import 'dart:convert';

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

import '../config/api_config.dart';
import '../models/guess_score_reset_result.dart';
import '../models/guess_score_summary.dart';
import '../models/incoming_question.dart';
import '../models/question_defer_result.dart';
import '../models/question_submit_result.dart';
import 'auth_service.dart';

/// HTTP client for question queue, answers, and deferrals.
class QuestionsApiService {
  QuestionsApiService({http.Client? client}) : _client = client ?? http.Client();

  final http.Client _client;

  /// Ensures login question state is initialized for the signed-in user.
  ///
  /// Returns the first unanswered question when present and always attempts to
  /// return persisted [GuessScoreSummary] for this Firebase user when the API
  /// includes it in the bootstrap payload.
  Future<({IncomingQuestion? question, GuessScoreSummary? score})>
      bootstrapOnLogin() async {
    final String? token = await AuthService.instance.getIdToken();
    if (token == null) {
      return (question: null, score: null);
    }

    final http.Response response = await _client.post(
      Uri.parse('$apiBaseUrl/v1/me/questions/bootstrap'),
      headers: _authHeaders(token),
    );
    if (response.statusCode != 200) {
      debugPrint(
        'bootstrapOnLogin failed: ${response.statusCode} ${response.body}',
      );
      return (question: null, score: null);
    }

    final Map<String, dynamic> body =
        jsonDecode(response.body) as Map<String, dynamic>;
    final Map<String, dynamic>? questionJson =
        body['question'] as Map<String, dynamic>?;
    final Map<String, dynamic>? scoreJson =
        body['score'] as Map<String, dynamic>?;
    return (
      question: questionJson == null
          ? null
          : IncomingQuestion.fromJson(questionJson),
      score: scoreJson == null
          ? null
          : GuessScoreSummary.fromJson(scoreJson),
    );
  }

  Future<List<IncomingQuestion>> fetchUnanswered() async {
    final String? token = await AuthService.instance.getIdToken();
    if (token == null) {
      return <IncomingQuestion>[];
    }

    final http.Response response = await _client.get(
      Uri.parse('$apiBaseUrl/v1/me/questions'),
      headers: _authHeaders(token),
    );
    if (response.statusCode != 200) {
      debugPrint(
        'fetchUnanswered failed: ${response.statusCode} ${response.body}',
      );
      return <IncomingQuestion>[];
    }

    final Map<String, dynamic> body =
        jsonDecode(response.body) as Map<String, dynamic>;
    final List<dynamic> raw = body['questions'] as List<dynamic>? ?? <dynamic>[];
    return raw
        .map(
          (dynamic item) =>
              IncomingQuestion.fromJson(item as Map<String, dynamic>),
        )
        .toList();
  }

  Future<QuestionSubmitResult?> submitAnswer({
    required String questionId,
    num answer = 0,
  }) async {
    final String? token = await AuthService.instance.getIdToken();
    if (token == null) {
      return null;
    }

    final http.Response response = await _client.post(
      Uri.parse('$apiBaseUrl/v1/me/questions/$questionId/answer'),
      headers: _authHeaders(token),
      body: jsonEncode(<String, num>{'answer': answer}),
    );
    if (response.statusCode != 200) {
      debugPrint(
        'submitAnswer failed: ${response.statusCode} ${response.body}',
      );
      return null;
    }

    final Map<String, dynamic> body =
        jsonDecode(response.body) as Map<String, dynamic>;
    final Map<String, dynamic>? scoreJson =
        body['score'] as Map<String, dynamic>?;
    final Map<String, dynamic>? nextQuestionJson =
        body['nextQuestion'] as Map<String, dynamic>?;
    return QuestionSubmitResult(
      unansweredCount: (body['unansweredCount'] as num?)?.toInt() ?? 0,
      score: scoreJson == null
          ? GuessScoreSummary.empty
          : GuessScoreSummary.fromJson(scoreJson),
      nextQuestion: nextQuestionJson == null
          ? null
          : IncomingQuestion.fromJson(nextQuestionJson),
    );
  }

  Future<QuestionDeferResult?> deferQuestion({required String questionId}) async {
    final String? token = await AuthService.instance.getIdToken();
    if (token == null) {
      return null;
    }

    final http.Response response = await _client.post(
      Uri.parse('$apiBaseUrl/v1/me/questions/$questionId/defer'),
      headers: _authHeaders(token),
    );
    if (response.statusCode != 200) {
      debugPrint(
        'deferQuestion failed: ${response.statusCode} ${response.body}',
      );
      return null;
    }

    final Map<String, dynamic> body =
        jsonDecode(response.body) as Map<String, dynamic>;
    final Map<String, dynamic>? nextQuestionJson =
        body['nextQuestion'] as Map<String, dynamic>?;
    return QuestionDeferResult(
      unansweredCount: (body['unansweredCount'] as num?)?.toInt() ?? 0,
      nextQuestion: nextQuestionJson == null
          ? null
          : IncomingQuestion.fromJson(nextQuestionJson),
    );
  }

  Future<GuessScoreSummary?> fetchGuessScoreSummary() async {
    final String? token = await AuthService.instance.getIdToken();
    if (token == null) {
      return null;
    }

    final http.Response response = await _client.get(
      Uri.parse('$apiBaseUrl/v1/me/questions/score'),
      headers: _authHeaders(token),
    );
    if (response.statusCode != 200) {
      debugPrint(
        'fetchGuessScoreSummary failed: ${response.statusCode} ${response.body}',
      );
      return null;
    }

    final Map<String, dynamic> body =
        jsonDecode(response.body) as Map<String, dynamic>;
    final Map<String, dynamic>? scoreJson =
        body['score'] as Map<String, dynamic>?;
    if (scoreJson == null) {
      return GuessScoreSummary.empty;
    }
    return GuessScoreSummary.fromJson(scoreJson);
  }

  Future<GuessScoreResetResult?> resetGuessScoreSummary() async {
    final String? token = await AuthService.instance.getIdToken();
    if (token == null) {
      return null;
    }

    final http.Response response = await _client.post(
      Uri.parse('$apiBaseUrl/v1/me/questions/score/reset'),
      headers: _authHeaders(token),
    );
    if (response.statusCode != 200) {
      debugPrint(
        'resetGuessScoreSummary failed: ${response.statusCode} ${response.body}',
      );
      return null;
    }

    final Map<String, dynamic> body =
        jsonDecode(response.body) as Map<String, dynamic>;
    final Map<String, dynamic>? scoreJson =
        body['score'] as Map<String, dynamic>?;
    final Map<String, dynamic>? questionJson =
        body['question'] as Map<String, dynamic>?;
    return GuessScoreResetResult(
      score: scoreJson == null
          ? GuessScoreSummary.empty
          : GuessScoreSummary.fromJson(scoreJson),
      unansweredCount: (body['unansweredCount'] as num?)?.toInt() ?? 0,
      question: questionJson == null
          ? null
          : IncomingQuestion.fromJson(questionJson),
    );
  }

  Map<String, String> _authHeaders(String token) {
    return <String, String>{
      'Authorization': 'Bearer $token',
      'Content-Type': 'application/json',
      'Accept': 'application/json',
    };
  }
}