<?php
/*============================*/
/* Gallery address definition */
/*============================*/

if (!empty($_SERVER['REQUEST_SCHEME'])) {
	$g_protocol = $_SERVER['REQUEST_SCHEME'];
} elseif (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] == 'on') {
	$g_protocol = 'https';
} else {
	$g_protocol = 'http';
}
$g_host = $_SERVER['HTTP_HOST'];
$g_port = $_SERVER['SERVER_PORT'];
$g_path = dirname($_SERVER['REQUEST_URI']);

// remove default ports
if (($g_protocol == 'https' && $g_port == '443') ||
	($g_protocol == 'http' && $g_port == '80')) {
	$g_port = '';
} else {
	$g_port = ':' . $g_port;
}

if ($g_path[0] != '/') {
	$g_path = '/' . $g_path;
}

$gallery_link = $g_protocol . '://' . $g_host . $g_port . $g_path;

/*===================*/
/* Functions         */
/*===================*/
# Hardly inspired from here : codes-sources.commentcamarche.net/source/35937-creation-d-une-arborescenceI
# Listing all files of a folder and sub folders.
function listFiles(&$content, $Folder, $SkipFileExts, $SkipObjects) {
	$dir = opendir($Folder);
	// Loop on all contained on the folder
	while (false !== ($Current = readdir($dir))) {
		if ($Current != '.' && $Current != '..' && in_array($Current, $SkipObjects) === false) {
			if (is_dir($Folder . '/' . $Current)) {
				ListFiles($content, $Folder . '/' . $Current, $SkipFileExts, $SkipObjects);
			} else {
				$FileExt = strtolower(substr(strrchr($Current, '.'), 1));
				// Should we display this extension ?
				if (in_array($FileExt, $SkipFileExts) === false) {
					$current_adress = $Folder . '/' . $Current;
					array_push($content, $current_adress);
				}
			}
		}
	}
	closedir($dir);
	return $content;
}

# Paul's Simple Diff Algorithm v 0.1 : http://paulbutler.org/archives/a-simple-diff-algorithm-in-php/
function diff($old, $new) {
	$matrix = array();
	$maxlen = 0;
	foreach ($old as $oindex => $ovalue) {
		$nkeys = array_keys($new, $ovalue);
		foreach ($nkeys as $nindex) {
			$matrix[$oindex][$nindex] = isset($matrix[$oindex - 1][$nindex - 1]) ?
			$matrix[$oindex - 1][$nindex - 1] + 1 : 1;
			if ($matrix[$oindex][$nindex] > $maxlen) {
				$maxlen = $matrix[$oindex][$nindex];
				$omax = $oindex + 1 - $maxlen;
				$nmax = $nindex + 1 - $maxlen;
			}
		}
	}
	if ($maxlen == 0) {
		return array(array('d' => $old, 'i' => $new));
	}

	return array_merge(
		diff(array_slice($old, 0, $omax), array_slice($new, 0, $nmax)),
		array_slice($new, $nmax, $maxlen),
		diff(array_slice($old, $omax + $maxlen), array_slice($new, $nmax + $maxlen)));
}

/*===================*/
/* Variables         */
/*===================*/
require "config-default.php";
include "config.php";
$folder = "photos";

$content = array();
$content = listFiles($content, $folder, $SkipExts, $SkipObjects);
usort($content, function ($a, $b) {return filemtime($a) < filemtime($b);});

if (is_writeable(".")) {
	$to_store = "";
	$old_files_list = "db_old_files"; //list of files in ./photos
	$db_feed_source = "db_feed_source";
	$db_rss_timestamp = "db_rss_timestamp";

	// Init files
	if (!file_exists($old_files_list)) {
		file_put_contents($old_files_list, "");
	}
	if (!file_exists($db_feed_source)) {
		file_put_contents($db_feed_source, "");
	}
	if (!file_exists($db_rss_timestamp)) {
		file_put_contents($db_rss_timestamp, "");
	}

	/*===================*/
	/* Computing         */
	/*===================*/
	#Todo : ajouter une condition : dois-je regénérer le flux ou utiliser les anciens fichiers ?
	$temp = file_get_contents($db_feed_source);
	$last_rss_gen = file_get_contents($db_rss_timestamp);
	$current_time = time();
	// If the RSS generation is already launched, don't do a second generation at the same time
	if (($current_time - $last_rss_gen) > $rss_refresh_interval && file_exists("rss.locker") == false) {
		file_put_contents("rss.locker", "");
		file_put_contents($db_rss_timestamp, time());
		// Load the list from files.
		$old_files_list_content = explode("\n", file_get_contents($old_files_list));
		$new_files_list_content = $content; #debug
		// Generate and stock new elements
		$differences = diff($old_files_list_content, $new_files_list_content);
		for ($i = 0; $i < count($differences); $i++) {
			if (is_array($differences[$i])) {
				for ($j = 0; $j < count($differences[$i]["i"]); $j++) {
					if (strlen($differences[$i]["i"][$j]) > 2) {
						$to_store .= $differences[$i]["i"][$j] . "\n";
					}
				}
			}
		}
		// Add new elements at the top of the feed's source
		$temp = $to_store . $temp;
		file_put_contents($db_feed_source, $temp);
		// Store the current file list for the next generation
		file_put_contents($old_files_list, join("/n", $content));
		unlink("rss.locker");
	}
	$content = explode("\n", $temp);
}

/*===================*/
/* XML Gen           */
/*===================*/
header('Content-Type: text/xml');
echo "<?xml version='1.0' encoding='UTF-8'?>\n";
echo "<rss version='2.0'>\n<channel>";
echo "<title>$title</title>";
echo "<link>$gallery_link</link>";
echo "<description>$description</description>\n";
for ($i = 0; $i < $nb_items_rss && $i < count($content); $i++) {
	if (empty($content[$i])) {
		continue;
	}

	$link = $gallery_link . '/' . str_replace(' ', '%20', $content[$i]);
	echo "<item>\n";
	echo " <title>" . basename($link) . "</title>\n";
	echo " <link>" . $link . "</link>\n";
	echo " <guid>" . $link . "</guid>\n";
	echo " <description><![CDATA[ <img src='" . $link . "'> ]]></description>\n";
	echo " <pubDate>" . date("D, j M Y H:i:s O", filemtime($content[$i])) . "</pubDate>";
	echo "</item>\n";
}
echo "</channel></rss>\n";