import 'dart:convert';

import 'package:http/http.dart' as http;

import '../models/models.dart';
import '../repositories/report_repository.dart';
import '../state/report_query.dart';

abstract class ReportDataSource extends ReportRepository {
  Future<List<ReportCardModel>> recommended();
  Future<List<ReportCardModel>> reports();
  Future<List<Institution>> institutions();
  Future<Institution> institutionDetail(String institutionId);
  Future<List<AudioItem>> listen();
  Future<ReportDetail> reportDetail(String reportId);
  Future<ModuleDetail> moduleDetail(String reportId, String moduleId);

  @override
  Future<List<ReportCardModel>> getRecommended({String? topic}) async {
    final items = await recommended();
    if (topic == null || topic == '全部') return items;
    return items.where((item) => item.topics.contains(topic)).toList();
  }

  @override
  Future<List<ReportCardModel>> getReports(ReportQuery query) async {
    final currentSearch = query.search.trim().toLowerCase();
    final items = await reports();
    final filtered = items.where((item) {
      final haystack =
          '${item.titleCn} ${item.subtitleCn} ${item.oneLiner} '
                  '${item.institution.nameCn} ${item.institution.nameEn} '
                  '${item.topics.join(' ')}'
              .toLowerCase();
      if (currentSearch.isNotEmpty && !haystack.contains(currentSearch)) {
        return false;
      }
      if (query.topic != null && !item.topics.contains(query.topic)) {
        return false;
      }
      if (query.institutionId != null &&
          item.institution.id != query.institutionId) {
        return false;
      }
      if (query.hasAudio && !item.hasAudio) {
        return false;
      }
      return true;
    }).toList();
    filtered.sort((a, b) {
      final result = (b.releasedAt ?? '').compareTo(a.releasedAt ?? '');
      return query.sort == ReportSort.oldest ? -result : result;
    });
    return filtered;
  }

  @override
  Future<ReportDetail> getReportDetail(String reportId) =>
      reportDetail(reportId);

  @override
  Future<List<Institution>> getInstitutions() => institutions();

  @override
  Future<Institution> getInstitutionDetail(String institutionId) =>
      institutionDetail(institutionId);

  @override
  Future<List<AudioItem>> getListenItems() => listen();

  @override
  Future<ModuleDetail> getModuleDetail(String reportId, String moduleId) =>
      moduleDetail(reportId, moduleId);
}

class RnbApiDataSource extends ReportDataSource {
  RnbApiDataSource({
    http.Client? client,
    this.baseUrl = const String.fromEnvironment('RNB_API_BASE'),
  }) : client = client ?? http.Client();

  final http.Client client;
  final String baseUrl;

  Future<JsonMap> _get(String path) async {
    if (baseUrl.isEmpty) {
      throw StateError('RNB_API_BASE is required for live API requests.');
    }
    final response = await client.get(Uri.parse('$baseUrl$path'));
    if (response.statusCode != 200) {
      throw StateError('Request failed: ${response.statusCode}');
    }
    return jsonDecode(utf8.decode(response.bodyBytes)) as JsonMap;
  }

  List<JsonMap> _items(JsonMap body) => asMapList(body['items']);

  @override
  Future<List<ReportCardModel>> recommended() async {
    final body = await _get('/feed/recommended');
    return _items(body).map(ReportCardModel.fromJson).toList();
  }

  @override
  Future<List<ReportCardModel>> reports() async {
    final body = await _get('/reports');
    return _items(body).map(ReportCardModel.fromJson).toList();
  }

  @override
  Future<List<Institution>> institutions() async {
    final body = await _get('/institutions');
    return _items(body).map(Institution.fromJson).toList();
  }

  @override
  Future<Institution> institutionDetail(String institutionId) async {
    return Institution.fromJson(await _get('/institutions/$institutionId'));
  }

  @override
  Future<List<AudioItem>> listen() async {
    final body = await _get('/listen');
    return _items(body).map(AudioItem.fromJson).toList();
  }

  @override
  Future<ReportDetail> reportDetail(String reportId) async {
    return ReportDetail.fromJson(await _get('/reports/$reportId'));
  }

  @override
  Future<ModuleDetail> moduleDetail(String reportId, String moduleId) async {
    return ModuleDetail.fromJson(
      await _get('/reports/$reportId/modules/$moduleId'),
    );
  }
}