/*
 * Copyright (c) 2011-2020 Contributors to the Eclipse Foundation
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
 * which is available at https://www.apache.org/licenses/LICENSE-2.0.
 *
 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 */
package io.vertx.httpproxy.impl;

import java.net.ConnectException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.function.BiFunction;

import org.apache.commons.lang3.StringUtils;

import com.sf.vertx.api.pojo.DataSecurity;
import com.sf.vertx.security.MainSecurity;
import com.sf.vertx.service.impl.AppConfigServiceImpl;
import com.sf.vertx.utils.ProxyTool;

import io.vertx.circuitbreaker.CircuitBreaker;
import io.vertx.core.Future;
import io.vertx.core.Promise;
import io.vertx.core.buffer.Buffer;
import io.vertx.core.http.HttpClient;
import io.vertx.core.http.HttpClientRequest;
import io.vertx.core.http.HttpClientResponse;
import io.vertx.core.http.HttpHeaders;
import io.vertx.core.http.HttpMethod;
import io.vertx.core.http.HttpServerRequest;
import io.vertx.core.http.HttpServerResponse;
import io.vertx.core.json.JsonObject;
import io.vertx.core.net.NetSocket;
import io.vertx.core.net.SocketAddress;
import io.vertx.ext.web.RoutingContext;
import io.vertx.ext.web.client.WebClient;
import io.vertx.ext.web.handler.HttpException;
import io.vertx.httpproxy.Body;
import io.vertx.httpproxy.HttpProxy;
import io.vertx.httpproxy.ProxyContext;
import io.vertx.httpproxy.ProxyInterceptor;
import io.vertx.httpproxy.ProxyOptions;
import io.vertx.httpproxy.ProxyRequest;
import io.vertx.httpproxy.ProxyResponse;
import io.vertx.httpproxy.cache.CacheOptions;
import io.vertx.httpproxy.spi.cache.Cache;
import lombok.extern.slf4j.Slf4j;

@Slf4j
public class ReverseProxy implements HttpProxy {

	private final HttpClient client;
	private final boolean supportWebSocket;
	private BiFunction<HttpServerRequest, HttpClient, Future<HttpClientRequest>> selector = (req, client) -> Future
			.failedFuture("No origin available");
	private final List<ProxyInterceptor> interceptors = new ArrayList<>();
	private RoutingContext ctx;
	private CircuitBreaker breaker;
	private WebClient mainWebClient;

	public ReverseProxy(ProxyOptions options, HttpClient client) {
		CacheOptions cacheOptions = options.getCacheOptions();
		if (cacheOptions != null) {
			Cache<String, Resource> cache = cacheOptions.newCache();
			addInterceptor(new CachingFilter(cache));
		}
		this.client = client;
		this.supportWebSocket = options.getSupportWebSocket();
	}

	@Override
	public HttpProxy originRequestProvider(
			BiFunction<HttpServerRequest, HttpClient, Future<HttpClientRequest>> provider) {
		selector = provider;
		return this;
	}

	@Override
	public HttpProxy addInterceptor(ProxyInterceptor interceptor) {
		interceptors.add(interceptor);
		return this;
	}

	@Override
	public void handle(WebClient mainWebClient, RoutingContext ctx, CircuitBreaker breaker) {
		// TODO 改造了这个地方
		this.ctx = ctx;
		this.breaker = breaker;
		this.mainWebClient = mainWebClient;
		handle(ctx.request());
	}

	@Override
	public void handle(HttpServerRequest request) {
		ProxyRequest proxyRequest = ProxyRequest.reverseProxy(request);

		// Encoding sanity check
		Boolean chunked = HttpUtils.isChunked(request.headers());
		if (chunked == null) {
			end(proxyRequest, 400);
			return;
		}

		// WebSocket upgrade tunneling
		if (supportWebSocket && io.vertx.core.http.impl.HttpUtils.canUpgradeToWebSocket(request)) {
			handleWebSocketUpgrade(proxyRequest);
			return;
		}

		Proxy proxy = new Proxy(proxyRequest);
		proxy.filters = interceptors.listIterator();
		proxy.sendRequest().compose(proxy::sendProxyResponse);
	}

	private void handleWebSocketUpgrade(ProxyRequest proxyRequest) {
		HttpServerRequest proxiedRequest = proxyRequest.proxiedRequest();
		resolveOrigin(proxiedRequest).onComplete(ar -> {
			if (ar.succeeded()) {
				HttpClientRequest request = ar.result();
				request.setMethod(HttpMethod.GET);
				request.setURI(proxiedRequest.uri());
				request.headers().addAll(proxiedRequest.headers());
				Future<HttpClientResponse> fut2 = request.connect();
				proxiedRequest.handler(request::write);
				proxiedRequest.endHandler(v -> request.end());
				proxiedRequest.resume();
				fut2.onComplete(ar2 -> {
					if (ar2.succeeded()) {
						HttpClientResponse proxiedResponse = ar2.result();
						if (proxiedResponse.statusCode() == 101) {
							HttpServerResponse response = proxiedRequest.response();
							response.setStatusCode(101);
							response.headers().addAll(proxiedResponse.headers());
							Future<NetSocket> otherso = proxiedRequest.toNetSocket();
							otherso.onComplete(ar3 -> {
								if (ar3.succeeded()) {
									NetSocket responseSocket = ar3.result();
									NetSocket proxyResponseSocket = proxiedResponse.netSocket();
									responseSocket.handler(proxyResponseSocket::write);
									proxyResponseSocket.handler(responseSocket::write);
									responseSocket.closeHandler(v -> proxyResponseSocket.close());
									proxyResponseSocket.closeHandler(v -> responseSocket.close());
								} else {
									// Find reproducer
									System.err.println("Handle this case");
									ar3.cause().printStackTrace();
								}
							});
						} else {
							// Rejection
							proxiedRequest.resume();
							end(proxyRequest, proxiedResponse.statusCode());
						}
					} else {
						proxiedRequest.resume();
						end(proxyRequest, 502);
					}
				});
			} else {
				proxiedRequest.resume();
				end(proxyRequest, 502);
			}
		});
	}

	/***
	 * 返回错误
	 * 
	 * @param proxyRequest
	 * @param sc
	 */
	private void end(ProxyRequest proxyRequest, int sc) {
		// TODO 处理反向代理返回结果
		if (ProxyTool._ERROR.containsKey(sc)) {
			Buffer buffer = Buffer.buffer(ProxyTool._ERROR.get(sc));
			proxyRequest.response().release().setStatusCode(sc).putHeader("content-type", "application/json")
					.putHeader(HttpHeaders.CONTENT_LENGTH, String.valueOf(buffer.length())).setBody(Body.body(buffer))
					.send();
		} else {
//			proxyRequest.response().release().setStatusCode(sc).putHeader(HttpHeaders.CONTENT_LENGTH, "0").setBody(null)
//					.send();
			Buffer buffer = Buffer.buffer(ProxyTool.DEFAULT_ERROR_MSG);
			proxyRequest.response().release().setStatusCode(sc).putHeader("content-type", "application/json")
					.putHeader(HttpHeaders.CONTENT_LENGTH, String.valueOf(ProxyTool.DEFAULT_ERROR_MSG.length()))
					.setBody(Body.body(buffer)).send();
		}
	}

	private Future<HttpClientRequest> resolveOrigin(HttpServerRequest proxiedRequest) {
		return selector.apply(proxiedRequest, client);
	}

	private class Proxy implements ProxyContext {

		private final ProxyRequest request;
		private ProxyResponse response;
		private final Map<String, Object> attachments = new HashMap<>();
		private ListIterator<ProxyInterceptor> filters;

		private Proxy(ProxyRequest request) {
			this.request = request;
		}

		@Override
		public void set(String name, Object value) {
			attachments.put(name, value);
		}

		@Override
		public <T> T get(String name, Class<T> type) {
			Object o = attachments.get(name);
			return type.isInstance(o) ? type.cast(o) : null;
		}

		@Override
		public ProxyRequest request() {
			return request;
		}

		@Override
		public Future<ProxyResponse> sendRequest() {
			if (filters.hasNext()) {
				ProxyInterceptor next = filters.next();
				return next.handleProxyRequest(this);
			} else {
				return sendProxyRequest(request);
			}
		}

		@Override
		public ProxyResponse response() {
			return response;
		}

		@Override
		public Future<Void> sendResponse() {
			if (filters.hasPrevious()) {
				ProxyInterceptor filter = filters.previous();
				return filter.handleProxyResponse(this);
			} else {
				return response.send();
			}
		}

		private Future<ProxyResponse> sendProxyRequest(ProxyRequest proxyRequest) {
			// TODO 服务熔断策略, 如果已经熔断,将剔除负载均衡策略
			// 发起一个请求
			String sacAppHeaderKey = proxyRequest.headers().get(AppConfigServiceImpl.getSacAppHeaderKey());
			if (StringUtils.isNotBlank(sacAppHeaderKey) && AppConfigServiceImpl.appDataSecurity(sacAppHeaderKey)) {
				return Future.future(p -> {
					breaker.executeWithFallback(promise -> {
						SocketAddress socketAddress = ProxyTool.resolveOriginAddress(proxyRequest.proxiedRequest());
						mainWebClient.post(socketAddress.port(), socketAddress.host(), proxyRequest.getURI())
								.putHeaders(proxyRequest.headers())
								.sendJson(bodyDecrypt(ctx.getBodyAsString(), sacAppHeaderKey), h -> {
									if (h.succeeded()) {
										log.info("begin date:{}", System.currentTimeMillis());
										// 释放资源
										proxyRequest.release();
										JsonObject responseData = h.result().bodyAsJsonObject();
										log.info("responseData:{}", responseData);
										// 加密
										String dataStr = bodyEncrypt(responseData.toString(), sacAppHeaderKey);
										log.info("aesEncrypt dataStr:{}", dataStr);
										Buffer buffer = Buffer.buffer(dataStr);
										ProxyResponse proxyResponse = proxyRequest.response().setStatusCode(200)
												.putHeader("content-type", "application/json")
												.setBody(Body.body(buffer));
										p.complete(proxyResponse);
										promise.complete("1");
										log.info("end date:{}", System.currentTimeMillis());
									} else {
										log.info("error: {}", h.cause());
										promise.fail("2");
									}
								});
					}, v -> {
						// Executed when the circuit is opened
						log.info("Executed when the circuit is opened:{}", v);
						return "3";
					}, ar -> {
						// Do something with the result
						log.info("failed:{}, Result:{}", ar.failed(), ar.result());
						if (StringUtils.equals(ar.result(), "1") == false) {
							end(proxyRequest, 502);
						}
					});
				});
			} else {
				Future<HttpClientRequest> f = resolveOrigin(proxyRequest.proxiedRequest());
				f.onFailure(err -> {
					log.info("error:{}", err);
					if (err instanceof ConnectException) {
						// TODO 配置重试策略
						// Connection refused: /127.0.0.1:9199
						log.info("connection url is error:{}", err.getMessage());
					}
					// Should this be done here ? I don't think so
					HttpServerRequest proxiedRequest = proxyRequest.proxiedRequest();
					proxiedRequest.resume();
					Promise<Void> promise = Promise.promise();
					proxiedRequest.exceptionHandler(promise::tryFail);
					proxiedRequest.endHandler(promise::tryComplete);
					promise.future().onComplete(ar2 -> {
						end(proxyRequest, 502);
					});
				});

				return f.compose(a -> sendProxyRequest(proxyRequest, a));
			}

		}

		private Future<ProxyResponse> sendProxyRequest(ProxyRequest proxyRequest, HttpClientRequest request) {
			Future<ProxyResponse> fut = proxyRequest.send(request);
			fut.onFailure(err -> {
				proxyRequest.proxiedRequest().response().setStatusCode(502).end();
			});
			return fut;
		}

		private Future<Void> sendProxyResponse(ProxyResponse response) {

			this.response = response;

			// Check validity
			Boolean chunked = HttpUtils.isChunked(response.headers());
			if (chunked == null) {
				// response.request().release(); // Is it needed ???
				end(response.request(), 501);
				return Future.succeededFuture(); // should use END future here ???
			}

			return sendResponse();
		}

		private String bodyEncrypt(String body, String sacAppHeaderKey) {
			DataSecurity dataSecurity = AppConfigServiceImpl.getAppConfig(sacAppHeaderKey).getDataSecurity();
			switch (dataSecurity.getAlgorithm()) {
			case "AES":
				return MainSecurity.aesEncrypt(body, dataSecurity.getPrivateKey());
			default:
				break;
			}
			log.info(" appcode:{}, encrypt key config is error.", sacAppHeaderKey);
			throw new HttpException(10001);
		}

		private String bodyDecrypt(String body, String sacAppHeaderKey) {
			DataSecurity dataSecurity = AppConfigServiceImpl.getAppConfig(sacAppHeaderKey).getDataSecurity();
			switch (dataSecurity.getAlgorithm()) {
			case "AES":
				return MainSecurity.aesDecrypt(body, dataSecurity.getPrivateKey());
			default:
				break;
			}
			log.info(" appcode:{}, decrypt key config is error.", sacAppHeaderKey);
			throw new HttpException(10001);
		}
	}
}