import org.json.simple.JSONObject;

import org.json.simple.parser.JSONParser;

import org.json.simple.parser.ParseException;

import java.io.*;

import java.net.HttpURLConnection;

import java.net.MalformedURLException;

import java.net.ProtocolException;

import java.net.URL;

import java.util.Map;

public class API {

private static API instance=new API();

private API(){}

public static API getInstance(){

if(instance == null) instance = new API();

return instance;

}

public JSONObject callAPI(String strUrl, String method, Map<String,String> header, Map<String,String> body) throws MalformedURLException {

URL url;

HttpURLConnection con;

try {

url = new URL(strUrl);

con = (HttpURLConnection) url.openConnection();

con.setRequestMethod(method);

if(header!=null) {

header.entrySet().stream().forEach(e->con.setRequestProperty(e.getKey(),e.getValue()));

}

con.setDoOutput(true);

con.setDoInput(true);

if(body!=null) {

JSONObject params = new JSONObject();

body.entrySet().forEach(e->{

params.put(e.getKey(),e.getValue());

});

OutputStreamWriter wr = new OutputStreamWriter(con.getOutputStream(), "UTF-8");

wr.write(params.toString());

wr.flush();

}

int responseCode=con.getResponseCode();

if(responseCode==HttpURLConnection.HTTP_OK){

BufferedReader br=new BufferedReader(new InputStreamReader(con.getInputStream()));

StringBuilder sb = new StringBuilder();

String line = "";

while ((line = br.readLine()) != null) {

sb.append(line);

}

JSONObject responseJson = new JSONObject();

JSONParser jsonParser=new JSONParser();

responseJson=(JSONObject) jsonParser.parse(sb.toString());

con.disconnect();

return responseJson;

}

else{

con.disconnect();

System.out.println("Error Code : "+responseCode);

}

} catch (ProtocolException e) {

e.printStackTrace();

} catch (UnsupportedEncodingException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

} catch (ParseException e) {

e.printStackTrace();

}

return null;

}

}