build the GooseRequest object.
    ///         .build();
    ///
    ///     // Make the configured DELETE request.
    ///     let _goose = user.request(goose_request).await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn method(mut self, method: GooseMethod) -> Self {
        self.method = method;
        self
    }

    /// Set a name for the request, affecting how it shows up in metrics.
    ///
    /// Must be set to a [`GooseMethod`].
    ///
    /// Defaults to [`GooseMethod::Get`].
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut a_transaction = transaction!(transaction_function);
    ///
    /// // Make a named request.
    /// async fn transaction_function(user: &mut GooseUser) -> TransactionResult {
    ///     // Manually create a GooseRequestBuilder object.
    ///     let goose_request = GooseRequest::builder()
    ///         // Set a relative path to request.
    ///         .path("path/to/request")
    ///         // Name the request in the metrics.
    ///         .name("custom name")
    ///         // Build the GooseRequest object.
    ///         .build();
    ///
    ///     // Make the configured request.
    ///     let _goose = user.request(goose_request).await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn name(mut self, name: impl Into<&'a str>) -> Self {
        self.name = Some(name.into());
        self
    }

    /// Manually configure the expected HTTP response status code.
    ///
    /// Defaults to [`reqwest::StatusCode::is_success`].
    ///
    /// # Example
    /// Intentionally request a 404 page, and do not trigger an error.
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut a_transaction = transaction!(transaction_function);
    ///
    /// // Make a named request.
    /// async fn transaction_function(user: &mut GooseUser) -> TransactionResult {
    ///     // Manually create a GooseRequestBuilder object.
    ///     let goose_request = GooseRequest::builder()
    ///         // Set a relative path to request.
    ///         .path("no/such/path")
    ///         // Tell Goose to expect a 404 HTTP response status code.
    ///         .expect_status_code(404)
    ///         // Build the GooseRequest object.
    ///         .build();
    ///
    ///     // Make the configured request.
    ///     let _goose = user.request(goose_request).await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn expect_status_code(mut self, status_code: u16) -> Self {
        self.expect_status_code = Some(status_code);
        self
    }

    /// Configure whether the request should return on error when it
    /// fails
    ///
    /// Defaults to [`false`].
    ///
    /// # Example
    /// Intentionally request a 404 page, and do not trigger an error.
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut a_transaction = transaction!(transaction_function);
    ///
    /// // Make a named request.
    /// async fn transaction_function(user: &mut GooseUser) -> TransactionResult {
    ///     // Manually create a GooseRequestBuilder object.
    ///     let goose_request = GooseRequest::builder()
    ///         // Set a relative path to request.
    ///         .path("no/such/path")
    ///         // Tell Goose to expect a 404 HTTP response status code.
    ///         .expect_status_code(404)
    ///         // Tell Goose to return an error if the status code is
    ///         // not a 404
    ///         .error_on_fail()
    ///         // Build the GooseRequest object.
    ///         .build();
    ///
    ///     // Make the configured request.
    ///     let _goose = user.request(goose_request).await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn error_on_fail(mut self) -> Self {
        self.error_on_fail = true;
        self
    }

    /// Manually create the [`reqwest::RequestBuilder`] used to make a request.
    ///
    /// # Example
    /// Manually create a `RequestBuilder` in order to set a timeout.
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let mut a_transaction = transaction!(transaction_function);
    ///
    /// async fn transaction_function(user: &mut GooseUser) -> TransactionResult {
    ///     use std::time::Duration;
    ///
    ///     // Manually interact with the Reqwest RequestBuilder object.
    ///     let request_builder = user.get_request_builder(&GooseMethod::Get, "no/such/path")?
    ///         // Configure the request to timeout if it takes longer than 500 milliseconds.
    ///         .timeout(Duration::from_millis(500));
    ///
    ///     // Manually build a GooseRequest in order to set our custom RequestBuilder.
    ///     let goose_request = GooseRequest::builder()
    ///         // Manually add our custom RequestBuilder object.
    ///         .set_request_builder(request_builder)
    ///         // Turn the GooseRequestBuilder object into a GooseRequest.
    ///         .build();
    ///
    ///     // Finally make the actual request with our custom GooseRequest object.
    ///     let _goose = user.request(goose_request).await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn set_request_builder(mut self, request_builder: RequestBuilder) -> Self {
        self.request_builder = Some(request_builder);
        self
    }

    /// Build the [`GooseRequest`] object which is then passed to [`GooseUser::request`].
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// // Build the default "GET /".
    /// let goose_request = GooseRequest::builder().build();
    /// ```
    pub fn build(self) -> GooseRequest<'a> {
        let Self {
            path,
            method,
            name,
            expect_status_code,
            error_on_fail,
            request_builder,
        } = self;
        GooseRequest {
            path,
            method,
            name,
            expect_status_code,
            error_on_fail,
            request_builder,
        }
    }
}

/// Remove path from Reqwest error to avoid having a lot of distincts error
/// when path parameters are used.
fn clean_reqwest_error(e: &reqwest::Error, request_name: &str) -> String {
    let kind = if e.is_builder() {
        "builder error"
    } else if e.is_request() {
        "error sending request"
    } else if e.is_body() {
        "request or response body error"
    } else if e.is_decode() {
        "error decoding response body"
    } else if e.is_redirect() {
        "error following redirect"
    } else {
        "Http status"
    };

    if let Some(ref e) = std::error::Error::source(e) {
        format!("{} {}: {}", kind, request_name, e)
    } else {
        format!("{} {}", kind, request_name)
    }
}

/// A helper to determine which host should be prepended to relative load test
/// paths in this Scenario.
///
/// The first of these defined will be returned as the prepended host:
///  1. `--host` (host specified on the command line when running load test)
///  2. [`Scenario`](./struct.Scenario.html)`.host` (default host defined
///     for the current scenario)
///  3. [`GooseDefault::Host`](../config/enum.GooseDefault.html#variant.Host) (default
///     host defined for the current load test)
pub fn get_base_url(
    config_host: Option<String>,
    scenario_host: Option<String>,
    default_host: Option<String>,
) -> Result<Url, GooseError> {
    // If the `--host` CLI option is set, build the URL with it.
    match config_host {
        Some(host) => Ok(
            Url::parse(&host).map_err(|parse_error| GooseError::InvalidHost {
                host,
                detail: "There was a failure parsing the host specified with --host.".to_string(),
                parse_error,
            })?,
        ),
        None => {
            match scenario_host {
                // Otherwise, if `Scenario.host` is defined, usee this
                Some(host) => {
                    Ok(
                        Url::parse(&host).map_err(|parse_error| GooseError::InvalidHost {
                            host,
                            detail: "There was a failure parsing the host specified with the Scenario.set_host() function.".to_string(),
                            parse_error,
                        })?,
                    )
                }
                // Otherwise, use global `GooseAttack.host`. `unwrap` okay as host validation was done at startup.
                None => {
                    // Host is required, if we get here it's safe to unwrap this variable.
                    let default_host = default_host.unwrap();
                    Ok(
                        Url::parse(&default_host).map_err(|parse_error| GooseError::InvalidHost {
                            host: default_host.to_string(),
                            detail: "There was a failure parsing the host specified globally with the GooseAttack.set_default() function.".to_string(),
                            parse_error,
                        })?,
                    )
                }
            }
        }
    }
}

/// The function type of a goose transaction function.
pub type TransactionFunction = Arc<
    dyn for<'r> Fn(
            &'r mut GooseUser,
        ) -> Pin<Box<dyn Future<Output = TransactionResult> + Send + 'r>>
        + Send
        + Sync,
>;

/// An individual transaction within a [`Scenario`](./struct.Scenario.html).
#[derive(Clone)]
pub struct Transaction {
    /// An index into [`Scenario`](./struct.Scenario.html)`.transaction`, indicating which
    /// transaction this is.
    pub transactions_index: usize,
    /// An optional name for the transaction, used when displaying metrics.
    pub name: String,
    /// An integer value that controls the frequency that this transaction will be run.
    pub weight: usize,
    /// An integer value that controls when this transaction runs compared to other transactions in the same
    /// [`Scenario`](./struct.Scenario.html).
    pub sequence: usize,
    /// A flag indicating that this transaction runs when the user starts.
    pub on_start: bool,
    /// A flag indicating that this transaction runs when the user stops.
    pub on_stop: bool,
    /// A required function that is executed each time this transaction runs.
    pub function: TransactionFunction,
}
impl Transaction {
    pub fn new(function: TransactionFunction) -> Self {
        trace!("new transaction");
        Transaction {
            transactions_index: usize::max_value(),
            name: "".to_string(),
            weight: 1,
            sequence: 0,
            on_start: false,
            on_stop: false,
            function,
        }
    }

    /// Set an optional name for the transaction, used when displaying metrics.
    ///
    /// Individual requests can also be named using [`GooseRequestBuilder`], or for GET
    /// requests with the [`GooseUser::get_named`] helper.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// transaction!(my_transaction_function).set_name("foo");
    ///
    /// async fn my_transaction_function(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.get("").await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn set_name(mut self, name: &str) -> Self {
        trace!("[{}] set_name: {}", self.transactions_index, self.name);
        self.name = name.to_string();
        self
    }

    /// Set an optional flag indicating that this transaction should be run when
    /// a user first starts. This could be used to log the user in, and
    /// so all subsequent transaction are done as a logged in user. A transaction
    /// with this flag set will only run at start time (and optionally at stop
    /// time as well, if that flag is also set).
    ///
    /// On-start transactions can be sequenced and weighted. Sequences allow
    /// multiple on-start transactions to run in a controlled order. Weights allow
    /// on-start transactions to run multiple times when a user starts.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// transaction!(my_on_start_function).set_on_start();
    ///
    /// async fn my_on_start_function(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.get("").await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn set_on_start(mut self) -> Self {
        trace!(
            "{} [{}] set_on_start transaction",
            self.name,
            self.transactions_index
        );
        self.on_start = true;
        self
    }

    /// Set an optional flag indicating that this transaction should be run when
    /// a user stops. This could be used to log a user out when the user
    /// finishes its load test. A transaction with this flag set will only run at
    /// stop time (and optionally at start time as well, if that flag is
    /// also set).
    ///
    /// On-stop transactions can be sequenced and weighted. Sequences allow
    /// multiple on-stop transactions to run in a controlled order. Weights allow
    /// on-stop transactions to run multiple times when a user stops.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// transaction!(my_on_stop_function).set_on_stop();
    ///
    /// async fn my_on_stop_function(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.get("").await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn set_on_stop(mut self) -> Self {
        trace!(
            "{} [{}] set_on_stop transaction",
            self.name,
            self.transactions_index
        );
        self.on_stop = true;
        self
    }

    /// Sets a weight on an individual transaction. The larger the value of weight, the more often it will be run
    /// in the Scenario. For example, if one transaction has a weight of 3 and another transaction has a weight of
    /// 1, the first transaction will run 3 times as often.
    ///
    /// # Example
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// #[tokio::main]
    /// async fn main() -> Result<(), GooseError> {
    ///     transaction!(transaction_function).set_weight(3)?;
    ///
    ///     Ok(())
    /// }
    ///
    /// async fn transaction_function(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.get("").await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    pub fn set_weight(mut self, weight: usize) -> Result<Self, GooseError> {
        trace!(
            "{} [{}] set_weight: {}",
            self.name,
            self.transactions_index,
            weight
        );
        if weight == 0 {
            return Err(GooseError::InvalidWeight {
                weight,
                detail: "Weight must be set to at least 1.".to_string(),
            });
        }
        self.weight = weight;

        Ok(self)
    }

    /// Defines the sequence value of an individual transactions. Transactions are run in order of their
    /// sequence value, so a transaction with a sequence value of 1 will run before a transaction with a
    /// sequence value of 2. Transactions with no sequence value (or a sequence value of 0) will run last,
    /// after all transactions with positive sequence values.
    ///
    /// All transactions with the same sequence value will run in a random order. Transactions can be
    /// assigned both squence values and weights.
    ///
    /// # Examples
    /// In this first example, the variable names indicate the order the transactions will be run in:
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// let runs_first = transaction!(first_transaction_function).set_sequence(3);
    /// let runs_second = transaction!(second_transaction_function).set_sequence(5835);
    /// let runs_last = transaction!(third_transaction_function);
    ///
    /// async fn first_transaction_function(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.get("1").await?;
    ///
    ///     Ok(())
    /// }
    ///
    /// async fn second_transaction_function(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.get("2").await?;
    ///
    ///     Ok(())
    /// }
    ///
    /// async fn third_transaction_function(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.get("3").await?;
    ///
    ///     Ok(())
    /// }
    /// ```
    ///
    /// In the following example, the `runs_first` transactions runs two times, then one instance of `runs_second`
    /// and two instances of `also_runs_second` are all three run. The user will do this over and over
    /// the entire time it runs, with `runs_first` always running first, then the other transactions being
    /// run in a random and weighted order:
    /// ```rust
    /// use goose::prelude::*;
    ///
    /// #[tokio::main]
    /// async fn main() -> Result<(), GooseError> {
    ///     let runs_first = transaction!(first_transaction_function).set_sequence(1).set_weight(2)?;
    ///     let runs_second = transaction!(second_transaction_function_a).set_sequence(2);
    ///     let also_runs_second = transaction!(second_transaction_function_b).set_sequence(2).set_weight(2)?;
    ///
    ///     Ok(())
    /// }
    ///
    /// async fn first_transaction_function(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.get("1").await?;
    ///
    ///     Ok(())
    /// }
    ///
    /// async fn second_transaction_function_a(user: &mut GooseUser) -> TransactionResult {
    ///     let _goose = user.get("2a").await?;
    ///
    ///     Ok(())
    /// }
    ///
    ///     async fn second_transaction_function_b(user: &mut GooseUser) -> TransactionResult {
    ///       let _goose = user.get("2b").await?;
    ///
    ///       Ok(())
    ///     }
    /// ```
    pub fn set_sequence(mut self, sequence: usize) -> Self {
        trace!(
            "{} [{}] set_sequence: {}",
            self.name,
            self.transactions_index,
            sequence
        );
        if sequence < 1 {
            info!(
                "setting sequence to 0 for transaction {} is unnecessary, sequence disabled",
                self.name
            );
        }
        self.sequence = sequence;
        self
    }
}
impl Hash for Transaction {
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.transactions_index.hash(state);
        self.name.hash(state);
        self.weight.hash(state);
        self.sequence.hash(state);
        self.on_start.hash(state);
        self.on_stop.hash(state);
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    use gumdrop::Options;
    use httpmock::{
        Method::{GET, POST},
        MockServer,
    };

    const EMPTY_ARGS: Vec<&str> = vec![];

    fn setup_user(server: &MockServer) -> Result<GooseUser, GooseError> {
        let mut configuration = GooseConfiguration::parse_args_default(&EMPTY_ARGS).unwrap();
        configuration.co_mitigation = Some(GooseCoordinatedOmissionMitigation::Average);
        let base_url = get_base_url(Some(server.url("/")), None, None).unwrap();
        GooseUser::single(base_url, &configuration)
    }

    #[test]
    fn goose_scenario() {
        // Simplistic test transaction functions.
        async fn test_function_a(user: &mut GooseUser) -> TransactionResult {
            let _goose = user.get("/a/").await?;

            Ok(())
        }

        async fn test_function_b(user: &mut GooseUser) -> TransactionResult {
            let _goose = user.get("/b/").await?;

            Ok(())
        }

        let mut scenario = scenario!("foo");
        assert_eq!(scenario.name, "foo");
        assert_eq!(scenario.scenarios_index, usize::max_value());
        assert_eq!(scenario.weight, 1);
        assert_eq!(scenario.transaction_wait, None);
        assert!(scenario.host.is_none());
        assert_eq!(scenario.transactions.len(), 0);
        assert_eq!(scenario.weighted_transactions.len(), 0);
        assert_eq!(scenario.weighted_on_start_transactions.len(), 0);
        assert_eq!(scenario.weighted_on_stop_transactions.len(), 0);

        // Registering a transaction adds it to transactions, but doesn't update weighted_transactions.
        scenario = scenario.register_transaction(transaction!(test_function_a));
        assert_eq!(scenario.transactions.len(), 1);
        assert_eq!(scenario.weighted_transactions.len(), 0);
        assert_eq!(scenario.scenarios_index, usize::max_value());
        assert_eq!(scenario.weight, 1);
        assert_eq!(scenario.transaction_wait, None);
        assert!(scenario.host.is_none());

        // Different transactions can be registered.
        scenario = scenario.register_transaction(transaction!(test_function_b));
        assert_eq!(scenario.transactions.len(), 2);
        assert_eq!(scenario.weighted_transactions.len(), 0);
        assert_eq!(scenario.scenarios_index, usize::max_value());
        assert_eq!(scenario.weight, 1);
        assert_eq!(scenario.transaction_wait, None);
        assert!(scenario.host.is_none());

        // Same transactions can be registered again.
        scenario = scenario.register_transaction(transaction!(test_function_a));
        assert_eq!(scenario.transactions.len(), 3);
        assert_eq!(scenario.weighted_transactions.len(), 0);
        assert_eq!(scenario.scenarios_index, usize::max_value());
        assert_eq!(scenario.weight, 1);
        assert_eq!(scenario.transaction_wait, None);
        assert!(scenario.host.is_none());

        // Setting weight only affects weight field.
        scenario = scenario.set_weight(50).unwrap();
        assert_eq!(scenario.weight, 50);
        assert_eq!(scenario.transactions.len(), 3);
        assert_eq!(scenario.weighted_transactions.len(), 0);
        assert_eq!(scenario.scenarios_index, usize::max_value());
        assert_eq!(scenario.transaction_wait, None);
        assert!(scenario.host.is_none());

        // Weight can be changed.
        scenario = scenario.set_weight(5).unwrap();
        assert_eq!(scenario.weight, 5);

        // Setting host only affects host field.
        scenario = scenario.set_host("http://foo.example.com/");
        assert_eq!(scenario.host, Some("http://foo.example.com/".to_string()));
        assert_eq!(scenario.weight, 5);
        assert_eq!(scenario.transactions.len(), 3);
        assert_eq!(scenario.weighted_transactions.len(), 0);
        assert_eq!(scenario.scenarios_index, usize::max_value());
        assert_eq!(scenario.transaction_wait, None);

        // Host field can be changed.
        scenario = scenario.set_host("https://bar.example.com/");
        assert_eq!(scenario.host, Some("https://bar.example.com/".to_string()));

        // Wait time only affects wait time fields.
        scenario = scenario
            .set_wait_time(Duration::from_secs(1), Duration::from_secs(10))
            .unwrap();
        assert_eq!(
            scenario.transaction_wait,
            Some((Duration::from_secs(1), Duration::from_secs(10)))
        );
        assert_eq!(scenario.host, Some("https://bar.example.com/".to_string()));
        assert_eq!(scenario.weight, 5);
        assert_eq!(scenario.transactions.len(), 3);
        assert_eq!(scenario.weighted_transactions.len(), 0);
        assert_eq!(scenario.scenarios_index, usize::max_value());

        // Wait time can be changed.
        scenario = scenario
            .set_wait_time(Duration::from_secs(3), Duration::from_secs(9))
            .unwrap();
        assert_eq!(
            scenario.transaction_wait,
            Some((Duration::from_secs(3), Duration::from_secs(9)))
        );
    }

    #[test]
    fn goose_transaction() {
        // Simplistic test transaction functions.
        async fn test_function_a(user: &mut GooseUser) -> TransactionResult {
            let _goose = user.get("/a/").await?;

            Ok(())
        }

        // Initialize scenario.
        let mut transaction = transaction!(test_function_a);
        assert_eq!(transaction.transactions_index, usize::max_value());
        assert_eq!(transaction.name, "".to_string());
        assert_eq!(transaction.weight, 1);
        assert_eq!(transaction.sequence, 0);
        assert!(!transaction.on_start);
        assert!(!transaction.on_stop);

        // Name can be set, without affecting other fields.
        transaction = transaction.set_name("foo");
        assert_eq!(transaction.name, "foo".to_string());
        assert_eq!(transaction.weight, 1);
        assert_eq!(transaction.sequence, 0);
        assert!(!transaction.on_start);
        assert!(!transaction.on_stop);

        // Name can be set multiple times.
        transaction = transaction.set_name("bar");
        assert_eq!(transaction.name, "bar".to_string());

        // On start flag can be set, without affecting other fields.
        transaction = transaction.set_on_start();
        assert!(transaction.on_start);
        assert_eq!(transaction.name, "bar".to_string());
        assert_eq!(transaction.weight, 1);
        assert_eq!(transaction.sequence, 0);
        assert!(!transaction.on_stop);

        // Setting on start flag twice doesn't change anything.
        transaction = transaction.set_on_start();
        assert!(transaction.on_start);

        // On stop flag can be set, without affecting other fields.
        // It's possible to set both on_start and on_stop for same transaction.
        transaction = transaction.set_on_stop();
        assert!(transaction.on_stop);
        assert!(transaction.on_start);
        assert_eq!(transaction.name, "bar".to_string());
        assert_eq!(transaction.weight, 1);
        assert_eq!(transaction.sequence, 0);

        // Setting on stop flag twice doesn't change anything.
        transaction = transaction.set_on_stop();
        assert!(transaction.on_stop);

        // Setting weight doesn't change anything else.
        transaction = transaction.set_weight(2).unwrap();
        assert_eq!(transaction.weight, 2);
        assert!(transaction.on_stop);
        assert!(transaction.on_start);
        assert_eq!(transaction.name, "bar".to_string());
        assert_eq!(transaction.sequence, 0);

        // Weight field can be changed multiple times.
        transaction = transaction.set_weight(3).unwrap();
        assert_eq!(transaction.weight, 3);

        // Setting sequence doesn't change anything else.
        transaction = transaction.set_sequence(4);
        assert_eq!(transaction.sequence, 4);
        assert_eq!(transaction.weight, 3);
        assert!(transaction.on_stop);
        assert!(transaction.on_start);
        assert_eq!(transaction.name, "bar".to_string());

        // Sequence field can be changed multiple times.
        transaction = transaction.set_sequence(8);
        assert_eq!(transaction.sequence, 8);
    }

    #[tokio::test]
    async fn goose_user() {
        const HOST: &str = "http://example.com/";
        let configuration = GooseConfiguration::parse_args_default(&EMPTY_ARGS).unwrap();
        let base_url = get_base_url(Some(HOST.to_string()), None, None).unwrap();
        let user = GooseUser::new(0, base_url, &configuration, 0).unwrap();
        assert_eq!(user.scenarios_index, 0);
        assert_eq!(user.weighted_users_index, usize::max_value());

        // Confirm the URLs are correctly built using the default_host.
        let url = user.build_url("/foo").unwrap();
        assert_eq!(&url, &[HOST, "foo"].concat());
        let url = user.build_url("bar/").unwrap();
        assert_eq!(&url, &[HOST, "bar/"].concat());
        let url = user.build_url("/foo/bar").unwrap();
        assert_eq!(&url, &[HOST, "foo/bar"].concat());

        // Confirm the URLs are built with their own specified host.
        let url = user.build_url("https://example.com/foo").unwrap();
        assert_eq!(url, "https://example.com/foo");
        let url = user
            .build_url("https://www.example.com/path/to/resource")
            .unwrap();
        assert_eq!(url, "https://www.example.com/path/to/resource");

        // Create a second user, this time setting a scenario_host.
        let base_url = get_base_url(
            None,
            Some("http://www2.example.com/".to_string()),
            Some("http://www.example.com/".to_string()),
        )
        .unwrap();
        let user2 = GooseUser::new(0, base_url, &configuration, 0).unwrap();

        // Confirm the URLs are correctly built using the scenario_host.
        let url = user2.build_url("/foo").unwrap();
        assert_eq!(url, "http://www2.example.com/foo");

        // Confirm URLs are still built with their own specified host.
        let url = user2.build_url("https://example.com/foo").unwrap();
        assert_eq!(url, "https://example.com/foo");

        // Confirm Goose can build a base_url that includes a path.
        const HOST_WITH_PATH: &str = "http://example.com/with/path/";
        let base_url = get_base_url(Some(HOST_WITH_PATH.to_string()), None, None).unwrap();
        let user = GooseUser::new(0, base_url, &configuration, 0).unwrap();

        // Confirm the URLs are correctly built using the default_host that includes a path.
        let url = user.build_url("foo").unwrap();
        assert_eq!(&url, &[HOST_WITH_PATH, "foo"].concat());
        let url = user.build_url("bar/").unwrap();
        assert_eq!(&url, &[HOST_WITH_PATH, "bar/"].concat());
        let url = user.build_url("foo/bar").unwrap();
        assert_eq!(&url, &[HOST_WITH_PATH, "foo/bar"].concat());

        // Confirm that URLs are correctly re-written if an absolute path is used.
        let url = user.build_url("/foo").unwrap();
        assert_eq!(&url, &[HOST, "foo"].concat());
    }

    #[tokio::test]
    async fn manual_requests() {
        let server = MockServer::start();

        let mut user = setup_user(&server).unwrap();

        // Set up a mock http server endpoint.
        const INDEX_PATH: &str = "/";
        let index = server.mock(|when, then| {
            when.method(GET).path(INDEX_PATH);
            then.status(200);
        });

        // Make a GET request to the mock http server and confirm we get a 200 response.
        assert_eq!(index.hits(), 0);
        let goose = user
            .get(INDEX_PATH)
            .await
            .expect("get returned unexpected error");
        let status = goose.response.unwrap().status();
        assert_eq!(status, 200);
        assert_eq!(goose.request.raw.method, GooseMethod::Get);
        assert_eq!(goose.request.name, INDEX_PATH);
        assert!(goose.request.success);
        assert!(!goose.request.update);
        assert_eq!(goose.request.status_code, 200);
        assert_eq!(index.hits(), 1);

        const NO_SUCH_PATH: &str = "/no/such/path";
        // Set up a mock http server endpoint.
        let not_found = server.mock(|when, then| {
            when.method(GET).path(NO_SUCH_PATH);
            then.status(404);
        });

        // Make an invalid GET request to the mock http server and confirm we get a 404 response.
        assert_eq!(not_found.hits(), 0);
        let goose = user
            .get(NO_SUCH_PATH)
            .await
            .expect("get returned unexpected error");
        let status = goose.response.unwrap().status();
        assert_eq!(status, 404);
        assert_eq!(goose.request.raw.method, GooseMethod::Get);
        assert_eq!(goose.request.name, NO_SUCH_PATH);
        assert!(!goose.request.success);
        assert!(!goose.request.update);
        assert_eq!(goose.request.status_code, 404,);
        not_found.assert_hits(1);

        // Set up a mock http server endpoint.
        const COMMENT_PATH: &str = "/comment";
        let comment = server.mock(|when, then| {
            when.method(POST).path(COMMENT_PATH).body("foo");
            then.status(200).body("foo");
        });

        // Make a POST request to the mock http server and confirm we get a 200 OK response.
        assert_eq!(comment.hits(), 0);
        let goose = user
            .post(COMMENT_PATH, "foo")
            .await
            .expect("post returned unexpected error");
        let unwrapped_response = goose.response.unwrap();
        let status = unwrapped_response.status();
        assert_eq!(status, 200);
        let body = unwrapped_response.text().await.unwrap();
        assert_eq!(body, "foo");
        assert_eq!(goose.request.raw.method, GooseMethod::Post);
        assert!(goose.request.success);
        assert!(!goose.request.update);
        assert_eq!(goose.request.status_code, 200);
        comment.assert_hits(1);
    }

    #[test]
    fn test_set_session_data() {
        #[derive(Debug, PartialEq, Eq, Clone)]
        struct CustomSessionData {
            data: String,
        }

        let session_data = CustomSessionData {
            data: "foo".to_owned(),
        };

        let configuration = GooseConfiguration::parse_args_default(&EMPTY_ARGS).unwrap();
        let mut user =
            GooseUser::single("http://localhost:8080".parse().unwrap(), &configuration).unwrap();

        user.set_session_data(session_data.clone());

        let session = user.get_session_data::<CustomSessionData>();
        assert!(session.is_some());
        assert_eq!(session.unwrap(), &session_data);

        let session = user.get_session_data_unchecked::<CustomSessionData>();
        assert_eq!(session, &session_data);
    }

    #[test]
    fn test_get_mut_session_data() {
        #[derive(Debug)]
        struct CustomSessionData {
            data: String,
        }

        let session_data = CustomSessionData {
            data: "foo".to_owned(),
        };

        let configuration = GooseConfiguration::parse_args_default(&EMPTY_ARGS).unwrap();
        let mut user =
            GooseUser::single("http://localhost:8080".parse().unwrap(), &configuration).unwrap();

        user.set_session_data(session_data);

        if let Some(session) = user.get_session_data_mut::<CustomSessionData>() {
            session.data = "bar".to_owned();
        }

        let session = user.get_session_data_unchecked::<CustomSessionData>();
        assert_eq!(session.data, "bar".to_string());

        let session = user.get_session_data_unchecked_mut::<CustomSessionData>();
        session.data = "foo".to_owned();
        let session = user.get_session_data_unchecked::<CustomSessionData>();
        assert_eq!(session.data, "foo".to_string());
    }

    #[test]
    fn test_set_session_data_override() {
        #[derive(Debug, Clone)]
        struct CustomSessionData {
            data: String,
        }

        let mut session_data = CustomSessionData {
            data: "foo".to_owned(),
        };

        let configuration = GooseConfiguration::parse_args_default(&EMPTY_ARGS).unwrap();
        let mut user =
            GooseUser::single("http://localhost:8080".parse().unwrap(), &configuration).unwrap();

        user.set_session_data(session_data.clone());

        session_data.data = "bar".to_owned();
        user.set_session_data(session_data);

        let session = user.get_session_data_unchecked::<CustomSessionData>();
        assert_eq!(session.data, "bar".to_string());
    }
}