<?php

declare(strict_types=1);

namespace Drupal\islandora_mirador_annotations\Controller;

use Drupal\Core\Controller\ControllerBase;
use Drupal\Core\Database\Connection;
use Drupal\Component\Datetime\TimeInterface;
use Drupal\Core\Session\AccountProxyInterface;
use Drupal\Component\Uuid\UuidInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpKernel\Exception\BadRequestHttpException;
use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;

/**
 * Provides the annotation persistence endpoint used by the Mirador adapter.
 */
final class AnnotationController extends ControllerBase {

  public function __construct(
    private readonly Connection $database,
    private readonly AccountProxyInterface $currentAccount,
    private readonly TimeInterface $time,
    private readonly UuidInterface $uuid,
  ) {}

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container): static {
    return new static(
      $container->get('database'),
      $container->get('current_user'),
      $container->get('datetime.time'),
      $container->get('uuid'),
    );
  }

  /**
   * Returns an IIIF AnnotationPage for a canvas.
   */
  public function collection(Request $request): JsonResponse {
    $canvas_id = trim((string) $request->query->get('canvas', ''));
    if ($canvas_id === '') {
      throw new BadRequestHttpException('The canvas query parameter is required.');
    }

    return new JsonResponse($this->annotationPage($canvas_id, $request));
  }


  /**
   * Returns annotations for a set of canvases in one request.
   *
   * This is used by the "All annotations" manifest sidebar. It deliberately
   * accepts canvas IDs rather than re-fetching the manifest on the server, so
   * it also works with authenticated/proxied manifests already available to
   * the browser.
   */
  public function manifestCollection(Request $request): JsonResponse {
    $data = $this->decodeRequest($request);
    $canvas_ids = $data['canvasIds'] ?? NULL;

    if (!is_array($canvas_ids)) {
      throw new BadRequestHttpException('canvasIds must be an array.');
    }

    $canvas_ids = array_values(array_unique(array_filter(array_map(
      static fn ($value) => is_string($value) ? trim($value) : '',
      $canvas_ids
    ))));

    // Keep an accidental or malicious request from building an enormous IN
    // clause. IIIF manifests with thousands of canvases remain supported.
    if (count($canvas_ids) > 10000) {
      throw new BadRequestHttpException('Too many canvas IDs requested.');
    }

    if (!$canvas_ids) {
      return new JsonResponse(['items' => []]);
    }

    $items = [];
    foreach (array_chunk($canvas_ids, 500) as $chunk) {
      $keys = array_map(static fn ($id) => hash('sha256', $id), $chunk);
      $result = $this->database->select('islandora_mirador_annotation', 'a')
        ->fields('a', ['canvas_id', 'annotation_json', 'created'])
        ->condition('canvas_key', $keys, 'IN')
        ->orderBy('created', 'ASC')
        ->execute();

      foreach ($result as $row) {
        try {
          $annotation = json_decode($row->annotation_json, TRUE, 512, JSON_THROW_ON_ERROR);
          if (is_array($annotation)) {
            $items[] = [
              'canvasId' => $row->canvas_id,
              'annotation' => $annotation,
            ];
          }
        }
        catch (\JsonException) {
          // Ignore a corrupt row rather than breaking the entire manifest list.
        }
      }
    }

    return new JsonResponse(['items' => $items]);
  }

  /**
   * Creates an annotation and returns the updated AnnotationPage.
   */
  public function store(Request $request): JsonResponse {
    [$canvas_id, $annotation] = $this->payload($request);

    if (empty($annotation['id'])) {
      $annotation['id'] = 'urn:uuid:' . $this->uuid->generate();
    }

    $annotation_id = (string) $annotation['id'];
    $now = $this->time->getRequestTime();
    $record = [
      'annotation_key' => hash('sha256', $annotation_id),
      'annotation_id' => $annotation_id,
      'canvas_key' => hash('sha256', $canvas_id),
      'canvas_id' => $canvas_id,
      'uid' => (int) $this->currentAccount->id(),
      'annotation_json' => json_encode($annotation, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_THROW_ON_ERROR),
      'created' => $now,
      'changed' => $now,
    ];

    // Treat a repeated create as an upsert; this makes retries safe.
    $existing = $this->database->select('islandora_mirador_annotation', 'a')
      ->fields('a', ['id'])
      ->condition('annotation_key', $record['annotation_key'])
      ->execute()
      ->fetchAssoc();

    if ($existing) {
      unset($record['created']);
      $this->database->update('islandora_mirador_annotation')
        ->fields($record)
        ->condition('id', $existing['id'])
        ->execute();
    }
    else {
      $this->database->insert('islandora_mirador_annotation')
        ->fields($record)
        ->execute();
    }

    return new JsonResponse($this->annotationPage($canvas_id, $request), 201);
  }

  /**
   * Updates an annotation and returns the updated AnnotationPage.
   */
  public function update(Request $request): JsonResponse {
    [$canvas_id, $annotation] = $this->payload($request);
    $annotation_id = trim((string) ($annotation['id'] ?? ''));
    if ($annotation_id === '') {
      throw new BadRequestHttpException('The annotation must contain an id.');
    }

    $count = $this->database->update('islandora_mirador_annotation')
      ->fields([
        'canvas_key' => hash('sha256', $canvas_id),
        'canvas_id' => $canvas_id,
        'annotation_json' => json_encode($annotation, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_THROW_ON_ERROR),
        'changed' => $this->time->getRequestTime(),
      ])
      ->condition('annotation_key', hash('sha256', $annotation_id))
      ->execute();

    if (!$count) {
      throw new NotFoundHttpException('Annotation not found.');
    }

    return new JsonResponse($this->annotationPage($canvas_id, $request));
  }

  /**
   * Deletes an annotation and returns the updated AnnotationPage.
   */
  public function delete(Request $request): JsonResponse {
    $data = $this->decodeRequest($request);
    $canvas_id = trim((string) ($data['canvasId'] ?? ''));
    $annotation_id = trim((string) ($data['annotationId'] ?? ''));

    if ($canvas_id === '' || $annotation_id === '') {
      throw new BadRequestHttpException('canvasId and annotationId are required.');
    }

    $this->database->delete('islandora_mirador_annotation')
      ->condition('annotation_key', hash('sha256', $annotation_id))
      ->execute();

    return new JsonResponse($this->annotationPage($canvas_id, $request));
  }

  /**
   * Parses a create/update request.
   */
  private function payload(Request $request): array {
    $data = $this->decodeRequest($request);
    $canvas_id = trim((string) ($data['canvasId'] ?? ''));
    $annotation = $data['annotation'] ?? NULL;

    if ($canvas_id === '' || !is_array($annotation)) {
      throw new BadRequestHttpException('canvasId and annotation are required.');
    }

    // The Web Annotation target is authoritative. MAE can occasionally save
    // through an adapter instance that was created for a previously active
    // canvas during rapid page changes. Store the annotation against its
    // actual target canvas so Mirador can retrieve and render it correctly.
    $target_canvas_id = $this->targetCanvasId($annotation);
    if ($target_canvas_id !== NULL) {
      $canvas_id = $target_canvas_id;
    }

    return [$canvas_id, $annotation];
  }

  /**
   * Returns the canvas targeted by a Web Annotation.
   */
  private function targetCanvasId(array $annotation): ?string {
    $target = $annotation['target'] ?? NULL;

    if (is_string($target)) {
      $value = explode('#', $target, 2)[0];
      return $value !== '' ? $value : NULL;
    }

    if (!is_array($target)) {
      return NULL;
    }

    $source = $target['source'] ?? NULL;
    if (is_string($source)) {
      $value = explode('#', $source, 2)[0];
      return $value !== '' ? $value : NULL;
    }

    if (is_array($source)) {
      $value = $source['id'] ?? $source['@id'] ?? NULL;
      if (is_string($value) && $value !== '') {
        return explode('#', $value, 2)[0];
      }
    }

    $value = $target['id'] ?? $target['@id'] ?? NULL;
    if (is_string($value) && $value !== '') {
      return explode('#', $value, 2)[0];
    }

    return NULL;
  }

  /**
   * Decodes a JSON request body.
   */
  private function decodeRequest(Request $request): array {
    try {
      $data = json_decode($request->getContent(), TRUE, 512, JSON_THROW_ON_ERROR);
    }
    catch (\JsonException $e) {
      throw new BadRequestHttpException('Invalid JSON request body.', $e);
    }

    if (!is_array($data)) {
      throw new BadRequestHttpException('A JSON object is required.');
    }

    return $data;
  }

  /**
   * Builds an AnnotationPage from stored rows.
   */
  private function annotationPage(string $canvas_id, Request $request): array {
    $items = [];
    $result = $this->database->select('islandora_mirador_annotation', 'a')
      ->fields('a', ['annotation_json'])
      ->condition('canvas_key', hash('sha256', $canvas_id))
      ->orderBy('created', 'ASC')
      ->execute();

    foreach ($result as $row) {
      try {
        $annotation = json_decode($row->annotation_json, TRUE, 512, JSON_THROW_ON_ERROR);
        if (is_array($annotation)) {
          $items[] = $annotation;
        }
      }
      catch (\JsonException) {
        // Ignore a corrupt row rather than breaking every annotation on canvas.
      }
    }

    $page_id = $request->getSchemeAndHttpHost() . $request->getBaseUrl()
      . '/islandora-mirador/annotations?canvas=' . rawurlencode($canvas_id);

    return [
      'id' => $page_id,
      'type' => 'AnnotationPage',
      'items' => $items,
    ];
  }

}