<?php
// AJAX-specific code follows

// Text must be returned as text/plain
header("Content-Type: text/plain");

// Cache-Control header must be supplied to prevent IE caching the XML response
header("Cache-Control: no-cache");

// Application-specific code follows

$bufferFile = dirname(__FILE__) . '/ajax-txt-shoutbox-buffer.txt';
$bufferLength = 10;

// If no chat buffer exists, create one
if (!file_exists($bufferFile))
	file_put_contents($bufferFile, '');

// Prevent abuse of GET fields
$nick = preg_replace('/[^A-Za-z0-9_\-]/', '', $_GET['shoutNick']);
$text = $_GET['shoutText'];

// Two possible things can happen - a form submission to add text to the buffer
// (in which case the hidden field 'insertIntoBuffer' will be set),
// or a timer-driven call which just requests us to supply an upto-date copy of the buffer

if (isset($_GET['insertIntoBuffer']))
{
	// Get buffer, one array entry per line
	$buffer = explode("\n", file_get_contents($bufferFile));
	
	// Add new line
	$buffer[] = strftime("[%H:%M:%S]") . ' <' . $nick . '> ' . $text;
	
	// Truncate old entries (store $bufferLength lines of text)
	$buffer = array_slice($buffer, -$bufferLength);
	
	// Save buffer
	// [NOTE: file locking issues - a real-world application must lock the file before writing]
	file_put_contents($bufferFile, implode("\n", $buffer));
}
	
// Read buffer and output as text
readfile($bufferFile);
exit;
?>