erizo-fr/erizo-mail-server

'use strict';
var MODULE_NAME = 'imapManager';

var logger = require('log4js').getLogger(MODULE_NAME);
var conf = require('nconf');
var Imap = require('imap');


//Connection pool
var connections = {};



// Public functions ///////////////////////////////////////

module.exports.getConnection = function (username, password, callback) {
    var connection = createImapConnection(username, password);

    connection.once('ready', function() {
        callback(null, connection);
    });

    connection.once('error', function(err) {
        callback(err, null);
    });

    connection.connect();
};
module.exports.getConnectionT = function (username, password) {
    return function(callback) {
        module.exports.getConnection(username, password, callback);
    };
};

module.exports.getKeepAliveConnection = function (username, password, callback) {
    if(! connections[username]) {        
        logger.debug('No active connection found for user#' + username);
        createConnection(username, password);
    }

    if(! connections[username].isInitialized) {
        logger.debug('Imap connection for user#' + username + ' is not initialized yet. Pushing callback into the callbacks list');
        connections[username].callbacks.push(callback);
    } else {
        logger.debug('Imap connection for user#' + username + ' is already initialized');
        resetTimeout(username);
        callback(null, connections[username].connection);
    }
};

module.exports.getKeepAliveConnectionT = function (username, password) {
    return function(callback) {
        module.exports.getKeepAliveConnection(username, password, callback);
    };
};


// Private functions ///////////////////////////////////////

function createImapConnection(username, password) {
    let host = conf.get('imap:host') || 'localhost';
    let port = conf.get('imap:port') || 143;
    let tls = conf.get('imap:tls') || false;
    let autotls = conf.get('imap:autotls') || 'never';
    logger.debug('Create raw connection object for user#' + username + ' to ' + host + ':' + port + ' with options (tls=' + tls + ', autotls=' + autotls + ')');
    return new Imap({
        user: username,
        password: password,
        host: host,
        port: port,
        tls: tls,
        autotls: autotls,
        debug: function(log) {
            logger.debug(log);
        }
    });
}

function createConnection(username, password) {
    logger.debug('Create connection structure for user#' + username);
    connections[username] = {
        "connection" : createImapConnection(username, password),
        "callbacks" : [],
        "isInitialized" : false,
        "timeoutId" : null
    };

    connections[username].connection.once('ready', function() {        
        var connection = connections[username];
        connection.isInitialized = true;

        //Call callbacks
        logger.debug('Connection ready, calling callbacks');
        for (var i = 0; i < connection.callbacks.length; i++) {
            connection.callbacks[i](null, connection.connection);
        }
        connection.callbacks = [];

        //Set timeout
        resetTimeout(username);
    });

    connections[username].connection.once('error', function(err) {
        logger.error('Connection error');
        var callbacks = connections[username].callbacks;

        logger.debug('Closing connection');
        closeConnection(username);

        logger.debug('Calling callbacks');
        for (var i = 0; i < callbacks.length; i++) {
            callbacks[i](err, null);
        }
    });

    connections[username].connection.connect();
}

function closeConnection(username) {
    var connection = connections[username];
    connections[username] = null;    
    logger.debug('Closing the connection of user#' + username);
    connection.connection.end();
}


function resetTimeout(username) {
    //Cancel the previous timeout
    if(connections[username].timeoutId) {        
        logger.debug('Delete timeout#' + connections[username].timeoutId + ' for connection of user#' + username);
        clearTimeout(connections[username].timeoutId);
    }

    //Set the new timeout    
    var keepalive = conf.get('imap:keepalive') || 60000;
    connections[username].timeoutId = setTimeout(function() {
        logger.debug('The connection of the user#' + username + ' has expired');
        closeConnection(username);
    }, keepalive);
    logger.debug('New timeout created (id#' + connections[username].timeoutId + ' for connection of user#' + username);
}