<?php

// Update PHP's include path to reference subdirectories within the project
$dir = dirname( __FILE__ );
set_include_path( $dir . '/includes' . PATH_SEPARATOR . $dir . '/events' . PATH_SEPARATOR . $dir . '/core' . PATH_SEPARATOR . get_include_path() );

require_once( 'ircConfig.php' );
require_once( 'ircCommands.php' );
require_once( 'constants.php' );
require_once( 'event.php' );
require_once( 'eventHandler.php' );

class IRC extends ircCommands {

	// Configuration object: connection and client settings
	protected $_config;    
	// Socket resource
	protected $_socket;

	// Output buffer to store data bound for the server
	private $_outputBuffer          = array();
	// Send delay: time to wait before writing to the socket
	public $sendDelay               = 250;
	// Used to calculate the difference in time between writing to the socket
	private $_lastStringSent        = 0;
	// Read delay: time to wait before reading from the socket
	public $_readDelay              = 50;
	// Used to calculate the difference in time between reading from the socket
	private $_lastStringReceived    = 0;

	// Enable user-tracking
	public $enableUserTracking      = false;
	// Debug (echo) input/output to console
	public $enableConsoleDebugging  = false;	

	/* Event members to cater for the most common events encountered within
	 * the IRC protocol */
	public $eveDataSent;
	public $eveDataReceived;
	public $evePing;
	public $eveConnected;
	public $eveJoin;
	public $evePrivmsg;
	public $eveAction;
	public $eveNotice;

	public function __construct( ircConfig $config )
	{
		// Load configuration
		$this->_config = $config;

		// Initialise events
		$this->eveDataSent      = new event();
		$this->eveDataReceived  = new event();
		$this->evePing          = new event();
		$this->eveConnected     = new event();
		$this->eveJoin          = new event();
		$this->evePrivmsg       = new event();
		$this->eveAction        = new event();
		$this->eveNotice        = new event();

		// Register core functionality
		$this->evePing->register( 'corePingHandler' );
		$this->eveDataSent->register( 'coreDebugger' );
		$this->eveDataReceived->register( 'coreDebugger' );
	}

	// Attempt to connect to an IRC server on the hostname/IP and port provided in the ircConfig object
	public function connect()
	{
		// Throw a detailed exception if it is not possible to connect to a given server
		if ( ! $this->_socket = fsockopen( $this->getHost(), $this->getPort(), $errno, $errstr ) )
		{
			throw new Exception( 'Could not connect to "' . $this->getHost() . ':' . $this->getPort . '" [' . $errno . '] ' . $errstr );
		}
		else
		{
			// Make the socket non-blocking
			stream_set_blocking( $this->_socket, 0 );

			// Register with the server: send a nickname and user details
			$this->sendString( 'NICK ' . $this->getNick() );
			$this->sendString( 'USER ' . $this->getIdent() . ' 0 0 :' . $this->getName() );
		}
	}

	// Listen for incoming data on a connection
	public function listen()
	{
		// Throw an exception if listen() is called without first connecting to an IRC server
		if ( ! $this->_socket )
		{
			throw new Exception( 'Could not initiate the listen loop because a connection has not yet been established' );
		}
		else
		{
			while ( ! feof( $this->_socket ) )
			{
				// Check the output buffer for data to send to the server
				$this->checkOutputBuffer();

				// Read data from the server
				$this->readData();
			}
		}
	}	

	// Read from the server at set intervals
	private function readData()
	{
		$time = microtime( true );

		if ( ( $time - $this->_lastStringReceived ) >= $this->_readDelay / 1000 )
		{
			// Read from the server in "lines", cut at n bytes or linebreaks
			$line = trim( fgets( $this->_socket, 1024 ) );
			// Catch 0-length packets
			if ( strlen( $line ) )
			{
				// Trigger the eveDataReceived event
				$data = new eveDataTransitArgs( $line, 'eveDataReceived' );
				$this->eveDataReceived->trigger( $this, $data );

				// Pass incoming data to the event handler
				eventHandler( $this, $line );
				$this->_lastStringReceived = $time;
			}
		}
	}

	// Disconnect from the active IRC connection and close the socket
	public function disconnect( $quit = 'Exiting' )
	{
		// Throw an exception if disconnect() is called without first connecting to an IRC server
		if ( ! $this->_socket )
		{
			throw new Exception( 'Could not disconnect from the server because a connection has not yet been established' );
		}
		else
		{
			// Send a quit message to the server
			$this->sendString( 'QUIT :' . $quit );
			fclose( $this->_socket );
		}
	}
	
	// Check the output buffer for new messages
	private function checkOutputBuffer()
	{
		$time = microtime( true );

		if ( ( $time - $this->_lastStringSent ) >= $this->sendDelay / 1000 )
		{
			$string = array_shift( $this->_outputBuffer );

			if ( $string != '' )
			{
				// Write to the socket and update the time for the lastStringSent
				$this->sendStringNow( $string );
				$this->_lastStringSent = $time;
			}
		}
	}

	// Add a string to the output buffering system's queue
	public function sendString( $string )
	{
		$this->_outputBuffer[] = $string;
	}

	// Send a string directly over the socket by avoiding the output buffering system
	private function sendStringNow( $string )
	{
		// Throw an exception if the sendStringNow() function is called without first connecting to an IRC server
		if ( ! $this->_socket )
		{
			throw new Exception( 'Cannot write to the server because a connection has not yet been established' );
		}
		else
		{
			if ( fwrite( $this->_socket, $string . "\n" ) )
			{
				// Trigger the eveDataSent event
				$data = new eveDataTransitArgs( $string, 'eveDataSent' );
				$this->eveDataSent->trigger( $this, $data );
			}
		}
	}
}