package utils

import (
	"encoding/json"
	"nCovTrack-Backend/global"
	"nCovTrack-Backend/models"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt/v4"
)

var JWT_KEY = []byte(global.ServerSettings.Jwt.Secret)

// GenerateToken Generate token for user
// Return: token generated
func GenerateToken(claims jwt.MapClaims) string {
	claims["exp"] = time.Now().Add(15 * 24 * time.Hour).Unix()
	claims["iat"] = time.Now().Unix()
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	tokenStr, err := token.SignedString(JWT_KEY)
	if err != nil {
		panic(err)
	}
	return tokenStr
}

// RenewToken Renew user's token
// tokenStr: user request token
// Return:
// 		BlankString: token is invalid or token is expired out of allowed time;
//		OldToken: token is not need to renew;
//		NewToken: token is renew;
func RenewToken(tokenStr string) string {
	token, err := jwt.Parse(tokenStr, func(t *jwt.Token) (interface{}, error) {
		return JWT_KEY, nil
	})

	// Token is invalid
	if err != nil {
		switch err.(*jwt.ValidationError).Errors {
		case jwt.ValidationErrorSignatureInvalid:
			return ""
		case jwt.ValidationErrorIssuedAt:
			return ""
		}
	}

	claims := token.Claims.(jwt.MapClaims)
	expireAt := time.Unix(int64(claims["exp"].(float64)), 0)
	expireDuration := expireAt.Sub(time.Now())

	// Token is out of allow expire duration
	if expireDuration.Hours() < -float64(global.ServerSettings.Jwt.RenewExpireDays*24) {
		return ""
	}
	// Token not need renew
	if expireDuration.Hours() > float64(global.ServerSettings.Jwt.RenewAheadDays*24) {
		return tokenStr
	}
	//fmt.Println(expireDuration)

	claims["exp"] = time.Now().Add(global.TOKEN_EXPIRE_DAYS * 24 * time.Hour).Unix()
	token = jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	tokenStr, err = token.SignedString(JWT_KEY)
	if err != nil {
		panic(err)
	}
	return tokenStr
}

func ParseClaims(tokenStr string) jwt.MapClaims {
	token, err := jwt.Parse(tokenStr, func(t *jwt.Token) (interface{}, error) {
		return JWT_KEY, nil
	})
	if err != nil {
		switch err.(*jwt.ValidationError).Errors {
		case jwt.ValidationErrorSignatureInvalid:
			return nil
		case jwt.ValidationErrorIssuedAt:
			return nil
		}
	}
	return token.Claims.(jwt.MapClaims)
}

func ClaimsFromHeader(c *gin.Context) models.TokenClaims {
	var claims models.TokenClaims
	json.Unmarshal([]byte(c.Request.Header.Get("claims")), &claims)
	return claims
}