import 'dart:convert';

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

import 'intra_api_exception.dart';

/// GET API 42 avec gestion 401 / 429 (retry + backoff).
Future<http.Response> intraApiGet(
  Uri uri, {
  required Map<String, String> headers,
  int maxAttempts = 4,
}) async {
  for (var attempt = 0; attempt < maxAttempts; attempt++) {
    final response = await http.get(uri, headers: headers);

    if (response.statusCode == 429) {
      if (attempt + 1 >= maxAttempts) {
        throw const IntraRateLimitException();
      }
      await Future<void>.delayed(_retryDelay(response, attempt));
      continue;
    }

    return response;
  }

  throw const IntraRateLimitException();
}

Duration _retryDelay(http.Response response, int attempt) {
  final header = response.headers['retry-after'];
  if (header != null) {
    final seconds = int.tryParse(header.trim());
    if (seconds != null && seconds > 0) {
      return Duration(seconds: seconds.clamp(1, 30));
    }
  }
  // 0.8s, 1.6s, 3.2s…
  final ms = 800 * (1 << attempt);
  return Duration(milliseconds: ms.clamp(800, 8000));
}

void ensureIntraOk(http.Response response) {
  if (response.statusCode == 401) {
    throw const IntraUnauthorizedException();
  }
  if (response.statusCode == 403) {
    throw const IntraForbiddenException();
  }
  if (response.statusCode == 429) {
    throw const IntraRateLimitException();
  }
  if (response.statusCode != 200) {
    throw IntraApiErrorException(
      'Erreur API (${response.statusCode})',
    );
  }
}

dynamic decodeIntraBody(http.Response response) {
  ensureIntraOk(response);
  return jsonDecode(response.body);
}