<?php
/* --------------------------------------------------------------------------
 * XIRE - eXtendable Information Rendering Engine
 * --------------------------------------------------------------------------
 * LICENSE
 * Copyright (C) 2006  David Duong
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 * -------------------------------------------------------------------------- */
class XIRE_CacheTemplate {
    private static $directories = array('' => './cache');
    // Read-only
    private $name;
    private $key;
    private $lifetime;
    // Private
    private $templateFile;
    private $template;
    private $path;

    private $validPath;

    public function __construct ($template) {
        // Accept both a string to the template file, or a XIRE_Template
        if ($template instanceof XIRE_Template) {
            $this->template = $template;
            $this->templateFile = $this->template->filename;
        } else {
            $this->templateFile = (string)$template;
        }
        $this->validPath = false;
        // Initialise name to the template file's base name
        $this->name = basename($this->templateFile);
    }

    public function __get ($name) {
        if ($name === 'template') {
            return $this->getTemplate();
        }
    }

    public function __set ($name, $value)
    {
        switch ($name) {
            case 'name':
                if (!isset($this->name)) {
                    $this->name = basename($this->templateFile);
                } else {
                    strpos($name, '\\') === false
                      or $name = str_replace('\\', '/', (string)$value);
                    $this->name = (string)$value;
                }
                $this->validPath = false;
            break;
            case 'key':
                $this->key = (string)$value;
                $this->validPath = false;
            break;
            case 'lifetime':
                $this->lifetime = (int)$value;
            break;
        }
    }

    private function update () {
        if (strpos($this->name, '/') === false) {
            $this->path = self::$directories[''] . "/$this->name";
        } else {
            list($cache, $path) = explode('/', $this->name, 2);
            isset(self::$directories[$cache])
              or self::$directories[$cache] = self::$directories[''] . "/$cache";
            $this->path = self::$directories[''] . "/$path";
        }

        isset($this->key) and $this->path .= "/{$this->key}";
        $this->path .= '.xml';
    }

    /**
     * Check if a valid, i.e. cache exists and has not expired
     */
    public function exists () {
        $this->validPath or $this->update();
        // Return false unless file exists and either lifetime is unset or has not expired
        if (file_exists($this->path)
          && (!isset($this->lifetime)
          || time() <= filemtime($this->path) + $this->lifetime)) {
            return true;
        }
        return false;
    }

    /**
     * Get the filename of a valid cache file
     */
    public function getFile () {
        $this->validPath or $this->update();
        $this->exists() or $this->make();
        return $this->path;
    }

    /**
     * @return the XIRE_Template object used by this instance
     */
    public function getTemplate () {
        if (!isset($this->template)) {
            // Create a template object if it does not exist
            require_once '../lib/Template.class.php';
            $this->template = new XIRE_Template($this->templateFile);
        }
        return $this->template;
    }

    /**
     * Create the cache version (ignores whethor or not the cache is valid)
     */
    public function make () {
        // Make sure that the environment is good
        $this->validPath or $this->update();
        if (!is_dir(dirname($this->path))
          && @mkdir(dirname($this->path), 0755, true) === false) {
            throw new XIRE_CouldNotCreateCacheException('Unable to create parent folder');
        }
        isset($this->template) or $this->getTemplate();
        $this->template->process();
        $this->template->save($this->path);
    }

    /**
     * Load the cache file into the template's DOM document
     */
    public function load() {
        isset($this->template) or $this->getTemplate();
        if(!@$this->template->document->load($this->getFile()) {
            throw new XIRE_InvalidFileException('Unable to load cache');
        }
    }

    /**
     * Set a directory to store caches.
     * @param string $cache caches with names that begin with '$cache/' will be stored in 
     * $directory
     * @param string $directory
     */
    public static function setCacheDirectory ($cache, $directory) {
        self::$directories[$cache] = $directory;
    }
}

class XIRE_CouldNotCreateCacheException extends XIRE_Exception{}
?>