package core

import (
	"github.com/golang-jwt/jwt/v5"
	"go-nkode/util"
	"log"
	"os"
	"time"
)

type AuthenticationTokens struct {
	AccessToken  string `json:"access_token"`
	RefreshToken string `json:"refresh_token"`
}

type ResetNKodeClaims struct {
	Reset bool `json:"reset"`
	jwt.RegisteredClaims
}

const (
	accessTokenExp     = 5 * time.Minute
	refreshTokenExp    = 30 * 24 * time.Hour
	resetNKodeTokenExp = 5 * time.Minute
)

var secret = getJwtSecret()

func getJwtSecret() []byte {
	jwtSecret := os.Getenv("JWT_SECRET")
	if jwtSecret == "" {
		log.Fatal("No JWT_SECRET found")
	}

	jwtBytes, err := util.ParseHexString(jwtSecret)
	if err != nil {
		log.Fatalf("error parsing jwt secret %v", err)
	}
	return jwtBytes
}

func NewAuthenticationTokens(username string, customerId CustomerId) (AuthenticationTokens, error) {
	accessClaims := NewAccessClaim(username, customerId)

	refreshClaims := jwt.RegisteredClaims{
		Subject:   username,
		Issuer:    CustomerIdToString(customerId),
		ExpiresAt: jwt.NewNumericDate(time.Now().Add(refreshTokenExp)),
	}

	accessJwt, err := EncodeAndSignClaims(accessClaims)
	if err != nil {
		return AuthenticationTokens{}, err
	}
	refreshJwt, err := EncodeAndSignClaims(refreshClaims)

	if err != nil {
		return AuthenticationTokens{}, err
	}
	return AuthenticationTokens{
		AccessToken:  accessJwt,
		RefreshToken: refreshJwt,
	}, nil
}

func NewAccessClaim(username string, customerId CustomerId) jwt.RegisteredClaims {
	return jwt.RegisteredClaims{
		Subject:   username,
		Issuer:    CustomerIdToString(customerId),
		ExpiresAt: jwt.NewNumericDate(time.Now().Add(accessTokenExp)),
	}
}

func EncodeAndSignClaims(claims jwt.Claims) (string, error) {
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString(secret)
}

func ParseRegisteredClaimToken(token string) (*jwt.RegisteredClaims, error) {
	return parseJwt[*jwt.RegisteredClaims](token, &jwt.RegisteredClaims{})
}

func ParseRestNKodeToken(resetNKodeToken string) (*ResetNKodeClaims, error) {
	return parseJwt[*ResetNKodeClaims](resetNKodeToken, &ResetNKodeClaims{})
}

func parseJwt[T *ResetNKodeClaims | *jwt.RegisteredClaims](tokenStr string, claim jwt.Claims) (T, error) {
	token, err := jwt.ParseWithClaims(tokenStr, claim, func(token *jwt.Token) (interface{}, error) {
		return secret, nil
	})
	if err != nil {
		log.Printf("error parsing refresh token: %v", err)
		return nil, ErrInvalidJwt
	}
	claims, ok := token.Claims.(T)
	if !ok {
		return nil, ErrInvalidJwt
	}
	return claims, nil
}

func ClaimExpired(claims jwt.RegisteredClaims) error {
	if claims.ExpiresAt == nil {
		return ErrClaimExpOrNil
	}
	if claims.ExpiresAt.Time.After(time.Now()) {
		return nil
	}
	return ErrClaimExpOrNil
}

func ResetNKodeToken(userEmail UserEmail, customerId CustomerId) (string, error) {
	resetClaims := ResetNKodeClaims{
		true,
		jwt.RegisteredClaims{
			Subject:   string(userEmail),
			Issuer:    CustomerIdToString(customerId),
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(resetNKodeTokenExp)),
		},
	}
	return EncodeAndSignClaims(resetClaims)
}