import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../api/bill_api.dart';
import '../api/category_api.dart';
import '../api/ocr_api.dart';
import '../core/network/api_exception.dart';
import '../models/bill_request.dart';
import '../models/ocr_result.dart';
import '../utils/date_util.dart';
import 'bill_refresh.dart';

/// OCR 识别流程状态
class OcrState {
  final String? imagePath;
  final List<OcrResult> results;
  final Set<int> expandedIndexes;
  final bool recognizing;
  final bool saving;
  final String? error;

  const OcrState({
    this.imagePath,
    this.results = const [],
    this.expandedIndexes = const {},
    this.recognizing = false,
    this.saving = false,
    this.error,
  });

  OcrState copyWith({
    Object? imagePath = _sentinel,
    List<OcrResult>? results,
    Set<int>? expandedIndexes,
    bool? recognizing,
    bool? saving,
    Object? error = _sentinel,
  }) {
    return OcrState(
      imagePath: imagePath == _sentinel ? this.imagePath : imagePath as String?,
      results: results ?? this.results,
      expandedIndexes: expandedIndexes ?? this.expandedIndexes,
      recognizing: recognizing ?? this.recognizing,
      saving: saving ?? this.saving,
      error: error == _sentinel ? this.error : error as String?,
    );
  }

  static const _sentinel = Object();
}

class OcrNotifier extends Notifier<OcrState> {
  @override
  OcrState build() => const OcrState();

  void setImagePath(String path) {
    state = OcrState(imagePath: path);
  }

  void clearImage() {
    state = const OcrState();
  }

  void toggleExpanded(int index) {
    final indexes = {...state.expandedIndexes};
    if (!indexes.remove(index)) indexes.add(index);
    state = state.copyWith(expandedIndexes: indexes);
  }

  /// 上传识别
  Future<void> recognize() async {
    final path = state.imagePath;
    if (path == null) throw ApiException(-1, '请先选择图片');
    state = state.copyWith(recognizing: true, error: null);
    try {
      final results = await ref.read(ocrApiProvider).recognize(path);
      state = state.copyWith(
        results: results,
        // 只有一条时自动展开
        expandedIndexes: results.length == 1 ? {0} : <int>{},
      );
    } on ApiException catch (e) {
      state = state.copyWith(error: e.message);
      rethrow;
    } finally {
      state = state.copyWith(recognizing: false);
    }
  }

  /// 直接批量存储：按金额正负推断类型，分类取该类型下第一项
  Future<void> saveDirectly() async {
    if (state.results.isEmpty) throw ApiException(-1, '没有可存储的识别结果');
    state = state.copyWith(saving: true, error: null);
    try {
      final categoryApi = ref.read(categoryApiProvider);
      final bills = <BillRequest>[];
      final cache = <int, int?>{}; // type -> 默认分类id
      for (final r in state.results) {
        final type = r.isExpense ? 1 : 2;
        if (!cache.containsKey(type)) {
          final categories = await categoryApi.getCategories(type);
          cache[type] = categories.isNotEmpty ? categories.first.id : null;
        }
        final categoryId = cache[type];
        if (categoryId == null) {
          throw ApiException(-1, '缺少${type == 1 ? '支出' : '收入'}分类，请先创建分类');
        }
        bills.add(BillRequest(
          categoryId: categoryId,
          amount: r.absAmount,
          description: r.merchant ?? '',
          billDate: parseBillDate(r.date),
          type: type,
        ));
      }
      await ref.read(billApiProvider).createBillsBatch(bills);
      // 让首页列表与统计页重新取数
      invalidateBillData(ref);
      state = const OcrState();
    } on ApiException catch (e) {
      state = state.copyWith(error: e.message);
      rethrow;
    } finally {
      state = state.copyWith(saving: false);
    }
  }
}

final ocrProvider = NotifierProvider<OcrNotifier, OcrState>(OcrNotifier.new);