import 'dart:convert';
import 'dart:typed_data';

import 'package:dio/dio.dart';

import '../../../common/network/dio_provider.dart';

/// Compatible with Yanting's protobuf `/api/v1/auth/onekey/verify` contract.
class OneKeyLoginApi {
  OneKeyLoginApi(this._dio);
  final Dio _dio;

  Future<OneKeyLoginReply> verify(String loginToken) async {
    final bytes = utf8.encode(loginToken);
    final request = Uint8List.fromList([
      0x0A,
      ..._varint(bytes.length),
      ...bytes,
    ]);
    final response = await _dio.post<List<int>>(
      '/api/v1/auth/onekey/verify',
      data: request,
      options: protobufOptions(),
    );
    return _decode(Uint8List.fromList(response.data ?? const []));
  }

  OneKeyLoginReply _decode(Uint8List data) {
    final fields = _fields(data);
    final token = utf8.decode(fields[1] ?? const []);
    final user = _fields(Uint8List.fromList(fields[3] ?? const []));
    if (token.isEmpty) throw StateError('一键登录服务未返回登录凭证');
    return OneKeyLoginReply(
      token: token,
      phone: utf8.decode(user[2] ?? const []),
    );
  }

  Map<int, List<int>> _fields(Uint8List data) {
    final result = <int, List<int>>{};
    var i = 0;
    while (i < data.length) {
      final tag = _readVarint(data, i);
      i = tag.$2;
      final wireType = tag.$1 & 7;
      if (wireType == 0) {
        i = _readVarint(data, i).$2;
        continue;
      }
      if (wireType != 2) {
        throw const FormatException('Unsupported protobuf field');
      }
      final length = _readVarint(data, i);
      i = length.$2;
      final end = i + length.$1;
      if (end > data.length) {
        throw const FormatException('Invalid protobuf payload');
      }
      result[tag.$1 >> 3] = data.sublist(i, end);
      i = end;
    }
    return result;
  }

  (int, int) _readVarint(Uint8List data, int index) {
    var value = 0;
    var shift = 0;
    while (index < data.length) {
      final byte = data[index++];
      value |= (byte & 0x7f) << shift;
      if (byte & 0x80 == 0) return (value, index);
      shift += 7;
    }
    throw const FormatException('Invalid protobuf varint');
  }

  List<int> _varint(int value) {
    final result = <int>[];
    while (value > 0x7f) {
      result.add((value & 0x7f) | 0x80);
      value >>= 7;
    }
    result.add(value);
    return result;
  }
}

class OneKeyLoginReply {
  const OneKeyLoginReply({required this.token, required this.phone});
  final String token;
  final String phone;
}