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
 */

return require __DIR__ . '/{<span class="php-variable">$relative_autoload_path</span>}';

EOF;
    }

}