package auth

import (
	"errors"
	"time"

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

// HashPassword bcrypt 哈希
func HashPassword(password string) (string, error) {
	b, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	if err != nil {
		return "", err
	}
	return string(b), nil
}

// VerifyPassword 校验密码
func VerifyPassword(password, hashed string) bool {
	return bcrypt.CompareHashAndPassword([]byte(hashed), []byte(password)) == nil
}

// CreateToken 签发 JWT（HS256），payload 对齐 Python：sub/role/iat/exp
func CreateToken(username, role, secret string, expireMin int) (string, error) {
	now := time.Now()
	claims := jwt.MapClaims{
		"sub":  username,
		"role": role,
		"iat":  now.Unix(),
		"exp":  now.Add(time.Duration(expireMin) * time.Minute).Unix(),
	}
	return jwt.NewWithClaims(jwt.SigningMethodHS256, claims).SignedString([]byte(secret))
}

// SignClaims 通用 JWT 签发（考试会话等复用）
func SignClaims(claims jwt.MapClaims, secret string) (string, error) {
	return jwt.NewWithClaims(jwt.SigningMethodHS256, claims).SignedString([]byte(secret))
}

// ParseToken 校验 JWT，返回 claims。失败返回 error。
func ParseToken(tokenStr, secret string) (jwt.MapClaims, error) {
	token, err := jwt.Parse(tokenStr, func(t *jwt.Token) (any, error) {
		if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, jwt.ErrSignatureInvalid
		}
		return []byte(secret), nil
	})
	if err != nil {
		return nil, err
	}
	claims, ok := token.Claims.(jwt.MapClaims)
	if !ok || !token.Valid {
		return nil, errors.New("invalid token claims")
	}
	return claims, nil
}