using AuthHex.Infra.UoW;
using AuthHex.Interfaces;
using AuthHex.Models;
using AuthHex.Models.IOs;
using AuthHex.Utility;
using AuthHex.Utility.passwordHasher;
using AuthSystem.API.Utils;
using Core_Archi.Helpers;
using System.Security.Cryptography;


namespace AuthHex.Services.AltOptionManager;

public class AltOptionManagerService
{
    private readonly IRecoveryManagerRepository _repository;
    private readonly IUserManageRepository _userRepository;
    private readonly IAltOptionManagerRepository _altOptionRepository;
    private readonly IUnitOfWork _uow;
    private readonly JwtTokenHelper _jwt;
    private readonly AppDBContext _dbContext;
    private readonly ThirdPartyService _thirdPartyService;
    private readonly IConfiguration _configuration;
    private readonly UserHelper _userHelper;

    public AltOptionManagerService(
        IRecoveryManagerRepository Recoveryrepository,
        IUserManageRepository userRepository,
        IAltOptionManagerRepository altOptionRepository,
        IUnitOfWork uow,
        JwtTokenHelper jwt,
        AppDBContext dbContext,
        ThirdPartyService thirdPartyService,
        IConfiguration configuration,
        UserHelper userHelper)
    {
        _repository = Recoveryrepository;
        _userRepository = userRepository;
        _altOptionRepository = altOptionRepository;
        _uow = uow;
        _jwt = jwt;
        _dbContext = dbContext;
        _thirdPartyService = thirdPartyService;
        _configuration = configuration;
        _userHelper = userHelper;
    }



    public async Task<object> IsAvailable(object payload, HttpContext httpContext)
    {

        var data = DeserializePayload.Deserialize(payload);
        var Identifier = data.ContainsKey("Identifier") ? data["Identifier"].GetString() : null;
        var Recovery = data.ContainsKey("Recovery") ? data["Recovery"].GetString() : null;

        var existingUsers = await _userRepository.GetUserByIdentifiers(
            email: Identifier,
            mobileNumber: Identifier,
            nic: Identifier,
            username: Identifier,
            Optional1: Identifier
        );

        if (existingUsers == null || !existingUsers.Any())
        {
            return new { IsAvailable = true, Message = "Identifier is available" };
        }

        if (Recovery == null)
        {
            return new { IsAvailable = false, Message = "Identifier already in use" };
        }

        return new { existingUsers };

    }

    public async Task<object> SendOtp(object payload, HttpContext httpContext)
    {
        await _uow.BeginAsync();

        try
        {
            var data = DeserializePayload.Deserialize(payload);

           
            var identifier = data.ContainsKey("identifier") ? data["identifier"].GetString() : null;
            var numberOfDigits = data.ContainsKey("numberOfDigits") ? data["numberOfDigits"].GetInt32() : 6;

            var newUser = data.ContainsKey("newUser") ? data["newUser"].GetBoolean() : false;

            if (string.IsNullOrWhiteSpace(identifier))
                throw new ArgumentException("Identifier is required.");

            var otpCode = await GenerateOtpCode(numberOfDigits);
            Recovery recovery;


            if (newUser)
            {
                recovery = new Recovery
                {
                    RecoveryReferenceNum = GenerateSecureReferenceNumber(),
                    OTP = otpCode,
                    Status = "Pending",
                    IsUsed = false,
                    CreatedAt = DateTime.UtcNow,
                    ExpirationTime = DateTime.UtcNow.AddMinutes(10),
                    RecoveryType = "OTP FOR NEW USER"
                };

                await _repository.AddRecoveryAsync(recovery);
                await _uow.CommitAsync();

                if (!string.IsNullOrWhiteSpace(identifier))
                {
                    if (IsEmail(identifier))
                    {
                        await _thirdPartyService.EmailConfiguration(
                            identifier,
                            otpCode,
                            "Verification OTP",
                            $@"
                            <h2>Verification OTP</h2>
                            <p>Your OTP code is:</p>
                            <h1>{otpCode}</h1>
                            <p>This code expires in 10 minutes.</p>
                            <p><strong>Reference Number:</strong> {recovery.RecoveryReferenceNum}</p>
                       "
                        );
                    }
                    else if (IsMobileNumber(identifier))
                    {
                        await _thirdPartyService.SendSmsAsync(
                            identifier,
                            otpCode,
                            $"Your OTP is {otpCode}. It expires in 10 minutes. Ref: {recovery.RecoveryReferenceNum}"
                        );
                    }
                    else
                    {
                        throw new ArgumentException("Invalid identifier format. Must be a valid email or mobile number.");
                    }
                }

                return new
                {
                    Success = true,
                    Message = "OTP sent successfully for new user.",
                    Data = new
                    {
                        ReferenceNumber = recovery.RecoveryReferenceNum,
                        ExpiresAt = recovery.ExpirationTime,
                        RecoveryType = recovery.RecoveryType
                    }
                };
            }


            //exisiting one

            var user = await _userRepository.GetUserByIdentifierAndType(identifier, null);

            if (user == null)
                throw new KeyNotFoundException("No user found with the provided identifier.");

            if (user.IsLocked == true)
                throw new InvalidOperationException("User account is locked. Please contact support.");

            if (user.IsActive == false)
                throw new InvalidOperationException("User account is inactive. Please contact support.");

            recovery = new Recovery
            {
                UserId = user.Id,
                RecoveryReferenceNum = GenerateSecureReferenceNumber(),
                OTP = otpCode,
                Status = "Pending",
                IsUsed = false,
                CreatedAt = DateTime.UtcNow,
                ExpirationTime = DateTime.UtcNow.AddMinutes(10),
                RecoveryType = "OTP FOR LOGIN"
            };

            await _repository.AddRecoveryAsync(recovery);
            await _uow.CommitAsync();

            if (!string.IsNullOrWhiteSpace(user.MobileNumber))
            {
                await _thirdPartyService.SendSmsAsync(
                    user.MobileNumber,
                    otpCode,
                    $"Your login OTP is {otpCode}. It expires in 10 minutes. Ref: {recovery.RecoveryReferenceNum}"
                );
            }

            if (!string.IsNullOrWhiteSpace(user.Email))
            {
                await _thirdPartyService.EmailConfiguration(
                    user.Email,
                    otpCode,
                    "Login OTP",
                    $@"
                <h2>Login OTP</h2>
                <p>Hello {user.FullName ?? user.UserName},</p>
                <p>Your OTP code is:</p>
                <h1>{otpCode}</h1>
                <p>This code expires in 10 minutes.</p>
                <p><strong>Reference Number:</strong> {recovery.RecoveryReferenceNum}</p>
                "
                );
            }

            return new
            {
                Success = true,
                Message = "OTP sent successfully.",
                Data = new
                {
                    ReferenceNumber = recovery.RecoveryReferenceNum,
                    ExpiresAt = recovery.ExpirationTime,
                    RecoveryType = recovery.RecoveryType
                }
            };
        }
        catch
        {
            await _uow.RollbackAsync();
            throw;
        }
    }



    public async Task<object> VerifyOTP(object payload, HttpContext httpContext)
    {
        await _uow.BeginAsync();
        try
        {

            var ipAddress = httpContext.Connection.RemoteIpAddress?.ToString();
            var userAgent = httpContext.Request.Headers["User-Agent"].ToString();

            

            var data = DeserializePayload.Deserialize(payload);

            Guid? userId = null;
            if (data.ContainsKey("userId") && Guid.TryParse(data["userId"].GetString(), out var parsedUserId))
            {
                userId = parsedUserId;
            }
            var referenceNumber = data.ContainsKey("referenceNumber") ? data["referenceNumber"].GetString() : null;
            var otpCode = data.ContainsKey("otpCode") ? data["otpCode"].GetString() : null;
            var newUser = data.ContainsKey("newUser") ? data["newUser"].GetBoolean() : false;
            var identifier = data.ContainsKey("identifier") ? data["identifier"].GetString() : null;
            var deviceName = data.ContainsKey("deviceName") ? data["deviceName"].GetString() : "Unknown Device";


            if (string.IsNullOrEmpty(referenceNumber) || string.IsNullOrEmpty(otpCode))
                throw new ArgumentException("Reference number and OTP code are required.");

            var recovery = await _repository.GetRecoveryByReferenceNumAsync(referenceNumber);

            if (recovery == null)
                throw new KeyNotFoundException("Invalid reference number.");

            if (recovery.IsUsed)
                throw new InvalidOperationException("This OTP has already been used.");

            if (recovery.Status != "Pending")
                throw new InvalidOperationException("This OTP is no longer valid.");

            if (DateTime.UtcNow > recovery.ExpirationTime)
            {
                recovery.Status = "Expired";
                await _repository.UpdateRecoveryAsync(recovery);
                await _uow.CommitAsync();
                throw new InvalidOperationException("This OTP has expired. Please request a new one.");
            }

            if (recovery.OTP != otpCode)
                throw new InvalidOperationException("Invalid OTP code.");

            


            recovery.Status = "Verified";
            recovery.IsUsed = true;
            await _repository.UpdateRecoveryAsync(recovery);

            User? user = null;
            if (!string.IsNullOrWhiteSpace(identifier))
            {
                user = await _userRepository.GetUserByIdentifierAndType(identifier, null);
            }

            if (user is null && userId.HasValue)
            {
                user = await _userRepository.GetUserByIdAsync(userId.Value);
            }

            if (user is null && recovery.UserId.HasValue)
            {
                user = await _userRepository.GetUserByIdAsync(recovery.UserId.Value);
            }

            if (user is null)
                throw new KeyNotFoundException("No user found for OTP verification.");

            if (!string.IsNullOrWhiteSpace(identifier))
            {
                if (IsEmail(identifier))
                {
                    user.Email = identifier;
                    user.EmailVerified = true;
                }
                else if (IsMobileNumber(identifier))
                {
                    user.MobileNumber = identifier;
                    user.MobileNumberVerified = true;
                }
                else
                {
                    user.Optional1 = identifier;
                    user.Optional1Verified = true;
                }
            }

            await _userRepository.UpdateUserAsync(user);

            var jwtToken = await _jwt.GenerateToken(user);
            var refreshToken = Guid.NewGuid().ToString();
            var refreshTokenHash = PasswordHasher.Hash(refreshToken);

            var userSession = new UserSession
            {
                UserId = user.Id,
                RefreshTokenHash = refreshTokenHash,
                DeviceName = deviceName,
                IPAddress = ipAddress,
                Browser = _userHelper.ExtractBrowser(userAgent),
                OS = _userHelper.ExtractOS(userAgent),
                ExpiresAt = DateTime.UtcNow.AddDays(30),
                CreatedAt = DateTime.UtcNow
            };

            _dbContext.UserSessions.Add(userSession);
            
            await LogAuthEvent(user.Id, "LOGIN_SUCCESS", ipAddress, userAgent);

            await _uow.CommitAsync();


            return new
            {
                Success = true,
                Message = newUser
                    ? "OTP verified successfully. Session started."
                    : "OTP verified successfully.",
                Data = new
                {
                    ReferenceNumber = recovery.RecoveryReferenceNum,
                    UserId = user.Id,
                    Verified = true,
                    AccessToken = jwtToken,
                    RefreshToken = refreshToken,
                    ExpiresIn = 3600,
                    User = new
                    {
                        user.Id,
                        user.FullName,
                        user.UserName,
                        user.Email,
                        user.MobileNumber,
                        user.EmailVerified,
                        user.MobileNumberVerified,
                        user.IsMfaEnabled,
                        RoleId = user.RoleId,
                        UserTypeId = user.UserTypeId
                    }
                }
            };
        }
        catch
        {
            await _uow.RollbackAsync();
            throw;
        }
    }







    

   














    private async Task<string> GenerateOtpCode(int numberOfDigits)
    {
        if (numberOfDigits <= 0)
            throw new ArgumentException("Number of digits must be at least 1", nameof(numberOfDigits));

        using var rng = RandomNumberGenerator.Create();
        var otpCode = "";

        for (int i = 0; i < numberOfDigits; i++)
        {
            byte[] randomBytes = new byte[4];
            rng.GetBytes(randomBytes);
            uint randomValue = BitConverter.ToUInt32(randomBytes, 0);
            otpCode += (randomValue % 10).ToString();
        }

        return await Task.FromResult(otpCode);
    }


    private string GenerateSecureReferenceNumber()
    {
        var timestamp = DateTimeOffset.UtcNow.ToUnixTimeSeconds();
        using var rng = RandomNumberGenerator.Create();

        byte[] randomBytes = new byte[8];
        rng.GetBytes(randomBytes);

        var randomPart = Convert.ToBase64String(randomBytes)
            .Replace("/", "")
            .Replace("+", "")
            .Replace("=", "")
            .Substring(0, 8).ToUpper();

        return $"REC{timestamp}{randomPart}";
    }

    private bool IsEmail(string identifier)
    {
        if (string.IsNullOrWhiteSpace(identifier))
            return false;

        try
        {
            var emailRegex = new System.Text.RegularExpressions.Regex(
                @"^[^@\s]+@[^@\s]+\.[^@\s]+$",
                System.Text.RegularExpressions.RegexOptions.IgnoreCase);

            return emailRegex.IsMatch(identifier);
        }
        catch
        {
            return false;
        }
    }

    private bool IsMobileNumber(string identifier)
    {
        if (string.IsNullOrWhiteSpace(identifier))
            return false;

        var cleaned = identifier.Replace(" ", "").Replace("-", "").Replace("(", "").Replace(")", "").Replace("+", "");
        return System.Text.RegularExpressions.Regex.IsMatch(cleaned, @"^\d{7,15}$");
    }

    private async Task LogAuthEvent(Guid? userId, string eventType, string? ipAddress, string? userAgent)
    {
        var authEvent = new AuthEventLog
        {
            UserId = userId,
            EventType = eventType,
            IPAddress = ipAddress,
            UserAgent = userAgent,
            CreatedAt = DateTime.UtcNow
        };

        _dbContext.AuthEventLogs.Add(authEvent);
        await Task.CompletedTask;
    }

}