package utils

import (
	"errors"
	"os"
	"strconv"
	"strings"
	"time"

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

// JWTClaims represents the JWT claims structure
type JWTClaims struct {
	UserID uint   `json:"user_id"`
	Email  string `json:"email"`
	Role   string `json:"role"`
	jwt.RegisteredClaims
}

// GenerateJWT generates a new JWT token for the given user
func GenerateJWT(userID uint, email, role string) (string, error) {
	// Respect configurable expiration via JWT_EXPIRATION_HOURS; default 24h
	expHours := 24
	if v := os.Getenv("JWT_EXPIRATION_HOURS"); v != "" {
		if n, err := strconv.Atoi(v); err == nil && n > 0 && n <= 24*365 {
			expHours = n
		}
	}
	expirationTime := time.Now().Add(time.Duration(expHours) * time.Hour)

	claims := &JWTClaims{
		UserID: userID,
		Email:  email,
		Role:   role,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(expirationTime),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
			NotBefore: jwt.NewNumericDate(time.Now()),
			Issuer:    "fotbal-club",
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	tokenString, err := token.SignedString([]byte(GetJWTSecret()))
	if err != nil {
		return "", err
	}

	return tokenString, nil
}

// ParseJWT parses and validates a JWT token
func ParseJWT(tokenString string) (*JWTClaims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &JWTClaims{}, func(token *jwt.Token) (interface{}, error) {
		return []byte(GetJWTSecret()), nil
	})

	if err != nil {
		return nil, err
	}

	if claims, ok := token.Claims.(*JWTClaims); ok && token.Valid {
		return claims, nil
	}

	return nil, errors.New("invalid token")
}

// GetJWTSecret returns the JWT secret from environment variable or a default value
func GetJWTSecret() string {
	secret := os.Getenv("JWT_SECRET")
	if secret == "" {
		return "default-secret-key-change-in-production"
	}
	return secret
}

// GetUserFromContext gets the authenticated user from Gin context
func GetUserFromContext(c *gin.Context) (*JWTClaims, error) {
	// Preferred: claims set by auth middleware
	if v, ok := c.Get("claims"); ok {
		if cl, ok2 := v.(*JWTClaims); ok2 {
			return cl, nil
		}
	}
	// Fallback: parse Authorization header (Bearer <token>)
	authHeader := c.GetHeader("Authorization")
	if authHeader == "" {
		return nil, errors.New("authorization header missing")
	}
	parts := strings.Split(authHeader, " ")
	if len(parts) != 2 || parts[0] != "Bearer" {
		return nil, errors.New("invalid authorization header format")
	}
	token := parts[1]
	cl, err := ParseJWT(token)
	if err != nil {
		return nil, err
	}
	return cl, nil
}