import 'dart:convert';
import 'dart:io';

import 'package:shelf/shelf.dart';
import '../cors_headers.dart';
import '../firebase_auth.dart';
import '../questions_db.dart';
import 'questions_hub_handler.dart';

/// REST helper to push a question to the signed-in user over SignalR.
Handler incomingQuestionHandler({
  required FirebaseAuthVerifier auth,
  required QuestionsDb questionsDb,
}) {
  return (Request request) async {
    if (request.method == 'OPTIONS') {
      return Response.ok('', headers: apiCorsHeaders());
    }

    final String? firebaseUid = await auth.verifyBearerToken(
      request.headers['Authorization'] ?? request.headers['authorization'],
    );
    if (firebaseUid == null) {
      return _jsonResponse(401, <String, dynamic>{'error': 'Unauthorized'});
    }

    if (request.requestedUri.path != '/v1/me/incoming-question') {
      return _jsonResponse(404, <String, dynamic>{'error': 'Not found'});
    }

    if (request.method != 'POST') {
      return _jsonResponse(405, <String, dynamic>{'error': 'Method not allowed'});
    }

    try {
      final String body = await request.readAsString();
      final Map<String, dynamic> json = body.isEmpty
          ? <String, dynamic>{}
          : jsonDecode(body) as Map<String, dynamic>;
      final String text = (json['text'] as String?)?.trim().isNotEmpty == true
          ? (json['text'] as String).trim()
          : 'You have a new question.';
      final num correctAnswer = (json['correctAnswer'] as num?) ?? 0;

      final Map<String, dynamic> question = await questionsDb.createQuestion(
        assignedUserId: firebaseUid,
        questionText: text,
        correctAnswer: correctAnswer,
      );
      final int unansweredCount =
          await questionsDb.countUnansweredQuestions(firebaseUid);
      final Map<String, dynamic> payload = questionsDb.toClientPayload(
        question,
        unansweredCount: unansweredCount,
      );

      final int delivered = await questionsHubConnections.pushQuestion(
        firebaseUid,
        payload,
      );

      return _jsonResponse(200, <String, dynamic>{
        'question': question,
        'deliveredToConnections': delivered,
      });
    } catch (e, st) {
      stderr.writeln('Incoming question handler error: $e\n$st');
      return _jsonResponse(500, <String, dynamic>{'error': 'Internal error'});
    }
  };
}

Response _jsonResponse(int status, Map<String, dynamic> body) {
  return Response(
    status,
    body: jsonEncode(body),
    headers: <String, String>{
      ...apiCorsHeaders(),
      'Content-Type': 'application/json',
    },
  );
}