/*
 * Copyright 2024 Jonas Kaninda
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package middlewares

import (
	"fmt"
	"github.com/jkaninda/goma-gateway/pkg/logger"
	"net/http"
	"regexp"
)

// BlockExploitsMiddleware Middleware to block common exploits
func BlockExploitsMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Patterns to detect SQL injection attempts
		sqlInjectionPattern := regexp.MustCompile(sqlPatterns)

		// Pattern to detect path traversal attempts
		pathTraversalPattern := regexp.MustCompile(traversalPatterns)

		// Pattern to detect simple XSS attempts
		xssPattern := regexp.MustCompile(xssPatterns)

		// Check query strings
		if sqlInjectionPattern.MatchString(r.URL.RawQuery) ||
			pathTraversalPattern.MatchString(r.URL.Path) ||
			xssPattern.MatchString(r.URL.RawQuery) {
			logger.Error("%s: %s Forbidden - Potential exploit detected", getRealIP(r), r.URL.Path)
			RespondWithError(w, http.StatusForbidden, fmt.Sprintf("%d Forbidden", http.StatusForbidden))
			return

		}
		// Check form data (for POST requests)
		if r.Method == http.MethodPost {
			if err := r.ParseForm(); err == nil {
				for _, values := range r.Form {
					for _, value := range values {
						if sqlInjectionPattern.MatchString(value) || xssPattern.MatchString(value) {
							logger.Error("%s: %s %s Forbidden - Potential exploit detected", getRealIP(r), r.Method, r.URL.Path)
							RespondWithError(w, http.StatusForbidden, fmt.Sprintf("%d Forbidden", http.StatusForbidden))
							return
						}
					}
				}
			}
		}

		// Pass to the next handler if no exploit patterns were detected
		next.ServeHTTP(w, r)
	})
}