using FreeSql;

using LiveForum.IService.Others;
using LiveForum.IService.RealName;
using LiveForum.Model;
using LiveForum.Model.Dto.RealName;

using Microsoft.Extensions.Logging;

using System.Security.Cryptography;
using System.Text;

namespace LiveForum.Service.RealName
{
    /// <summary>
    /// 实名认证业务服务
    /// </summary>
    public class RealNameService : IRealNameService
    {
        private readonly IBaseRepository<T_Users> _userRepository;
        private readonly IBaseRepository<T_RealNameVerifyLogs> _logRepository;
        private readonly ISystemSettingsService _settings;
        private readonly ILogger<RealNameService> _logger;
        private readonly IEnumerable<IRealNameVerifyProvider> _providers;

        private const string REAL_NAME_ENABLED_KEY = "real_name_enabled";
        private const string REAL_NAME_PROVIDER_KEY = "real_name_provider";
        private const string DAILY_LIMIT_KEY = "real_name_daily_limit";
        private const string INTERVAL_KEY = "real_name_interval_seconds";
        // AES加密密钥（实际项目应从配置读取）
        private const string AES_KEY = "LiveForum@RealName2024!AesKey32B";

        public RealNameService(
            IBaseRepository<T_Users> userRepository,
            IBaseRepository<T_RealNameVerifyLogs> logRepository,
            ISystemSettingsService settings,
            ILogger<RealNameService> logger,
            IEnumerable<IRealNameVerifyProvider> providers)
        {
            _userRepository = userRepository;
            _logRepository = logRepository;
            _settings = settings;
            _logger = logger;
            _providers = providers;
        }

        public async Task<RealNameStatusDto> CheckStatusAsync(long userId)
        {
            var enabled = await IsEnabledAsync();
            var user = await _userRepository.Select.Where(x => x.Id == userId).FirstAsync();
            return new RealNameStatusDto
            {
                RealNameEnabled = enabled,
                IsVerified = user?.IsRealNameVerified ?? false
            };
        }

        public async Task<bool> RequiresRealNameAsync(long userId)
        {
            var enabled = await IsEnabledAsync();
            if (!enabled) return false;

            var user = await _userRepository.Select.Where(x => x.Id == userId).FirstAsync();
            return !(user?.IsRealNameVerified ?? false);
        }

        public async Task<string> VerifyAsync(long userId, string realName, string idCardNumber, string? clientIp)
        {
            // 1. 限流检查
            var rateLimitMsg = await CheckRateLimitAsync(userId);
            if (rateLimitMsg != null) return rateLimitMsg;

            // 2. 获取当前服务商
            var provider = await GetProviderAsync();
            if (provider == null) return "实名认证服务未配置，请联系管理员";

            // 3. 调用服务商验证
            var result = await provider.VerifyAsync(realName, idCardNumber);

            // 4. 记录日志
            await _logRepository.InsertAsync(new T_RealNameVerifyLogs
            {
                UserId = userId,
                RealName = MaskName(realName),
                IdCardNumberMasked = MaskIdCard(idCardNumber),
                IsSuccess = result.IsMatch,
                FailReason = result.IsMatch ? null : result.Message,
                ClientIp = clientIp
            });

            // 5. 成功则更新用户状态
            if (result.IsMatch)
            {
                var isMinor = IsMinorByIdCard(idCardNumber);

                await _userRepository.UpdateDiy
                    .Where(x => x.Id == userId)
                    .Set(x => x.IsRealNameVerified, true)
                    .Set(x => x.RealName, MaskName(realName))
                    .Set(x => x.IdCardNumber, EncryptAes(idCardNumber))
                    .Set(x => x.RealNameVerifiedAt, DateTime.Now)
                    .Set(x => x.IsMinor, isMinor)
                    .ExecuteAffrowsAsync();

                return "实名认证成功";
            }

            return result.Message;
        }

        private async Task<bool> IsEnabledAsync()
        {
            var val = await _settings.GetSettingAsync(REAL_NAME_ENABLED_KEY);
            return string.Equals(val, "true", StringComparison.OrdinalIgnoreCase);
        }

        private async Task<IRealNameVerifyProvider?> GetProviderAsync()
        {
            var providerName = await _settings.GetSettingAsync(REAL_NAME_PROVIDER_KEY) ?? "aliyun";
            return _providers.FirstOrDefault(p => p.ProviderName.Equals(providerName, StringComparison.OrdinalIgnoreCase));
        }

        private async Task<string?> CheckRateLimitAsync(long userId)
        {
            var dailyLimitStr = await _settings.GetSettingAsync(DAILY_LIMIT_KEY) ?? "5";
            var intervalStr = await _settings.GetSettingAsync(INTERVAL_KEY) ?? "60";
            int.TryParse(dailyLimitStr, out var dailyLimit);
            int.TryParse(intervalStr, out var intervalSeconds);
            if (dailyLimit <= 0) dailyLimit = 5;
            if (intervalSeconds <= 0) intervalSeconds = 60;

            var today = DateTime.Today;
            var todayCount = await _logRepository.Select
                .Where(x => x.UserId == userId && x.CreatedAt >= today)
                .CountAsync();

            if (todayCount >= dailyLimit)
                return "今日验证次数已用完，请明天再试";

            var lastLog = await _logRepository.Select
                .Where(x => x.UserId == userId)
                .OrderByDescending(x => x.CreatedAt)
                .FirstAsync();

            if (lastLog != null)
            {
                var elapsed = (DateTime.Now - lastLog.CreatedAt).TotalSeconds;
                if (elapsed < intervalSeconds)
                {
                    var remaining = (int)Math.Ceiling(intervalSeconds - elapsed);
                    return $"操作过于频繁，请 {remaining} 秒后再试";
                }
            }

            return null;
        }

        private static string MaskName(string name)
        {
            if (string.IsNullOrEmpty(name)) return "";
            if (name.Length <= 1) return name;
            if (name.Length == 2) return name[0] + "*";
            return name[0] + new string('*', name.Length - 2) + name[^1];
        }

        private static string MaskIdCard(string idCard)
        {
            if (string.IsNullOrEmpty(idCard) || idCard.Length < 4) return "****";
            return "**************" + idCard[^4..];
        }

        /// <summary>
        /// 根据身份证号判断是否未成年（不满18周岁）
        /// 身份证号第7-14位为出生日期（yyyyMMdd）
        /// </summary>
        private static bool IsMinorByIdCard(string idCardNumber)
        {
            if (string.IsNullOrEmpty(idCardNumber) || idCardNumber.Length != 18)
                return false;

            var birthStr = idCardNumber.Substring(6, 8);
            if (!DateTime.TryParseExact(birthStr, "yyyyMMdd", null, System.Globalization.DateTimeStyles.None, out var birthDate))
                return false;

            var today = DateTime.Today;
            var age = today.Year - birthDate.Year;
            if (birthDate.Date > today.AddYears(-age))
                age--;

            return age < 18;
        }

        private static string EncryptAes(string plainText)
        {
            using var aes = Aes.Create();
            aes.Key = Encoding.UTF8.GetBytes(AES_KEY);
            aes.GenerateIV();
            using var encryptor = aes.CreateEncryptor();
            var plainBytes = Encoding.UTF8.GetBytes(plainText);
            var encrypted = encryptor.TransformFinalBlock(plainBytes, 0, plainBytes.Length);
            // IV + 密文 一起存储
            var result = new byte[aes.IV.Length + encrypted.Length];
            Buffer.BlockCopy(aes.IV, 0, result, 0, aes.IV.Length);
            Buffer.BlockCopy(encrypted, 0, result, aes.IV.Length, encrypted.Length);
            return Convert.ToBase64String(result);
        }
    }
}