using Microsoft.Extensions.Options;
using SPMS.Application.DTOs.Account;
using SPMS.Application.DTOs.Auth;
using SPMS.Application.Interfaces;
using SPMS.Application.Settings;
using SPMS.Domain.Common;
using SPMS.Domain.Entities;
using SPMS.Domain.Enums;
using SPMS.Domain.Exceptions;
using SPMS.Domain.Interfaces;

namespace SPMS.Application.Services;

public class AuthService : IAuthService
{
    private readonly IAdminRepository _adminRepository;
    private readonly IUnitOfWork _unitOfWork;
    private readonly IJwtService _jwtService;
    private readonly JwtSettings _jwtSettings;
    private readonly ITokenStore _tokenStore;
    private readonly IEmailService _emailService;

    public AuthService(
        IAdminRepository adminRepository,
        IUnitOfWork unitOfWork,
        IJwtService jwtService,
        IOptions<JwtSettings> jwtSettings,
        ITokenStore tokenStore,
        IEmailService emailService)
    {
        _adminRepository = adminRepository;
        _unitOfWork = unitOfWork;
        _jwtService = jwtService;
        _jwtSettings = jwtSettings.Value;
        _tokenStore = tokenStore;
        _emailService = emailService;
    }

    public async Task<SignupResponseDto> SignupAsync(SignupRequestDto request)
    {
        // 1. 동의 검증
        if (!request.AgreeTerms)
            throw new SpmsException(ErrorCodes.TermsNotAgreed, "서비스 이용약관에 동의해야 합니다.", 400);
        if (!request.AgreePrivacy)
            throw new SpmsException(ErrorCodes.PrivacyNotAgreed, "개인정보 처리방침에 동의해야 합니다.", 400);

        // 2. 이메일 중복 검사
        if (await _adminRepository.EmailExistsAsync(request.Email))
        {
            throw new SpmsException(
                ErrorCodes.Conflict,
                "이미 사용 중인 이메일입니다.",
                409);
        }

        // 3. AdminCode 생성 (UUID 12자)
        var adminCode = Guid.NewGuid().ToString("N")[..12].ToUpper();

        // 4. Admin 엔티티 생성 (동의 필드 포함)
        var admin = new Admin
        {
            AdminCode = adminCode,
            Email = request.Email,
            Password = BCrypt.Net.BCrypt.HashPassword(request.Password),
            Name = request.Name,
            Phone = request.Phone,
            Role = AdminRole.User,
            EmailVerified = false,
            CreatedAt = DateTime.UtcNow,
            IsDeleted = false,
            AgreeTerms = true,
            AgreePrivacy = true,
            AgreedAt = DateTime.UtcNow
        };

        // 5. 저장
        await _adminRepository.AddAsync(admin);
        await _unitOfWork.SaveChangesAsync();

        // 6. 이메일 인증 코드 생성/저장 (5분 TTL)
        var verificationCode = Random.Shared.Next(100000, 999999).ToString();
        await _tokenStore.StoreAsync(
            $"email_verify:{request.Email}",
            verificationCode,
            TimeSpan.FromMinutes(5));

        // 7. Verify Session 생성 (sessionId → email 매핑)
        var verifySessionId = Guid.NewGuid().ToString("N");
        await _tokenStore.StoreAsync(
            $"verify_session:{verifySessionId}",
            request.Email,
            TimeSpan.FromHours(1));

        // 8. 메일 발송 (실패해도 가입은 유지)
        var emailSent = true;
        try
        {
            await _emailService.SendVerificationCodeAsync(request.Email, verificationCode);
        }
        catch
        {
            emailSent = false;
        }

        // 9. 응답 반환
        return new SignupResponseDto
        {
            AdminCode = admin.AdminCode,
            Email = admin.Email,
            VerifySessionId = verifySessionId,
            EmailSent = emailSent
        };
    }

    public async Task<LoginResponseDto> LoginAsync(LoginRequestDto request)
    {
        // 1. 이메일로 관리자 조회
        var admin = await _adminRepository.GetByEmailAsync(request.Email);
        if (admin is null)
        {
            throw new SpmsException(
                ErrorCodes.LoginFailed,
                "이메일 또는 비밀번호가 일치하지 않습니다.",
                401);
        }

        // 2. 삭제된 계정 확인
        if (admin.IsDeleted)
        {
            throw new SpmsException(
                ErrorCodes.LoginFailed,
                "이메일 또는 비밀번호가 일치하지 않습니다.",
                401);
        }

        // 3. 비밀번호 검증 (BCrypt)
        if (!BCrypt.Net.BCrypt.Verify(request.Password, admin.Password))
        {
            throw new SpmsException(
                ErrorCodes.LoginFailed,
                "이메일 또는 비밀번호가 일치하지 않습니다.",
                401);
        }

        // 4. 토큰 생성
        var accessToken = _jwtService.GenerateAccessToken(
            admin.Id,
            admin.Role.ToString());
        var refreshToken = _jwtService.GenerateRefreshToken();

        // 5. Refresh Token 및 최종 로그인 시간 저장
        admin.RefreshToken = refreshToken;
        admin.RefreshTokenExpiresAt = DateTime.UtcNow.AddDays(_jwtSettings.RefreshTokenExpiryDays);
        admin.LastLoginAt = DateTime.UtcNow;
        _adminRepository.Update(admin);
        await _unitOfWork.SaveChangesAsync();

        // 6. 분기 판정 + verify session 생성
        var nextAction = "GO_DASHBOARD";
        string? verifySessionId = null;
        bool? emailSent = null;

        if (!admin.EmailVerified)
        {
            nextAction = "VERIFY_EMAIL";

            // 인증코드 생성/저장 (5분 TTL)
            var verificationCode = Random.Shared.Next(100000, 999999).ToString();
            await _tokenStore.StoreAsync(
                $"email_verify:{admin.Email}",
                verificationCode,
                TimeSpan.FromMinutes(5));

            // Verify Session 생성
            verifySessionId = Guid.NewGuid().ToString("N");
            await _tokenStore.StoreAsync(
                $"verify_session:{verifySessionId}",
                admin.Email,
                TimeSpan.FromHours(1));

            // 메일 발송 (실패해도 로그인은 유지)
            emailSent = true;
            try
            {
                await _emailService.SendVerificationCodeAsync(admin.Email, verificationCode);
            }
            catch
            {
                emailSent = false;
            }
        }

        // 7. 응답 반환
        return new LoginResponseDto
        {
            AccessToken = accessToken,
            RefreshToken = refreshToken,
            ExpiresIn = _jwtSettings.ExpiryMinutes * 60,
            NextAction = nextAction,
            EmailVerified = admin.EmailVerified,
            VerifySessionId = verifySessionId,
            EmailSent = emailSent,
            Admin = new AdminInfoDto
            {
                AdminCode = admin.AdminCode,
                Email = admin.Email,
                Name = admin.Name,
                Role = admin.Role.ToString()
            }
        };
    }

    public async Task<TokenRefreshResponseDto> RefreshTokenAsync(TokenRefreshRequestDto request)
    {
        // 1. Refresh Token으로 관리자 조회
        var admin = await _adminRepository.GetByRefreshTokenAsync(request.RefreshToken);
        if (admin is null)
        {
            throw new SpmsException(
                ErrorCodes.Unauthorized,
                "유효하지 않은 Refresh Token입니다.",
                401);
        }

        // 2. Refresh Token 만료 확인
        if (admin.RefreshTokenExpiresAt < DateTime.UtcNow)
        {
            throw new SpmsException(
                ErrorCodes.Unauthorized,
                "Refresh Token이 만료되었습니다. 다시 로그인해주세요.",
                401);
        }

        // 3. 새 토큰 생성
        var newAccessToken = _jwtService.GenerateAccessToken(
            admin.Id,
            admin.Role.ToString());
        var newRefreshToken = _jwtService.GenerateRefreshToken();

        // 4. 새 Refresh Token 저장 (Rotation)
        admin.RefreshToken = newRefreshToken;
        admin.RefreshTokenExpiresAt = DateTime.UtcNow.AddDays(_jwtSettings.RefreshTokenExpiryDays);
        _adminRepository.Update(admin);
        await _unitOfWork.SaveChangesAsync();

        // 5. 응답 반환
        return new TokenRefreshResponseDto
        {
            AccessToken = newAccessToken,
            RefreshToken = newRefreshToken,
            ExpiresIn = _jwtSettings.ExpiryMinutes * 60
        };
    }

    public async Task LogoutAsync(long adminId, string accessToken)
    {
        // 1. 관리자 조회
        var admin = await _adminRepository.GetByIdAsync(adminId);
        if (admin is null)
        {
            throw new SpmsException(
                ErrorCodes.NotFound,
                "관리자를 찾을 수 없습니다.",
                404);
        }

        // 2. Refresh Token 무효화
        admin.RefreshToken = null;
        admin.RefreshTokenExpiresAt = null;
        _adminRepository.Update(admin);
        await _unitOfWork.SaveChangesAsync();

        // 3. Access Token 블랙리스트 (JTI 기반, TTL = 남은 만료시간)
        var (jti, validTo) = _jwtService.GetTokenInfo(accessToken);
        if (!string.IsNullOrEmpty(jti))
        {
            var remaining = validTo - DateTime.UtcNow;
            if (remaining > TimeSpan.Zero)
                await _tokenStore.StoreAsync($"blacklist:{jti}", "revoked", remaining);
        }
    }

    public async Task ChangePasswordAsync(long adminId, ChangePasswordRequestDto request)
    {
        // 1. 관리자 조회
        var admin = await _adminRepository.GetByIdAsync(adminId);
        if (admin is null)
        {
            throw new SpmsException(
                ErrorCodes.NotFound,
                "관리자를 찾을 수 없습니다.",
                404);
        }

        // 2. 현재 비밀번호 검증
        if (!BCrypt.Net.BCrypt.Verify(request.CurrentPassword, admin.Password))
        {
            throw new SpmsException(
                ErrorCodes.PasswordValidationFailed,
                "현재 비밀번호가 일치하지 않습니다.",
                400);
        }

        // 3. 새 비밀번호 해싱 및 저장
        admin.Password = BCrypt.Net.BCrypt.HashPassword(request.NewPassword);
        _adminRepository.Update(admin);
        await _unitOfWork.SaveChangesAsync();
    }

    public async Task<EmailCheckResponseDto> CheckEmailAsync(EmailCheckRequestDto request)
    {
        var exists = await _adminRepository.EmailExistsAsync(request.Email);
        return new EmailCheckResponseDto
        {
            Email = request.Email,
            IsAvailable = !exists
        };
    }

    public async Task<EmailVerifyResponseDto> VerifyEmailAsync(EmailVerifyRequestDto request)
    {
        // 1. 이메일 결정: verifySessionId 우선, email 하위호환
        string? email = null;
        if (!string.IsNullOrEmpty(request.VerifySessionId))
        {
            email = await _tokenStore.GetAsync($"verify_session:{request.VerifySessionId}");
            if (email is null)
                throw new SpmsException(ErrorCodes.VerificationCodeError, "인증 세션이 만료되었거나 유효하지 않습니다.", 400);
        }
        else if (!string.IsNullOrEmpty(request.Email))
        {
            email = request.Email;
        }
        else
        {
            throw new SpmsException(ErrorCodes.BadRequest, "verify_session_id 또는 email 중 하나는 필수입니다.", 400);
        }

        // 2. 시도 횟수 체크 (최대 5회, 30분 TTL)
        var attemptsKey = $"verify_attempts:{email}";
        var attemptsStr = await _tokenStore.GetAsync(attemptsKey);
        var attempts = int.TryParse(attemptsStr, out var a) ? a : 0;
        if (attempts >= 5)
            throw new SpmsException(ErrorCodes.VerifyAttemptExceeded, "인증 시도 횟수를 초과했습니다. 30분 후 다시 시도해주세요.", 429);

        // 3. 관리자 조회
        var admin = await _adminRepository.GetByEmailAsync(email);
        if (admin is null)
            throw new SpmsException(ErrorCodes.VerificationCodeError, "인증 코드가 유효하지 않습니다.", 400);

        if (admin.EmailVerified)
            throw new SpmsException(ErrorCodes.VerificationCodeError, "이미 인증된 이메일입니다.", 400);

        // 4. 인증코드 검증
        var storedCode = await _tokenStore.GetAsync($"email_verify:{email}");
        if (storedCode is null || storedCode != request.Code)
        {
            // 시도 횟수 증가
            await _tokenStore.StoreAsync(attemptsKey, (attempts + 1).ToString(), TimeSpan.FromMinutes(30));
            throw new SpmsException(ErrorCodes.VerificationCodeError, "인증 코드가 유효하지 않거나 만료되었습니다.", 400);
        }

        // 5. 인증 성공 처리
        admin.EmailVerified = true;
        admin.EmailVerifiedAt = DateTime.UtcNow;
        _adminRepository.Update(admin);
        await _unitOfWork.SaveChangesAsync();

        // 6. 관련 Redis 키 정리
        await _tokenStore.RemoveAsync($"email_verify:{email}");
        await _tokenStore.RemoveAsync(attemptsKey);
        if (!string.IsNullOrEmpty(request.VerifySessionId))
            await _tokenStore.RemoveAsync($"verify_session:{request.VerifySessionId}");

        return new EmailVerifyResponseDto
        {
            Verified = true,
            NextAction = "GO_LOGIN"
        };
    }

    public async Task<EmailResendResponseDto> ResendVerificationAsync(EmailResendRequestDto request)
    {
        // 1. 세션에서 이메일 해석
        var email = await _tokenStore.GetAsync($"verify_session:{request.VerifySessionId}");
        if (email is null)
            throw new SpmsException(ErrorCodes.VerificationCodeError, "인증 세션이 만료되었거나 유효하지 않습니다.", 400);

        // 2. 쿨다운 체크 (60초)
        var cooldownKey = $"resend_cooldown:{email}";
        var cooldownExists = await _tokenStore.GetAsync(cooldownKey);
        if (cooldownExists is not null)
            throw new SpmsException(ErrorCodes.VerifyResendCooldown, "재전송 대기 시간입니다. 잠시 후 다시 시도해주세요.", 429);

        // 3. 이미 인증된 계정인지 확인
        var admin = await _adminRepository.GetByEmailAsync(email);
        if (admin is null)
            throw new SpmsException(ErrorCodes.VerificationCodeError, "유효하지 않은 인증 세션입니다.", 400);

        if (admin.EmailVerified)
            throw new SpmsException(ErrorCodes.VerificationCodeError, "이미 인증된 이메일입니다.", 400);

        // 4. 새 인증코드 생성 → 기존 코드 덮어씀 (5분 TTL)
        var verificationCode = Random.Shared.Next(100000, 999999).ToString();
        await _tokenStore.StoreAsync($"email_verify:{email}", verificationCode, TimeSpan.FromMinutes(5));

        // 5. 쿨다운 키 설정 (60초)
        await _tokenStore.StoreAsync(cooldownKey, "1", TimeSpan.FromSeconds(60));

        // 6. 메일 발송
        await _emailService.SendVerificationCodeAsync(email, verificationCode);

        return new EmailResendResponseDto
        {
            Resent = true,
            CooldownSeconds = 60,
            ExpiresInSeconds = 300
        };
    }

    public async Task ForgotPasswordAsync(PasswordForgotRequestDto request)
    {
        var admin = await _adminRepository.GetByEmailAsync(request.Email);

        // 보안: 이메일 존재 여부와 관계없이 동일한 성공 응답 반환
        if (admin is null)
            return;

        var resetToken = Guid.NewGuid().ToString("N");
        await _tokenStore.StoreAsync(
            $"password_reset:{request.Email}",
            resetToken,
            TimeSpan.FromMinutes(30));
        await _emailService.SendPasswordResetTokenAsync(request.Email, resetToken);
    }

    public async Task ResetPasswordAsync(PasswordResetRequestDto request)
    {
        var storedToken = await _tokenStore.GetAsync($"password_reset:{request.Email}");
        if (storedToken is null || storedToken != request.ResetToken)
        {
            throw new SpmsException(
                ErrorCodes.ResetTokenError,
                "재설정 토큰이 유효하지 않거나 만료되었습니다.",
                400);
        }

        var admin = await _adminRepository.GetByEmailAsync(request.Email);
        if (admin is null)
        {
            throw new SpmsException(
                ErrorCodes.ResetTokenError,
                "재설정 토큰이 유효하지 않거나 만료되었습니다.",
                400);
        }

        admin.Password = BCrypt.Net.BCrypt.HashPassword(request.NewPassword);
        _adminRepository.Update(admin);
        await _unitOfWork.SaveChangesAsync();

        await _tokenStore.RemoveAsync($"password_reset:{request.Email}");
    }

    public async Task<ProfileResponseDto> GetProfileAsync(long adminId)
    {
        var admin = await _adminRepository.GetByIdAsync(adminId);
        if (admin is null)
        {
            throw new SpmsException(
                ErrorCodes.NotFound,
                "관리자를 찾을 수 없습니다.",
                404);
        }

        return new ProfileResponseDto
        {
            AdminCode = admin.AdminCode,
            Email = admin.Email,
            Name = admin.Name,
            Phone = admin.Phone,
            Role = (int)admin.Role,
            CreatedAt = admin.CreatedAt
        };
    }

    public async Task<ProfileResponseDto> UpdateProfileAsync(long adminId, UpdateProfileRequestDto request)
    {
        var admin = await _adminRepository.GetByIdAsync(adminId);
        if (admin is null)
        {
            throw new SpmsException(
                ErrorCodes.NotFound,
                "관리자를 찾을 수 없습니다.",
                404);
        }

        var hasChange = false;

        if (request.Name is not null && request.Name != admin.Name)
        {
            admin.Name = request.Name;
            hasChange = true;
        }

        if (request.Phone is not null && request.Phone != admin.Phone)
        {
            admin.Phone = request.Phone;
            hasChange = true;
        }

        if (!hasChange)
        {
            throw new SpmsException(
                ErrorCodes.NoChange,
                "변경된 내용이 없습니다.",
                400);
        }

        _adminRepository.Update(admin);
        await _unitOfWork.SaveChangesAsync();

        return new ProfileResponseDto
        {
            AdminCode = admin.AdminCode,
            Email = admin.Email,
            Name = admin.Name,
            Phone = admin.Phone,
            Role = (int)admin.Role,
            CreatedAt = admin.CreatedAt
        };
    }
}