class Handler

class Handler {
    
    /**
     * Composer hook called before scaffolding begins.
     */
    const PRE_DRUPAL_SCAFFOLD_CMD = 'pre-drupal-scaffold-cmd';
    
    /**
     * Composer hook called after scaffolding completes.
     */
    const POST_DRUPAL_SCAFFOLD_CMD = 'post-drupal-scaffold-cmd';
    
    /**
     * The Composer service.
     *
     * @var \Composer\Composer
     */
    protected $composer;
    
    /**
     * Composer's I/O service.
     *
     * @var \Composer\IO\IOInterface
     */
    protected $io;
    
    /**
     * The scaffold options in the top-level composer.json's 'extra' section.
     *
     * @var \Drupal\Composer\Plugin\Scaffold\ManageOptions
     */
    protected $manageOptions;
    
    /**
     * The manager that keeps track of which packages are allowed to scaffold.
     *
     * @var \Drupal\Composer\Plugin\Scaffold\AllowedPackages
     */
    protected $manageAllowedPackages;
    
    /**
     * The list of listeners that are notified after a package event.
     *
     * @var \Drupal\Composer\Plugin\Scaffold\PostPackageEventListenerInterface[]
     */
    protected $postPackageListeners = [];
    
    /**
     * Handler constructor.
     *
     * @param \Composer\Composer $composer
     *   The Composer service.
     * @param \Composer\IO\IOInterface $io
     *   The Composer I/O service.
     */
    public function __construct(Composer $composer, IOInterface $io) {
        $this->composer = $composer;
        $this->io = $io;
        $this->manageOptions = new ManageOptions($composer);
        $this->manageAllowedPackages = new AllowedPackages($composer, $io, $this->manageOptions);
    }
    
    /**
     * Registers post-package events if the 'require' command was called.
     */
    public function requireWasCalled() {
        // In order to differentiate between post-package events called after
        // 'composer require' vs. the same events called at other times, we will
        // only install our handler when a 'require' event is detected.
        $this->postPackageListeners[] = $this->manageAllowedPackages;
    }
    
    /**
     * Posts package command event.
     *
     * We want to detect packages 'require'd that have scaffold files, but are not
     * yet allowed in the top-level composer.json file.
     *
     * @param \Composer\Installer\PackageEvent $event
     *   Composer package event sent on install/update/remove.
     */
    public function onPostPackageEvent(PackageEvent $event) {
        foreach ($this->postPackageListeners as $listener) {
            $listener->event($event);
        }
    }
    
    /**
     * Creates scaffold operation objects for all items in the file mappings.
     *
     * @param \Composer\Package\PackageInterface $package
     *   The package that relative paths will be relative from.
     * @param array $package_file_mappings
     *   The package file mappings array keyed by destination path and the values
     *   are operation metadata arrays.
     *
     * @return \Drupal\Composer\Plugin\Scaffold\Operations\OperationInterface[]
     *   A list of scaffolding operation objects
     */
    protected function createScaffoldOperations(PackageInterface $package, array $package_file_mappings) {
        $scaffold_op_factory = new OperationFactory($this->composer);
        $scaffold_ops = [];
        foreach ($package_file_mappings as $dest_rel_path => $data) {
            $operation_data = new OperationData($dest_rel_path, $data);
            $scaffold_ops[$dest_rel_path] = $scaffold_op_factory->create($package, $operation_data);
        }
        return $scaffold_ops;
    }
    
    /**
     * Copies all scaffold files from source to destination.
     */
    public function scaffold() {
        // Recursively get the list of allowed packages. Only allowed packages
        // may declare scaffold files. Note that the top-level composer.json file
        // is implicitly allowed.
        $allowed_packages = $this->manageAllowedPackages
            ->getAllowedPackages();
        if (empty($allowed_packages)) {
            $this->io
                ->write("Nothing scaffolded because no packages are allowed in the top-level composer.json file.");
            return;
        }
        // Call any pre-scaffold scripts that may be defined.
        $dispatcher = $this->composer
            ->getEventDispatcher();
        $dispatcher->dispatchScript(self::PRE_DRUPAL_SCAFFOLD_CMD);
        // Fetch the list of file mappings from each allowed package and normalize
        // them.
        $file_mappings = $this->getFileMappingsFromPackages($allowed_packages);
        $location_replacements = $this->manageOptions
            ->getLocationReplacements();
        $scaffold_options = $this->manageOptions
            ->getOptions();
        // Create a collection of scaffolded files to process. This determines which
        // take priority and which are combined.
        $scaffold_files = new ScaffoldFileCollection($file_mappings, $location_replacements);
        // Get the scaffold files whose contents on disk match what we are about to
        // write. We can remove these from consideration, as rewriting would be a
        // no-op.
        $unchanged = $scaffold_files->checkUnchanged();
        $scaffold_files->filterFiles($unchanged);
        // Process the list of scaffolded files.
        $scaffold_results = $scaffold_files->processScaffoldFiles($this->io, $scaffold_options);
        // Generate an autoload file in the document root that includes the
        // autoload.php file in the vendor directory, wherever that is. Drupal
        // requires this in order to easily locate relocated vendor dirs.
        $web_root = $this->manageOptions
            ->getOptions()
            ->getLocation('web-root');
        if (!GenerateAutoloadReferenceFile::autoloadFileCommitted($this->io, $this->rootPackageName(), $web_root)) {
            $scaffold_results[] = GenerateAutoloadReferenceFile::generateAutoload($this->io, $this->rootPackageName(), $web_root, $this->getVendorPath());
        }
        // Add the managed scaffold files to .gitignore if applicable.
        $gitIgnoreManager = new ManageGitIgnore($this->io, getcwd());
        $gitIgnoreManager->manageIgnored($scaffold_results, $scaffold_options);
        // Call post-scaffold scripts.
        $dispatcher->dispatchScript(self::POST_DRUPAL_SCAFFOLD_CMD);
    }
    
    /**
     * Gets the path to the 'vendor' directory.
     *
     * @return string
     *   The file path of the vendor directory.
     */
    protected function getVendorPath() {
        $vendor_dir = $this->composer
            ->getConfig()
            ->get('vendor-dir');
        $filesystem = new Filesystem();
        return $filesystem->normalizePath(realpath($vendor_dir));
    }
    
    /**
     * Gets a consolidated list of file mappings from all allowed packages.
     *
     * @param \Composer\Package\PackageInterface[] $allowed_packages
     *   A multidimensional array of file mappings, as returned by
     *   self::getAllowedPackages().
     *
     * @return \Drupal\Composer\Plugin\Scaffold\Operations\OperationInterface[][]
     *   An array of destination paths => scaffold operation objects.
     */
    protected function getFileMappingsFromPackages(array $allowed_packages) {
        $file_mappings = [];
        foreach ($allowed_packages as $package_name => $package) {
            $file_mappings[$package_name] = $this->getPackageFileMappings($package);
        }
        return $file_mappings;
    }
    
    /**
     * Gets the array of file mappings provided by a given package.
     *
     * @param \Composer\Package\PackageInterface $package
     *   The Composer package from which to get the file mappings.
     *
     * @return \Drupal\Composer\Plugin\Scaffold\Operations\OperationInterface[]
     *   An array of destination paths => scaffold operation objects.
     */
    protected function getPackageFileMappings(PackageInterface $package) {
        $options = $this->manageOptions
            ->packageOptions($package);
        if ($options->hasFileMapping()) {
            return $this->createScaffoldOperations($package, $options->fileMapping());
        }
        // Warn the user if they allow a package that does not have any scaffold
        // files. We will ignore drupal/core, though, as it is implicitly allowed,
        // but might not have scaffold files (version 8.7.x and earlier).
        if (!$options->hasAllowedPackages() && $package->getName() != 'drupal/core') {
            $this->io
                ->writeError("The allowed package {$package->getName()} does not provide a file mapping for Composer Scaffold.");
        }
        return [];
    }
    
    /**
     * Gets the root package name.
     *
     * @return string
     *   The package name of the root project
     */
    protected function rootPackageName() {
        $root_package = $this->composer
            ->getPackage();
        return $root_package->getName();
    }

}