<?php

function v($v, $czyscHtmlIExit = false) {
	if ($czyscHtmlIExit) ob_end_clean();
    echo '<pre>' . print_r($v, true) . '</pre>';
	if ($czyscHtmlIExit) exit;
}
function vv($v, $czyscHtmlIExit = false) {
	if ($czyscHtmlIExit) ob_end_clean();
    echo '<pre>';
	var_dump($v);
	echo '</pre>';
	if ($czyscHtmlIExit) exit;
}
function vvv($var, & $result = null, $is_view = true)
{
    if (is_array($var) || is_object($var)) foreach ($var as $key=> $value) vvv($value, $result[$key], false);
    else $result = $var;

    if ($is_view) v($result);
}

$id = isset($_POST['id']) ? $_POST['id'] : '';
$room = isset($_POST['room']) ? $_POST['room'] : '';

if ($id === '' || $room === '') return;

$isApc = extension_loaded('apc');
$cache = $isApc ? apc_fetch('chat') : @unserialize(file_get_contents('./history/'.$room.'cache2100-01-01'));
$data = array();
if ($id === 'undefined') {
    $id = empty($cache) ? 0 : $cache[0][0];
// first refresh : loads 50 last msg from history    
    $file = './history/'.$room.date('Y-m-d');
    if (file_exists($file)) { 
      $history = file($file, FILE_IGNORE_NEW_LINES);
      $history = array_reverse($history);
      foreach ($history as & $ref) {
          $ref = explode('>', $ref);
      }
      $data = array_slice($history, 0, 50);
    }  
} elseif ($id === '0') {
    if (!empty($cache)) {
        $id = $cache[0][0];
        $data = $cache;
    }
} else {
    $end = end($cache);
    // read data from cache
    if ($id >= $end[0]) {
        foreach ($cache as $k => $c) {
            if ($c[0] === $id) break;
        }
        $data = array_slice($cache, 0, $k);
    }
    // read data from history (any problem witch Internet and are delays)
    else {
        $date = date('Y-m-d');
        $history = array();
        while (($history = array_merge(file('./history/'.$room.$date, FILE_IGNORE_NEW_LINES), $history)) && $history[0] > $id) {
            $date = date('Y-m-d', strtotime('-1 day', strtotime($date)));
            if (!file_exists('./history/'.$room.$date)) break;
        }
        // prepare history
        $history = array_reverse($history);
        foreach ($history as & $ref) {
            $ref = explode('>', $ref);
        }
        // get data
        foreach ($history as $k => $h) {
            if ($h[0] === $id) break;
        }
        $data = array_slice($history, 0, $k);
    }
    $id = $cache[0][0];
}

echo json_encode(array('id' => $id, 'data' => $data));