use std::ops::Deref;

use argon2::{password_hash::SaltString, Argon2, PasswordHasher};
use rocket::{
    async_trait,
    http::Status,
    request::{self, FromRequest, Outcome},
    Request,
};
use serde::{Deserialize, Serialize};
use sqlx::{FromRow, SqlitePool};

#[derive(FromRow, Debug, Serialize, Deserialize)]
pub struct User {
    pub id: i64,
    pub name: String,
    pw: Option<String>,
    pub is_cox: bool,
    pub is_admin: bool,
    pub is_guest: bool,
    #[serde(default = "bool::default")]
    deleted: bool,
}

#[derive(Debug)]
pub enum LoginError {
    InvalidAuthenticationCombo,
    NotLoggedIn,
    NotAnAdmin,
    NotACox,
    NoPasswordSet(User),
    DeserializationError,
}

impl User {
    pub async fn find_by_id(db: &SqlitePool, id: i32) -> Option<Self> {
        sqlx::query_as!(
            User,
            "
SELECT id, name, pw, is_cox, is_admin, is_guest, deleted
FROM user 
WHERE id like ?
        ",
            id
        )
        .fetch_one(db)
        .await
        .ok()
    }

    pub async fn find_by_name(db: &SqlitePool, name: String) -> Option<Self> {
        sqlx::query_as!(
            User,
            "
SELECT id, name, pw, is_cox, is_admin, is_guest, deleted
FROM user 
WHERE name like ?
        ",
            name
        )
        .fetch_one(db)
        .await
        .ok()
    }

    pub async fn all(db: &SqlitePool) -> Vec<Self> {
        sqlx::query_as!(
            User,
            "
SELECT id, name, pw, is_cox, is_admin, is_guest, deleted
FROM user
WHERE deleted = 0
ORDER BY name
        "
        )
        .fetch_all(db)
        .await
        .unwrap() //TODO: fixme
    }

    pub async fn create(db: &SqlitePool, name: String, is_guest: bool) -> bool {
        sqlx::query!(
            "INSERT INTO USER(name, is_guest) VALUES (?,?)",
            name,
            is_guest,
        )
        .execute(db)
        .await
        .is_ok()
    }

    pub async fn update(&self, db: &SqlitePool, is_cox: bool, is_admin: bool, is_guest: bool) {
        sqlx::query!(
            "UPDATE user SET is_cox = ?, is_admin = ?, is_guest = ? where id = ?",
            is_cox,
            is_admin,
            is_guest,
            self.id
        )
        .execute(db)
        .await
        .unwrap(); //Okay, because we can only create a User of a valid id
    }

    pub async fn login(db: &SqlitePool, name: String, pw: String) -> Result<Self, LoginError> {
        let Some(user) = User::find_by_name(db, name).await else {
            return Err(LoginError::InvalidAuthenticationCombo); // Username not found
        };

        if user.deleted {
            return Err(LoginError::InvalidAuthenticationCombo); //User existed sometime ago; has
                                                                //been deleted
        }

        match user.pw.clone() {
            Some(user_pw) => {
                let password_hash = Self::get_hashed_pw(&pw);
                if password_hash == user_pw {
                    return Ok(user);
                }

                Err(LoginError::InvalidAuthenticationCombo)
            }
            None => Err(LoginError::NoPasswordSet(user)),
        }
    }

    pub async fn reset_pw(&self, db: &SqlitePool) {
        sqlx::query!("UPDATE user SET pw = null where id = ?", self.id)
            .execute(db)
            .await
            .unwrap(); //Okay, because we can only create a User of a valid id
    }

    pub async fn update_pw(&self, db: &SqlitePool, pw: String) {
        let pw = Self::get_hashed_pw(&pw);
        sqlx::query!("UPDATE user SET pw = ? where id = ?", pw, self.id)
            .execute(db)
            .await
            .unwrap(); //Okay, because we can only create a User of a valid id
    }

    fn get_hashed_pw(pw: &str) -> String {
        let salt = SaltString::from_b64("dS/X5/sPEKTj4Rzs/CuvzQ").unwrap();
        let argon2 = Argon2::default();
        argon2
            .hash_password(pw.as_bytes(), &salt)
            .unwrap()
            .to_string()
    }

    pub async fn delete(&self, db: &SqlitePool) {
        sqlx::query!("UPDATE user SET deleted=1 WHERE id=?", self.id)
            .execute(db)
            .await
            .unwrap(); //Okay, because we can only create a User of a valid id
    }
}

#[async_trait]
impl<'r> FromRequest<'r> for User {
    type Error = LoginError;

    async fn from_request(req: &'r Request<'_>) -> request::Outcome<Self, Self::Error> {
        match req.cookies().get_private("loggedin_user") {
            Some(user) => match serde_json::from_str(user.value()) {
                Ok(user) => Outcome::Success(user),
                Err(_) => {
                    Outcome::Failure((Status::Unauthorized, LoginError::DeserializationError))
                }
            },
            None => Outcome::Failure((Status::Unauthorized, LoginError::NotLoggedIn)),
        }
    }
}

pub struct CoxUser {
    user: User,
}

impl Deref for CoxUser {
    type Target = User;

    fn deref(&self) -> &Self::Target {
        &self.user
    }
}

impl TryFrom<User> for CoxUser {
    type Error = LoginError;

    fn try_from(user: User) -> Result<Self, Self::Error> {
        if user.is_cox {
            Ok(CoxUser { user })
        } else {
            Err(LoginError::NotACox)
        }
    }
}

#[async_trait]
impl<'r> FromRequest<'r> for CoxUser {
    type Error = LoginError;

    async fn from_request(req: &'r Request<'_>) -> request::Outcome<Self, Self::Error> {
        match User::from_request(req).await {
            Outcome::Success(user) => match user.try_into() {
                Ok(user) => Outcome::Success(user),
                Err(_) => Outcome::Failure((Status::Unauthorized, LoginError::NotACox)),
            },
            Outcome::Failure(f) => Outcome::Failure(f),
            Outcome::Forward(f) => Outcome::Forward(f),
        }
    }
}

#[derive(Debug, Serialize, Deserialize)]
pub struct AdminUser {
    pub(crate) user: User,
}

impl TryFrom<User> for AdminUser {
    type Error = LoginError;

    fn try_from(user: User) -> Result<Self, Self::Error> {
        if user.is_admin {
            Ok(AdminUser { user })
        } else {
            Err(LoginError::NotAnAdmin)
        }
    }
}

#[async_trait]
impl<'r> FromRequest<'r> for AdminUser {
    type Error = LoginError;

    async fn from_request(req: &'r Request<'_>) -> request::Outcome<Self, Self::Error> {
        match User::from_request(req).await {
            Outcome::Success(user) => match user.try_into() {
                Ok(user) => Outcome::Success(user),
                Err(_) => Outcome::Failure((Status::Unauthorized, LoginError::NotAnAdmin)),
            },
            Outcome::Failure(f) => Outcome::Failure(f),
            Outcome::Forward(f) => Outcome::Forward(f),
        }
    }
}

#[cfg(test)]
mod test {
    use crate::testdb;

    use super::User;
    use sqlx::SqlitePool;

    #[sqlx::test]
    fn test_find_correct_id() {
        let pool = testdb!();
        let user = User::find_by_id(&pool, 1).await.unwrap();
        assert_eq!(user.id, 1);
    }

    #[sqlx::test]
    fn test_find_wrong_id() {
        let pool = testdb!();
        let user = User::find_by_id(&pool, 1337).await;
        assert!(user.is_none());
    }

    #[sqlx::test]
    fn test_find_correct_name() {
        let pool = testdb!();
        let user = User::find_by_name(&pool, "admin".into()).await.unwrap();
        assert_eq!(user.id, 1);
    }

    #[sqlx::test]
    fn test_find_wrong_name() {
        let pool = testdb!();
        let user = User::find_by_name(&pool, "name-does-not-exist".into()).await;
        assert!(user.is_none());
    }

    #[sqlx::test]
    fn test_all() {
        let pool = testdb!();
        let res = User::all(&pool).await;
        assert!(res.len() > 3);
    }

    #[sqlx::test]
    fn test_succ_create() {
        let pool = testdb!();

        assert_eq!(
            User::create(&pool, "new-user-name".into(), false).await,
            true
        );
    }

    #[sqlx::test]
    fn test_duplicate_name_create() {
        let pool = testdb!();

        assert_eq!(User::create(&pool, "admin".into(), false).await, false);
    }

    #[sqlx::test]
    fn test_update() {
        let pool = testdb!();

        let user = User::find_by_id(&pool, 1).await.unwrap();
        user.update(&pool, false, false, false).await;

        let user = User::find_by_id(&pool, 1).await.unwrap();
        assert_eq!(user.is_admin, false);
    }

    #[sqlx::test]
    fn succ_login_with_test_db() {
        let pool = testdb!();
        User::login(&pool, "admin".into(), "admin".into())
            .await
            .unwrap();
    }

    #[sqlx::test]
    fn wrong_pw() {
        let pool = testdb!();
        assert!(User::login(&pool, "admin".into(), "admi".into())
            .await
            .is_err());
    }

    #[sqlx::test]
    fn wrong_username() {
        let pool = testdb!();
        assert!(User::login(&pool, "admi".into(), "admin".into())
            .await
            .is_err());
    }

    #[sqlx::test]
    fn reset() {
        let pool = testdb!();
        let user = User::find_by_id(&pool, 1).await.unwrap();

        user.reset_pw(&pool).await;

        let user = User::find_by_id(&pool, 1).await.unwrap();
        assert_eq!(user.pw, None);
    }

    #[sqlx::test]
    fn update_pw() {
        let pool = testdb!();
        let user = User::find_by_id(&pool, 1).await.unwrap();

        assert!(User::login(&pool, "admin".into(), "abc".into())
            .await
            .is_err());

        user.update_pw(&pool, "abc".into()).await;

        User::login(&pool, "admin".into(), "abc".into())
            .await
            .unwrap();
    }
}