<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * This file is responsible for serving of yui images
 *
 * @package   core
 * @copyright 2009 Petr Skoda (skodak)  {@link http://skodak.org}
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */


// disable moodle specific debug messages and any errors in output,
// comment out when debugging or better look into error log!
define('NO_DEBUG_DISPLAY', true);

// we need just the values from config.php and minlib.php
define('ABORT_AFTER_CONFIG', true);
require('../config.php'); // this stops immediately at the beginning of lib/setup.php

// get special url parameters

list($parts, $slasharguments) = combo_params();
if (!$parts) {
    combo_not_found();
}

$etag = sha1($parts);
$parts = trim($parts, '&');

// find out what we are serving - only one type per request
$content = '';
if (substr($parts, -3) === '.js') {
    $mimetype = 'application/javascript';
} else if (substr($parts, -4) === '.css') {
    $mimetype = 'text/css';
} else {
    combo_not_found();
}

// if they are requesting a revision that's not -1, and they have supplied an
// If-Modified-Since header, we can send back a 304 Not Modified since the
// content never changes (the rev number is increased any time the content changes)
if (strpos($parts, '/-1/') === false and (!empty($_SERVER['HTTP_IF_NONE_MATCH']) || !empty($_SERVER['HTTP_IF_MODIFIED_SINCE']))) {
    $lifetime = 60*60*24*360; // 1 year, we do not change YUI versions often, there are a few custom yui modules
    header('HTTP/1.1 304 Not Modified');
    header('Expires: '. gmdate('D, d M Y H:i:s', time() + $lifetime) .' GMT');
    header('Cache-Control: public, max-age='.$lifetime);
    header('Content-Type: '.$mimetype);
    header('Etag: '.$etag);
    die;
}

$parts = explode('&', $parts);
$cache = true;
$lastmodified = 0;

foreach ($parts as $part) {
    if (empty($part)) {
        continue;
    }
    $filecontent = '';
    $part = min_clean_param($part, 'SAFEPATH');
    $bits = explode('/', $part);
    if (count($bits) < 2) {
        $content .= "\n// Wrong combo resource $part!\n";
        continue;
    }
    //debug($bits);
    $version = array_shift($bits);
    if ($version === 'moodle') {
        if (count($bits) <= 3) {
            // This is an invalid module load attempt.
            $content .= "\n// Incorrect moodle module inclusion. Not enough component information in {$part}.\n";
            continue;
        }
        if (!defined('ABORT_AFTER_CONFIG_CANCEL')) {
            define('ABORT_AFTER_CONFIG_CANCEL', true);
            define('NO_UPGRADE_CHECK', true);
            define('NO_MOODLE_COOKIES', true);
            require($CFG->libdir.'/setup.php');
        }
        $revision = (int)array_shift($bits);
        if ($revision === -1) {
            // Revision -1 says please don't cache the JS
            $cache = false;
        }
        $frankenstyle = array_shift($bits);
        $filename = array_pop($bits);
        $modulename = $bits[0];
        $dir = get_component_directory($frankenstyle);

        // For shifted YUI modules, we need the YUI module name in frankenstyle format.
        $frankenstylemodulename = join('-', array($version, $frankenstyle, $modulename));
        $frankenstylefilename = preg_replace('/' . $modulename . '/', $frankenstylemodulename, $filename);

        // By default, try and use the /yui/build directory.
        if ($mimetype == 'text/css') {
            // CSS assets are in a slightly different place to the JS.
            $contentfile = $dir . '/yui/build/' . $frankenstylemodulename . '/assets/skins/sam/' . $frankenstylefilename;

            // Add the path to the bits to handle fallback for non-shifted assets.
            $bits[] = 'assets';
            $bits[] = 'skins';
            $bits[] = 'sam';
        } else {
            $contentfile = $dir . '/yui/build/' . $frankenstylemodulename . '/' . $frankenstylefilename;
        }

        // If the shifted versions don't exist, fall back to the non-shifted file.
        if (!file_exists($contentfile) or !is_file($contentfile)) {
            // We have to revert to the non-minified and non-debug versions.
            $filename = preg_replace('/-(min|debug)\./', '.', $filename);
            $contentfile = $dir . '/yui/' . join('/', $bits) . '/' . $filename;
        }
    } else if ($version === '2in3') {
        $contentfile = "$CFG->libdir/yuilib/$part";

    } else if ($version == 'gallery') {
        $contentfile = "$CFG->libdir/yui/$part";

    } else {
        if ($version != $CFG->yui3version) {
            $content .= "\n// Wrong yui version $part!\n";
            continue;
        }
        $contentfile = "$CFG->libdir/yuilib/$part";
    }
    if (!file_exists($contentfile) or !is_file($contentfile)) {
        $location = '$CFG->dirroot'.preg_replace('/^'.preg_quote($CFG->dirroot, '/').'/', '', $contentfile);
        $content .= "\n// Combo resource $part ($location) not found!\n";
        continue;
    }

    if (empty($filecontent)) {
        $filecontent = file_get_contents($contentfile);
    }
    $fmodified = filemtime($contentfile);
    if ($fmodified > $lastmodified) {
        $lastmodified = $fmodified;
    }

    $relroot = preg_replace('|^http.?://[^/]+|', '', $CFG->wwwroot);
    $sep = ($slasharguments ? '/' : '?file=');

    if ($mimetype === 'text/css') {
        if ($version == 'moodle') {
            // Search for all images in the file and replace with an appropriate link to the yui_image.php script
            $imagebits = array(
                $sep . $version,
                $frankenstyle,
                $modulename,
                array_shift($bits),
                '$1.$2'
            );

            $filecontent = preg_replace('/([a-z0-9_-]+)\.(png|gif)/', $relroot . '/theme/yui_image.php' . implode('/', $imagebits), $filecontent);
        } else if ($version == '2in3') {
            // First we need to remove relative paths to images. These are used by YUI modules to make use of global assets.
            // I've added this as a separate regex so it can be easily removed once
            // YUI standardise there CSS methods
            $filecontent = preg_replace('#(\.\./\.\./\.\./\.\./assets/skins/sam/)?([a-z0-9_-]+)\.(png|gif)#', '$2.$3', $filecontent);

            // search for all images in yui2 CSS and serve them through the yui_image.php script
            $filecontent = preg_replace('/([a-z0-9_-]+)\.(png|gif)/', $relroot.'/theme/yui_image.php'.$sep.$CFG->yui2version.'/$1.$2', $filecontent);

        } else if ($version == 'gallery') {
            // search for all images in gallery module CSS and serve them through the yui_image.php script
            $filecontent = preg_replace('/([a-z0-9_-]+)\.(png|gif)/', $relroot.'/theme/yui_image.php'.$sep.$version.'/'.$bits[0].'/'.$bits[1].'/$1.$2', $filecontent);

        } else {
            // First we need to remove relative paths to images. These are used by YUI modules to make use of global assets.
            // I've added this as a separate regex so it can be easily removed once
            // YUI standardise there CSS methods
            $filecontent = preg_replace('#(\.\./\.\./\.\./\.\./assets/skins/sam/)?([a-z0-9_-]+)\.(png|gif)#', '$2.$3', $filecontent);

            // search for all images in yui2 CSS and serve them through the yui_image.php script
            $filecontent = preg_replace('/([a-z0-9_-]+)\.(png|gif)/', $relroot.'/theme/yui_image.php'.$sep.$version.'/$1.$2', $filecontent);
        }
    }

    $content .= $filecontent;
}

if ($lastmodified == 0) {
    $lastmodified = time();
}

if ($cache) {
    combo_send_cached($content, $mimetype, $etag, $lastmodified);
} else {
    combo_send_uncached($content, $mimetype);
}


/**
 * Send the JavaScript cached
 * @param string $content
 * @param string $mimetype
 * @param string $etag
 * @param int $lastmodified
 */
function combo_send_cached($content, $mimetype, $etag, $lastmodified) {
    $lifetime = 60*60*24*360; // 1 year, we do not change YUI versions often, there are a few custom yui modules

    header('Content-Disposition: inline; filename="combo"');
    header('Last-Modified: '. gmdate('D, d M Y H:i:s', $lastmodified) .' GMT');
    header('Expires: '. gmdate('D, d M Y H:i:s', time() + $lifetime) .' GMT');
    header('Pragma: ');
    header('Cache-Control: public, max-age='.$lifetime);
    header('Accept-Ranges: none');
    header('Content-Type: '.$mimetype);
    header('Etag: '.$etag);
    if (!min_enable_zlib_compression()) {
        header('Content-Length: '.strlen($content));
    }

    echo $content;
    die;
}

/**
 * Send the JavaScript uncached
 * @param string $content
 * @param string $mimetype
 */
function combo_send_uncached($content, $mimetype) {
    header('Content-Disposition: inline; filename="combo"');
    header('Last-Modified: '. gmdate('D, d M Y H:i:s', time()) .' GMT');
    header('Expires: '. gmdate('D, d M Y H:i:s', time() + 2) .' GMT');
    header('Pragma: ');
    header('Accept-Ranges: none');
    header('Content-Type: '.$mimetype);
    if (!min_enable_zlib_compression()) {
        header('Content-Length: '.strlen($content));
    }

    echo $content;
    die;
}

function combo_not_found($message = '') {
    header('HTTP/1.0 404 not found');
    if ($message) {
        echo $message;
    } else {
        echo 'Combo resource not found, sorry.';
    }
    die;
}

function combo_params() {
    if (isset($_SERVER['QUERY_STRING']) and strpos($_SERVER['QUERY_STRING'], 'file=/') === 0) {
        // url rewriting
        $slashargument = substr($_SERVER['QUERY_STRING'], 6);
        return array($slashargument, true);

    } else if (isset($_SERVER['REQUEST_URI']) and strpos($_SERVER['REQUEST_URI'], '?') !== false) {
        $parts = explode('?', $_SERVER['REQUEST_URI'], 2);
        return array($parts[1], false);

    } else if (isset($_SERVER['QUERY_STRING']) and strpos($_SERVER['QUERY_STRING'], '?') !== false) {
        // note: buggy or misconfigured IIS does return the query string in REQUEST_URI
        return array($_SERVER['QUERY_STRING'], false);

    } else if ($slashargument = min_get_slash_argument()) {
        $slashargument = ltrim($slashargument, '/');
        return array($slashargument, true);

    } else {
        // unsupported server, sorry!
        combo_not_found('Unsupported server - query string can not be determined, try disabling YUI combo loading in admin settings.');
    }
}
