use crate::{errors::*, pragma::*};
use diesel::{connection::Connection, SqliteConnection};
use r2d2::{CustomizeConnection, ManageConnection, Pool};
use scheduled_thread_pool::ScheduledThreadPool;
use std::{
    sync::{
        atomic::{AtomicUsize, Ordering::SeqCst},
        Arc,
    },
    time::Duration,
};

lazy_static::lazy_static! {
    static ref DB_POOL: Arc<ScheduledThreadPool> = Arc::new(
        ScheduledThreadPool::with_name("db-pool-{}:", 4)
    );
}

pub struct ConnectionPool {
    pub(crate) inner: Pool<ConnectionManager>,
}

impl std::ops::Deref for ConnectionPool {
    type Target = Pool<ConnectionManager>;

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

impl ConnectionPool {
    pub fn new<T>(config: PoolConfig, uri: T) -> Result<Self>
    where
        T: Into<String>,
    {
        let manager = ConnectionManager::new(uri);
        let thread_pool = DB_POOL.clone();
        let config = Arc::new(config);
        let customizer_config = DatabaseCustomizerConfig::default();

        let pool = r2d2::Pool::builder()
            .thread_pool(thread_pool)
            .min_idle(Some(config.min_idle))
            .connection_customizer(Box::new(DatabaseCustomizer::new(customizer_config)))
            .max_size(config.max_size)
            .max_lifetime(None)
            .connection_timeout(config.connection_timeout)
            .idle_timeout(Some(config.idle_timeout))
            .build_unchecked(manager);
        Ok(ConnectionPool { inner: pool })
    }
}

pub type OnExecFunc = Box<dyn Fn() -> Box<dyn Fn(&SqliteConnection, &str)> + Send + Sync>;

pub struct PoolConfig {
    min_idle: u32,
    max_size: u32,
    connection_timeout: Duration,
    idle_timeout: Duration,
}

impl Default for PoolConfig {
    fn default() -> Self {
        Self {
            min_idle: 1,
            max_size: 10,
            connection_timeout: Duration::from_secs(10),
            idle_timeout: Duration::from_secs(5 * 60),
        }
    }
}

impl PoolConfig {
    #[allow(dead_code)]
    pub fn min_idle(mut self, min_idle: u32) -> Self {
        self.min_idle = min_idle;
        self
    }

    #[allow(dead_code)]
    pub fn max_size(mut self, max_size: u32) -> Self {
        self.max_size = max_size;
        self
    }
}

pub struct ConnectionManager {
    db_uri: String,
}

impl ManageConnection for ConnectionManager {
    type Connection = SqliteConnection;
    type Error = crate::Error;

    fn connect(&self) -> Result<Self::Connection> { Ok(SqliteConnection::establish(&self.db_uri)?) }

    fn is_valid(&self, conn: &mut Self::Connection) -> Result<()> { Ok(conn.execute("SELECT 1").map(|_| ())?) }

    fn has_broken(&self, _conn: &mut Self::Connection) -> bool { false }
}

impl ConnectionManager {
    pub fn new<S: Into<String>>(uri: S) -> Self { ConnectionManager { db_uri: uri.into() } }
}

#[derive(Debug)]
pub struct DatabaseCustomizerConfig {
    pub(crate) journal_mode: SQLiteJournalMode,
    pub(crate) synchronous: SQLiteSynchronous,
    pub(crate) busy_timeout: i32,
    pub(crate) secure_delete: bool,
}

impl Default for DatabaseCustomizerConfig {
    fn default() -> Self {
        Self {
            journal_mode: SQLiteJournalMode::WAL,
            synchronous: SQLiteSynchronous::NORMAL,
            busy_timeout: 5000,
            secure_delete: true,
        }
    }
}

#[derive(Debug)]
struct DatabaseCustomizer {
    config: DatabaseCustomizerConfig,
}

impl DatabaseCustomizer {
    fn new(config: DatabaseCustomizerConfig) -> Self
    where
        Self: Sized,
    {
        Self { config }
    }
}

impl CustomizeConnection<SqliteConnection, crate::Error> for DatabaseCustomizer {
    fn on_acquire(&self, conn: &mut SqliteConnection) -> Result<()> {
        conn.pragma_set_busy_timeout(self.config.busy_timeout)?;
        if self.config.journal_mode != SQLiteJournalMode::WAL {
            conn.pragma_set_journal_mode(self.config.journal_mode, None)?;
        }
        conn.pragma_set_synchronous(self.config.synchronous, None)?;

        Ok(())
    }
}