/**
 * Mongo Factory functions
 *
 *  Copyright (C) 2010-2019 R-T Specialty, LLC.
 *
 *  This file is part of the Liza Data Collection Framework.
 *
 *  liza is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as
 *  published by the Free Software Foundation, either version 3 of the
 *  License, or (at your option) any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * These definitions are for a very old mongodb library, which will be
 * once we get around to updating node.  Quite a failure on the maintenance
 * front.
 *
 * instantiate objects for MongoDb
 */
import { MongoDb, MongoDbConfig, MongoCollection } from '../../types/mongodb';
import { DaoError } from '../../error/DaoError';


const {
    Db:             MongoDb,
    Server:         MongoServer,
    ReplSetServers: ReplSetServers,
} = require( 'mongodb' );


/**
 * Create a mongodb configuration from the environment
 *
 * @param env - the environment variables
 *
 * @return the mongo configuration
 */
export function createMongoConfig( env: NodeJS.ProcessEnv ): MongoDbConfig
{
    return <MongoDbConfig>{
        'port':       +( env.MONGODB_PORT || 0 ),
        'ha':         +( env.LIZA_MONGODB_HA || 0 ) == 1,
        'replset':    env.LIZA_MONGODB_REPLSET,
        'host':       env.MONGODB_HOST,
        'host_a':     env.LIZA_MONGODB_HOST_A,
        'port_a':     +( env.LIZA_MONGODB_PORT_A || 0 ),
        'host_b':     env.LIZA_MONGODB_HOST_B,
        'port_b':     +( env.LIZA_MONGODB_PORT_B || 0 ),
        'collection': 'quotes',
    };
}


/**
 * Create the database connection
 *
 * @param conf - the configuration from the environment
 *
 * @return the mongodb connection
 */
export function createMongoDB( conf: MongoDbConfig ): MongoDb
{
    if( conf.ha )
    {
        var mongodbPort = conf.port || 27017;
        var mongodbReplSet = conf.replset || 'rs0';
        var dbServers = new ReplSetServers(
            [
                new MongoServer( conf.host_a, conf.port_a || mongodbPort),
                new MongoServer( conf.host_b, conf.port_b || mongodbPort),
            ],
            {rs_name: mongodbReplSet, auto_reconnect: true}
        );
    }
    else
    {
        var dbServers = new MongoServer(
            conf.host || '127.0.0.1',
            conf.port || 27017,
            {auto_reconnect: true}
        );
    }
    var db = new MongoDb(
        'program',
        dbServers,
        {native_parser: false, safe: false}
    );
    return db;
}


/**
 * Attempts to connect to the database and retrieve the collection
 *
 * connectError event will be emitted on failure.
 *
 * @param db   - the mongo database
 * @param conf - the mongo configuration
 *
 * @return the collection
 */
export function getMongoCollection(
    db:   MongoDb,
    conf: MongoDbConfig
): Promise<MongoCollection>
{
    return new Promise( ( resolve, reject ) =>
    {
        // attempt to connect to the database
        db.open( ( e: any, db: any ) =>
        {
            // if there was an error, don't bother with anything else
            if ( e )
            {
                // in some circumstances, it may just be telling us that
                // we're already connected (even though the connection may
                // have been broken)
                if ( e.errno !== undefined )
                {
                    reject( new Error(
                        'Error opening mongo connection: ' + e
                    ) );
                    return;
                }
            } else if ( db == null )
            {
                reject( new DaoError( 'No database connection' ) );
                return;
            }

            // quotes collection
            db.collection(
                conf.collection,
                ( e: any, collection: MongoCollection ) =>
                {
                    if ( e )
                    {
                        reject( new DaoError(
                            'Error creating collection: ' + e
                        ) );
                        return;
                    }

                    let createdCount = 0
                    const checkAllCreated = (): void =>
                    {
                        if( createdCount >= 3 )
                        {
                            resolve( collection );
                        }
                    };

                    const cb = ( e: any, _index: { [P: string]: any } ): void =>
                    {
                        if ( e )
                        {
                            reject( new DaoError(
                                'Error creating index: ' + e
                            ) );
                            return;
                        }

                        createdCount++;
                        checkAllCreated();
                    };

                    // initialize indexes
                    collection.createIndex( [ ['published', 1] ], false, cb );
                    collection.createIndex( [ ['deltaError', 1] ], false, cb);
                    collection.createIndex(
                        [
                            [ 'published', 1 ],
                            [ 'deltaError', 1 ],
                        ],
                        false,
                        cb
                    );
                }
            );
        } );
    } );
}