package com.gpaer.service.v3;

import org.apache.http.Header;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.CookieStore;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.conn.socket.LayeredConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.cookie.Cookie;
import org.apache.http.impl.client.BasicCookieStore;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.springframework.stereotype.Service;

import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URI;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by neo on 19/10/2017.
 * <p>
 * 模拟 CAS 登录目标客户端服务，返回对应的会话 ID 和 CAS TGC 票据
 * <p>
 * <不依赖任何自有类，独立文件>
 */
@Service
public class CASConnector {


 /**
 * @param username
 * @param password
 * @param redirectUrl 目标地址（可以为空）
 * @return
 * @throws Exception
 */
 public CASResult genLogin(String username, String password, String redirectUrl) throws Exception {
 // 创建客户端
 CookieStore httpCookieStore = new BasicCookieStore();
 CloseableHttpClient client = createHttpClientWithNoSsl(httpCookieStore);

/* 第一次请求[GET] 拉取流水号信息 */
 HttpGet request = new HttpGet("https://cas.sustc.edu.cn/cas/login?service=" + redirectUrl);
 HttpResponse response = client.execute(request);

Document htmlPage = Jsoup.parse(readResponse(response));
 Element form = htmlPage.select("#fm1").first();
 String execution = form.select("[name=execution]").first().val();
 String _eventId = "submit";
 String submit = "登录";

/* 第二次请求[POST] 发送表单验证信息 */
 HttpPost request2 = new HttpPost("https://cas.sustc.edu.cn/cas/login");
 List<NameValuePair> params = new ArrayList<NameValuePair>();
 params.add(new BasicNameValuePair("username", username));
 params.add(new BasicNameValuePair("password", password));
 params.add(new BasicNameValuePair("execution", execution));
 params.add(new BasicNameValuePair("_eventId", _eventId));
 params.add(new BasicNameValuePair("submit", submit));
 request2.setEntity(new UrlEncodedFormEntity(params));
 HttpResponse response2 = client.execute(request2);

Header headerSetCookie = response2.getFirstHeader("Set-Cookie");
 String TGC = headerSetCookie == null ? null : headerSetCookie.getValue().substring(4, headerSetCookie.getValue().indexOf(";")); // TGC
 Header headerLocation = response2.getFirstHeader("Location");
 String location = headerLocation == null ? null : headerLocation.getValue();

/* 第三次请求[GET]，前往 CAS 客户端进行验证获取会话 */
 HttpGet request3 = new HttpGet(location);
 HttpResponse response3 = client.execute(request3);

CASResult casResult = new CASResult();
 List<Cookie> cookies = httpCookieStore.getCookies();
 for (Cookie cookie : cookies) {
 if (cookie != null && cookie.getName().equals("TGC")) {
 casResult.setTGC(cookie.getValue());
 continue;
 }
 if (cookie != null && cookie.getName().equals("JSESSIONID")) {
 casResult.setJSESSIONID(cookie.getValue());
 continue;
 }
 }
 // set Uri (scheme, host, path, query..)
 casResult.setUri(request3.getURI());
 /* 第四次请求[GET]，获取目标页面内容 */
 /* 该获取移交由用户自行操作，不在此做多余请求 */

return casResult;
 }

/* 读取 response body 内容为字符串 */
 private String readResponse(HttpResponse response) throws IOException {
 BufferedReader in = new BufferedReader(
 new InputStreamReader(response.getEntity().getContent()));
 String result = new String();
 String line;
 while ((line = in.readLine()) != null) {
 result += line;
 }
 return result;
 }


 /**
 * 创建模拟客户端（针对 https 客户端禁用 SSL 验证）
 *
 * @param cookieStore 缓存的 Cookies 信息
 * @return
 * @throws Exception
 */
 private CloseableHttpClient createHttpClientWithNoSsl(CookieStore cookieStore) throws Exception {
 // Create a trust manager that does not validate certificate chains
 TrustManager[] trustAllCerts = new TrustManager[]{
 new X509TrustManager() {
 public X509Certificate[] getAcceptedIssuers() {
 return null;
 }

public void checkClientTrusted(X509Certificate[] certs, String authType) {
 // don't check
 }

public void checkServerTrusted(X509Certificate[] certs, String authType) {
 // don't check
 }
 }
 };

SSLContext ctx = SSLContext.getInstance("TLS");
 ctx.init(null, trustAllCerts, null);
 LayeredConnectionSocketFactory sslSocketFactory = new SSLConnectionSocketFactory(ctx);
 return HttpClients.custom()
 .setSSLSocketFactory(sslSocketFactory)
 .setDefaultCookieStore(cookieStore == null ? new BasicCookieStore() : cookieStore)
 .build();
 }

/**
 * 最终返回结果集
 */
 public class CASResult {
 /* 认证通过则返回 TGC，否则为空 */
 private String TGC;
 private String JSESSIONID; // 会话 ID
 private URI uri; // 包含 (scheme, host, path, query..)

public String getTGC() {
 return TGC;
 }

public void setTGC(String TGC) {
 this.TGC = TGC;
 }

public String getJSESSIONID() {
 return JSESSIONID;
 }

public void setJSESSIONID(String JSESSIONID) {
 this.JSESSIONID = JSESSIONID;
 }

public URI getUri() {
 return uri;
 }

public void setUri(URI uri) {
 this.uri = uri;
 }
 }
}