package services

import (
	"fmt"
	"time"

	"veza-backend-api/internal/models"

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

type JWTService struct {
	secretKey []byte
	issuer    string
	audience  string
	Config    *models.JWTConfig
}

func NewJWTService(secret, issuer, audience string) (*JWTService, error) {
	if secret == "" {
		return nil, fmt.Errorf("JWT secret is required")
	}
	// SEC-005: Enforce minimum secret length to prevent brute-force
	if len(secret) < 32 {
		return nil, fmt.Errorf("JWT secret must be at least 32 characters")
	}
	if issuer == "" {
		issuer = "veza-api"
	}
	if audience == "" {
		audience = "veza-app"
	}

	// Default config - SEC-006: Reduced TTLs for improved security
	config := &models.JWTConfig{
		AccessTokenTTL:            5 * time.Minute,
		RefreshTokenTTL:           14 * 24 * time.Hour,  // 14 days (was 30)
		RememberMeRefreshTokenTTL: 30 * 24 * time.Hour, // 30 days (was 90)
	}

	return &JWTService{
		secretKey: []byte(secret),
		issuer:    issuer,
		audience:  audience,
		Config:    config,
	}, nil
}

func (s *JWTService) GetConfig() *models.JWTConfig {
	return s.Config
}

func (s *JWTService) GenerateAccessToken(user *models.User) (string, error) {
	claims := models.CustomClaims{
		UserID:       user.ID,
		Email:        user.Email,
		Username:     user.Username,
		Role:         user.Role,
		TokenVersion: user.TokenVersion,
		TokenType:    "access",
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(s.Config.AccessTokenTTL)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
			Issuer:    s.issuer,
			Audience:  jwt.ClaimStrings{s.audience},
			ID:        uuid.NewString(),
		},
	}

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

func (s *JWTService) GenerateRefreshToken(user *models.User) (string, error) {
	claims := models.CustomClaims{
		UserID:       user.ID,
		TokenVersion: user.TokenVersion,
		IsRefresh:    true, // Mark as refresh token
		TokenType:    "refresh",
		TokenFamily:  uuid.NewString(), // Nouvelle famille de token
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(s.Config.RefreshTokenTTL)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
			Issuer:    s.issuer,
			Audience:  jwt.ClaimStrings{s.audience},
			ID:        uuid.NewString(),
		},
	}

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

// GenerateTokenPair génère une paire de tokens (access + refresh) en une seule opération
func (s *JWTService) GenerateTokenPair(user *models.User) (*models.TokenPair, error) {
	// Generate access token
	accessToken, err := s.GenerateAccessToken(user)
	if err != nil {
		return nil, fmt.Errorf("failed to generate access token: %w", err)
	}

	// Generate refresh token
	refreshToken, err := s.GenerateRefreshToken(user)
	if err != nil {
		return nil, fmt.Errorf("failed to generate refresh token: %w", err)
	}

	return &models.TokenPair{
		AccessToken:  accessToken,
		RefreshToken: refreshToken,
		ExpiresIn:    int(s.Config.AccessTokenTTL.Seconds()),
	}, nil
}

// VerifyToken valide et parse un token JWT
func (s *JWTService) VerifyToken(tokenString string) (*models.CustomClaims, error) {
	return s.ValidateToken(tokenString)
}

// ValidateToken valide un token JWT et retourne les claims
func (s *JWTService) ValidateToken(tokenString string) (*models.CustomClaims, error) {
	// Parse avec validation des claims standards (exp, iat, nbf) ET custom (iss, aud)
	token, err := jwt.ParseWithClaims(tokenString, &models.CustomClaims{}, func(token *jwt.Token) (interface{}, error) {
		// Validation stricte de l'algorithme (MOD-P2-002)
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
		}
		if token.Method.Alg() != "HS256" {
			return nil, fmt.Errorf("invalid signing algorithm: %v, expected HS256", token.Method.Alg())
		}
		return s.secretKey, nil
	},
		// Options de validation stricte
		jwt.WithIssuer(s.issuer),
		jwt.WithAudience(s.audience),
		jwt.WithExpirationRequired(),
	)

	if err != nil {
		return nil, fmt.Errorf("failed to parse token: %w", err)
	}

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

	return nil, fmt.Errorf("invalid token")
}

// ParseToken parse un token JWT sans validation complète (utilise ValidateToken)
func (s *JWTService) ParseToken(tokenString string) (*models.CustomClaims, error) {
	return s.ValidateToken(tokenString)
}

// ExtractClaims extrait les claims d'un token JWT
func (s *JWTService) ExtractClaims(tokenString string) (*models.CustomClaims, error) {
	return s.ValidateToken(tokenString)
}

// ExtractUserID extrait l'ID utilisateur depuis un token JWT
// MIGRATION UUID: retourne uuid.UUID au lieu de int64
func (s *JWTService) ExtractUserID(tokenString string) (uuid.UUID, error) {
	claims, err := s.ValidateToken(tokenString)
	if err != nil {
		return uuid.Nil, fmt.Errorf("failed to extract user ID: %w", err)
	}
	return claims.UserID, nil
}

// VerifyTokenVersion vérifie si la version du token correspond à celle de l'utilisateur
func (s *JWTService) VerifyTokenVersion(claims *models.CustomClaims, userTokenVersion int) error {
	if claims.TokenVersion != userTokenVersion {
		return fmt.Errorf("token version mismatch: token version %d does not match user version %d", claims.TokenVersion, userTokenVersion)
	}
	return nil
}

// GenerateStreamToken generates a short-lived JWT for HLS/WebSocket auth.
// Uses issuer "veza-platform" and audience "veza-services" for compatibility with stream server.
// TTL: 5 minutes. Claims match stream server Claims struct (sub, username, roles, etc.).
func (s *JWTService) GenerateStreamToken(user *models.User) (string, error) {
	ttl := 5 * time.Minute
	now := time.Now()
	role := mapUserRoleToStreamRole(user.Role)
	claims := jwt.MapClaims{
		"sub":         user.ID.String(),
		"user_id":     user.ID.String(), // Chat server expects user_id
		"username":    user.Username,
		"email":      user.Email,
		"roles":      []string{role},
		"permissions": []string{"StreamAudio"},
		"exp":       now.Add(ttl).Unix(),
		"iat":       now.Unix(),
		"iss":       "veza-platform",
		"aud":       "veza-services",
		"session_id": uuid.NewString(),
	}

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

func mapUserRoleToStreamRole(role string) string {
	switch role {
	case "admin":
		return "Admin"
	case "moderator":
		return "Moderator"
	case "premium":
		return "Premium"
	case "artist":
		return "Artist"
	case "guest":
		return "Guest"
	default:
		return "User"
	}
}