use argon2::{
    password_hash::{PasswordHash, PasswordVerifier},
    Argon2,
};
use axum::{
    extract::State,
    http::StatusCode,
    response::{IntoResponse, Redirect, Response},
    Form,
};
use serde::{Deserialize, Serialize};
use sqlx::SqlitePool;

use crate::{AuthContext, LoginPage, LogoutPage, LogoutSuccess, User};

//-************************************************************************
// Constants
//-************************************************************************

//-************************************************************************
// Login error and success types
//-************************************************************************

#[Error]
pub struct LoginError(#[from] LoginErrorKind);

#[Error]
#[non_exhaustive]
pub enum LoginErrorKind {
    Internal,
    BadPassword,
    Unknown,
}

impl IntoResponse for LoginError {
    fn into_response(self) -> Response {
        match self.0 {
            LoginErrorKind::Internal => (
                StatusCode::INTERNAL_SERVER_ERROR,
                "An unknown error occurred; you cursed, brah?",
            )
                .into_response(),
            LoginErrorKind::Unknown => (StatusCode::OK, "Not successful.").into_response(),
            _ => (StatusCode::OK, format!("{self}")).into_response(),
        }
    }
}

// for receiving form submissions
#[derive(Debug, Default, Deserialize, Serialize, PartialEq, Eq)]
pub struct LoginPostForm {
    pub username: String,
    pub password: String,
}

//-************************************************************************
// Login handlers
//-************************************************************************

/// Handle login queries
#[axum::debug_handler]
pub async fn post_login(
    mut auth: AuthContext,
    State(pool): State<SqlitePool>,
    Form(login): Form<LoginPostForm>,
) -> Result<impl IntoResponse, LoginError> {
    let username = &login.username;
    let username = username.trim();

    let pw = &login.password;
    let pw = pw.trim();

    let user = User::try_get(username, &pool)
        .await
        .map_err(|_| LoginErrorKind::Unknown)?;

    let verifier = Argon2::default();
    let hash = PasswordHash::new(&user.pwhash).map_err(|_| LoginErrorKind::Internal)?;
    match verifier.verify_password(pw.as_bytes(), &hash) {
        Ok(_) => {
            // log them in and set a session cookie
            auth.login(&user)
                .await
                .map_err(|_| LoginErrorKind::Internal)?;

            Ok(Redirect::to("/"))
        }
        _ => Err(LoginErrorKind::BadPassword.into()),
    }
}

pub async fn get_login() -> impl IntoResponse {
    LoginPage::default()
}

pub async fn get_logout() -> impl IntoResponse {
    LogoutPage
}

pub async fn post_logout(mut auth: AuthContext) -> impl IntoResponse {
    if auth.current_user.is_some() {
        auth.logout().await;
    }
    LogoutSuccess
}

#[cfg(test)]
mod test {
    use crate::{
        templates::{LoginPage, LogoutPage, LogoutSuccess, MainPage},
        test_utils::{get_test_user, massage, server, FORM_CONTENT_TYPE},
    };

    const LOGIN_FORM: &str = "username=test_user&password=a";

    #[tokio::test]
    async fn get_login() {
        let s = server().await;
        let resp = s.get("/login").await;
        let body = std::str::from_utf8(resp.bytes()).unwrap().to_string();
        assert_eq!(body, LoginPage::default().to_string());
    }

    #[tokio::test]
    async fn post_login_success() {
        let s = server().await;

        let body = massage(LOGIN_FORM);

        let resp = s
            .post("/login")
            .expect_failure()
            .content_type(FORM_CONTENT_TYPE)
            .bytes(body)
            .await;
        assert_eq!(resp.status_code(), 303);
    }

    #[tokio::test]
    async fn post_login_bad_user() {
        let s = server().await;

        let form = "username=test_LOSER&password=aaaa";
        let body = massage(form);

        let resp = s
            .post("/login")
            .expect_success()
            .content_type(FORM_CONTENT_TYPE)
            .bytes(body)
            .await;
        assert_eq!(resp.status_code(), 200);
    }

    #[tokio::test]
    async fn post_login_bad_password() {
        let s = server().await;

        let form = "username=test_user&password=bbbb";
        let body = massage(form);

        let resp = s
            .post("/login")
            .expect_success()
            .content_type(FORM_CONTENT_TYPE)
            .bytes(body)
            .await;
        assert_eq!(resp.status_code(), 200);
    }

    #[tokio::test]
    async fn get_logout() {
        let s = server().await;
        let resp = s.get("/logout").await;
        let body = std::str::from_utf8(resp.bytes()).unwrap().to_string();
        assert_eq!(body, LogoutPage.to_string());
    }

    #[tokio::test]
    async fn post_logout_not_logged_in() {
        let s = server().await;
        let resp = s.post("/logout").await;
        resp.assert_status_ok();
        let body = std::str::from_utf8(resp.bytes()).unwrap();
        let default = LogoutSuccess.to_string();
        assert_eq!(body, &default);
    }

    #[tokio::test]
    async fn post_logout_logged_in() {
        let s = server().await;

        // log in and prove it
        {
            let body = massage(LOGIN_FORM);
            let resp = s
                .post("/login")
                .expect_failure()
                .content_type(FORM_CONTENT_TYPE)
                .bytes(body)
                .await;
            assert_eq!(resp.status_code(), 303);

            let logged_in = MainPage {
                user: Some(get_test_user()),
            }
            .to_string();

            let main_page = s.get("/").await;
            let body = std::str::from_utf8(main_page.bytes()).unwrap();
            assert_eq!(&logged_in, body);
        }

        let resp = s.post("/logout").await;
        let body = std::str::from_utf8(resp.bytes()).unwrap();
        let default = LogoutSuccess.to_string();
        assert_eq!(body, &default);
    }
}