photoplaces/backend/internal/middleware/auth.go

package middleware

import (
	"context"
	"encoding/json"
	"net/http"
	"strings"

	"github.com/photoplaces/backend/internal/services"
)

type contextKey string

const (
	UserIDKey contextKey = "user_id"
	UserRoleKey contextKey = "user_role"
)

func AuthMiddleware(authSvc *services.AuthService) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			authHeader := r.Header.Get("Authorization")
			if authHeader == "" {
				writeAuthError(w, "missing authorization header")
				return
			}

			parts := strings.SplitN(authHeader, " ", 2)
			if len(parts) != 2 || parts[0] != "Bearer" {
				writeAuthError(w, "invalid authorization format")
				return
			}

			claims, err := authSvc.ValidateAccessToken(parts[1])
			if err != nil {
				writeAuthError(w, "invalid or expired token")
				return
			}

			ctx := context.WithValue(r.Context(), UserIDKey, claims.UserID)
			ctx = context.WithValue(ctx, UserRoleKey, claims.Role)
			next.ServeHTTP(w, r.WithContext(ctx))
		})
	}
}

func RoleMiddleware(roles ...string) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			role := r.Context().Value(UserRoleKey).(string)
			for _, allowed := range roles {
				if role == allowed {
					next.ServeHTTP(w, r)
					return
				}
			}
			writeAuthError(w, "insufficient permissions")
		})
	}
}

func GetUserID(ctx context.Context) string {
	v, _ := ctx.Value(UserIDKey).(string)
	return v
}

func GetUserRole(ctx context.Context) string {
	v, _ := ctx.Value(UserRoleKey).(string)
	return v
}

func writeAuthError(w http.ResponseWriter, msg string) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusUnauthorized)
	json.NewEncoder(w).Encode(map[string]string{"error": msg})
}