// Copyright (c) 2018-2022  Brendan Molloy <brendan@bbqsrc.net>,
//                          Ilya Solovyiov <ilya.solovyiov@gmail.com>,
//                          Kai Ren <tyranron@gmail.com>
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! [`Writer`]-wrapper for collecting a summary of execution.

use std::{borrow::Cow, collections::HashMap, sync::Arc};

use async_trait::async_trait;
use derive_more::Deref;
use itertools::Itertools as _;

use crate::{
    cli::Colored,
    event,
    event::Retries,
    parser,
    writer::{self, out::Styles},
    Event, World, Writer,
};

/// Execution statistics.
///
/// [`Step`]: gherkin::Step
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct Stats {
    /// Number of passed [`Step`]s (or [`Scenario`]s).
    ///
    /// [`Scenario`]: gherkin::Scenario
    /// [`Step`]: gherkin::Step
    pub passed: usize,

    /// Number of skipped [`Step`]s (or [`Scenario`]s).
    ///
    /// [`Scenario`]: gherkin::Scenario
    /// [`Step`]: gherkin::Step
    pub skipped: usize,

    /// Number of failed [`Step`]s (or [`Scenario`]s).
    ///
    /// [`Scenario`]: gherkin::Scenario
    /// [`Step`]: gherkin::Step
    pub failed: usize,

    /// Number of retried [`Step`]s (or [`Scenario`]s).
    ///
    /// [`Scenario`]: gherkin::Scenario
    /// [`Step`]: gherkin::Step
    pub retried: usize,
}

impl Stats {
    /// Returns total number of [`Step`]s (or [`Scenario`]s), these [`Stats`]
    /// have been collected for.
    ///
    /// [`Scenario`]: gherkin::Scenario
    /// [`Step`]: gherkin::Step
    #[must_use]
    pub const fn total(&self) -> usize {
        // We intentionally don't include `self.retried` number here, as it's
        // already counted either in `self.passed` or `self.failed`.
        self.passed + self.skipped + self.failed
    }
}

/// Alias for [`fn`] used to determine should [`Skipped`] test considered as
/// [`Failed`] or not.
///
/// [`Failed`]: event::Step::Failed
/// [`Skipped`]: event::Step::Skipped
pub type SkipFn =
    fn(&gherkin::Feature, Option<&gherkin::Rule>, &gherkin::Scenario) -> bool;

/// Indicator of a [`Failed`], [`Skipped`] or retried [`Scenario`].
///
/// [`Failed`]: event::Step::Failed
/// [`Scenario`]: gherkin::Scenario
/// [`Skipped`]: event::Step::Skipped
#[derive(Clone, Copy, Debug)]
enum Indicator {
    /// [`Failed`] [`Scenario`].
    ///
    /// [`Failed`]: event::Step::Failed
    /// [`Scenario`]: gherkin::Scenario
    Failed,

    /// [`Skipped`] [`Scenario`].
    ///
    /// [`Scenario`]: gherkin::Scenario
    /// [`Skipped`]: event::Step::Skipped
    Skipped,

    /// Retried [`Scenario`].
    ///
    /// [`Scenario`]: gherkin::Scenario
    /// [`Skipped`]: event::Step::Skipped
    Retried,
}

/// Possible states of a [`Summarize`] [`Writer`].
#[derive(Clone, Copy, Debug)]
enum State {
    /// [`Finished`] event hasn't been encountered yet.
    ///
    /// [`Finished`]: event::Cucumber::Finished
    InProgress,

    /// [`Finished`] event was encountered, but summary hasn't been output yet.
    ///
    /// [`Finished`]: event::Cucumber::Finished
    FinishedButNotOutput,

    /// [`Finished`] event was encountered and summary was output.
    ///
    /// [`Finished`]: event::Cucumber::Finished
    FinishedAndOutput,
}

/// Wrapper for a [`Writer`] for outputting an execution summary (number of
/// executed features, scenarios, steps and parsing errors).
///
/// Underlying [`Writer`] has to be [`Summarizable`] and [`ArbitraryWriter`]
/// with `Value` accepting [`String`]. If your underlying [`ArbitraryWriter`]
/// operates with something like JSON (or any other type), you should implement
/// a [`Writer`] on [`Summarize`] by yourself, to provide the required summary
/// format.
///
/// [`ArbitraryWriter`]: writer::Arbitrary
#[derive(Clone, Debug, Deref)]
pub struct Summarize<Writer> {
    /// Original [`Writer`] to summarize output of.
    #[deref]
    writer: Writer,

    /// Number of started [`Feature`]s.
    ///
    /// [`Feature`]: gherkin::Feature
    features: usize,

    /// Number of started [`Rule`]s.
    ///
    /// [`Rule`]: gherkin::Rule
    rules: usize,

    /// [`Scenario`]s [`Stats`].
    ///
    /// [`Scenario`]: gherkin::Scenario
    scenarios: Stats,

    /// [`Step`]s [`Stats`].
    ///
    /// [`Step`]: gherkin::Step
    steps: Stats,

    /// Number of [`Parser`] errors.
    ///
    /// [`Parser`]: crate::Parser
    parsing_errors: usize,

    /// Number of failed [`Scenario`] hooks.
    ///
    /// [`Scenario`]: gherkin::Scenario
    failed_hooks: usize,

    /// Current [`State`] of this [`Writer`].
    state: State,

    /// Handled [`Scenario`]s to collect [`Stats`].
    ///
    /// [`Scenario`]: gherkin::Scenario
    handled_scenarios: HandledScenarios,
}

/// [`HashMap`] for keeping track of handled [`Scenario`]s. Whole path with
/// [`Feature`] and [`Rule`] is used to avoid collisions in case [`Scenario`]s
/// themself look identical.
///
/// [`Feature`]: gherkin::Feature
/// [`Rule`]: gherkin::Rule
/// [`Scenario`]: gherkin::Scenario
type HandledScenarios = HashMap<
    (
        Arc<gherkin::Feature>,
        Option<Arc<gherkin::Rule>>,
        Arc<gherkin::Scenario>,
    ),
    Indicator,
>;

#[async_trait(?Send)]
impl<W, Wr> Writer<W> for Summarize<Wr>
where
    W: World,
    Wr: for<'val> writer::Arbitrary<'val, W, String> + Summarizable,
    Wr::Cli: Colored,
{
    type Cli = Wr::Cli;

    async fn handle_event(
        &mut self,
        ev: parser::Result<Event<event::Cucumber<W>>>,
        cli: &Self::Cli,
    ) {
        use event::{Cucumber, Feature, Rule};

        // Once `Cucumber::Finished` is emitted, we just pass events through,
        // without collecting `Stats`.
        // This is done to avoid miscalculations if this `Writer` happens to be
        // wrapped by a `writer::Repeat` or similar.
        if let State::InProgress = self.state {
            match ev.as_deref() {
                Err(_) => self.parsing_errors += 1,
                Ok(Cucumber::Feature(feat, ev)) => match ev {
                    Feature::Started => self.features += 1,
                    Feature::Rule(_, Rule::Started) => {
                        self.rules += 1;
                    }
                    Feature::Rule(rule, Rule::Scenario(sc, ev)) => {
                        self.handle_scenario(
                            Arc::clone(feat),
                            Some(Arc::clone(rule)),
                            Arc::clone(sc),
                            ev,
                        );
                    }
                    Feature::Scenario(sc, ev) => {
                        self.handle_scenario(
                            Arc::clone(feat),
                            None,
                            Arc::clone(sc),
                            ev,
                        );
                    }
                    Feature::Finished | Feature::Rule(..) => {}
                },
                Ok(Cucumber::Finished) => {
                    self.state = State::FinishedButNotOutput;
                }
                Ok(Cucumber::Started | Cucumber::ParsingFinished { .. }) => {}
            };
        }

        self.writer.handle_event(ev, cli).await;

        if let State::FinishedButNotOutput = self.state {
            self.state = State::FinishedAndOutput;

            let mut styles = Styles::new();
            styles.apply_coloring(cli.coloring());
            self.writer.write(styles.summary(self)).await;
        }
    }
}

#[warn(clippy::missing_trait_methods)]
#[async_trait(?Send)]
impl<'val, W, Wr, Val> writer::Arbitrary<'val, W, Val> for Summarize<Wr>
where
    W: World,
    Self: Writer<W>,
    Wr: writer::Arbitrary<'val, W, Val>,
    Val: 'val,
{
    async fn write(&mut self, val: Val)
    where
        'val: 'async_trait,
    {
        self.writer.write(val).await;
    }
}

impl<W, Wr> writer::Stats<W> for Summarize<Wr>
where
    W: World,
    Self: Writer<W>,
{
    fn passed_steps(&self) -> usize {
        self.steps.passed
    }

    fn skipped_steps(&self) -> usize {
        self.steps.skipped
    }

    fn failed_steps(&self) -> usize {
        self.steps.failed
    }

    fn retried_steps(&self) -> usize {
        self.steps.retried
    }

    fn parsing_errors(&self) -> usize {
        self.parsing_errors
    }

    fn hook_errors(&self) -> usize {
        self.failed_hooks
    }
}

#[warn(clippy::missing_trait_methods)]
impl<Wr: writer::Normalized> writer::Normalized for Summarize<Wr> {}

#[warn(clippy::missing_trait_methods)]
impl<Wr: writer::NonTransforming> writer::NonTransforming for Summarize<Wr> {}

impl<Writer> From<Writer> for Summarize<Writer> {
    fn from(writer: Writer) -> Self {
        Self {
            writer,
            features: 0,
            rules: 0,
            scenarios: Stats {
                passed: 0,
                skipped: 0,
                failed: 0,
                retried: 0,
            },
            steps: Stats {
                passed: 0,
                skipped: 0,
                failed: 0,
                retried: 0,
            },
            parsing_errors: 0,
            failed_hooks: 0,
            state: State::InProgress,
            handled_scenarios: HashMap::new(),
        }
    }
}

impl<Writer> Summarize<Writer> {
    /// Keeps track of [`Step`]'s [`Stats`].
    ///
    /// [`Step`]: gherkin::Step
    fn handle_step<W>(
        &mut self,
        feature: Arc<gherkin::Feature>,
        rule: Option<Arc<gherkin::Rule>>,
        scenario: Arc<gherkin::Scenario>,
        step: &gherkin::Step,
        ev: &event::Step<W>,
        retries: Option<Retries>,
    ) {
        use self::{
            event::Step,
            Indicator::{Failed, Retried, Skipped},
        };

        match ev {
            Step::Started => {}
            Step::Passed(..) => {
                self.steps.passed += 1;
                if scenario.steps.last().filter(|s| *s == step).is_some() {
                    let _ = self
                        .handled_scenarios
                        .remove(&(feature, rule, scenario));
                }
            }
            Step::Skipped => {
                self.steps.skipped += 1;
                self.scenarios.skipped += 1;
                let _ = self
                    .handled_scenarios
                    .insert((feature, rule, scenario), Skipped);
            }
            Step::Failed(_, _, _, err) => {
                if retries
                    .filter(|r| {
                        r.left > 0 && !matches!(err, event::StepError::NotFound)
                    })
                    .is_some()
                {
                    self.steps.retried += 1;

                    let inserted_before = self
                        .handled_scenarios
                        .insert((feature, rule, scenario), Retried);

                    if inserted_before.is_none() {
                        self.scenarios.retried += 1;
                    }
                } else {
                    self.steps.failed += 1;
                    self.scenarios.failed += 1;

                    let _ = self
                        .handled_scenarios
                        .insert((feature, rule, scenario), Failed);
                }
            }
        }
    }

    /// Keeps track of [`Scenario`]'s [`Stats`].
    ///
    /// [`Scenario`]: gherkin::Scenario
    fn handle_scenario<W>(
        &mut self,
        feature: Arc<gherkin::Feature>,
        rule: Option<Arc<gherkin::Rule>>,
        scenario: Arc<gherkin::Scenario>,
        ev: &event::RetryableScenario<W>,
    ) {
        use event::{Hook, Scenario};

        let path = (feature, rule, scenario);

        let ret = ev.retries;
        match &ev.event {
            Scenario::Started
            | Scenario::Hook(_, Hook::Passed | Hook::Started) => {}
            Scenario::Hook(_, Hook::Failed(..)) => {
                // - If Scenario's last Step failed and then After Hook failed
                //   too, we don't need to track second failure;
                // - If Scenario's last Step was skipped and then After Hook
                //   failed, we need to override skipped Scenario with failed;
                // - If Scenario executed no Steps and then Hook failed, we
                //   track Scenario as failed.
                match self.handled_scenarios.get(&path) {
                    Some(Indicator::Failed | Indicator::Retried) => {}
                    Some(Indicator::Skipped) => {
                        self.scenarios.skipped -= 1;
                        self.scenarios.failed += 1;
                    }
                    None => {
                        self.scenarios.failed += 1;
                        let _ = self
                            .handled_scenarios
                            .insert(path, Indicator::Failed);
                    }
                }
                self.failed_hooks += 1;
            }
            Scenario::Background(st, ev) | Scenario::Step(st, ev) => {
                self.handle_step(path.0, path.1, path.2, st.as_ref(), ev, ret);
            }
            Scenario::Finished => {
                // We don't remove retried `Scenario`s immediately, because we
                // want to deduplicate. For example if some `Scenario` is
                // retried 3 times, we'll see in summary 1 retried `Scenario`
                // and 3 retried `Step`s.
                let is_retried = self
                    .handled_scenarios
                    .get(&path)
                    .map(|indicator| matches!(indicator, Indicator::Retried))
                    .unwrap_or_default();

                if !is_retried && self.handled_scenarios.remove(&path).is_none()
                {
                    self.scenarios.passed += 1;
                }
            }
        }
    }
}

impl<Writer> Summarize<Writer> {
    /// Wraps the given [`Writer`] into a new [`Summarize`]d one.
    #[must_use]
    pub fn new(writer: Writer) -> Self {
        Self::from(writer)
    }

    /// Returns the original [`Writer`], wrapped by this [`Summarize`]d one.
    #[must_use]
    pub const fn inner_writer(&self) -> &Writer {
        &self.writer
    }

    /// Returns collected [`Scenario`]s [`Stats`] of this [`Summarize`]d
    /// [`Writer`].
    ///
    /// [`Scenario`]: gherkin::Scenario
    #[must_use]
    pub const fn scenarios_stats(&self) -> &Stats {
        &self.scenarios
    }

    /// Returns collected [`Step`]s [`Stats`] of this [`Summarize`]d [`Writer`].
    ///
    /// [`Step`]: gherkin::Step
    #[must_use]
    pub const fn steps_stats(&self) -> &Stats {
        &self.steps
    }
}

/// Marker indicating that a [`Writer`] can be wrapped into a [`Summarize`].
///
/// Not any [`Writer`] can be wrapped into a [`Summarize`], as it may transform
/// events inside and the summary won't reflect outputted events correctly.
///
/// So, this trait ensures that a wrong [`Writer`]s pipeline cannot be build.
///
/// # Example
///
/// ```rust,compile_fail
/// # use cucumber::{writer, World, WriterExt as _};
/// #
/// # #[derive(Debug, Default, World)]
/// # struct MyWorld;
/// #
/// # #[tokio::main(flavor = "current_thread")]
/// # async fn main() {
/// MyWorld::cucumber()
///     .with_writer(
///         // `Writer`s pipeline is constructed in a reversed order.
///         writer::Basic::stdout()
///             .fail_on_skipped() // Fails as `Summarize` will count skipped
///             .summarized()      // steps instead of failed.
///     )
///     .run_and_exit("tests/features/readme")
///     .await;
/// # }
/// ```
///
/// ```rust
/// # use std::panic::AssertUnwindSafe;
/// #
/// # use cucumber::{writer, World, WriterExt as _};
/// # use futures::FutureExt as _;
/// #
/// # #[derive(Debug, Default, World)]
/// # struct MyWorld;
/// #
/// # #[tokio::main(flavor = "current_thread")]
/// # async fn main() {
/// # let fut = async {
/// MyWorld::cucumber()
///     .with_writer(
///         // `Writer`s pipeline is constructed in a reversed order.
///         writer::Basic::stdout() // And, finally, print them.
///             .summarized()       // Only then, count summary for them.
///             .fail_on_skipped()  // First, transform skipped steps to failed.
///     )
///     .run_and_exit("tests/features/readme")
///     .await;
/// # };
/// # let err = AssertUnwindSafe(fut)
/// #         .catch_unwind()
/// #         .await
/// #         .expect_err("should err");
/// # let err = err.downcast_ref::<String>().unwrap();
/// # assert_eq!(err, "1 step failed");
/// # }
/// ```
pub trait Summarizable {}

impl<T: writer::NonTransforming> Summarizable for T {}

// We better keep this here, as it's related to summarization only.
#[allow(clippy::multiple_inherent_impl)]
impl Styles {
    /// Generates a formatted summary [`String`].
    #[must_use]
    pub fn summary<W>(&self, summary: &Summarize<W>) -> String {
        let features = self.maybe_plural("feature", summary.features);

        let rules = (summary.rules > 0)
            .then(|| format!("{}\n", self.maybe_plural("rule", summary.rules)))
            .unwrap_or_default();

        let scenarios =
            self.maybe_plural("scenario", summary.scenarios.total());
        let scenarios_stats = self.format_stats(summary.scenarios);

        let steps = self.maybe_plural("step", summary.steps.total());
        let steps_stats = self.format_stats(summary.steps);

        let parsing_errors = (summary.parsing_errors > 0)
            .then(|| {
                self.err(
                    self.maybe_plural("parsing error", summary.parsing_errors),
                )
            })
            .unwrap_or_default();

        let hook_errors = (summary.failed_hooks > 0)
            .then(|| {
                self.err(self.maybe_plural("hook error", summary.failed_hooks))
            })
            .unwrap_or_default();

        let comma = (!parsing_errors.is_empty() && !hook_errors.is_empty())
            .then(|| self.err(", "))
            .unwrap_or_default();

        format!(
            "{summary}\n{features}\n{rules}{scenarios}{scenarios_stats}\n\
             {steps}{steps_stats}\n{parsing_errors}{comma}{hook_errors}",
            summary = self.bold(self.header("[Summary]")),
        )
        .trim_end_matches('\n')
        .to_owned()
    }

    /// Formats [`Stats`] for a terminal output.
    #[must_use]
    pub fn format_stats(&self, stats: Stats) -> Cow<'static, str> {
        let mut formatted = [
            (stats.passed > 0)
                .then(|| self.bold(self.ok(format!("{} passed", stats.passed))))
                .unwrap_or_default(),
            (stats.skipped > 0)
                .then(|| {
                    self.bold(
                        self.skipped(format!("{} skipped", stats.skipped)),
                    )
                })
                .unwrap_or_default(),
            (stats.failed > 0)
                .then(|| {
                    self.bold(self.err(format!("{} failed", stats.failed)))
                })
                .unwrap_or_default(),
        ]
        .into_iter()
        .filter(|s| !s.is_empty())
        .join(&self.bold(", "));
        if stats.retried > 0 {
            formatted.push_str(" with ");
            formatted.push_str(&self.bold(self.retry(format!(
                "{} retr{}",
                stats.retried,
                if stats.retried == 1 { "y" } else { "ies" },
            ))));
        }

        (!formatted.is_empty())
            .then(|| {
                self.bold(format!(
                    " {}{formatted}{}",
                    self.bold("("),
                    self.bold(")"),
                ))
            })
            .unwrap_or_default()
    }

    /// Adds `s` to `singular` if the given `num` is not `1`.
    fn maybe_plural(
        &self,
        singular: impl Into<Cow<'static, str>>,
        num: usize,
    ) -> Cow<'static, str> {
        self.bold(format!(
            "{num} {}{}",
            singular.into(),
            (num != 1).then_some("s").unwrap_or_default(),
        ))
    }
}