package com.utils;

import org.apache.commons.codec.digest.DigestUtils;

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.util.*;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;


public class PayUtil {

 public static String exec(Map<String, String> map, String key, String gateway) {
 Map<String, String> sortedMap = sortMapByKey(map);
 String sign = getLinkToSign(sortedMap, key);
 String xml = mapToXml(sortedMap, sign);
 String result = PayUtil.httpRequest(gateway, "POST", xml);
 return result;
 }

 public static String getRandomStringByLength(int length) {
 String base = "abcdefghijklmnopqrstuvwxyz0123456789";
 Random random = new Random();
 StringBuilder stringBuilder = new StringBuilder();
 for (int i = 0; i < length; i++) {
 int number = random.nextInt(base.length());
 stringBuilder.append(base.charAt(number));
 }
 return stringBuilder.toString();
 }

 public static Map<String, String> xmlToMap(String strXML) throws Exception {
 Map<String, String> data = new HashMap<>();
 DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
 DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
 InputStream stream = new ByteArrayInputStream(strXML.getBytes(StandardCharsets.UTF_8));
 org.w3c.dom.Document doc = documentBuilder.parse(stream);
 doc.getDocumentElement().normalize();
 NodeList nodeList = doc.getDocumentElement().getChildNodes();
 for (int idx = 0; idx < nodeList.getLength(); ++idx) {
 Node node = nodeList.item(idx);
 if (node.getNodeType() == Node.ELEMENT_NODE) {
 org.w3c.dom.Element element = (org.w3c.dom.Element) node;
 data.put(element.getNodeName(), element.getTextContent());
 }
 }
 return data;
 }

 public static boolean verifySign(Map<String, String> map, String key){
 String sign = map.get("sign");
 map.remove("sign");
 Map<String, String> sortedMap = sortMapByKey(map);
 String xmlSign = getLinkToSign(sortedMap, key);
 return xmlSign.equals(sign);
 }

 public static String acceptXML(){
 return "<xml><return_code>SUCCESS</return_code></xml>";
 }


 private static String sign(String text, String key) {
 text = text + "key=" + key;
// System.out.println("Sign Url: " + text);
 return DigestUtils.md5Hex(getContentBytes(text)).toUpperCase();
 }


 private static byte[] getContentBytes(String content) {
 return content.getBytes(StandardCharsets.UTF_8);
 }


 private static String getLinkToSign(Map<String, String> map, String payKey) {
 StringBuilder preStr = new StringBuilder();
 for (Map.Entry<String, String> m : map.entrySet()) {
 String key = m.getKey();
 String value = m.getValue();
 preStr.append(key).append("=").append(value).append("&");
 }
 String link = preStr.toString();
 return sign(link, payKey);
 }

 private static String httpRequest(String requestUrl, String requestMethod, String outputStr) {
 StringBuilder stringBuilder = new StringBuilder();
 try {
 URL url = new URL(requestUrl);
 HttpURLConnection conn = (HttpURLConnection) url.openConnection();
 conn.setRequestMethod(requestMethod);
 conn.setDoOutput(true);
 conn.setDoInput(true);
 conn.connect();
 if (null != outputStr) {
 OutputStream os = conn.getOutputStream();
 os.write(outputStr.getBytes(StandardCharsets.UTF_8));
 os.close();
 }
 InputStream is = conn.getInputStream();
 InputStreamReader isr = new InputStreamReader(is, StandardCharsets.UTF_8);
 BufferedReader br = new BufferedReader(isr);
 String line;
 while ((line = br.readLine()) != null) {
 stringBuilder.append(line);
 }
 br.close();
 } catch (Exception e) {
 e.printStackTrace();
 }
 return stringBuilder.toString();
 }


 private static Map<String, String> sortMapByKey(Map<String, String> map) {
 List<String> keys = new ArrayList<>(map.keySet());
 Collections.sort(keys);
 // HashMap底层是数组加链表,会把key的值放在通过哈希算法散列后的对象的数组坐标上,
 // 所以取得的值是按哈希表来取的,所以和放入的顺序无关
 // 保持有序需要用LinkedHashMap
 Map<String, String> m = new LinkedHashMap<>();
 for (String key : keys) {
 m.put(key, map.get(key));
 }
 map.clear();
 return m;
 }

 private static String mapToXml(Map<String, String> map, String sign) {
 StringBuilder stringBuilder = new StringBuilder().append("<xml>");
 for (Map.Entry<String, String> m : map.entrySet()) {
 stringBuilder.append("<").append(m.getKey()).append(">")
 .append(m.getValue()).append("</").append(m.getKey()).append(">");
 }
 stringBuilder.append("<sign>").append(sign).append("</sign>").append("</xml>");
 return stringBuilder.toString();
 }

}