package services

import (
	"errors"
	"fmt"
	"strings"
	"time"

	config "learnsteam/cslms-api/configs"
	"learnsteam/cslms-api/internal/models"
	"learnsteam/cslms-api/internal/repositories"

	"github.com/golang-jwt/jwt/v5"
)

type tokenService struct {
	repository repositories.TokenRepository
}

type TokenService interface {
	Find(int64) (*models.Token, error)
	Create(int64, string) (*models.Token, error)
	Update(*models.Token) (*models.Token, error)
	Delete(string) error

	Refresh(string) (*models.Token, error)

	Generate(int64, int64, string) (string, error)
	Verify(string) (*jwt.Token, error)
	Invalid(int64, string) error

	GetJwtToken(string) (*jwt.Token, error)
	ExtractTokenString(string) string
	VerifyTokenString(string) (*jwt.Token, error)
	ValidToken(*jwt.Token) (bool, error)
}

func NewTokenService(repository repositories.TokenRepository) TokenService {
	return &tokenService{
		repository: repository,
	}
}

func (s *tokenService) Find(id int64) (*models.Token, error) {
	return s.repository.Find(id)
}

func (s *tokenService) Create(user_id int64, role string) (*models.Token, error) {
	expiredAt := time.Now().Add(time.Hour * 24 * 30)
	accessToken, err := s.repository.Generate(user_id, expiredAt.Unix(), role)
	if err != nil {
		return nil, err
	}

	refreshExpiredAt := time.Now().Add(time.Hour * 24 * 90)
	refreshToken, err := s.repository.Generate(user_id, refreshExpiredAt.Unix(), role)
	if err != nil {
		return nil, err
	}

	newToken := &models.Token{
		UserID:       user_id,
		Token:        accessToken,
		RefreshToken: refreshToken,
		Status:       "on",
		EndingAt:     expiredAt,
		RegisterAt:   time.Now(),
	}

	token, err := s.repository.Create(newToken)

	return token, err
}

func (s *tokenService) Update(token *models.Token) (*models.Token, error) {
	return s.repository.Update(token)
}

func (s *tokenService) Delete(id string) error {
	return s.repository.Delete(id)
}

func (s *tokenService) Verify(tokenString string) (*jwt.Token, error) {
	jwtToken, err := jwt.Parse(tokenString, func(jwtToken *jwt.Token) (interface{}, error) {
		if _, ok := jwtToken.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", jwtToken.Header["alg"])
		}
		return []byte(config.SECRET_KEY), nil
	})

	return jwtToken, err
}

func (s *tokenService) Invalid(user_id int64, tokenString string) error {
	err := s.repository.Invalid(user_id, tokenString)
	return err
}

func (s *tokenService) Generate(user_id int64, expire_at int64, role string) (string, error) {
	claims := jwt.MapClaims{}
	claims["authorized"] = true
	claims["sub"] = user_id
	claims["exp"] = expire_at
	claims["role"] = role
	at := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	token, err := at.SignedString([]byte(config.SECRET_KEY))

	return token, err
}

func (s *tokenService) GetJwtToken(tokenString string) (*jwt.Token, error) {
	jwtToken, err := jwt.Parse(tokenString, func(jwtToken *jwt.Token) (interface{}, error) {
		if _, ok := jwtToken.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", jwtToken.Header["alg"])
		}
		return []byte(config.SECRET_KEY), nil
	})
	return jwtToken, err
}

func (s *tokenService) ExtractTokenString(authorization string) string {
	strArr := strings.Split(authorization, " ")
	if len(strArr) == 2 {
		return strArr[1]
	}
	return ""
}

func (s *tokenService) VerifyTokenString(tokenString string) (*jwt.Token, error) {
	jwtToken, err := jwt.Parse(tokenString, func(jwtToken *jwt.Token) (interface{}, error) {
		if _, ok := jwtToken.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", jwtToken.Header["alg"])
		}
		return []byte(config.SECRET_KEY), nil
	})

	if err != nil {
		return nil, err
	}

	return jwtToken, nil
}

func (s *tokenService) ValidToken(jwtToken *jwt.Token) (bool, error) {
	if jwtToken == nil {
		return false, fmt.Errorf("no token")
	}
	return jwtToken.Valid, nil
}

func (s *tokenService) Refresh(refreshToken string) (*models.Token, error) {
	fmt.Println("refresh_token", refreshToken)

	jwtToken, err := jwt.Parse(refreshToken, func(jwtToken *jwt.Token) (interface{}, error) {
		if _, ok := jwtToken.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", jwtToken.Header["alg"])
		}
		return []byte(config.SECRET_KEY), nil
	})

	if err != nil {
		return nil, err
	}

	claims, ok := jwtToken.Claims.(jwt.MapClaims)
	if !ok || !jwtToken.Valid {
		return nil, errors.New("refresh token is invalid")
	}

	sub := claims["sub"].(int64)
	if err != nil {
		return nil, errors.New("wrong user")
	}

	role := claims["role"].(string)

	token, err := s.repository.FindByRefreshToken(sub, refreshToken)
	if err != nil {
		return nil, errors.New("wrong token")
	}

	expiredAt := time.Now().Add(time.Hour * 24 * 30)
	accessToken, err := s.repository.Generate(sub, expiredAt.Unix(), role)
	if err != nil {
		return nil, err
	}

	refreshExpiredAt := time.Now().Add(time.Hour * 24 * 90)
	refreshToken, err = s.repository.Generate(sub, refreshExpiredAt.Unix(), role)
	if err != nil {
		return nil, err
	}

	token.Token = accessToken
	token.EndingAt = expiredAt
	token.RefreshToken = refreshToken

	return s.repository.Update(token)
}