use anyhow::Result;
use async_session::{async_trait, Session, SessionStore};
use chrono::{DateTime, TimeDelta, Utc};
use diesel::{pg::Pg, prelude::*, upsert::excluded};

use crate::schema::browser_sessions::dsl::*;

#[derive(Clone, Debug, Identifiable, Queryable, Selectable)]
#[diesel(table_name = crate::schema::browser_sessions)]
#[diesel(check_for_backend(Pg))]
pub struct BrowserSession {
    pub id: String,
    pub serialized: String,
    pub last_seen_at: DateTime<Utc>,
}

#[derive(Clone)]
pub struct PgStore {
    pool: deadpool_diesel::postgres::Pool,
}

impl PgStore {
    pub fn new(pool: deadpool_diesel::postgres::Pool) -> PgStore {
        Self { pool }
    }
}

impl std::fmt::Debug for PgStore {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "PgStore")?;
        Ok(()).into()
    }
}

#[async_trait]
impl SessionStore for PgStore {
    async fn load_session(&self, cookie_value: String) -> Result<Option<Session>> {
        let session_id = Session::id_from_cookie_value(&cookie_value)?;
        let timestamp_stale = Utc::now() - TimeDelta::days(7);
        let conn = self.pool.get().await?;
        let row = conn
            .interact(move |conn| {
                // Drop all sessions without recent activity
                diesel::delete(browser_sessions.filter(last_seen_at.lt(timestamp_stale)))
                    .execute(conn)?;
                diesel::update(browser_sessions.filter(id.eq(session_id)))
                    .set(last_seen_at.eq(diesel::dsl::now))
                    .returning(BrowserSession::as_returning())
                    .get_result(conn)
                    .optional()
            })
            .await
            .unwrap()?;
        Ok(match row {
            Some(session) => Some(serde_json::from_str::<Session>(
                session.serialized.as_str(),
            )?),
            None => None,
        })
    }

    async fn store_session(&self, session: Session) -> Result<Option<String>> {
        let serialized_data = serde_json::to_string(&session)?;
        let session_id = session.id().to_string();
        let conn = self.pool.get().await?;
        conn.interact(move |conn| {
            diesel::insert_into(browser_sessions)
                .values((
                    id.eq(session_id),
                    serialized.eq(serialized_data),
                    last_seen_at.eq(diesel::dsl::now),
                ))
                .on_conflict(id)
                .do_update()
                .set((
                    serialized.eq(excluded(serialized)),
                    last_seen_at.eq(excluded(last_seen_at)),
                ))
                .execute(conn)
        })
        .await
        .unwrap()?;
        session.reset_data_changed();
        Ok(session.into_cookie_value())
    }

    async fn destroy_session(&self, session: Session) -> Result<()> {
        let conn = self.pool.get().await?;
        conn.interact(move |conn| {
            diesel::delete(browser_sessions.filter(id.eq(session.id().to_string()))).execute(conn)
        })
        .await
        .unwrap()?;
        Ok(())
    }

    async fn clear_store(&self) -> Result<()> {
        let conn = self.pool.get().await?;
        conn.interact(move |conn| diesel::delete(browser_sessions).execute(conn))
            .await
            .unwrap()?;
        Ok(())
    }
}