<?php

declare(strict_types=1);

namespace Drupal\islandora_collection_harvest\Controller;

use Drupal\Core\Controller\ControllerBase;
use Drupal\Core\File\FileSystemInterface;
use Drupal\Core\StreamWrapper\StreamWrapperManagerInterface;
use Drupal\Core\TempStore\PrivateTempStoreFactory;
use Drupal\flysystem\FlysystemFactory;
use Symfony\Component\HttpFoundation\StreamedResponse;
use Symfony\Component\DependencyInjection\ContainerInterface;
use ZipStream\ZipStream;
use Drupal\media\MediaInterface;
use Drupal\file\FileInterface;

/**
 * Controller responsible for streaming ZIP downloads of collection media.
 *
 * This class:
 *  - Loads media entities stored by the form in PrivateTempStore.
 *  - Builds and streams a ZIP archive using ZipStream without
 *    temporary files or memory-heavy buffering.
 *  - Supports both local and Flysystem (remote) file schemes.
 *
 * @see \Drupal\islandora_collection_harvest\Form\CollectionHarvestForm
 */
final class HarvestDownloadController extends ControllerBase {

  /**
   * The file system service.
   *
   * @var \Drupal\Core\File\FileSystemInterface
   */
  protected FileSystemInterface $fileSystem;

  /**
   * The private tempstore factory.
   *
   * @var \Drupal\Core\TempStore\PrivateTempStoreFactory
   */
  protected PrivateTempStoreFactory $tempStoreFactory;

  /**
   * The Flysystem factory service.
   *
   * @var \Drupal\flysystem\FlysystemFactory
   */
  protected FlysystemFactory $flysystemFactory;

  /**
   * The stream wrapper manager service.
   *
   * @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface
   */
  protected StreamWrapperManagerInterface $streamWrapperManager;

  /**
   * Constructs a new HarvestDownloadController.
   *
   * @param \Drupal\Core\File\FileSystemInterface $file_system
   *   The file system service.
   * @param \Drupal\Core\TempStore\PrivateTempStoreFactory $tempStoreFactory
   *   The private tempstore factory.
   * @param \Drupal\flysystem\FlysystemFactory $flysystemFactory
   *   The Flysystem factory.
   * @param \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface $streamWrapperManager
   *   The stream wrapper manager.
   */
  public function __construct(
    FileSystemInterface $file_system,
    PrivateTempStoreFactory $tempStoreFactory,
    FlysystemFactory $flysystemFactory,
    StreamWrapperManagerInterface $streamWrapperManager
  ) {
    $this->fileSystem = $file_system;
    $this->tempStoreFactory = $tempStoreFactory;
    $this->flysystemFactory = $flysystemFactory;
    $this->streamWrapperManager = $streamWrapperManager;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container): self {
    return new self(
      $container->get('file_system'),
      $container->get('tempstore.private'),
      $container->get('flysystem_factory'),
      $container->get('stream_wrapper_manager')
    );
  }

  /**
   * Streams a ZIP file containing the requested media files.
   *
   * The media IDs were stored in PrivateTempStore by the form submit handler.
   * This method:
   *  - Reloads all referenced media entities.
   *  - Iterates through each file, adding it to a ZipStream stream.
   *  - Handles both local and remote file systems gracefully.
   *
   * @param string $filename
   *   The generated filename (used as the PrivateTempStore key and download name).
   *
   * @return \Symfony\Component\HttpFoundation\StreamedResponse
   *   The streaming ZIP response.
   *
   * @throws \Symfony\Component\HttpKernel\Exception\NotFoundHttpException
   *   Thrown if the media list cannot be found in tempstore.
   */
  public function download(string $filename): StreamedResponse {
    set_time_limit(0);
    ignore_user_abort(true);

    // Retrieve stored media IDs.
    $temp_store = $this->tempStoreFactory->get('islandora_collection_harvest');
    $media_ids = $temp_store->get($filename);

    if (empty($media_ids)) {
      throw new \Symfony\Component\HttpKernel\Exception\NotFoundHttpException('No media found.');
    }

    // Reload media entities for this request.
    /** @var \Drupal\media\MediaInterface[] $media_entities */
    $media_entities = \Drupal::entityTypeManager()
      ->getStorage('media')
      ->loadMultiple($media_ids);

    // Build the streamed ZIP response.
    $response = new StreamedResponse(function () use ($media_entities) {
      // Clean any buffered output.
      if (ob_get_level()) {
        @ob_end_clean();
      }

      ignore_user_abort(true);
      set_time_limit(0);

      // Initialize the ZipStream object.
      $zip = new ZipStream();

      // Process each media entity.
      foreach ($media_entities as $media) {
        if (!$media instanceof MediaInterface) {
          continue;
        }

        $source_field = $media->getSource()->getConfiguration()['source_field'] ?? NULL;
        if (!$source_field || !$media->hasField($source_field) || $media->get($source_field)->isEmpty()) {
          continue;
        }

        /** @var \Drupal\file\FileInterface|null $file */
        $file = $media->get($source_field)->entity;
        if (!$file instanceof FileInterface) {
          continue;
        }

        $uri = $file->getFileUri();
        $name_in_zip = basename($uri);

        // Try to use a local file path first.
        $realpath = $this->fileSystem->realpath($uri);
        if ($realpath && file_exists($realpath)) {
          $zip->addFileFromPath($name_in_zip, $realpath);
          continue;
        }

        // Fall back to Flysystem (remote storage).
        try {
          $scheme = $this->streamWrapperManager->getScheme($uri);
          $path = substr($uri, strlen($scheme) + 3);
          $filesystem = $this->flysystemFactory->getFilesystem($scheme);

          if ($filesystem && $filesystem->has($path)) {
            // Try stream-based read first.
            if (method_exists($filesystem, 'readStream')) {
              $stream = $filesystem->readStream($path);
              if ($stream) {
                $zip->addFileFromStream($name_in_zip, $stream);
                @fclose($stream);
              }
            }
            else {
              // Fallback to full read (less memory-efficient).
              $contents = $filesystem->read($path);
              if ($contents !== false) {
                $zip->addFile($name_in_zip, $contents);
              }
            }
          }
        }
        catch (\Exception $e) {
          $this->logger('islandora_collection_harvest')->error(
            'Flysystem read failed for @uri: @msg',
            ['@uri' => $uri, '@msg' => $e->getMessage()]
          );
        }
      }

      // Finalize the ZIP output and flush to browser.
      $zip->finish();
      @flush();
    });

    // Set appropriate download headers.
    $response->headers->set('Content-Type', 'application/zip');
    $response->headers->set('Content-Disposition', 'attachment; filename="' . $filename . '"');

    return $response;
  }

}