use uuid::Uuid;
use diesel::prelude::*;
use diesel::result::Error as DieselError;
use diesel_derive_enum::DbEnum;
use rocket::{State, request::{FromRequest, Request, Outcome}};
use serde::{Serialize, Deserialize};
use chrono::serde::ts_seconds;
use chrono::prelude::{DateTime, Utc};
use chrono::Duration;
// TODO: Maybe just use argon2 crate directly
use djangohashers::{make_password_with_algorithm, check_password, HasherError, Algorithm};
use jsonwebtoken::{
    encode, decode,
    Header, Validation,
    Algorithm as JwtAlgorithm, EncodingKey, DecodingKey,
    errors::Result as JwtResult,
    errors::ErrorKind as JwtErrorKind
};

use crate::schema::*;
use crate::DbConn;
use crate::config::Config;
use crate::models::errors::ErrorResponse;


const BEARER: &'static str = "Bearer ";
const AUTH_HEADER: &'static str = "Authentication";


#[derive(Debug, DbEnum, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum Role {
    Admin,
    ZoneAdmin,
}

// TODO: Store Uuid instead of string??
// TODO: Store role as Role and not String.
#[derive(Debug, Queryable, Identifiable, Insertable)]
#[table_name = "user"]
pub struct User {
    pub id: String,
    pub role: String,
}

#[derive(Debug, Queryable, Identifiable, Insertable)]
#[table_name = "localuser"]
#[primary_key(user_id)]
pub struct LocalUser {
    pub user_id: String,
    pub username: String,
    pub password: String,
}

#[derive(Debug, Deserialize)]
pub struct CreateUserRequest {
    pub username: String,
    pub password: String,
    pub email: String,
    pub role: Option<Role>
}

// pub struct LdapUserAssociation {
//     user_id: Uuid,
//     ldap_id: String
// }

#[derive(Debug, Serialize, Deserialize)]
pub struct AuthClaims {
    pub jti: String,
    pub sub: String,
    #[serde(with = "ts_seconds")]
    pub exp: DateTime<Utc>,
    #[serde(with = "ts_seconds")]
    pub iat: DateTime<Utc>,
}

#[derive(Debug, Serialize)]
pub struct AuthTokenResponse {
    pub token: String
}

#[derive(Debug, Deserialize)]
pub struct AuthTokenRequest {
    pub username: String,
    pub password: String,
}

#[derive(Debug)]
pub struct UserInfo {
    pub id: String,
    pub role: String,
    pub username: String,
}

#[rocket::async_trait]
impl<'r> FromRequest<'r> for UserInfo {
    type Error = ErrorResponse;

    async fn from_request(request: &'r Request<'_>) -> Outcome<Self, Self::Error> {
        let auth_header = match request.headers().get_one(AUTH_HEADER) {
            None => return Outcome::Forward(()),
            Some(auth_header) => auth_header,
        };

        let token = if auth_header.starts_with(BEARER) {
            auth_header.trim_start_matches(BEARER)
        } else {
            return ErrorResponse::from(UserError::MalformedHeader).into()
        };

        // TODO: Better error handling
        let config = request.guard::<State<Config>>().await.unwrap();
        let conn = request.guard::<DbConn>().await.unwrap();

        let token_data = AuthClaims::decode(
            token, &config.web_app.secret
        ).map_err(|e| match e.into_kind() {
            JwtErrorKind::ExpiredSignature => UserError::ExpiredToken,
            _ => UserError::BadToken,
        });

        let token_data = match token_data {
            Err(e) => return ErrorResponse::from(e).into(),
            Ok(data) => data
        };

        let user_id = token_data.sub;

        conn.run(|c| {
            match LocalUser::get_user_by_uuid(c, user_id) {
                Err(UserError::NotFound) => ErrorResponse::from(UserError::NotFound).into(),
                Err(e) => ErrorResponse::from(e).into(),
                Ok(d) => Outcome::Success(d),
            }
        }).await
    }
}

#[derive(Debug)]
pub enum UserError {
    NotFound,
    UserExists,
    BadToken,
    ExpiredToken,
    MalformedHeader,
    PermissionDenied,
    DbError(DieselError),
    PasswordError(HasherError),
}

impl From<DieselError> for UserError {
    fn from(e: DieselError) -> Self {
        match e {
            DieselError::NotFound => UserError::NotFound,
            DieselError::DatabaseError(diesel::result::DatabaseErrorKind::UniqueViolation, _) => UserError::UserExists,
            other => UserError::DbError(other)
        }
    }
}

impl From<HasherError> for UserError {
    fn from(e: HasherError) -> Self {
        match e {
            other => UserError::PasswordError(other)
        }
    }
}

impl LocalUser {
    pub fn create_user(conn: &diesel::SqliteConnection, user_request: CreateUserRequest) -> Result<UserInfo, UserError> {
        use crate::schema::localuser::dsl::*;
        use crate::schema::user::dsl::*;

        let new_user_id = Uuid::new_v4().to_simple().to_string();

        let new_user = User {
            id: new_user_id.clone(),
            // TODO: Use role from request
            role: "zoneadmin".into(),
        };

        let new_localuser = LocalUser {
            user_id: new_user_id.clone(),
            username: user_request.username.clone(),
            password: make_password_with_algorithm(&user_request.password, Algorithm::Argon2),
        };

        let res = UserInfo {
            id: new_user.id.clone(),
            role: new_user.role.clone(),
            username: new_localuser.username.clone(),
        };

        conn.immediate_transaction(|| -> diesel::QueryResult<()> {
            diesel::insert_into(user)
                .values(new_user)
                .execute(conn)?;

            diesel::insert_into(localuser)
                .values(new_localuser)
                .execute(conn)?;

            Ok(())
        })?;

        Ok(res)
    }

    pub fn get_user_by_creds(
        conn: &diesel::SqliteConnection,
        request_username: &str,
        request_password: &str
    ) ->  Result<UserInfo, UserError> {

        use crate::schema::localuser::dsl::*;
        use crate::schema::user::dsl::*;

        let (client_user, client_localuser): (User, LocalUser) = user.inner_join(localuser)
            .filter(username.eq(request_username))
            .get_result(conn)?;

        if !check_password(&request_password, &client_localuser.password)? {
            return Err(UserError::NotFound);
        }

        Ok(UserInfo {
            id: client_user.id,
            role: client_user.role,
            username: client_localuser.username,
        })
    }

    pub fn get_user_by_uuid(conn: &diesel::SqliteConnection, request_user_id: String) -> Result<UserInfo, UserError> {
        use crate::schema::localuser::dsl::*;
        use crate::schema::user::dsl::*;

        let (client_user, client_localuser): (User, LocalUser) = user.inner_join(localuser)
            .filter(id.eq(request_user_id))
            .get_result(conn)?;

        Ok(UserInfo {
            id: client_user.id,
            role: client_user.role,
            username: client_localuser.username,
        })
    }

}

impl AuthClaims {
    pub fn new(user_info: &UserInfo, token_duration: Duration) -> AuthClaims {
        let jti = Uuid::new_v4().to_simple().to_string();
        let iat = Utc::now();
        let exp = iat + token_duration;

        AuthClaims {
            jti: jti,
            sub: user_info.id.clone(),
            exp: exp,
            iat: iat,
        }
    }

    pub fn decode(token: &str, secret: &str) -> JwtResult<AuthClaims> {
        decode::<AuthClaims>(
            token,
            &DecodingKey::from_secret(secret.as_ref()),
            &Validation::new(JwtAlgorithm::HS256)
        ).and_then(|data| Ok(data.claims))
    }

    pub fn encode(self, secret: &str) -> JwtResult<String> {
        encode(&Header::default(), &self, &EncodingKey::from_secret(secret.as_ref()))
    }
}