import 'package:flutter/foundation.dart';
import 'package:result_monad/result_monad.dart';

import '../friendica_client/friendica_client.dart';
import '../friendica_client/paging_data.dart';
import '../globals.dart';
import '../models/exec_error.dart';
import '../models/gallery_data.dart';
import '../models/image_entry.dart';
import 'auth_service.dart';

class GalleryService extends ChangeNotifier {
  static const IMAGES_PER_PAGE = 50;
  final _galleries = <String, GalleryData>{};
  final _galleryPages = <String, List<PagingData>>{};
  final _images = <String, Set<ImageEntry>>{};
  var _loaded = false;

  bool get loaded => _loaded;

  List<GalleryData> getGalleries() {
    if (_galleries.isEmpty) {
      updateGalleries();
    }

    return _galleries.values.toList(growable: false);
  }

  Result<GalleryData, ExecError> getGallery(String galleryName) {
    final gallery = _galleries[galleryName];

    if (gallery == null) {
      return buildErrorResult(
        type: ErrorType.notFound,
        message: 'Gallery $galleryName not found',
      );
    }

    return Result.ok(gallery);
  }

  FutureResult<List<GalleryData>, ExecError> updateGalleries() async {
    final result = await GalleryClient(getIt<AccountsService>().currentProfile)
        .getGalleryData();
    if (result.isFailure) {
      return result.errorCast();
    }

    for (final gallery in result.value) {
      _galleries[gallery.name] = gallery;
    }

    _loaded = true;
    notifyListeners();
    return Result.ok(_galleries.values.toList(growable: false));
  }

  Result<List<ImageEntry>, ExecError> getGalleryImageList(String galleryName) {
    if (!_galleries.containsKey(galleryName)) {
      return Result.error(
        ExecError(
          type: ErrorType.localError,
          message: 'Unknown Gallery: $galleryName',
        ),
      );
    }

    if (!_images.containsKey(galleryName)) {
      updateGalleryImageList(galleryName: galleryName, withNextPage: true);
      return Result.ok([]);
    } else {
      return Result.ok(_images[galleryName]!.toList(growable: false));
    }
  }

  //TODO Paging
  FutureResult<List<ImageEntry>, ExecError> updateGalleryImageList(
      {required String galleryName,
      required bool withNextPage,
      bool nextPageOnly = true}) async {
    final pages = _galleryPages.putIfAbsent(galleryName, () => []);
    if (pages.isEmpty) {
      pages.add(PagingData(offset: 0, limit: IMAGES_PER_PAGE));
    } else if (withNextPage) {
      final offset = pages.last.offset! + 1;
      pages.add(PagingData(offset: offset, limit: IMAGES_PER_PAGE));
    }

    final imageSet = _images.putIfAbsent(galleryName, () => {});

    final pagesToUse = nextPageOnly ? [pages.last] : pages;
    for (final page in pagesToUse) {
      final result =
          await GalleryClient(getIt<AccountsService>().currentProfile)
              .getGalleryImages(galleryName, page);
      if (result.isFailure) {
        return result.errorCast();
      }

      imageSet.addAll(result.value);
    }
    notifyListeners();
    return Result.ok(imageSet.toList(growable: false));
  }
}