<?php

/*
 * This file is part of Twig.
 *
 * (c) 2009 Fabien Potencier
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

/**
 * Loads template from the filesystem.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
class Twig_Loader_Filesystem implements Twig_LoaderInterface, Twig_ExistsLoaderInterface
{
  /** Identifier of the main namespace. */
  const MAIN_NAMESPACE = '__main__';

  protected $paths = [];
  protected $cache = [];

  /**
   * Constructor.
   *
   * @param string|array $paths A path or an array of paths where to look for templates
   */
  public function __construct($paths = [])
  {
    if ($paths) {
      $this->setPaths($paths);
    }
  }

  /**
   * Returns the paths to the templates.
   *
   * @param string $namespace A path namespace
   *
   * @return array The array of paths where to look for templates
   */
  public function getPaths($namespace = self::MAIN_NAMESPACE)
  {
    return isset($this->paths[$namespace]) ? $this->paths[$namespace] : [];
  }

  /**
   * Returns the path namespaces.
   *
   * The main namespace is always defined.
   *
   * @return array The array of defined namespaces
   */
  public function getNamespaces()
  {
    return array_keys($this->paths);
  }

  /**
   * Sets the paths where templates are stored.
   *
   * @param string|array $paths     A path or an array of paths where to look for templates
   * @param string       $namespace A path namespace
   */
  public function setPaths($paths, $namespace = self::MAIN_NAMESPACE)
  {
    if (!is_array($paths)) {
      $paths = [$paths];
    }

    $this->paths[$namespace] = [];
    foreach ($paths as $path) {
      $this->addPath($path, $namespace);
    }
  }

  /**
   * Adds a path where templates are stored.
   *
   * @param string $path      A path where to look for templates
   * @param string $namespace A path name
   *
   * @throws Twig_Error_Loader
   */
  public function addPath($path, $namespace = self::MAIN_NAMESPACE)
  {
    // invalidate the cache
    $this->cache = [];

    if (!is_dir($path)) {
      throw new Twig_Error_Loader(sprintf('The "%s" directory does not exist.', $path));
    }

    $this->paths[$namespace][] = rtrim($path, '/\\');
  }

  /**
   * Prepends a path where templates are stored.
   *
   * @param string $path      A path where to look for templates
   * @param string $namespace A path name
   *
   * @throws Twig_Error_Loader
   */
  public function prependPath($path, $namespace = self::MAIN_NAMESPACE)
  {
    // invalidate the cache
    $this->cache = [];

    if (!is_dir($path)) {
      throw new Twig_Error_Loader(sprintf('The "%s" directory does not exist.', $path));
    }

    $path = rtrim($path, '/\\');

    if (!isset($this->paths[$namespace])) {
      $this->paths[$namespace][] = $path;
    } else {
      array_unshift($this->paths[$namespace], $path);
    }
  }

  /**
   * {@inheritdoc}
   */
  public function getSource($name)
  {
    return file_get_contents($this->findTemplate($name));
  }

  /**
   * {@inheritdoc}
   */
  public function getCacheKey($name)
  {
    return $this->findTemplate($name);
  }

  /**
   * {@inheritdoc}
   */
  public function exists($name)
  {
    $name = $this->normalizeName($name);

    if (isset($this->cache[$name])) {
      return true;
    }

    try {
      $this->findTemplate($name);

      return true;
    } catch (Twig_Error_Loader $exception) {
      return false;
    }
  }

  /**
   * {@inheritdoc}
   */
  public function isFresh($name, $time)
  {
    return filemtime($this->findTemplate($name)) <= $time;
  }

  protected function findTemplate($name)
  {
    $name = $this->normalizeName($name);

    if (isset($this->cache[$name])) {
      return $this->cache[$name];
    }

    $this->validateName($name);

    [$namespace, $shortname] = $this->parseName($name);

    if (!isset($this->paths[$namespace])) {
      throw new Twig_Error_Loader(sprintf('There are no registered paths for namespace "%s".', $namespace));
    }

    foreach ($this->paths[$namespace] as $path) {
      if (is_file($path . '/' . $shortname)) {
        return $this->cache[$name] = $path . '/' . $shortname;
      }
    }

    throw new Twig_Error_Loader(sprintf('Unable to find template "%s" (looked into: %s).', $name, implode(', ', $this->paths[$namespace])));
  }

  protected function parseName($name, $default = self::MAIN_NAMESPACE)
  {
    if (isset($name[0]) && '@' == $name[0]) {
      if (false === ($pos = strpos($name, '/'))) {
        throw new Twig_Error_Loader(sprintf('Malformed namespaced template name "%s" (expecting "@namespace/template_name").', $name));
      }

      $namespace = substr($name, 1, $pos - 1);
      $shortname = substr($name, $pos + 1);

      return [$namespace, $shortname];
    }

    return [$default, $name];
  }

  protected function normalizeName($name)
  {
    return preg_replace('#/{2,}#', '/', strtr((string) $name, '\\', '/'));
  }

  protected function validateName($name)
  {
    if (false !== strpos($name, "\0")) {
      throw new Twig_Error_Loader('A template name cannot contain NUL bytes.');
    }

    $name = ltrim($name, '/');
    $parts = explode('/', $name);
    $level = 0;
    foreach ($parts as $part) {
      if ('..' === $part) {
        --$level;
      } elseif ('.' !== $part) {
        ++$level;
      }

      if ($level < 0) {
        throw new Twig_Error_Loader(sprintf('Looks like you try to load a template outside configured directories (%s).', $name));
      }
    }
  }
}
