<?php

class Qs_Packer
{
    protected static $_defaultScriptPath = 'js';
    protected static $_defaultStylesheetPath = 'css';
    protected static $_config = array(
        'individualScriptPaths'     => array(),
        'individualStylesheetPaths' => array(),
        'stylesheet'                => array(),
        'script'                    => array(),
    );
    protected static $_configLoaded = false;
    protected static $_configChanged = false;
    
    protected static function _getConfigFileName()
    {
        return WWW_PATH . '/_lib/packer.config.php';
    }
    
    public static function loadConfig()
    {
        if (Qs_Packer::$_configLoaded) {
            return false;
        }
        $file = Qs_Packer::_getConfigFileName();
        if (!file_exists($file)) {
            $content = "<?php\n\nreturn " . var_export(Qs_Packer::$_config, true) . ';';
            file_put_contents($file, $content);
        } else {
            Qs_Packer::$_config = include($file);
        }
        Qs_Packer::$_configLoaded = true;
        return true;
    }

    public static function updateConfig()
    {
        if (!Qs_Packer::$_configChanged) {
            return false;
        }
        $file = Qs_Packer::_getConfigFileName();
        $content = "<?php\n\nreturn " . var_export(Qs_Packer::$_config, true) . ';';
        file_put_contents($file, $content);
        return true;
    }

    protected static function _getSuffix()
    {
        return ((Qs_Constant::get('USE_PACKED_RESOURCES')) ? '.pack' : '');
    }
    
    protected static function _isRegistered($type, $name)
    {
        if (false !== array_search($name, Qs_Packer::$_config[$type])) {
            return true;
        }
        return false;
    }
    
    public static function isRegisteredStylesheet($name)
    {
        return Qs_Packer::_isRegistered('stylesheet', $name);
    }
    
    public static function isRegisteredScript($name)
    {
        return Qs_Packer::_isRegistered('script', $name);
    }
    
    protected static function _register($type, $name)
    {
        Qs_Packer::$_config[$type][] = $name;
        Qs_Packer::$_configChanged = true;
    }
    
    public static function registerStylesheet($name)
    {
        Qs_Packer::_register('stylesheet', $name);
    }
    
    public static function registerScript($name)
    {
        Qs_Packer::_register('script', $name);
    }
    
    protected static function _getIndex($type, $name)
    {
        return array_search($name, Qs_Packer::$_config[$type]);
    }
    
    public static function getStylesheetIndex($name)
    {
        return Qs_Packer::_getIndex('stylesheet', $name);
    }
    
    public static function getScriptIndex($name)
    {
        return Qs_Packer::_getIndex('script', $name);
    }
    
    public static function getMergedStylesheets($list)
    {
        if (empty($list)) {
            return false;
        }

        Qs_Packer::loadConfig();

        $result = array();
        $indexes = array();

        foreach ($list as $options) {
            if ('text/css' != strtolower($options['type'])
                || !Qs_Packer::_isLocalFile($options['href'])
                || Qs_Array::get($options, 'skipPacking', false)
            ) {
                $href = $options['href'];
                unset($options['href']);
                $result[] = array('href' => $href, 'attribs' => $options);
                continue;
            }

            if (!Qs_Packer::isRegisteredStylesheet($options['href'])) {
                Qs_Packer::registerStylesheet($options['href']);
            }
            $path = $_path = dirname($options['href']);
            $media = Qs_Array::get($options, 'media', 'screen');
            $isIndividualPath = false;
            do {
                if (in_array($_path, Qs_Packer::$_config['individualStylesheetPaths'])) {
                    $isIndividualPath = true;
                    break;
                }
            } while ('.' != ($_path = dirname($_path)) && '/' != $_path);
            if (!$isIndividualPath) {
                $path = Qs_Packer::$_defaultStylesheetPath;
            }
            $itemIndex = $path . ':' . $media;
            if (!array_key_exists($itemIndex, $indexes)) {
                $indexes[$itemIndex] = array(
                    'path'    => $path,
                    'media'   => $media,
                    'indexes' => array(),
                );
            }
            $indexes[$itemIndex]['indexes'][] = Qs_Packer::getStylesheetIndex($options['href']);
        }

        foreach ($indexes as $options) {
            $href = $options['path'] . '/' . implode('-', $options['indexes']) . Qs_Packer::_getSuffix() . '.merge.css';
            $mergedStylesheets = array(
                // 1-st argument in doc->addStylesheet function
                'href'    => $href, 
                // 2-nd argument in doc->addStylesheet function
                'attribs' => array(
                    'media' => $options['media']
                )
            );
            array_unshift($result, $mergedStylesheets);
        }

        Qs_Packer::updateConfig();

        return $result;
    }
    
    public static function getMergedScripts($list)
    {
        if (empty($list)) {
            return false;
        }

        Qs_Packer::loadConfig();

        $result = array();
        $indexes = array();

        foreach ($list as $options) {
            if (!Qs_Packer::_isLocalFile($options['src']) || Qs_Array::get($options, 'skipPacking', false)) {
                $result[] = $options['src'];
                continue;
            }

            if (!Qs_Packer::isRegisteredScript($options['src'])) {
                Qs_Packer::registerScript($options['src']);
            }
            $path = $_path = dirname($options['src']);
            $isIndividualPath = false;
            do {
                if (in_array($_path, Qs_Packer::$_config['individualScriptPaths'])) {
                    $isIndividualPath = true;
                    break;
                }
            } while ('.' != ($_path = dirname($_path)));
            if (!$isIndividualPath) {
                $path = Qs_Packer::$_defaultScriptPath;
            }
            $indexes[$path][] = Qs_Packer::getScriptIndex($options['src']);
        }

        foreach ($indexes as $path => $pathIndexes) {
            array_unshift($result, $path . '/' . implode('-', $pathIndexes) . Qs_Packer::_getSuffix(). '.merge.js');
        }

        Qs_Packer::updateConfig();

        return $result;
    }

    protected static function _isLocalFile($file)
    {
        // gag: parse_url does not support protocol related urls (https://bugs.php.net/bug.php?id=43721)
        if ('//' == substr($file, 0, 2)) {
            $file = 'http:' . $file;
        }
        $fileHost = parse_url($file, PHP_URL_HOST);
        if ($fileHost && $fileHost != parse_url(constant('BASE_URL'), PHP_URL_HOST)) {
            return false;
        }
        return true;
    }

    public static function merge($indexes, $file, $suffix, $extension)
    {
        if (empty($indexes)) {
            return false;
        }
        Qs_Packer::loadConfig();
        switch ($extension) {
            case 'css':
                $files = Qs_Packer::$_config['stylesheet'];
                $delimiter = "\n";
                break;
            case 'js':
                $files = Qs_Packer::$_config['script'];
                $delimiter = ";\n";
                break;
            default:
                return false;
        }
        $list = array();
        foreach ($indexes as $index) {
            if (array_key_exists($index, $files)) {
                $list[$index] = $files[$index];
                if ($suffix == 'pack') {
                    $list[$index] = str_replace('.' . $extension, '.' . $suffix . '.' . $extension, $list[$index]);
                }
            }
        }
        if (!$handle = fopen(WWW_PATH . '/' . $file, 'w+')) {
            return false;
        }
        foreach ($list as $name) {
            $content = file_get_contents(WWW_PATH . '/' . $name);
            if ('css' === $extension) {
                $content = self::_prepareCssResourcePaths($file, $name, $content);
            }
            fwrite($handle, $content . $delimiter);
        }
        fclose($handle);
        return true;
    }

    /**
     * Method replace related paths for resources inside css
     * @param string $dstFile Relative name of destination file (ex. css/0-1-2.merge.css)
     * @param string $srcFile Relative name of source file (ex. css/modules/site.css)
     * @param string $content Source file content
     * @return string
     * @throws Exception
     */
    protected static function _prepareCssResourcePaths($dstFile, $srcFile, $content)
    {
        $dstPathDepth = (int) substr_count($dstFile, '/');
        $pathDepth = (int)substr_count($srcFile, '/');
        $pathDiff = $pathDepth - $dstPathDepth;

        if (0 > $pathDiff) {
            throw new Exception('Wrong location of resource file "' . $srcFile . '"');
        } elseif (0 < $pathDiff) {
            $resourcePath = ($resourcePath = substr(dirname($srcFile), strlen('css/')))
                ? $resourcePath
                : BASE_URL . '/' . dirname($srcFile);
            $content = preg_replace_callback(
                '#url\(\s*(([\'"])?([^\s\)]+)?\1?)\s*\)#',
                function ($match) use ($resourcePath) {
                    $quote = $match[2];
                    $path = $match[1];

                    if (0 === strpos($path, 'data:')) {
                        return $match[0];
                    }

                    if ($quote) {
                        $path = trim($path, $quote);
                    }

                    if (false !== strpos($path, '://') || '/' === $path[0]) {
                        return $match[0];
                    }

                    $path = $resourcePath . '/' . $path;
                    return "url({$quote}{$path}{$quote})";
                },
                $content
            );
        }

        return $content;
    }
}