use actix_web::dev::{Service, ServiceRequest, ServiceResponse};
use actix_web::{HttpRequest, ResponseError};
use futures::future::Either;
use sha2::{Digest, Sha256, Sha512};
use std::future::{ready, Future};

use crate::errors::ContextualError;

#[derive(Clone, Debug)]
/// HTTP Basic authentication parameters
pub struct BasicAuthParams {
    pub username: String,
    pub password: String,
}

impl BasicAuthParams {
    fn try_from_request(req: &HttpRequest) -> actix_web::Result<Self> {
        use actix_web::http::header::Header;
        use actix_web_httpauth::headers::authorization::{Authorization, Basic};

        let auth = Authorization::<Basic>::parse(req)?.into_scheme();
        Ok(Self {
            username: auth.user_id().to_string(),
            password: auth.password().unwrap_or(&"".into()).to_string(),
        })
    }
}

#[derive(Clone, Debug, PartialEq)]
/// `password` field of `RequiredAuth`
pub enum RequiredAuthPassword {
    Plain(String),
    Sha256(Vec<u8>),
    Sha512(Vec<u8>),
}

#[derive(Clone, Debug, PartialEq)]
/// Authentication structure to match `BasicAuthParams` against
pub struct RequiredAuth {
    pub username: String,
    pub password: RequiredAuthPassword,
}

/// Return `true` if `basic_auth` is matches any of `required_auth`
pub fn match_auth(basic_auth: &BasicAuthParams, required_auth: &[RequiredAuth]) -> bool {
    required_auth
        .iter()
        .any(|RequiredAuth { username, password }| {
            basic_auth.username == *username && compare_password(&basic_auth.password, password)
        })
}

/// Return `true` if `basic_auth_pwd` meets `required_auth_pwd`'s requirement
pub fn compare_password(basic_auth_pwd: &str, required_auth_pwd: &RequiredAuthPassword) -> bool {
    match &required_auth_pwd {
        RequiredAuthPassword::Plain(required_password) => *basic_auth_pwd == *required_password,
        RequiredAuthPassword::Sha256(password_hash) => {
            compare_hash::<Sha256>(basic_auth_pwd, password_hash)
        }
        RequiredAuthPassword::Sha512(password_hash) => {
            compare_hash::<Sha512>(basic_auth_pwd, password_hash)
        }
    }
}

/// Return `true` if hashing of `password` by `T` algorithm equals to `hash`
pub fn compare_hash<T: Digest>(password: &str, hash: &[u8]) -> bool {
    get_hash::<T>(password) == hash
}

/// Get hash of a `text`
pub fn get_hash<T: Digest>(text: &str) -> Vec<u8> {
    let mut hasher = T::new();
    hasher.update(text);
    hasher.finalize().to_vec()
}
pub struct CurrentUser {
    pub name: String,
}

fn handle_auth(req: &HttpRequest) -> Result<(), ContextualError> {
    let required_auth = &req.app_data::<crate::MiniserveConfig>().unwrap().auth;

    if required_auth.is_empty() {
        // auth is disabled by configuration
        return Ok(());
    }

    match BasicAuthParams::try_from_request(req) {
        Ok(cred) => match match_auth(&cred, required_auth) {
            true => {
                req.extensions_mut().insert(CurrentUser {
                    name: cred.username,
                });
                Ok(())
            }
            false => Err(ContextualError::InvalidHttpCredentials),
        },
        Err(_) => Err(ContextualError::RequireHttpCredentials),
    }
}

pub fn auth_middleware<S>(
    mut req: ServiceRequest,
    srv: &S,
) -> impl Future<Output = actix_web::Result<ServiceResponse>> + 'static
where
    S: Service<ServiceRequest, Response = ServiceResponse, Error = actix_web::Error>,
    S::Future: 'static,
{
    match handle_auth(req.parts_mut().0) {
        Ok(_) => Either::Left(srv.call(req)),
        Err(err) => {
            let resp = req.into_response(err.error_response());
            Either::Right(ready(Ok(resp)))
        }
    }
}

#[rustfmt::skip]
#[cfg(test)]
mod tests {
    use super::*;
    use rstest::{rstest, fixture};
    use pretty_assertions::assert_eq;

    /// Return a hashing function corresponds to given name
    fn get_hash_func(name: &str) -> impl FnOnce(&str) -> Vec<u8> {
        match name {
            "sha256" => get_hash::<Sha256>,
            "sha512" => get_hash::<Sha512>,
            _ => panic!("Invalid hash method"),
        }
    }

    #[rstest(
        password, hash_method, hash,
        case("abc", "sha256", "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad"),
        case("abc", "sha512", "ddaf35a193617abacc417349ae20413112e6fa4e89a97ea20a9eeee64b55d39a2192992a274fc1a836ba3c23a3feebbd454d4423643ce80e2a9ac94fa54ca49f"),
    )]
    fn test_get_hash(password: &str, hash_method: &str, hash: &str) {
        let hash_func = get_hash_func(hash_method);
        let expected = hex::decode(hash).expect("Provided hash is not a valid hex code");
        let received = hash_func(&password.to_owned());
        assert_eq!(received, expected);
    }

    /// Helper function that creates a `RequiredAuth` structure and encrypt `password` if necessary
    fn create_required_auth(username: &str, password: &str, encrypt: &str) -> RequiredAuth {
        use RequiredAuthPassword::*;

        let password = match encrypt {
            "plain" => Plain(password.to_owned()),
            "sha256" => Sha256(get_hash::<sha2::Sha256>(&password.to_owned())),
            "sha512" => Sha512(get_hash::<sha2::Sha512>(&password.to_owned())),
            _ => panic!("Unknown encryption type"),
        };

        RequiredAuth {
            username: username.to_owned(),
            password,
        }
    }

    #[rstest(
        should_pass, param_username, param_password, required_username, required_password, encrypt,
        case(true, "obi", "hello there", "obi", "hello there", "plain"),
        case(false, "obi", "hello there", "obi", "hi!", "plain"),
        case(true, "obi", "hello there", "obi", "hello there", "sha256"),
        case(false, "obi", "hello there", "obi", "hi!", "sha256"),
        case(true, "obi", "hello there", "obi", "hello there", "sha512"),
        case(false, "obi", "hello there", "obi", "hi!", "sha512")
    )]
    fn test_single_auth(
        should_pass: bool,
        param_username: &str,
        param_password: &str,
        required_username: &str,
        required_password: &str,
        encrypt: &str,
    ) {
        assert_eq!(
            match_auth(
                &BasicAuthParams {
                    username: param_username.to_owned(),
                    password: param_password.to_owned(),
                },
                &[create_required_auth(required_username, required_password, encrypt)],
            ),
            should_pass,
        )
    }

    /// Helper function that creates a sample of multiple accounts
    #[fixture]
    fn account_sample() -> Vec<RequiredAuth> {
        [
            ("usr0", "pwd0", "plain"),
            ("usr1", "pwd1", "plain"),
            ("usr2", "pwd2", "sha256"),
            ("usr3", "pwd3", "sha256"),
            ("usr4", "pwd4", "sha512"),
            ("usr5", "pwd5", "sha512"),
        ]
            .iter()
            .map(|(username, password, encrypt)| create_required_auth(username, password, encrypt))
            .collect()
    }

    #[rstest(
        username, password,
        case("usr0", "pwd0"),
        case("usr1", "pwd1"),
        case("usr2", "pwd2"),
        case("usr3", "pwd3"),
        case("usr4", "pwd4"),
        case("usr5", "pwd5"),
    )]
    fn test_multiple_auth_pass(
        account_sample: Vec<RequiredAuth>,
        username: &str,
        password: &str,
    ) {
        assert!(match_auth(
            &BasicAuthParams {
                username: username.to_owned(),
                password: password.to_owned(),
            },
            &account_sample,
        ));
    }

    #[rstest]
    fn test_multiple_auth_wrong_username(account_sample: Vec<RequiredAuth>) {
        assert_eq!(match_auth(
            &BasicAuthParams {
                username: "unregistered user".to_owned(),
                password: "pwd0".to_owned(),
            },
            &account_sample,
        ), false);
    }

    #[rstest(
        username, password,
        case("usr0", "pwd5"),
        case("usr1", "pwd4"),
        case("usr2", "pwd3"),
        case("usr3", "pwd2"),
        case("usr4", "pwd1"),
        case("usr5", "pwd0"),
    )]
    fn test_multiple_auth_wrong_password(
        account_sample: Vec<RequiredAuth>,
        username: &str,
        password: &str,
    ) {
        assert_eq!(match_auth(
            &BasicAuthParams {
                username: username.to_owned(),
                password: password.to_owned(),
            },
            &account_sample,
        ), false);
    }
}