/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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 cn.exlive.exbooter.configure;

import com.google.common.collect.Sets;
import lombok.Getter;
import lombok.Setter;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang.StringUtils;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.web.ServerProperties;
import org.springframework.cloud.netflix.zuul.filters.SimpleRouteLocator;
import org.springframework.cloud.netflix.zuul.filters.ZuulProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.HashSet;
import java.util.Map;
import java.util.Optional;
import java.util.Set;

/**
 *
 * Http 代理， WebSocket 代理
 *
 * <pre>
 *
 * Created by zhenqin.
 * User: zhenqin
 * Date: 2022/4/25
 * Time: 下午7:08
 *
 * </pre>
 *
 * @author zhenqin
 */
@Slf4j
@Setter
@Getter
@Configuration
public class ApiGatewayConfig implements InitializingBean {

    @Autowired
    ApiRouteProperties apiRouteProperties;

    @Autowired
    ServerProperties serverProperties;

    @Autowired
    ZuulProperties zuulProperties;

    @Override
    public void afterPropertiesSet() throws Exception {
        final Map<String, ApiRoute> routers = apiRouteProperties.getRouters();
        final Set<String> ignoreUrlSet = new HashSet<>(); // 排除的 URL
        for (Map.Entry<String, ApiRoute> entry : routers.entrySet()) {
            if (entry.getValue() == null || StringUtils.isBlank(entry.getValue().getUrl())) {
                continue;
            }

            // 代理地址
            final String url = entry.getValue().getUrl();
            final String api = entry.getValue().getApi();

            // 代理路由
            String path = Optional.ofNullable(StringUtils.trimToNull(api)).orElse("/" + entry.getKey() + "/**");
            final ZuulProperties.ZuulRoute route = new ZuulProperties.ZuulRoute();
            route.setId(entry.getKey());
            route.setPath(path);
            route.setUrl(url);

            // WebSocket 的代理需要特殊处理
            if ("WS".equalsIgnoreCase(entry.getValue().getType())) {
                // websocket 是绝对路径，不需要做正则处理
                route.setPath(api);
                route.setUrl(url);
                log.info("add websocket router {}{} to path: {}", serverProperties.getServlet().getContextPath(), api, url);
                ignoreUrlSet.add(api);
            } else {
                // 返回拼接的地址
                String tmpUrl = apiRouteProperties.getServletPath().endsWith("/") ?
                        apiRouteProperties.getServletPath().substring(0, apiRouteProperties.getServletPath().length() - 1) + path
                        :
                        apiRouteProperties.getServletPath() + path;
                log.info("add router {}{} to path: {}", serverProperties.getServlet().getContextPath(), tmpUrl, url);
                zuulProperties.getRoutes().putIfAbsent(entry.getKey(), route);
            }
        }

        // 需要排除的 URL， 因为 WebSocket 连接地址 /api/live/ws 是包含在：/api/**， 因此需要排除
        zuulProperties.setIgnoredPatterns(Sets.newHashSet(ignoreUrlSet));
        // 初始化
        zuulProperties.init();
    }

    /**
     * 支持简单的负载均衡
     * @return
     */
    @Bean
    public SimpleRouteLocator simpleRouteLocator() {
        final ApiRouteLocator apiRouteLocator = new ApiRouteLocator(apiRouteProperties.getServletPath(), this.zuulProperties);
        apiRouteLocator.getIgnoredPaths();
        return apiRouteLocator;
    }
}