/*
 * Copyright 1999-2018 Alibaba Group Holding Ltd.
 *
 * 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 com.alibaba.csp.sentinel.dashboard.auth;

import com.alibaba.csp.sentinel.dashboard.domain.Result;
import com.alibaba.fastjson.JSON;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.Method;

/**
 * The web interceptor for privilege-based authorization.
 *
 * @author lkxiaolou
 * @since 1.7.1
 */
@Component
public class AuthorizationInterceptor implements HandlerInterceptor {

	@Autowired
	private AuthService<HttpServletRequest> authService;

	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {
		if (handler.getClass().isAssignableFrom(HandlerMethod.class)) {
			Method method = ((HandlerMethod) handler).getMethod();

			AuthAction authAction = method.getAnnotation(AuthAction.class);
			if (authAction != null) {
				AuthService.AuthUser authUser = authService.getAuthUser(request);
				if (authUser == null) {
					responseNoPrivilegeMsg(response, authAction.message());
					return false;
				}
				String target = request.getParameter(authAction.targetName());

				if (!authUser.authTarget(target, authAction.value())) {
					responseNoPrivilegeMsg(response, authAction.message());
					return false;
				}
			}
		}

		return true;
	}

	private void responseNoPrivilegeMsg(HttpServletResponse response, String message) throws IOException {
		Result result = Result.ofFail(-1, message);
		response.addHeader("Content-Type", "application/json;charset=UTF-8");
		response.getOutputStream().write(JSON.toJSONBytes(result));
	}

}
