import 'dart:convert';

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

import '../data/models/analysis_models.dart';

class AnalysisApiService {
  AnalysisApiService({http.Client? client, String? baseUrl})
    : _client = client ?? http.Client(),
      _baseUri = _normalizeBaseUri(baseUrl ?? 'http://127.0.0.1:8000/api');

  final http.Client _client;
  final Uri _baseUri;

  Future<ObservationSummary> createObservation({
    required int durationMs,
    required int sampleRate,
    required int channels,
    List<String> tags = const [],
    Map<String, dynamic> captureMetadata = const {},
  }) async {
    final response = await _client.post(
      _endpointUri('observations'),
      headers: {'Content-Type': 'application/json'},
      body: jsonEncode({
        'modality': 'audio',
        'duration_ms': durationMs,
        'sample_rate': sampleRate,
        'channels': channels,
        'tags': tags,
        'capture_metadata': captureMetadata,
      }),
    );
    return ObservationSummary.fromJson(
      _decodeJson(response) as Map<String, dynamic>,
    );
  }

  Future<ObservationSummary> uploadObservation({
    required String filePath,
    required int durationMs,
    required int sampleRate,
    required int channels,
    List<String> tags = const [],
    Map<String, dynamic> captureMetadata = const {},
  }) async {
    final request = http.MultipartRequest(
      'POST',
      _endpointUri('observations/upload'),
    );
    request.fields['duration_ms'] = '$durationMs';
    request.fields['sample_rate'] = '$sampleRate';
    request.fields['channels'] = '$channels';
    request.fields['tags_json'] = jsonEncode(tags);
    request.fields['capture_metadata_json'] = jsonEncode(captureMetadata);
    request.files.add(
      await http.MultipartFile.fromPath('audio_file', filePath),
    );

    final streamed = await request.send();
    final response = await http.Response.fromStream(streamed);
    return ObservationSummary.fromJson(
      _decodeJson(response) as Map<String, dynamic>,
    );
  }

  Future<AnalysisSessionSummary> createSession({
    required String observationId,
    String mode = 'initial_analysis',
  }) async {
    final response = await _client.post(
      _endpointUri('analysis/sessions'),
      headers: {'Content-Type': 'application/json'},
      body: jsonEncode({'observation_id': observationId, 'mode': mode}),
    );
    return AnalysisSessionSummary.fromJson(
      _decodeJson(response) as Map<String, dynamic>,
    );
  }

  Future<List<AnalysisSessionSummary>> listSessions() async {
    final response = await _client.get(_endpointUri('analysis/sessions'));
    final json = _decodeJson(response) as Map<String, dynamic>;
    final items = (json['items'] as List<dynamic>? ?? const []);
    return items
        .map(
          (item) =>
              AnalysisSessionSummary.fromJson(item as Map<String, dynamic>),
        )
        .toList();
  }

  Future<List<ObservationSummary>> listObservations() async {
    final response = await _client.get(_endpointUri('observations'));
    final json = _decodeJson(response) as Map<String, dynamic>;
    final items = (json['items'] as List<dynamic>? ?? const []);
    return items
        .map(
          (item) => ObservationSummary.fromJson(item as Map<String, dynamic>),
        )
        .toList();
  }

  Future<ObservationSummary> getObservation(String observationId) async {
    final response = await _client.get(_endpointUri('observations/$observationId'));
    return ObservationSummary.fromJson(
      _decodeJson(response) as Map<String, dynamic>,
    );
  }

  Future<AnalysisSessionSnapshot> getSession(String sessionId) async {
    final response = await _client.get(
      _endpointUri('analysis/sessions/$sessionId'),
    );
    return AnalysisSessionSnapshot.fromJson(
      _decodeJson(response) as Map<String, dynamic>,
    );
  }

  Object _decodeJson(http.Response response) {
    if (response.statusCode < 200 || response.statusCode >= 300) {
      throw AnalysisApiException(
        'Backend request failed with status ${response.statusCode}: ${response.body}',
      );
    }
    return jsonDecode(response.body);
  }

  Uri _endpointUri(String path) => _baseUri.resolve(path);

  static Uri _normalizeBaseUri(String rawBaseUrl) {
    final normalized = rawBaseUrl.endsWith('/') ? rawBaseUrl : '$rawBaseUrl/';
    return Uri.parse(normalized);
  }
}

class AnalysisApiException implements Exception {
  AnalysisApiException(this.message);

  final String message;

  @override
  String toString() => message;
}