//
// imag - the personal information management suite for the commandline
// Copyright (C) 2015-2020 Matthias Beyer <mail@beyermatthias.de> and contributors
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; version
// 2.1 of the License.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
//

use std::sync::Mutex;
use std::sync::Arc;
use std::path::Path;

use failure::Fallible as Result;
use failure::Error;
use notmuch_rs::Database;
use notmuch_rs::DatabaseMode;

use libimagerror::errors::ErrorMsg;

#[derive(Debug)]
pub struct NotmuchConnection {
    db: Arc<Mutex<Database>>,
    open: bool,
}

impl Drop for NotmuchConnection {
    fn drop(&mut self) {
        if self.open {
            let _ = self.db
                .lock()
                .map_err(|e| error!("Failed to get lock for connection to close notmuch database: {:?}", e))
                .unwrap() // will panic.
                .close()
                .map_err(|e| error!("Could not close notmuch database: {:?}", e));
        }
    }
}

impl NotmuchConnection {

    pub fn open<P>(p: P) -> Result<Self>
        where P: AsRef<Path>
    {
        Database::open(&p, DatabaseMode::ReadOnly)
            .map(Mutex::new)
            .map(Arc::new)
            .map(|db| {
                NotmuchConnection {
                    db,
                    open: true,
                }
            })
            .map_err(Error::from)
    }

    /// Close the connection
    ///
    /// # Note
    ///
    /// Use this function. If you don't, the destructor will close the connection and this might
    /// panic!(), so be advised to use this non-panicing function to close the connection.
    ///
    pub fn close(mut self) -> Result<()> {
        self.db
            .lock()
            .map_err(|_| ErrorMsg::LockError)
            .map_err(Error::from)
            .and_then(|db| db.close().map_err(Error::from))?;
        self.open = false;
        Ok(())
    }

    pub(crate) fn execute<F, T>(&self, f: F) -> Result<T>
        where F: FnOnce(&Database) -> Result<T>
    {
        self.db
            .lock()
            .map_err(|_| ErrorMsg::LockError)
            .map_err(Error::from)
            .and_then(|lock| f(&lock))
    }

    pub(crate) fn execute_atomic<F, T>(&self, f: F) -> Result<T>
        where F: FnOnce(&Database) -> Result<T>
    {
        self.db
            .lock()
            .map_err(|_| ErrorMsg::LockError)
            .map_err(Error::from)
            .and_then(|lock| {
                lock.begin_atomic()?;
                let r = f(&lock);
                lock.end_atomic()?;
                r
            })
    }

}