var EventEmitter = require('events').EventEmitter;
var Client = require(__dirname+'/client');
var defaults =  require(__dirname + '/defaults');
var genericPool = require('generic-pool');

//cache of existing client pools
var pools = {};

//returns connect function using supplied client constructor
var makeConnectFunction = function(ClientConstructor) {
  return function(config, callback) {
    var c = config;
    var cb = callback;
    //allow for no config to be passed
    if(typeof c === 'function') {
      cb = c;
      c = defaults;
    }
    //get unique pool name if using a config object instead of config string
    var poolName = typeof(c) === 'string' ? c : c.user+c.host+c.port+c.database;
    var pool = pools[poolName];
    if(pool) return pool.acquire(cb);
    var pool = pools[poolName] = genericPool.Pool({
      name: poolName,
      create: function(callback) {
        var client = new ClientConstructor(c);
        client.connect();
        var connectError = function(err) {
          client.removeListener('connect', connectSuccess);
          callback(err, null);
        };
        var connectSuccess = function() {
          client.removeListener('error', connectError);
          callback(null, client);
        };
        client.once('connect', connectSuccess);
        client.once('error', connectError);
        client.on('drain', function() {
          pool.release(client);
        });
      },
      destroy: function(client) {
        client.end();
      },
      max: defaults.poolSize,
      idleTimeoutMillis: defaults.poolIdleTimeout
    });
    return pool.acquire(cb);
  }
}

var end = function() {
  Object.keys(pools).forEach(function(name) {
    var pool = pools[name];
    pool.drain(function() {
      pool.destroyAllNow();
    });
  })
};

module.exports = {
  Client: Client,
  Connection: require(__dirname + '/connection'),
  connect: makeConnectFunction(Client),
  end: end,
  defaults: defaults
}

var nativeExport = null;
//lazy require native module...the c++ may not have been compiled
module.exports.__defineGetter__("native", function() {
  if(nativeExport === null) {
    var NativeClient = require(__dirname + '/native');
    nativeExport = {
      Client: NativeClient,
      connect: makeConnectFunction(NativeClient),
      end: end,
      defaults: defaults
    }
  }
  return nativeExport;
})