package auth

import (
	"fmt"
	"time"

	"github.com/golang-jwt/jwt/v5"
	"golang.org/x/crypto/bcrypt"
)

// Claims holds the JWT payload.
type Claims struct {
	Username string `json:"username"`
	Role     string `json:"role"`
	jwt.RegisteredClaims
}

// GenerateJWT creates a JWT token valid for 24h.
func GenerateJWT(secret string, userID int64, username, role string) (string, error) {
	claims := Claims{
		Username: username,
		Role:     role,
		RegisteredClaims: jwt.RegisteredClaims{
			Subject:   fmt.Sprintf("%d", userID),
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(24 * time.Hour)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
		},
	}
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString([]byte(secret))
}

// ParseJWT verifies the token and returns claims.
func ParseJWT(secret, tokenStr string) (*Claims, error) {
	token, err := jwt.ParseWithClaims(tokenStr, &Claims{}, func(t *jwt.Token) (interface{}, error) {
		if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", t.Header["alg"])
		}
		return []byte(secret), nil
	})
	if err != nil {
		return nil, err
	}
	claims, ok := token.Claims.(*Claims)
	if !ok || !token.Valid {
		return nil, fmt.Errorf("invalid token")
	}
	return claims, nil
}

// VerifyPassword compares a plain-text password against a bcrypt hash.
func VerifyPassword(hash, password string) error {
	return bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
}

// HashPassword generates a bcrypt hash from the given password.
func HashPassword(password string) (string, error) {
	b, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	return string(b), err
}