class GenerateAutoloadReferenceFile

final class GenerateAutoloadReferenceFile {
  
  /**
   * This class provides only static methods.
   */
  private function __construct() {
  }
  
  /**
   * Generates the autoload file at the specified location.
   *
   * This only writes a bit of PHP that includes the autoload file that
   * Composer generated. Drupal does this so that it can guarantee that there
   * will always be an `autoload.php` file in a well-known location.
   *
   * @param \Composer\IO\IOInterface $io
   *   IOInterface to write to.
   * @param string $package_name
   *   The name of the package defining the autoload file (the root package).
   * @param string $web_root
   *   The path to the web root.
   * @param string $vendor
   *   The path to the vendor directory.
   *
   * @return \Drupal\Composer\Plugin\Scaffold\Operations\ScaffoldResult
   *   The result of the autoload file generation.
   */
  public static function generateAutoload(IOInterface $io, $package_name, $web_root, $vendor) {
    $autoload_path = static::autoloadPath($package_name, $web_root);
    // Calculate the relative path from the webroot (location of the project
    // autoload.php) to the vendor directory.
    $fs = new Filesystem();
    $relative_autoload_path = $fs->findShortestPath($autoload_path->fullPath(), "{$vendor}/autoload.php");
    file_put_contents($autoload_path->fullPath(), static::autoLoadContents($relative_autoload_path));
    return new ScaffoldResult($autoload_path, TRUE);
  }
  
  /**
   * Determines whether or not the autoload file has been committed.
   *
   * @param \Composer\IO\IOInterface $io
   *   IOInterface to write to.
   * @param string $package_name
   *   The name of the package defining the autoload file (the root package).
   * @param string $web_root
   *   The path to the web root.
   *
   * @return bool
   *   True if autoload.php file exists and has been committed to the repository
   */
  public static function autoloadFileCommitted(IOInterface $io, $package_name, $web_root) {
    $autoload_path = static::autoloadPath($package_name, $web_root);
    $autoload_file = $autoload_path->fullPath();
    $location = dirname($autoload_file);
    if (!file_exists($autoload_file)) {
      return FALSE;
    }
    return Git::checkTracked($io, $autoload_file, $location);
  }
  
  /**
   * Generates a scaffold file path object for the autoload file.
   *
   * @param string $package_name
   *   The name of the package defining the autoload file (the root package).
   * @param string $web_root
   *   The path to the web root.
   *
   * @return \Drupal\Composer\Plugin\Scaffold\ScaffoldFilePath
   *   Object wrapping the relative and absolute path to the destination file.
   */
  protected static function autoloadPath($package_name, $web_root) {
    $rel_path = 'autoload.php';
    $dest_rel_path = '[web-root]/' . $rel_path;
    $dest_full_path = $web_root . '/' . $rel_path;
    return new ScaffoldFilePath('autoload', $package_name, $dest_rel_path, $dest_full_path);
  }
  
  /**
   * Builds the contents of the autoload file.
   *
   * @param string $relative_autoload_path
   *   The relative path to the autoloader in vendor.
   *
   * @return string
   *   Return the contents for the autoload.php.
   */
  protected static function autoLoadContents($relative_autoload_path) {
    $relative_autoload_path = preg_replace('#^\\./#', '', $relative_autoload_path);
    return <<<EOF
    <?php
    
    /**
     * @file
     * Includes the autoloader created by Composer.
     *
     * This file was generated by drupal-scaffold.
     *
     * @see composer.json
     * @see index.php
     * @see core/install.php
     * @see core/rebuild.php
     * @see core/modules/statistics/statistics.php
     */
    
    return require __DIR__ . '/{<span class="php-variable">$relative_autoload_path</span>}';
    
    EOF;
  }

}