mod query_logger;

use std::{
    sync::{Arc, OnceLock},
    time::Duration,
};

use diesel::{
    connection::SimpleConnection,
    r2d2::{CustomizeConnection, Pool, PooledConnection},
    Connection, RunQueryDsl,
};

use rocket::{
    http::Status,
    request::{FromRequest, Outcome},
    Request,
};

use tokio::{
    sync::{Mutex, OwnedSemaphorePermit, Semaphore},
    time::timeout,
};

use crate::{
    error::{Error, MapResult},
    CONFIG,
};

// These changes are based on Rocket 0.5-rc wrapper of Diesel: https://github.com/SergioBenitez/Rocket/blob/v0.5-rc/contrib/sync_db_pools
// A wrapper around spawn_blocking that propagates panics to the calling code.
pub async fn run_blocking<F, R>(job: F) -> R
where
    F: FnOnce() -> R + Send + 'static,
    R: Send + 'static,
{
    match tokio::task::spawn_blocking(job).await {
        Ok(ret) => ret,
        Err(e) => match e.try_into_panic() {
            Ok(panic) => std::panic::resume_unwind(panic),
            Err(_) => unreachable!("spawn_blocking tasks are never cancelled"),
        },
    }
}

// This is used to generate the main DbConn and DbPool enums, which contain one variant for each database supported
#[derive(diesel::MultiConnection)]
pub enum DbConnInner {
    #[cfg(mysql)]
    Mysql(diesel::mysql::MysqlConnection),
    #[cfg(postgresql)]
    Postgresql(diesel::pg::PgConnection),
    #[cfg(sqlite)]
    Sqlite(diesel::sqlite::SqliteConnection),
}

/// Custom connection manager that implements manual connection establishment
pub struct DbConnManager {
    database_url: String,
}

impl DbConnManager {
    pub fn new(database_url: &str) -> Self {
        Self {
            database_url: database_url.to_string(),
        }
    }

    fn establish_connection(&self) -> Result<DbConnInner, diesel::r2d2::Error> {
        match DbConnType::from_url(&self.database_url) {
            #[cfg(mysql)]
            Ok(DbConnType::Mysql) => {
                let conn = diesel::mysql::MysqlConnection::establish(&self.database_url)?;
                Ok(DbConnInner::Mysql(conn))
            }
            #[cfg(postgresql)]
            Ok(DbConnType::Postgresql) => {
                let conn = diesel::pg::PgConnection::establish(&self.database_url)?;
                Ok(DbConnInner::Postgresql(conn))
            }
            #[cfg(sqlite)]
            Ok(DbConnType::Sqlite) => {
                let conn = diesel::sqlite::SqliteConnection::establish(&self.database_url)?;
                Ok(DbConnInner::Sqlite(conn))
            }

            Err(e) => Err(diesel::r2d2::Error::ConnectionError(diesel::ConnectionError::InvalidConnectionUrl(
                format!("Unable to estabilsh a connection: {e:?}"),
            ))),
        }
    }
}

impl diesel::r2d2::ManageConnection for DbConnManager {
    type Connection = DbConnInner;
    type Error = diesel::r2d2::Error;

    fn connect(&self) -> Result<Self::Connection, Self::Error> {
        self.establish_connection()
    }

    fn is_valid(&self, conn: &mut Self::Connection) -> Result<(), Self::Error> {
        use diesel::r2d2::R2D2Connection;
        conn.ping().map_err(diesel::r2d2::Error::QueryError)
    }

    fn has_broken(&self, conn: &mut Self::Connection) -> bool {
        use diesel::r2d2::R2D2Connection;
        conn.is_broken()
    }
}

#[derive(Eq, PartialEq)]
pub enum DbConnType {
    #[cfg(mysql)]
    Mysql,
    #[cfg(postgresql)]
    Postgresql,
    #[cfg(sqlite)]
    Sqlite,
}

pub static ACTIVE_DB_TYPE: OnceLock<DbConnType> = OnceLock::new();

pub struct DbConn {
    conn: Arc<Mutex<Option<PooledConnection<DbConnManager>>>>,
    permit: Option<OwnedSemaphorePermit>,
}

#[derive(Debug)]
pub struct DbConnOptions {
    pub init_stmts: String,
}

impl CustomizeConnection<DbConnInner, diesel::r2d2::Error> for DbConnOptions {
    fn on_acquire(&self, conn: &mut DbConnInner) -> Result<(), diesel::r2d2::Error> {
        if !self.init_stmts.is_empty() {
            conn.batch_execute(&self.init_stmts).map_err(diesel::r2d2::Error::QueryError)?;
        }
        Ok(())
    }
}

#[derive(Clone)]
pub struct DbPool {
    // This is an 'Option' so that we can drop the pool in a 'spawn_blocking'.
    pool: Option<Pool<DbConnManager>>,
    semaphore: Arc<Semaphore>,
}

impl Drop for DbConn {
    fn drop(&mut self) {
        let conn = Arc::clone(&self.conn);
        let permit = self.permit.take();

        // Since connection can't be on the stack in an async fn during an
        // await, we have to spawn a new blocking-safe thread...
        tokio::task::spawn_blocking(move || {
            // And then re-enter the runtime to wait on the async mutex, but in a blocking fashion.
            let mut conn = tokio::runtime::Handle::current().block_on(conn.lock_owned());

            if let Some(conn) = conn.take() {
                drop(conn);
            }

            // Drop permit after the connection is dropped
            drop(permit);
        });
    }
}

impl Drop for DbPool {
    fn drop(&mut self) {
        let pool = self.pool.take();
        // Only use spawn_blocking if the Tokio runtime is still available
        // Otherwise the pool will be dropped on the current thread
        if let Ok(handle) = tokio::runtime::Handle::try_current() {
            handle.spawn_blocking(move || drop(pool));
        }
    }
}

impl DbPool {
    // For the given database URL, guess its type, run migrations, create pool, and return it
    pub fn from_config() -> Result<Self, Error> {
        let db_url = CONFIG.database_url();
        let conn_type = DbConnType::from_url(&db_url)?;

        // Only set the default instrumentation if the log level is specifically set to either warn, info or debug
        if log_enabled!(target: "vaultwarden::db::query_logger", log::Level::Warn)
            || log_enabled!(target: "vaultwarden::db::query_logger", log::Level::Info)
            || log_enabled!(target: "vaultwarden::db::query_logger", log::Level::Debug)
        {
            drop(diesel::connection::set_default_instrumentation(query_logger::simple_logger));
        }

        match conn_type {
            #[cfg(mysql)]
            DbConnType::Mysql => {
                mysql_migrations::run_migrations(&db_url)?;
            }
            #[cfg(postgresql)]
            DbConnType::Postgresql => {
                postgresql_migrations::run_migrations(&db_url)?;
            }
            #[cfg(sqlite)]
            DbConnType::Sqlite => {
                sqlite_migrations::run_migrations(&db_url)?;
            }
        }

        let max_conns = CONFIG.database_max_conns();
        let manager = DbConnManager::new(&db_url);
        let pool = Pool::builder()
            .max_size(max_conns)
            .min_idle(Some(CONFIG.database_min_conns()))
            .idle_timeout(Some(Duration::from_secs(CONFIG.database_idle_timeout())))
            .connection_timeout(Duration::from_secs(CONFIG.database_timeout()))
            .connection_customizer(Box::new(DbConnOptions {
                init_stmts: conn_type.get_init_stmts(),
            }))
            .build(manager)
            .map_res("Failed to create pool")?;

        // Set a global to determine the database more easily throughout the rest of the code
        if ACTIVE_DB_TYPE.set(conn_type).is_err() {
            error!("Tried to set the active database connection type more than once.")
        }

        Ok(DbPool {
            pool: Some(pool),
            semaphore: Arc::new(Semaphore::new(max_conns as usize)),
        })
    }

    // Get a connection from the pool
    pub async fn get(&self) -> Result<DbConn, Error> {
        let duration = Duration::from_secs(CONFIG.database_timeout());
        let permit = match timeout(duration, Arc::clone(&self.semaphore).acquire_owned()).await {
            Ok(p) => p.expect("Semaphore should be open"),
            Err(_) => {
                err!("Timeout waiting for database connection");
            }
        };

        let p = self.pool.as_ref().expect("DbPool.pool should always be Some()");
        let pool = p.clone();
        let c =
            run_blocking(move || pool.get_timeout(duration)).await.map_res("Error retrieving connection from pool")?;
        Ok(DbConn {
            conn: Arc::new(Mutex::new(Some(c))),
            permit: Some(permit),
        })
    }
}

impl DbConnType {
    pub fn from_url(url: &str) -> Result<Self, Error> {
        // Mysql
        if url.len() > 6 && &url[..6] == "mysql:" {
            #[cfg(mysql)]
            return Ok(DbConnType::Mysql);

            #[cfg(not(mysql))]
            err!("`DATABASE_URL` is a MySQL URL, but the 'mysql' feature is not enabled")

        // Postgresql
        } else if url.len() > 11 && (&url[..11] == "postgresql:" || &url[..9] == "postgres:") {
            #[cfg(postgresql)]
            return Ok(DbConnType::Postgresql);

            #[cfg(not(postgresql))]
            err!("`DATABASE_URL` is a PostgreSQL URL, but the 'postgresql' feature is not enabled")

        //Sqlite
        } else {
            #[cfg(sqlite)]
            return Ok(DbConnType::Sqlite);

            #[cfg(not(sqlite))]
            err!("`DATABASE_URL` looks like a SQLite URL, but 'sqlite' feature is not enabled")
        }
    }

    pub fn get_init_stmts(&self) -> String {
        let init_stmts = CONFIG.database_conn_init();
        if !init_stmts.is_empty() {
            init_stmts
        } else {
            self.default_init_stmts()
        }
    }

    pub fn default_init_stmts(&self) -> String {
        match self {
            #[cfg(mysql)]
            Self::Mysql => String::new(),
            #[cfg(postgresql)]
            Self::Postgresql => String::new(),
            #[cfg(sqlite)]
            Self::Sqlite => "PRAGMA busy_timeout = 5000; PRAGMA synchronous = NORMAL;".to_string(),
        }
    }
}

impl DbConn {
    pub async fn run<F, R>(&self, f: F) -> R
    where
        F: FnOnce(&mut DbConnInner) -> R + Send,
        R: Send + 'static,
    {
        let conn = Arc::clone(&self.conn);
        let mut conn = conn.lock_owned().await;
        let conn = conn.as_mut().expect("Internal invariant broken: self.conn is Some");

        // Run blocking can't be used due to the 'static limitation, use block_in_place instead
        tokio::task::block_in_place(move || f(conn))
    }
}

#[macro_export]
macro_rules! db_run {
    ( $conn:ident: $body:block ) => {
        $conn.run(move |$conn| $body).await
    };

    ( $conn:ident: $( $($db:ident),+ $body:block )+ ) => {
        $conn.run(move |$conn| {
            match $conn {
                $($(
                #[cfg($db)]
                pastey::paste!(&mut $crate::db::DbConnInner::[<$db:camel>](ref mut $conn)) => {
                    $body
                },
            )+)+}
        }).await
    };
}

pub mod schema;

// Reexport the models, needs to be after the macros are defined so it can access them
pub mod models;

/// Creates a back-up of the sqlite database
/// MySQL/MariaDB and PostgreSQL are not supported.
#[cfg(sqlite)]
pub fn backup_sqlite() -> Result<String, Error> {
    use diesel::Connection;
    use std::{fs::File, io::Write};

    let db_url = CONFIG.database_url();
    if DbConnType::from_url(&CONFIG.database_url()).map(|t| t == DbConnType::Sqlite).unwrap_or(false) {
        // Since we do not allow any schema for sqlite database_url's like `file:` or `sqlite:` to be set, we can assume here it isn't
        // This way we can set a readonly flag on the opening mode without issues.
        let mut conn = diesel::sqlite::SqliteConnection::establish(&format!("sqlite://{db_url}?mode=ro"))?;

        let db_path = std::path::Path::new(&db_url).parent().unwrap();
        let backup_file = db_path
            .join(format!("db_{}.sqlite3", chrono::Utc::now().format("%Y%m%d_%H%M%S")))
            .to_string_lossy()
            .into_owned();

        match File::create(backup_file.clone()) {
            Ok(mut f) => {
                let serialized_db = conn.serialize_database_to_buffer();
                f.write_all(serialized_db.as_slice()).expect("Error writing SQLite backup");
                Ok(backup_file)
            }
            Err(e) => {
                err_silent!(format!("Unable to save SQLite backup: {e:?}"))
            }
        }
    } else {
        err_silent!("The database type is not SQLite. Backups only works for SQLite databases")
    }
}

#[cfg(not(sqlite))]
pub fn backup_sqlite() -> Result<String, Error> {
    err_silent!("The database type is not SQLite. Backups only works for SQLite databases")
}

/// Get the SQL Server version
pub async fn get_sql_server_version(conn: &DbConn) -> String {
    db_run! { conn:
        postgresql,mysql {
            diesel::select(diesel::dsl::sql::<diesel::sql_types::Text>("version();"))
            .get_result::<String>(conn)
            .unwrap_or_else(|_| "Unknown".to_string())
        }
        sqlite {
            diesel::select(diesel::dsl::sql::<diesel::sql_types::Text>("sqlite_version();"))
            .get_result::<String>(conn)
            .unwrap_or_else(|_| "Unknown".to_string())
        }
    }
}

/// Attempts to retrieve a single connection from the managed database pool. If
/// no pool is currently managed, fails with an `InternalServerError` status. If
/// no connections are available, fails with a `ServiceUnavailable` status.
#[rocket::async_trait]
impl<'r> FromRequest<'r> for DbConn {
    type Error = ();

    async fn from_request(request: &'r Request<'_>) -> Outcome<Self, Self::Error> {
        match request.rocket().state::<DbPool>() {
            Some(p) => match p.get().await {
                Ok(dbconn) => Outcome::Success(dbconn),
                _ => Outcome::Error((Status::ServiceUnavailable, ())),
            },
            None => Outcome::Error((Status::InternalServerError, ())),
        }
    }
}

// Embed the migrations from the migrations folder into the application
// This way, the program automatically migrates the database to the latest version
// https://docs.rs/diesel_migrations/*/diesel_migrations/macro.embed_migrations.html
#[cfg(sqlite)]
mod sqlite_migrations {
    use diesel::{Connection, RunQueryDsl};
    use diesel_migrations::{EmbeddedMigrations, MigrationHarness};
    pub const MIGRATIONS: EmbeddedMigrations = embed_migrations!("migrations/sqlite");

    pub fn run_migrations(db_url: &str) -> Result<(), super::Error> {
        // Establish a connection to the sqlite database (this will create a new one, if it does
        // not exist, and exit if there is an error).
        let mut connection = diesel::sqlite::SqliteConnection::establish(db_url)?;

        // Run the migrations after successfully establishing a connection
        // Disable Foreign Key Checks during migration
        // Scoped to a connection.
        diesel::sql_query("PRAGMA foreign_keys = OFF")
            .execute(&mut connection)
            .expect("Failed to disable Foreign Key Checks during migrations");

        // Turn on WAL in SQLite
        if crate::CONFIG.enable_db_wal() {
            diesel::sql_query("PRAGMA journal_mode=wal").execute(&mut connection).expect("Failed to turn on WAL");
        }

        connection.run_pending_migrations(MIGRATIONS).expect("Error running migrations");
        Ok(())
    }
}

#[cfg(mysql)]
mod mysql_migrations {
    use diesel::{Connection, RunQueryDsl};
    use diesel_migrations::{EmbeddedMigrations, MigrationHarness};
    pub const MIGRATIONS: EmbeddedMigrations = embed_migrations!("migrations/mysql");

    pub fn run_migrations(db_url: &str) -> Result<(), super::Error> {
        // Make sure the database is up to date (create if it doesn't exist, or run the migrations)
        let mut connection = diesel::mysql::MysqlConnection::establish(db_url)?;

        // Disable Foreign Key Checks during migration
        // Scoped to a connection/session.
        diesel::sql_query("SET FOREIGN_KEY_CHECKS = 0")
            .execute(&mut connection)
            .expect("Failed to disable Foreign Key Checks during migrations");

        connection.run_pending_migrations(MIGRATIONS).expect("Error running migrations");
        Ok(())
    }
}

#[cfg(postgresql)]
mod postgresql_migrations {
    use diesel::Connection;
    use diesel_migrations::{EmbeddedMigrations, MigrationHarness};
    pub const MIGRATIONS: EmbeddedMigrations = embed_migrations!("migrations/postgresql");

    pub fn run_migrations(db_url: &str) -> Result<(), super::Error> {
        // Make sure the database is up to date (create if it doesn't exist, or run the migrations)
        let mut connection = diesel::pg::PgConnection::establish(db_url)?;

        connection.run_pending_migrations(MIGRATIONS).expect("Error running migrations");
        Ok(())
    }
}