/**
 * Node.js class that watches the CouchDB _changes API and emits events on new changes.
 */
var EventEmitter = require('events').EventEmitter;
var cradle = require('cradle');

CouchWatcher = function(options) {
	this.userid = options.userid;
	this.password = options.password;
	this.dbname = options.dbname;
	this.host = options.host || '127.0.0.1';
	this.port = options.port || 5984;
	this.heartbeat = options.heartbeat || 1000;
};

CouchWatcher.prototype = new EventEmitter;

CouchWatcher.prototype.watch = function(filter, since) {

	var self = this;

	// Create new connection to CouchDB instance.
	var db = new (cradle.Connection)(self.host, self.port,
			{
				auth : {
					username : self.userid,
					password : self.password
				}
			}).database(self.dbname);

	// Watch changes API and emit event with document.
	var options = { include_docs : true, feed : 'continuous', heartbeat : self.heartbeat};
	if(filter) {
		options.filter = filter;
	}
	if(since) {
		options.since = since;
	}
	db.changes(options).on('response', function(res) {
		res.on('data', function(change) {
			self.emit('doc', change.doc);
		});
		res.on('end', function() {
			self.emit('end');
		});
	});

};

exports.CouchWatcher = CouchWatcher;