//! Hook
//!
//! Hook is a struct that contains the information needed for validating the payload and the work after that.
//!
//! ## Example
//!
//! To create a Hook object, use the new method:
//!
//! ```
//! extern crate rifling;
//!
//! use rifling::{Hook, Delivery};
//!
//! // Create the hook
//! let hook = Hook::new("push", None, |_: &Delivery| println!("Pushed!"));
//! ```
//!
//! The last parameter is a trait object of the trait `HookFunc`, it's currently implemented to `Fn(&Delivery)`.
//! `Delivery` contains the information of the request received.
//!
//! To use the hook, you need to register it to the `Constructor`.

#[cfg(any(feature = "crypto-use-rustcrypto", feature = "crypto-use-ring"))]
use hex::FromHex;
#[cfg(feature = "crypto-use-rustcrypto")]
use hmac::{Hmac, Mac};
#[cfg(feature = "crypto-use-ring")]
use ring::digest;
#[cfg(feature = "crypto-use-ring")]
use ring::hmac;
#[cfg(feature = "crypto-use-rustcrypto")]
use sha1::Sha1;

use std::sync::Arc;

use super::handler::Delivery;
use super::handler::DeliveryType;

#[cfg(feature = "crypto-use-rustcrypto")]
type HmacSha1 = Hmac<Sha1>;

/// Unwrap `Option<T>` or return false
#[macro_export]
macro_rules! unwrap_or_false {
    ($e:expr) => {
        match $e {
            Some(content) => content,
            _ => return false,
        }
    };
}

/// The part of the hook that will be executed after validating the payload
/// You can implement this trait to your own struct
pub trait HookFunc: Sync + Send {
    fn run(&self, delivery: &Delivery);
}

/// The actual hook, contains the event it's going to listen, the secret to authenticate the payload, and the function to execute.
#[derive(Clone)]
pub struct Hook {
    pub event: &'static str,
    pub secret: Option<String>,
    pub func: Arc<HookFunc>, // To allow the registration of multiple hooks, it has to be a trait object.
}

/// Implement `HookFunc` to `Fn(&Delivery)`.
impl<F> HookFunc for F
where
    F: Fn(&Delivery) + Clone + Sync + Send + 'static,
{
    /// Run the function
    fn run(&self, delivery: &Delivery) {
        self(delivery)
    }
}

/// Main impl clause of `Hook`()
impl Hook {
    /// Create a new hook
    ///
    /// Example:
    ///
    /// ```
    /// extern crate rifling;
    ///
    /// use rifling::{Hook, Delivery};
    ///
    /// let hook = Hook::new("push", None, |_: &Delivery| println!("Pushed!"));
    /// ```
    pub fn new(event: &'static str, secret: Option<String>, func: impl HookFunc + 'static) -> Self {
        Self {
            event,
            secret,
            func: Arc::new(func),
        }
    }

    #[cfg(feature = "crypto-use-ring")]
    /// Authenticate the payload using `ring`
    pub fn auth(&self, delivery: &Delivery) -> bool {
        if let Some(secret) = &self.secret {
            let signature = unwrap_or_false!(&delivery.signature);
            debug!("Signature/Token: {}", signature);
            match delivery.delivery_type {
                DeliveryType::GitHub => {
                    let request_body = unwrap_or_false!(&delivery.request_body);
                    debug!("Request body: {}", &request_body);
                    let signature_hex = signature[5..signature.len()].as_bytes();
                    if let Ok(signature_bytes) = Vec::from_hex(signature_hex) {
                        let secret_bytes = secret.as_bytes();
                        let request_body_bytes = request_body.as_bytes();
                        let key = hmac::SigningKey::new(&digest::SHA1, &secret_bytes);
                        debug!("Validating payload with given secret");
                        return hmac::verify_with_own_key(
                            &key,
                            &request_body_bytes,
                            &signature_bytes,
                        )
                        .is_ok();
                    }
                    debug!("Invalid signature");
                    return false;
                }
                DeliveryType::GitLab => {
                    if signature == secret {
                        return true;
                    } else {
                        debug!("Invalid token");
                        return false;
                    }
                }
            }
        } else {
            debug!("No secret given, passing...");
            return true;
        }
    }

    #[cfg(feature = "crypto-use-rustcrypto")]
    /// Authenticate the payload using crates provided by RustCrypto team
    pub fn auth(&self, delivery: &Delivery) -> bool {
        if let Some(secret) = &self.secret {
            let signature = unwrap_or_false!(&delivery.signature);
            debug!("Signature/Token: {}", &signature);
            match delivery.delivery_type {
                DeliveryType::GitHub => {
                    let request_body = unwrap_or_false!(&delivery.request_body);
                    debug!("Request body: {}", &request_body);
                    let signature_hex = signature[5..signature.len()].as_bytes();
                    if let Ok(signature_bytes) = Vec::from_hex(signature_hex) {
                        let secret_bytes = secret.as_bytes();
                        let request_body_bytes = request_body.as_bytes();
                        let mut mac = unwrap_or_false!(HmacSha1::new_varkey(secret_bytes).ok());
                        mac.input(request_body_bytes);
                        debug!("Validating payload with given secret");
                        return mac.verify(&signature_bytes).is_ok();
                    }
                    debug!("Invalid signature");
                    return false;
                }
                DeliveryType::GitLab => {
                    if signature == secret {
                        return true;
                    } else {
                        debug!("Invalid token");
                        return false;
                    }
                }
            }
        } else {
            debug!("No secret given, passing...");
            return false;
        }
    }

    #[cfg(all(
        not(feature = "crypto-use-rustcrypto"),
        not(feature = "crypto-use-ring")
    ))]
    pub fn auth(&self, delivery: &Delivery) -> bool {
        if let Some(secret) = &self.secret {
            match delivery.delivery_type {
                DeliveryType::GitHub => {
                    info!(
                        "Payload authentication not enabled for requests from GitHub, passing..."
                    );
                    true
                }
                DeliveryType::GitLab => {
                    let signature = unwrap_or_false!(&delivery.signature);
                    debug!("Signature/token: {}", &signature);
                    if signature == secret {
                        true
                    } else {
                        debug!("Invalid token");
                        false
                    }
                }
            }
        } else {
            debug!("No secret given, passing...");
            true
        }
    }

    /// Handle the request
    pub fn handle_delivery(self, delivery: &Delivery) {
        if self.auth(delivery) {
            debug!("Valid payload found");
            self.func.run(delivery);
            return;
        }
        debug!("Invalid payload");
    }
}

#[cfg(any(feature = "crypto-use-rustcrypto", feature = "crypto-use-ring"))]
#[cfg(test)]
mod tests {
    use super::super::handler::ContentType;
    use super::super::handler::DeliveryType;
    #[cfg(feature = "crypto-use-rustcrypto")]
    use super::HmacSha1;
    use super::*;
    use hex::ToHex;
    #[cfg(feature = "crypto-use-ring")]
    use ring::digest;
    #[cfg(feature = "crypto-use-ring")]
    use ring::hmac;

    /// Test payload authentication with `ring`: Valid signature
    #[cfg(feature = "crypto-use-ring")]
    #[test]
    fn payload_authentication_ring() {
        let secret = String::from("secret");
        let hook = Hook::new("*", Some(secret.clone()), |_: &Delivery| {});
        let payload = String::from(r#"{"zen": "Bazinga!"}"#);
        let request_body = payload.clone();
        let secret_bytes = secret.as_bytes();
        let request_bytes = request_body.as_bytes();
        let key = hmac::SigningKey::new(&digest::SHA1, &secret_bytes);
        let mut signature = String::new();
        hmac::sign(&key, &request_bytes)
            .as_ref()
            .write_hex(&mut signature)
            .unwrap();
        let signature_field = String::from(format!("sha1={}", signature));
        let delivery = Delivery::new(
            DeliveryType::GitHub,
            None,
            Some(String::from("push")),
            Some(signature_field),
            ContentType::JSON,
            Some(request_body),
        );
        assert!(hook.auth(&delivery));
    }

    /// Test payload authentication with crates from RustCrypto team: Valid signature
    #[cfg(feature = "crypto-use-rustcrypto")]
    #[test]
    fn payload_authentication_rustcrypto() {
        let secret = String::from("secret");
        let hook = Hook::new("*", Some(secret.clone()), |_: &Delivery| {});
        let payload = String::from(r#"{"zen": "Bazinga!"}"#);
        let request_body = payload.clone();
        let secret_bytes = secret.as_bytes();
        let request_bytes = request_body.as_bytes();
        let mut mac = HmacSha1::new_varkey(&secret_bytes).expect("Invalid key");
        mac.input(&request_bytes);
        let mut signature = String::new();
        mac.result()
            .code()
            .as_ref()
            .write_hex(&mut signature)
            .expect("Invalid signature");
        let signature_field = String::from(format!("sha1={}", signature));
        let delivery = Delivery::new(
            DeliveryType::GitHub,
            None,
            Some(String::from("push")),
            Some(signature_field),
            ContentType::JSON,
            Some(request_body),
        );
        assert!(hook.auth(&delivery));
        //assert!(true);
    }

    /// Test payload authentication: Invalid signature
    #[test]
    fn payload_authentication_fail() {
        let secret = String::from("secret");
        let hook = Hook::new("*", Some(secret.clone()), |_: &Delivery| {});
        let payload = String::from(r#"{"zen": "Another test!"}"#);
        let request_body = payload.clone();
        let signature = String::from("sha1=ec760ee6d10bf638089f078b5a0c23f6575821e7");
        let delivery = Delivery::new(
            DeliveryType::GitHub,
            None,
            Some(String::from("push")),
            Some(signature),
            ContentType::JSON,
            Some(request_body),
        );
        assert_eq!(hook.auth(&delivery), false);
    }
}