using Microsoft.Extensions.Logging;
using OrpaonVision.Core.Results;
using OrpaonVision.Model.Security;
using System.Security.Cryptography;
using System.Text;

namespace OrpaonVision.ConfigApp.Infrastructure.Services;

/// <summary>
/// 用户管理服务实现。
/// </summary>
public sealed class UserService : IUserService
{
    private readonly ILogger<UserService> _logger;
    private readonly List<UserModel> _users;
    private readonly Dictionary<string, int> _loginFailCounts;

    /// <summary>
    /// 构造函数。
    /// </summary>
    public UserService(ILogger<UserService> logger)
    {
        _logger = logger;
        _users = new List<UserModel>();
        _loginFailCounts = new Dictionary<string, int>();
        
        // 初始化示例数据
        InitializeSampleData();
    }

    /// <inheritdoc />
    public Result<UserModel> CreateUser(UserModel user)
    {
        try
        {
            if (user == null)
            {
                return Result<UserModel>.Fail("USER_NULL", "用户不能为空。");
            }

            if (string.IsNullOrWhiteSpace(user.Username))
            {
                return Result<UserModel>.Fail("USERNAME_REQUIRED", "用户名不能为空。");
            }

            // 检查用户名是否已存在
            if (_users.Any(u => u.Username.Equals(user.Username, StringComparison.OrdinalIgnoreCase)))
            {
                return Result<UserModel>.Fail("USERNAME_EXISTS", "用户名已存在。");
            }

            _logger.LogInformation("正在创建用户: {Username}", user.Username);

            // 生成密码哈希
            var (hash, salt) = GeneratePasswordHash(user.PasswordHash);
            
            user.Id = Guid.NewGuid();
            user.PasswordHash = hash;
            user.PasswordSalt = salt;
            user.Status = UserStatus.Enabled;
            user.IsFirstLogin = true;
            user.LoginFailedCount = 0;
            user.CreatedAtUtc = DateTime.UtcNow;
            user.UpdatedAtUtc = DateTime.UtcNow;

            _users.Add(user);

            _logger.LogInformation("用户创建成功: {UserId} - {Username}", user.Id, user.Username);
            return Result<UserModel>.Success(user, message: "用户创建成功。");
        }
        catch (Exception ex)
        {
            var traceId = Guid.NewGuid().ToString("N");
            _logger.LogError(ex, "创建用户失败。TraceId: {TraceId}", traceId);
            var result = Result.FromException(ex, "CREATE_USER_FAILED", "创建用户失败。", traceId);
            return Result<UserModel>.FailWithTrace(result.Code, result.Message, result.TraceId ?? traceId, result.Errors.ToArray());
        }
    }

    /// <inheritdoc />
    public Result<UserModel> UpdateUser(UserModel user)
    {
        try
        {
            if (user == null)
            {
                return Result<UserModel>.Fail("USER_NULL", "用户不能为空。");
            }

            var existingUser = _users.FirstOrDefault(u => u.Id == user.Id);
            if (existingUser == null)
            {
                return Result<UserModel>.Fail("USER_NOT_FOUND", $"未找到ID为 {user.Id} 的用户。");
            }

            _logger.LogInformation("正在更新用户: {UserId} - {Username}", user.Id, user.Username);

            // 更新属性（不包含密码相关字段）
            existingUser.DisplayName = user.DisplayName;
            existingUser.Email = user.Email;
            existingUser.PhoneNumber = user.PhoneNumber;
            existingUser.Remark = user.Remark;
            existingUser.UpdatedAtUtc = DateTime.UtcNow;
            existingUser.UpdatedBy = user.UpdatedBy;

            _logger.LogInformation("用户更新成功: {UserId} - {Username}", user.Id, user.Username);
            return Result<UserModel>.Success(existingUser, message: "用户更新成功。");
        }
        catch (Exception ex)
        {
            var traceId = Guid.NewGuid().ToString("N");
            _logger.LogError(ex, "更新用户失败。TraceId: {TraceId}", traceId);
            var result = Result.FromException(ex, "UPDATE_USER_FAILED", "更新用户失败。", traceId);
            return Result<UserModel>.FailWithTrace(result.Code, result.Message, result.TraceId ?? traceId, result.Errors.ToArray());
        }
    }

    /// <inheritdoc />
    public Result DeleteUser(Guid userId)
    {
        try
        {
            var user = _users.FirstOrDefault(u => u.Id == userId);
            if (user == null)
            {
                return Result.Fail("USER_NOT_FOUND", $"未找到ID为 {userId} 的用户。");
            }

            _logger.LogInformation("正在删除用户: {UserId} - {Username}", user.Id, user.Username);

            // 软删除
            user.Status = UserStatus.Deleted;
            user.UpdatedAtUtc = DateTime.UtcNow;
            user.UpdatedBy = "System";

            _logger.LogInformation("用户删除成功: {UserId} - {Username}", user.Id, user.Username);
            return Result.Success(message: "用户删除成功。");
        }
        catch (Exception ex)
        {
            var traceId = Guid.NewGuid().ToString("N");
            _logger.LogError(ex, "删除用户失败。TraceId: {TraceId}", traceId);
            var result = Result.FromException(ex, "DELETE_USER_FAILED", "删除用户失败。", traceId);
            return Result.FailWithTrace(result.Code, result.Message, result.TraceId ?? traceId, result.Errors.ToArray());
        }
    }

    /// <inheritdoc />
    public Result<UserModel> GetUserById(Guid userId)
    {
        try
        {
            var user = _users.FirstOrDefault(u => u.Id == userId);
            if (user == null)
            {
                return Result<UserModel>.Fail("USER_NOT_FOUND", $"未找到ID为 {userId} 的用户。");
            }

            // 清除敏感信息
            var safeUser = CloneUserWithoutSensitiveData(user);
            return Result<UserModel>.Success(safeUser, message: "获取用户成功。");
        }
        catch (Exception ex)
        {
            var traceId = Guid.NewGuid().ToString("N");
            _logger.LogError(ex, "获取用户失败。TraceId: {TraceId}", traceId);
            var result = Result.FromException(ex, "GET_USER_FAILED", "获取用户失败。", traceId);
            return Result<UserModel>.FailWithTrace(result.Code, result.Message, result.TraceId ?? traceId, result.Errors.ToArray());
        }
    }

    /// <inheritdoc />
    public Result<UserModel> GetUserByUsername(string username)
    {
        try
        {
            if (string.IsNullOrWhiteSpace(username))
            {
                return Result<UserModel>.Fail("USERNAME_REQUIRED", "用户名不能为空。");
            }

            var user = _users.FirstOrDefault(u => u.Username.Equals(username, StringComparison.OrdinalIgnoreCase));
            if (user == null)
            {
                return Result<UserModel>.Fail("USER_NOT_FOUND", $"未找到用户名为 {username} 的用户。");
            }

            // 清除敏感信息
            var safeUser = CloneUserWithoutSensitiveData(user);
            return Result<UserModel>.Success(safeUser, message: "获取用户成功。");
        }
        catch (Exception ex)
        {
            var traceId = Guid.NewGuid().ToString("N");
            _logger.LogError(ex, "获取用户失败。TraceId: {TraceId}", traceId);
            var result = Result.FromException(ex, "GET_USER_FAILED", "获取用户失败。", traceId);
            return Result<UserModel>.FailWithTrace(result.Code, result.Message, result.TraceId ?? traceId, result.Errors.ToArray());
        }
    }

    /// <inheritdoc />
    public Result<bool> VerifyPassword(string username, string password)
    {
        try
        {
            if (string.IsNullOrWhiteSpace(username))
            {
                return Result<bool>.Fail("USERNAME_REQUIRED", "用户名不能为空。");
            }

            if (string.IsNullOrWhiteSpace(password))
            {
                return Result<bool>.Fail("PASSWORD_REQUIRED", "密码不能为空。");
            }

            var user = _users.FirstOrDefault(u => u.Username.Equals(username, StringComparison.OrdinalIgnoreCase));
            if (user == null)
            {
                return Result<bool>.Fail("USER_NOT_FOUND", $"未找到用户名为 {username} 的用户。");
            }

            if (user.Status != UserStatus.Enabled)
            {
                return Result<bool>.Fail("USER_INACTIVE", "用户已被禁用。");
            }

            // 检查登录失败次数
            if (_loginFailCounts.TryGetValue(username, out var failCount) && failCount >= 5)
            {
                return Result<bool>.Fail("ACCOUNT_LOCKED", "账户已被锁定，请联系管理员。");
            }

            // 验证密码（简化版本，实际应该使用哈希比较）
            var isPasswordValid = VerifyPasswordHash(password, user.PasswordHash);
            
            if (isPasswordValid)
            {
                // 登录成功，清除失败计数
                _loginFailCounts.Remove(username);
                _logger.LogInformation("用户 {Username} 登录成功", username);
                return Result<bool>.Success(true, "登录成功。");
            }
            else
            {
                // 登录失败，增加失败计数
                _loginFailCounts[username] = _loginFailCounts.GetValueOrDefault(username, 0) + 1;
                _logger.LogWarning("用户 {Username} 登录失败，当前失败次数: {FailCount}", username, _loginFailCounts[username]);
                
                var remainingAttempts = 5 - _loginFailCounts[username];
                var message = remainingAttempts > 0 
                    ? $"密码错误，还有 {remainingAttempts} 次尝试机会。"
                    : "账户已被锁定，请联系管理员。";
                    
                return Result<bool>.Fail("PASSWORD_INCORRECT", message);
            }
        }
        catch (Exception ex)
        {
            var traceId = Guid.NewGuid().ToString("N");
            _logger.LogError(ex, "验证密码失败。TraceId: {TraceId}", traceId);
            var result = Result.FromException(ex, "VERIFY_PASSWORD_FAILED", "验证密码失败。", traceId);
            return Result<bool>.FailWithTrace(result.Code, result.Message, result.TraceId ?? traceId, result.Errors.ToArray());
        }
    }

    /// <inheritdoc />
    public Result<PagedResult<UserModel>> GetUserPagedList(int pageIndex = 1, int pageSize = 20, UserStatus? status = null, string? keyword = null)
    {
        try
        {
            var query = _users.Where(u => u.Status != UserStatus.Deleted).AsQueryable();

            // 状态过滤
            if (status.HasValue)
            {
                query = query.Where(u => u.Status == status.Value);
            }

            // 关键词搜索
            if (!string.IsNullOrWhiteSpace(keyword))
            {
                query = query.Where(u => 
                    u.Username.Contains(keyword, StringComparison.OrdinalIgnoreCase) ||
                    u.DisplayName.Contains(keyword, StringComparison.OrdinalIgnoreCase) ||
                    (u.Email != null && u.Email.Contains(keyword, StringComparison.OrdinalIgnoreCase)));
            }

            // 排序
            query = query.OrderByDescending(u => u.CreatedAtUtc);

            var totalCount = query.Count();
            var items = query.Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList();

            // 清除敏感信息
            var safeItems = items.Select(CloneUserWithoutSensitiveData).ToList();

            var pagedResult = PagedResult<UserModel>.Success(safeItems, totalCount, pageIndex, pageSize);

            return Result<PagedResult<UserModel>>.Success(pagedResult, message: "获取用户列表成功。");
        }
        catch (Exception ex)
        {
            var traceId = Guid.NewGuid().ToString("N");
            _logger.LogError(ex, "获取用户列表失败。TraceId: {TraceId}", traceId);
            var result = Result.FromException(ex, "GET_USER_LIST_FAILED", "获取用户列表失败。", traceId);
            return Result<PagedResult<UserModel>>.FailWithTrace(result.Code, result.Message, result.TraceId ?? traceId, result.Errors.ToArray());
        }
    }

    /// <inheritdoc />
    public Result EnableUser(Guid userId, string enabledBy)
    {
        try
        {
            var user = _users.FirstOrDefault(u => u.Id == userId);
            if (user == null)
            {
                return Result.Fail("USER_NOT_FOUND", $"未找到ID为 {userId} 的用户。");
            }

            _logger.LogInformation("正在启用用户: {UserId} - {Username}", user.Id, user.Username);

            user.Status = UserStatus.Enabled;
            user.UpdatedAtUtc = DateTime.UtcNow;
            user.UpdatedBy = enabledBy;

            _logger.LogInformation("用户启用成功: {UserId} - {Username}", user.Id, user.Username);
            return Result.Success(message: "用户启用成功。");
        }
        catch (Exception ex)
        {
            var traceId = Guid.NewGuid().ToString("N");
            _logger.LogError(ex, "启用用户失败。TraceId: {TraceId}", traceId);
            var result = Result.FromException(ex, "ENABLE_USER_FAILED", "启用用户失败。", traceId);
            return Result.FailWithTrace(result.Code, result.Message, result.TraceId ?? traceId, result.Errors.ToArray());
        }
    }

    /// <inheritdoc />
    public Result DisableUser(Guid userId, string disabledBy)
    {
        try
        {
            var user = _users.FirstOrDefault(u => u.Id == userId);
            if (user == null)
            {
                return Result.Fail("USER_NOT_FOUND", $"未找到ID为 {userId} 的用户。");
            }

            _logger.LogInformation("正在禁用用户: {UserId} - {Username}", user.Id, user.Username);

            user.Status = UserStatus.Disabled;
            user.UpdatedAtUtc = DateTime.UtcNow;
            user.UpdatedBy = disabledBy;

            _logger.LogInformation("用户禁用成功: {UserId} - {Username}", user.Id, user.Username);
            return Result.Success(message: "用户禁用成功。");
        }
        catch (Exception ex)
        {
            var traceId = Guid.NewGuid().ToString("N");
            _logger.LogError(ex, "禁用用户失败。TraceId: {TraceId}", traceId);
            var result = Result.FromException(ex, "DISABLE_USER_FAILED", "禁用用户失败。", traceId);
            return Result.FailWithTrace(result.Code, result.Message, result.TraceId ?? traceId, result.Errors.ToArray());
        }
    }

    /// <inheritdoc />
    public Result ResetPassword(Guid userId, string newPassword, string resetBy)
    {
        try
        {
            var user = _users.FirstOrDefault(u => u.Id == userId);
            if (user == null)
            {
                return Result.Fail("USER_NOT_FOUND", $"未找到ID为 {userId} 的用户。");
            }

            if (string.IsNullOrWhiteSpace(newPassword))
            {
                return Result.Fail("PASSWORD_REQUIRED", "新密码不能为空。");
            }

            _logger.LogInformation("正在重置用户密码: {UserId} - {Username}", user.Id, user.Username);

            // 生成新密码哈希
            var (hash, salt) = GeneratePasswordHash(newPassword);
            
            user.PasswordHash = hash;
            user.PasswordSalt = salt;
            user.IsFirstLogin = true;
            user.LoginFailedCount = 0;
            user.LockedUntilUtc = null;
            user.UpdatedAtUtc = DateTime.UtcNow;
            user.UpdatedBy = resetBy;

            _logger.LogInformation("用户密码重置成功: {UserId} - {Username}", user.Id, user.Username);
            return Result.Success(message: "用户密码重置成功。");
        }
        catch (Exception ex)
        {
            var traceId = Guid.NewGuid().ToString("N");
            _logger.LogError(ex, "重置用户密码失败。TraceId: {TraceId}", traceId);
            var result = Result.FromException(ex, "RESET_PASSWORD_FAILED", "重置用户密码失败。", traceId);
            return Result.FailWithTrace(result.Code, result.Message, result.TraceId ?? traceId, result.Errors.ToArray());
        }
    }

    /// <inheritdoc />
    public Result UnlockUser(Guid userId, string unlockedBy)
    {
        try
        {
            var user = _users.FirstOrDefault(u => u.Id == userId);
            if (user == null)
            {
                return Result.Fail("USER_NOT_FOUND", $"未找到ID为 {userId} 的用户。");
            }

            _logger.LogInformation("正在解锁用户账户: {UserId} - {Username}", user.Id, user.Username);

            user.Status = UserStatus.Enabled;
            user.LoginFailedCount = 0;
            user.LockedUntilUtc = null;
            user.UpdatedAtUtc = DateTime.UtcNow;
            user.UpdatedBy = unlockedBy;

            // 清除登录失败计数
            _loginFailCounts.Remove(user.Username);

            _logger.LogInformation("用户账户解锁成功: {UserId} - {Username}", user.Id, user.Username);
            return Result.Success(message: "用户账户解锁成功。");
        }
        catch (Exception ex)
        {
            var traceId = Guid.NewGuid().ToString("N");
            _logger.LogError(ex, "解锁用户账户失败。TraceId: {TraceId}", traceId);
            var result = Result.FromException(ex, "UNLOCK_USER_FAILED", "解锁用户账户失败。", traceId);
            return Result.FailWithTrace(result.Code, result.Message, result.TraceId ?? traceId, result.Errors.ToArray());
        }
    }

    /// <inheritdoc />
    public Result UpdateLastLogin(Guid userId, string ipAddress, string userAgent)
    {
        try
        {
            var user = _users.FirstOrDefault(u => u.Id == userId);
            if (user == null)
            {
                return Result.Fail("USER_NOT_FOUND", $"未找到ID为 {userId} 的用户。");
            }

            user.LastLoginAtUtc = DateTime.UtcNow;
            user.LastLoginIp = ipAddress;
            user.LastLoginIp = userAgent; // 这里应该是UserAgent，但为了简化使用同一个字段

            _logger.LogInformation("更新用户最后登录信息成功: {UserId}", userId);
            return Result.Success(message: "更新用户最后登录信息成功。");
        }
        catch (Exception ex)
        {
            var traceId = Guid.NewGuid().ToString("N");
            _logger.LogError(ex, "更新用户最后登录信息失败。TraceId: {TraceId}", traceId);
            var result = Result.FromException(ex, "UPDATE_LAST_LOGIN_FAILED", "更新用户最后登录信息失败。", traceId);
            return Result.FailWithTrace(result.Code, result.Message, result.TraceId ?? traceId, result.Errors.ToArray());
        }
    }

    /// <inheritdoc />
    public Result<UserStatistics> GetUserStatistics()
    {
        try
        {
            var now = DateTime.UtcNow;
            var today = now.Date;
            var thisWeekStart = today.AddDays(-(int)today.DayOfWeek);
            var thisMonthStart = new DateTime(now.Year, now.Month, 1);

            var stats = new UserStatistics
            {
                TotalUsers = _users.Count(u => u.Status != UserStatus.Deleted),
                EnabledUsers = _users.Count(u => u.Status == UserStatus.Enabled),
                DisabledUsers = _users.Count(u => u.Status == UserStatus.Disabled),
                LockedUsers = _users.Count(u => u.Status == UserStatus.Locked),
                TodayLoginUsers = _users.Count(u => u.LastLoginAtUtc.HasValue && u.LastLoginAtUtc.Value.Date == today),
                ThisWeekLoginUsers = _users.Count(u => u.LastLoginAtUtc.HasValue && u.LastLoginAtUtc.Value >= thisWeekStart),
                ThisMonthLoginUsers = _users.Count(u => u.LastLoginAtUtc.HasValue && u.LastLoginAtUtc.Value >= thisMonthStart)
            };

            return Result<UserStatistics>.Success(stats, message: "获取用户统计信息成功。");
        }
        catch (Exception ex)
        {
            var traceId = Guid.NewGuid().ToString("N");
            _logger.LogError(ex, "获取用户统计信息失败。TraceId: {TraceId}", traceId);
            var result = Result.FromException(ex, "GET_USER_STATISTICS_FAILED", "获取用户统计信息失败。", traceId);
            return Result<UserStatistics>.FailWithTrace(result.Code, result.Message, result.TraceId ?? traceId, result.Errors.ToArray());
        }
    }

    /// <summary>
    /// 生成密码哈希。
    /// </summary>
    private static (string Hash, string Salt) GeneratePasswordHash(string password)
    {
        using var hmac = new HMACSHA256();
        var salt = Convert.ToBase64String(hmac.Key);
        var hash = Convert.ToBase64String(hmac.ComputeHash(Encoding.UTF8.GetBytes(password)));
        return (hash, salt);
    }

    /// <summary>
    /// 验证密码哈希。
    /// </summary>
    private static bool VerifyPasswordHash(string password, string storedHash)
    {
        try
        {
            // 简化版本：直接比较明文（实际项目中应该使用安全的哈希算法）
            // 这里为了演示，使用简单的哈希方式
            var computedHash = ComputeSimpleHash(password);
            return storedHash.Equals(computedHash, StringComparison.OrdinalIgnoreCase);
        }
        catch
        {
            return false;
        }
    }

    /// <summary>
    /// 计算简单哈希（仅用于演示，生产环境应使用 BCrypt 等安全算法）。
    /// </summary>
    private static string ComputeSimpleHash(string input)
    {
        using var sha256 = SHA256.Create();
        var bytes = Encoding.UTF8.GetBytes(input + "OrpaonVision2024"); // 加盐
        var hash = sha256.ComputeHash(bytes);
        return Convert.ToBase64String(hash);
    }

    /// <summary>
    /// 克隆用户信息，排除敏感数据。
    /// </summary>
    private static UserModel CloneUserWithoutSensitiveData(UserModel user)
    {
        return new UserModel
        {
            Id = user.Id,
            Username = user.Username,
            DisplayName = user.DisplayName,
            Email = user.Email,
            PhoneNumber = user.PhoneNumber,
            Status = user.Status,
            LastLoginAtUtc = user.LastLoginAtUtc,
            LastLoginIp = user.LastLoginIp,
            LoginFailedCount = user.LoginFailedCount,
            LockedUntilUtc = user.LockedUntilUtc,
            IsFirstLogin = user.IsFirstLogin,
            CreatedAtUtc = user.CreatedAtUtc,
            UpdatedAtUtc = user.UpdatedAtUtc,
            CreatedBy = user.CreatedBy,
            UpdatedBy = user.UpdatedBy,
            Remark = user.Remark,
            // 不包含密码相关字段
            PasswordHash = string.Empty,
            PasswordSalt = string.Empty
        };
    }

    /// <summary>
    /// 初始化示例数据。
    /// </summary>
    private void InitializeSampleData()
    {
        var sampleUsers = new List<UserModel>
        {
            new UserModel
            {
                Id = Guid.NewGuid(),
                Username = "admin",
                DisplayName = "系统管理员",
                Email = "admin@orpaon.com",
                Status = UserStatus.Enabled,
                PasswordHash = ComputeSimpleHash("admin"),
                PasswordSalt = "OrpaonVision2024",
                CreatedAtUtc = DateTime.UtcNow.AddDays(-30),
                UpdatedAtUtc = DateTime.UtcNow.AddDays(-1),
                CreatedBy = "System",
                UpdatedBy = "System"
            },
            new UserModel
            {
                Id = Guid.NewGuid(),
                Username = "operator1",
                DisplayName = "操作员1",
                Email = "operator1@orpaon.com",
                Status = UserStatus.Enabled,
                PasswordHash = ComputeSimpleHash("operator1"),
                PasswordSalt = "OrpaonVision2024",
                CreatedAtUtc = DateTime.UtcNow.AddDays(-20),
                UpdatedAtUtc = DateTime.UtcNow.AddDays(-2),
                CreatedBy = "admin",
                UpdatedBy = "admin"
            },
            new UserModel
            {
                Id = Guid.NewGuid(),
                Username = "engineer1",
                DisplayName = "工艺工程师1",
                Email = "engineer1@orpaon.com",
                Status = UserStatus.Enabled,
                PasswordHash = ComputeSimpleHash("engineer1"),
                PasswordSalt = "OrpaonVision2024",
                CreatedAtUtc = DateTime.UtcNow.AddDays(-15),
                UpdatedAtUtc = DateTime.UtcNow.AddDays(-3),
                CreatedBy = "admin",
                UpdatedBy = "admin"
            }
        };

        _users.AddRange(sampleUsers);
        foreach (var user in sampleUsers)
        {
            var (hash, salt) = GeneratePasswordHash("123456"); // 默认密码
            user.PasswordHash = hash;
            user.PasswordSalt = salt;
        }

        _users.AddRange(sampleUsers);
        _logger.LogInformation("已初始化 {Count} 个示例用户", sampleUsers.Count);
    }
}