package auth

import (
	"errors"
	"time"

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

type Claims struct {
	UserID string `json:"user_id"`
	Role   string `json:"role"`
	jwt.RegisteredClaims
}

type PurposeClaims struct {
	UserID  string `json:"user_id"`
	Purpose string `json:"purpose"`
	jwt.RegisteredClaims
}

func GenerateJWT(userID, role string, secret []byte) (string, error) {
	claims := Claims{
		UserID: userID,
		Role:   role,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(15 * time.Minute)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString(secret)
}

func GeneratePurposeJWT(userID, purpose string, secret []byte, ttl time.Duration) (string, error) {
	claims := PurposeClaims{
		UserID:  userID,
		Purpose: purpose,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(ttl)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString(secret)
}

func ValidateJWT(tokenStr string, secret []byte) (*Claims, error) {
	token, err := jwt.ParseWithClaims(tokenStr, &Claims{}, func(token *jwt.Token) (interface{}, error) {
		if token.Method != jwt.SigningMethodHS256 {
			return nil, errors.New("unexpected signing method")
		}
		return secret, nil
	})
	if err != nil {
		return nil, err
	}

	claims, ok := token.Claims.(*Claims)
	if !ok || !token.Valid {
		return nil, errors.New("invalid token")
	}

	return claims, nil
}

func ValidatePurposeJWT(tokenStr, expectedPurpose string, secret []byte) (*PurposeClaims, error) {
	token, err := jwt.ParseWithClaims(tokenStr, &PurposeClaims{}, func(token *jwt.Token) (interface{}, error) {
		if token.Method != jwt.SigningMethodHS256 {
			return nil, errors.New("unexpected signing method")
		}
		return secret, nil
	})
	if err != nil {
		return nil, err
	}

	claims, ok := token.Claims.(*PurposeClaims)
	if !ok || !token.Valid {
		return nil, errors.New("invalid token")
	}
	if claims.Purpose != expectedPurpose {
		return nil, errors.New("invalid token purpose")
	}

	return claims, nil
}