#![deny(missing_docs)]

//! # Integration of Http Signature Normalization with Actix Web
//!
//! This library provides middlewares for verifying HTTP Signature headers and, optionally, Digest
//! headers with the `digest` feature enabled. It also extends awc's ClientRequest type to
//! add signatures and digests to the request
//!
//! ### Use it in a server
//! ```rust,ignore
//! use actix_web::{http::StatusCode, web, App, HttpRequest, HttpResponse, HttpServer, ResponseError};
//! use http_signature_normalization_actix::prelude::*;
//! use sha2::{Digest, Sha256};
//! use std::future::{ready, Ready};
//! use tracing::info;
//! use tracing_actix_web::TracingLogger;
//! use tracing_error::ErrorLayer;
//! use tracing_subscriber::{layer::SubscriberExt, EnvFilter};
//!
//! #[derive(Clone, Debug)]
//! struct MyVerify;
//!
//! impl SignatureVerify for MyVerify {
//!     type Error = MyError;
//!     type Future = Ready<Result<bool, Self::Error>>;
//!
//!     fn signature_verify(
//!         &mut self,
//!         algorithm: Option<Algorithm>,
//!         key_id: String,
//!         signature: String,
//!         signing_string: String,
//!     ) -> Self::Future {
//!         match algorithm {
//!             Some(Algorithm::Hs2019) => (),
//!             _ => return ready(Err(MyError::Algorithm)),
//!         };
//!
//!         if key_id != "my-key-id" {
//!             return ready(Err(MyError::Key));
//!         }
//!
//!         let decoded = match base64::decode(&signature) {
//!             Ok(decoded) => decoded,
//!             Err(_) => return ready(Err(MyError::Decode)),
//!         };
//!
//!         info!("Signing String\n{}", signing_string);
//!
//!         ready(Ok(decoded == signing_string.as_bytes()))
//!     }
//! }
//!
//! async fn index(
//!     (_, sig_verified): (DigestVerified, SignatureVerified),
//!     req: HttpRequest,
//!     _body: web::Bytes,
//! ) -> &'static str {
//!     info!("Verified request for {}", sig_verified.key_id());
//!     info!("{:?}", req);
//!     "Eyyyyup"
//! }
//!
//! #[actix_rt::main]
//! async fn main() -> Result<(), Box<dyn std::error::Error>> {
//!     let env_filter = EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("info"));
//!
//!     let subscriber = tracing_subscriber::Registry::default()
//!         .with(env_filter)
//!         .with(ErrorLayer::default())
//!         .with(tracing_subscriber::fmt::layer());
//!
//!     tracing::subscriber::set_global_default(subscriber)?;
//!
//!     let config = Config::default().require_header("accept").require_digest();
//!
//!     HttpServer::new(move || {
//!         App::new()
//!             .wrap(VerifyDigest::new(Sha256::new()).optional())
//!             .wrap(VerifySignature::new(MyVerify, config.clone()).optional())
//!             .wrap(TracingLogger::default())
//!             .route("/", web::post().to(index))
//!     })
//!     .bind("127.0.0.1:8010")?
//!     .run()
//!     .await?;
//!
//!     Ok(())
//! }
//!
//! #[derive(Debug, thiserror::Error)]
//! enum MyError {
//!     #[error("Failed to verify, {0}")]
//!     Verify(#[from] PrepareVerifyError),
//!
//!     #[error("Unsupported algorithm")]
//!     Algorithm,
//!
//!     #[error("Couldn't decode signature")]
//!     Decode,
//!
//!     #[error("Invalid key")]
//!     Key,
//! }
//!
//! impl ResponseError for MyError {
//!     fn status_code(&self) -> StatusCode {
//!         StatusCode::BAD_REQUEST
//!     }
//!
//!     fn error_response(&self) -> HttpResponse {
//!         HttpResponse::BadRequest().finish()
//!     }
//! }
//! ```
//!
//! ### Use it in a client
//! ```rust,ignore
//! use actix_rt::task::JoinError;
//! use awc::Client;
//! use http_signature_normalization_actix::prelude::*;
//! use sha2::{Digest, Sha256};
//! use std::time::SystemTime;
//! use tracing::{error, info};
//! use tracing_error::ErrorLayer;
//! use tracing_subscriber::{layer::SubscriberExt, EnvFilter};
//!
//! async fn request(config: Config) -> Result<(), Box<dyn std::error::Error>> {
//!     let digest = Sha256::new();
//!
//!     let mut response = Client::default()
//!         .post("http://127.0.0.1:8010/")
//!         .append_header(("User-Agent", "Actix Web"))
//!         .append_header(("Accept", "text/plain"))
//!         .insert_header(actix_web::http::header::Date(SystemTime::now().into()))
//!         .signature_with_digest(config, "my-key-id", digest, "Hewwo-owo", |s| {
//!             info!("Signing String\n{}", s);
//!             Ok(base64::encode(s)) as Result<_, MyError>
//!         })
//!         .await?
//!         .send()
//!         .await
//!         .map_err(|e| {
//!             error!("Error, {}", e);
//!             MyError::SendRequest
//!         })?;
//!
//!     let body = response.body().await.map_err(|e| {
//!         error!("Error, {}", e);
//!         MyError::Body
//!     })?;
//!
//!     info!("{:?}", body);
//!     Ok(())
//! }
//!
//! #[actix_rt::main]
//! async fn main() -> Result<(), Box<dyn std::error::Error>> {
//!     let env_filter = EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("info"));
//!
//!     let subscriber = tracing_subscriber::Registry::default()
//!         .with(env_filter)
//!         .with(ErrorLayer::default())
//!         .with(tracing_subscriber::fmt::layer());
//!
//!     tracing::subscriber::set_global_default(subscriber)?;
//!
//!     let config = Config::default().require_header("accept").require_digest();
//!
//!     request(config.clone()).await?;
//!     request(config.mastodon_compat()).await?;
//!     Ok(())
//! }
//!
//! #[derive(Debug, thiserror::Error)]
//! pub enum MyError {
//!     #[error("Failed to create signing string, {0}")]
//!     Convert(#[from] PrepareSignError),
//!
//!     #[error("Failed to create header, {0}")]
//!     Header(#[from] InvalidHeaderValue),
//!
//!     #[error("Failed to send request")]
//!     SendRequest,
//!
//!     #[error("Failed to retrieve request body")]
//!     Body,
//!
//!     #[error("Blocking operation was canceled")]
//!     Canceled,
//! }
//!
//! impl From<JoinError> for MyError {
//!     fn from(_: JoinError) -> Self {
//!         MyError::Canceled
//!     }
//! }
//! ```

use std::time::Duration;

#[cfg(any(feature = "client", feature = "server"))]
use actix_http::{
    header::{HeaderMap, ToStrError},
    uri::PathAndQuery,
    Method,
};
#[cfg(any(feature = "client", feature = "server"))]
use std::collections::BTreeMap;

#[cfg(feature = "client")]
mod sign;

#[cfg(feature = "digest")]
pub mod digest;

#[cfg(feature = "client")]
pub mod create;
#[cfg(feature = "server")]
pub mod middleware;

pub use http_signature_normalization::RequiredError;

/// Useful types and traits for using this library in Actix Web
pub mod prelude {
    pub use crate::{Config, RequiredError};

    #[cfg(feature = "client")]
    pub use crate::{PrepareSignError, Sign};

    #[cfg(feature = "server")]
    pub use crate::{
        middleware::{SignatureVerified, VerifySignature},
        verify::{Algorithm, DeprecatedAlgorithm, Unverified},
        PrepareVerifyError, SignatureVerify,
    };

    #[cfg(all(feature = "digest", feature = "client"))]
    pub use crate::digest::{DigestClient, DigestCreate, SignExt};

    #[cfg(all(feature = "digest", feature = "server"))]
    pub use crate::digest::{
        middleware::{DigestVerified, VerifyDigest},
        DigestPart, DigestVerify,
    };

    pub use actix_http::header::{InvalidHeaderValue, ToStrError};
}

#[cfg(feature = "server")]
/// Types for Verifying an HTTP Signature
pub mod verify {
    pub use http_signature_normalization::verify::{
        Algorithm, DeprecatedAlgorithm, ParseSignatureError, ParsedHeader, Unvalidated, Unverified,
        ValidateError,
    };
}

#[cfg(feature = "client")]
pub use self::client::{PrepareSignError, Sign};

#[cfg(feature = "server")]
pub use self::server::{PrepareVerifyError, SignatureVerify};

#[derive(Clone, Debug, Default)]
/// Configuration for signing and verifying signatures
///
/// By default, the config is set up to create and verify signatures that expire after 10
/// seconds, and use the `(created)` and `(expires)` fields that were introduced in draft 11
pub struct Config<Spawner = DefaultSpawner> {
    /// The inner config type
    config: http_signature_normalization::Config,

    /// Whether to set the Host header
    set_host: bool,

    /// Whether to set the Date header
    set_date: bool,

    /// The spawner used to create blocking operations
    spawner: Spawner,
}

/// A default implementation of Spawner for spawning blocking operations
#[derive(Clone, Copy, Debug, Default)]
pub struct DefaultSpawner;

/// An error that indicates a blocking operation panicked and cannot return a response
#[derive(Debug)]
pub struct Canceled;

impl std::fmt::Display for Canceled {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "Operation was canceled")
    }
}

impl std::error::Error for Canceled {}

/// A trait dictating how to spawn a future onto a blocking threadpool. By default,
/// http-signature-normalization-actix will use actix_rt's built-in blocking threadpool, but this
/// can be customized
pub trait Spawn {
    /// The future type returned by spawn_blocking
    type Future<T>: std::future::Future<Output = Result<T, Canceled>>;

    /// Spawn the blocking function onto the threadpool
    fn spawn_blocking<Func, Out>(&self, func: Func) -> Self::Future<Out>
    where
        Func: FnOnce() -> Out + Send + 'static,
        Out: Send + 'static;
}

/// The future returned by DefaultSpawner when spawning blocking operations on the actix_rt
/// blocking threadpool
pub struct DefaultSpawnerFuture<Out> {
    inner: actix_rt::task::JoinHandle<Out>,
}

impl Spawn for DefaultSpawner {
    type Future<T> = DefaultSpawnerFuture<T>;

    fn spawn_blocking<Func, Out>(&self, func: Func) -> Self::Future<Out>
    where
        Func: FnOnce() -> Out + Send + 'static,
        Out: Send + 'static,
    {
        DefaultSpawnerFuture {
            inner: actix_rt::task::spawn_blocking(func),
        }
    }
}

impl<Out> std::future::Future for DefaultSpawnerFuture<Out> {
    type Output = Result<Out, Canceled>;

    fn poll(
        mut self: std::pin::Pin<&mut Self>,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<Self::Output> {
        let res = std::task::ready!(std::pin::Pin::new(&mut self.inner).poll(cx));

        std::task::Poll::Ready(res.map_err(|_| Canceled))
    }
}

#[cfg(feature = "client")]
mod client {
    use super::{Config, RequiredError, Spawn};
    use actix_http::header::{InvalidHeaderValue, ToStrError};
    use actix_rt::task::JoinError;
    use std::{fmt::Display, future::Future, pin::Pin};

    /// A trait implemented by the awc ClientRequest type to add an HTTP signature to the request
    pub trait Sign {
        /// Add an Authorization Signature to the request
        fn authorization_signature<F, E, K, S>(
            self,
            config: Config<S>,
            key_id: K,
            f: F,
        ) -> Pin<Box<dyn Future<Output = Result<Self, E>>>>
        where
            F: FnOnce(&str) -> Result<String, E> + Send + 'static,
            E: From<JoinError>
                + From<PrepareSignError>
                + From<crate::Canceled>
                + From<InvalidHeaderValue>
                + std::fmt::Debug
                + Send
                + 'static,
            K: Display + 'static,
            S: Spawn + 'static,
            Self: Sized;

        /// Add a Signature to the request
        fn signature<F, E, K, S>(
            self,
            config: Config<S>,
            key_id: K,
            f: F,
        ) -> Pin<Box<dyn Future<Output = Result<Self, E>>>>
        where
            F: FnOnce(&str) -> Result<String, E> + Send + 'static,
            E: From<JoinError>
                + From<PrepareSignError>
                + From<crate::Canceled>
                + From<InvalidHeaderValue>
                + std::fmt::Debug
                + Send
                + 'static,
            K: Display + 'static,
            S: Spawn + 'static,
            Self: Sized;
    }

    #[derive(Debug, thiserror::Error)]
    /// An error when preparing to sign a request
    pub enum PrepareSignError {
        #[error("Failed to read header")]
        /// An error occurred when reading the request's headers
        Header(#[from] ToStrError),

        #[error("Missing required header")]
        /// Some headers were marked as required, but are missing
        RequiredError(#[from] RequiredError),

        #[error("No host provided for URL, {0}")]
        /// Missing host
        Host(String),

        #[error("Failed to set header")]
        /// Invalid Date header
        InvalidHeader(#[from] actix_http::header::InvalidHeaderValue),
    }
}

#[cfg(feature = "server")]
mod server {
    use super::RequiredError;
    use actix_http::header::ToStrError;
    use std::future::Future;

    /// A trait for verifying signatures
    pub trait SignatureVerify {
        /// An error produced while attempting to verify the signature. This can be anything
        /// implementing ResponseError
        type Error: actix_web::ResponseError;

        /// The future that resolves to the verification state of the signature
        type Future: Future<Output = Result<bool, Self::Error>>;

        /// Given the algorithm, key_id, signature, and signing_string, produce a future that resulves
        /// to a the verification status
        fn signature_verify(
            &mut self,
            algorithm: Option<super::verify::Algorithm>,
            key_id: String,
            signature: String,
            signing_string: String,
        ) -> Self::Future;
    }

    #[derive(Debug, thiserror::Error)]
    /// An error when preparing to verify a request
    pub enum PrepareVerifyError {
        #[error("Header is missing")]
        /// Header is missing
        Missing,

        #[error("{0}")]
        /// Header is expired
        Expired(String),

        #[error("Couldn't parse required field, {0}")]
        /// Couldn't parse required field
        ParseField(&'static str),

        #[error("Failed to read header, {0}")]
        /// An error converting the header to a string for validation
        Header(#[from] ToStrError),

        #[error("{0}")]
        /// Required headers were missing from request
        Required(#[from] RequiredError),
    }

    impl From<http_signature_normalization::PrepareVerifyError> for PrepareVerifyError {
        fn from(e: http_signature_normalization::PrepareVerifyError) -> Self {
            use http_signature_normalization as hsn;

            match e {
                hsn::PrepareVerifyError::Parse(parse_error) => {
                    PrepareVerifyError::ParseField(parse_error.missing_field())
                }
                hsn::PrepareVerifyError::Validate(validate_error) => match validate_error {
                    hsn::verify::ValidateError::Missing => PrepareVerifyError::Missing,
                    e @ hsn::verify::ValidateError::Expired { .. } => {
                        PrepareVerifyError::Expired(e.to_string())
                    }
                },
                hsn::PrepareVerifyError::Required(required_error) => {
                    PrepareVerifyError::Required(required_error)
                }
            }
        }
    }

    impl actix_web::ResponseError for super::Canceled {
        fn status_code(&self) -> actix_http::StatusCode {
            actix_http::StatusCode::INTERNAL_SERVER_ERROR
        }

        fn error_response(&self) -> actix_web::HttpResponse<actix_http::body::BoxBody> {
            actix_web::HttpResponse::new(self.status_code())
        }
    }
}

impl Config {
    /// Create a new Config with a default expiration of 10 seconds
    pub fn new() -> Self {
        Config::default()
    }
}

impl<Spawner> Config<Spawner> {
    /// Since manually setting the Host header doesn't work so well in AWC, you can use this method
    /// to enable setting the Host header for signing requests without breaking client
    /// functionality
    pub fn set_host_header(self) -> Self {
        Config {
            config: self.config,
            set_host: true,
            set_date: self.set_date,
            spawner: self.spawner,
        }
    }

    #[cfg(feature = "client")]
    /// Set the spawner for spawning blocking tasks
    ///
    /// http-signature-normalization-actix offloads signing messages and generating hashes to a
    /// blocking threadpool, which can be configured by providing a custom spawner.
    pub fn spawner<S>(self, spawner: S) -> Config<S>
    where
        S: Spawn,
    {
        Config {
            config: self.config,
            set_host: self.set_host,
            set_date: self.set_date,
            spawner,
        }
    }

    /// Enable mastodon compatibility
    ///
    /// This is the same as disabling the use of `(created)` and `(expires)` signature fields,
    /// requiring the Date header, and requiring the Host header
    pub fn mastodon_compat(self) -> Self {
        Config {
            config: self.config.mastodon_compat(),
            set_host: true,
            set_date: true,
            spawner: self.spawner,
        }
    }

    /// Require the Digest header be set
    ///
    /// This is useful for POST, PUT, and PATCH requests, but doesn't make sense for GET or DELETE.
    pub fn require_digest(self) -> Self {
        Config {
            config: self.config.require_digest(),
            set_host: self.set_host,
            set_date: self.set_date,
            spawner: self.spawner,
        }
    }

    /// Opt out of using the (created) and (expires) fields introduced in draft 11
    ///
    /// Note that by enabling this, the Date header becomes required on requests. This is to
    /// prevent replay attacks
    pub fn dont_use_created_field(self) -> Self {
        Config {
            config: self.config.dont_use_created_field(),
            set_host: self.set_host,
            set_date: self.set_date,
            spawner: self.spawner,
        }
    }

    /// Set the expiration to a custom duration
    pub fn set_expiration(self, expires_after: Duration) -> Self {
        Config {
            config: self.config.set_expiration(expires_after),
            set_host: self.set_host,
            set_date: self.set_date,
            spawner: self.spawner,
        }
    }

    /// Require a header on signed and verified requests
    pub fn require_header(self, header: &str) -> Self {
        Config {
            config: self.config.require_header(header),
            set_host: self.set_host,
            set_date: self.set_date,
            spawner: self.spawner,
        }
    }

    #[cfg(feature = "client")]
    /// Begin the process of singing a request
    pub fn begin_sign(
        &self,
        method: &Method,
        path_and_query: Option<&PathAndQuery>,
        headers: HeaderMap,
    ) -> Result<self::create::Unsigned, PrepareSignError> {
        let headers = headers
            .iter()
            .map(|(k, v)| v.to_str().map(|v| (k.to_string(), v.to_string())))
            .collect::<Result<BTreeMap<_, _>, ToStrError>>()?;

        let path_and_query = path_and_query
            .map(|p| p.to_string())
            .unwrap_or_else(|| "/".to_string());

        let unsigned = self
            .config
            .begin_sign(method.as_ref(), &path_and_query, headers)?;

        Ok(self::create::Unsigned { unsigned })
    }

    #[cfg(feature = "server")]
    /// Begin the proess of verifying a request
    pub fn begin_verify(
        &self,
        method: &Method,
        path_and_query: Option<&PathAndQuery>,
        headers: HeaderMap,
    ) -> Result<self::verify::Unverified, PrepareVerifyError> {
        let headers = headers
            .iter()
            .map(|(k, v)| v.to_str().map(|v| (k.to_string(), v.to_string())))
            .collect::<Result<BTreeMap<_, _>, ToStrError>>()?;

        let path_and_query = path_and_query
            .map(|p| p.to_string())
            .unwrap_or_else(|| "/".to_string());

        let unverified = self
            .config
            .begin_verify(method.as_ref(), &path_and_query, headers)?;

        Ok(unverified)
    }
}