import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:image_picker/image_picker.dart';

import '../core/network/api_exception.dart';
import '../services/upload_service.dart';

/// 上传发布流程步骤：选视频 → 填信息 → 发布中 → 完成
enum UploadStep { pick, edit, publishing, done }

/// 上传发布状态（《03-接口文档》5.5/5.6 三步链路）
class UploadState {
  const UploadState({
    this.step = UploadStep.pick,
    this.file,
    this.fileSize = 0,
    this.progress = 0,
    this.result,
    this.error = '',
  });

  final UploadStep step;
  final XFile? file; // 已选择的视频
  final int fileSize; // 字节
  final int progress; // 上传进度 0-100
  final PublishResult? result;
  final String error; // 发布失败文案（停留在 edit 步骤展示）

  bool get publishing => step == UploadStep.publishing;

  UploadState copyWith({
    UploadStep? step,
    XFile? file,
    int? fileSize,
    int? progress,
    PublishResult? result,
    String? error,
  }) =>
      UploadState(
        step: step ?? this.step,
        file: file ?? this.file,
        fileSize: fileSize ?? this.fileSize,
        progress: progress ?? this.progress,
        result: result ?? this.result,
        error: error ?? this.error,
      );
}

class UploadNotifier extends StateNotifier<UploadState> {
  UploadNotifier() : super(const UploadState());

  final _picker = ImagePicker();

  /// 从相册选择视频 → 进入填信息步骤
  Future<void> pickVideo() async {
    final file = await _picker.pickVideo(source: ImageSource.gallery);
    if (file == null) return;
    final size = await file.length();
    state = UploadState(step: UploadStep.edit, file: file, fileSize: size);
  }

  /// 重新选择（回到选视频步骤）
  void reset() => state = const UploadState();

  /// 发布：获取凭证 → 上传文件（进度） → 创建视频
  Future<void> submit({
    required String title,
    String description = '',
    required int categoryId,
    List<String> tags = const [],
  }) async {
    final file = state.file;
    if (file == null || state.publishing) return;
    state = state.copyWith(step: UploadStep.publishing, progress: 0, error: '');
    try {
      final token = await UploadService.fetchUploadToken(
        fileName: file.name,
        fileSize: state.fileSize,
      );
      await UploadService.uploadFile(
        objectKey: token.objectKey,
        filePath: file.path,
        fileName: file.name,
        onProgress: (sent, total) {
          if (total > 0) {
            state = state.copyWith(progress: (sent * 100) ~/ total);
          }
        },
      );
      final result = await UploadService.publish(
        objectKey: token.objectKey,
        title: title,
        description: description,
        categoryId: categoryId,
        tags: tags,
      );
      state = state.copyWith(step: UploadStep.done, result: result);
    } on ApiException catch (e) {
      // 失败回到表单步骤，保留已填内容，展示服务端文案
      state = state.copyWith(step: UploadStep.edit, error: e.message);
    } catch (_) {
      state = state.copyWith(step: UploadStep.edit, error: '网络异常，请稍后重试');
    }
  }
}

/// 上传发布（autoDispose：离开页面即重置流程）
final uploadProvider =
    StateNotifierProvider.autoDispose<UploadNotifier, UploadState>(
  (ref) => UploadNotifier(),
);

/// 分类列表（发布表单用）
final uploadCategoriesProvider =
    FutureProvider.autoDispose<List<VideoCategory>>(
  (ref) => UploadService.fetchCategories(),
);