use axum::{
    extract::FromRequestParts,
    http::request::Parts,
    response::{IntoResponse, Redirect, Response},
    RequestPartsExt,
};
use diesel::{
    associations::Identifiable,
    deserialize::Queryable,
    dsl::{insert_into, AsSelect, Eq, Select},
    pg::Pg,
    prelude::*,
    Selectable,
};
use uuid::Uuid;

use crate::{app_error::AppError, app_state::AppState, auth::AuthInfo, schema::users::dsl::*};

#[derive(Clone, Debug, Identifiable, Insertable, Queryable, Selectable)]
#[diesel(table_name = crate::schema::users)]
#[diesel(check_for_backend(Pg))]
pub struct User {
    pub id: Uuid,
    pub uid: String,
    pub email: String,
}

impl User {
    pub fn all() -> Select<users, AsSelect<User, Pg>> {
        users.select(User::as_select())
    }

    pub fn with_uid(uid_value: &str) -> Eq<uid, &str> {
        uid.eq(uid_value)
    }
}

#[derive(Clone, Debug)]
pub struct CurrentUser(pub User);

impl FromRequestParts<AppState> for CurrentUser {
    type Rejection = CurrentUserRejection;

    async fn from_request_parts(
        parts: &mut Parts,
        state: &AppState,
    ) -> Result<Self, <Self as FromRequestParts<AppState>>::Rejection> {
        let auth_info = parts
            .extract_with_state::<AuthInfo, AppState>(state)
            .await
            .map_err(|_| CurrentUserRejection::AuthRequired(state.settings.base_path.clone()))?;
        let current_user = state
            .db_pool
            .get()
            .await
            .map_err(|err| CurrentUserRejection::InternalServerError(err.into()))?
            .interact(move |conn| {
                let maybe_current_user = User::all()
                    .filter(User::with_uid(&auth_info.sub))
                    .first(conn)
                    .optional()?;
                if let Some(current_user) = maybe_current_user {
                    return Ok(current_user);
                }
                let new_user = User {
                    id: Uuid::now_v7(),
                    uid: auth_info.sub,
                    email: auth_info.email,
                };
                insert_into(users)
                    .values(new_user)
                    .on_conflict(uid)
                    .do_nothing()
                    .returning(User::as_returning())
                    .get_result(conn)
            })
            .await
            .unwrap()
            .map_err(|err| CurrentUserRejection::InternalServerError(err.into()))?;
        Ok(CurrentUser(current_user))
    }
}

pub enum CurrentUserRejection {
    AuthRequired(String),
    InternalServerError(AppError),
}

impl IntoResponse for CurrentUserRejection {
    fn into_response(self) -> Response {
        match self {
            Self::AuthRequired(base_path) => {
                Redirect::to(&format!("{}/auth/login", base_path)).into_response()
            }
            Self::InternalServerError(err) => err.into_response(),
        }
    }
}