package com.ssc.eam.api;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Base64;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Client {
	
	public static void main(String[] args) throws Exception {
		
		String hostname            = "api.statestreet.com";
		String exampleClientId     = "example_id";
		String exampleClientSecret = "example_secret";
		
		String tokenUrl = "https://" + hostname + "/oauth/accesstoken";
		String apiUrl = "https://" + hostname + "/sampleTransactions/v1/transactions";
		
		String token = getAccessToken(tokenUrl, exampleClientId, exampleClientSecret);
		System.out.println("API Response: " + getAPIResponse(apiUrl, token));
		
	}
	
	private static String getAccessToken(String tokenUrl, String key, String secret) throws Exception{

	    String accessToken = "";
	    
    	URL url = new URL(tokenUrl);
    	HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("POST");
        connection.setDoOutput(true);
	    String authentication = Base64.getEncoder().encodeToString((key + ":" + secret).getBytes());
        connection.setRequestProperty("Authorization", "Basic " + authentication);
        connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
        connection.setRequestProperty("Accept", "application/json");
        
        PrintStream os = new PrintStream(connection.getOutputStream());
        os.print("grant_type=client_credentials");
        os.close();
        
        int responseCode = connection.getResponseCode();
        StringBuffer response = new StringBuffer();
        if (responseCode == HttpURLConnection.HTTP_OK) { //success
        	response = getHttpResponse (connection.getInputStream());
			//log response
    		Pattern pat = Pattern.compile(".*\"access_token\"\\s*:\\s*\"([^\"]+)\".*");
            Matcher matcher = pat.matcher(response.toString());
            if (matcher.matches() && matcher.groupCount() > 0) {
            	accessToken = matcher.group(1);
            }
        	
        } else {
        	response = getHttpResponse (connection.getErrorStream());
			//log response
        	throw new Exception ("Authentication Failed.");
        }        
        connection.disconnect();
	    return accessToken;
	}

	
	 private static String getAPIResponse(String url,String authToken) throws Exception{	
		 	StringBuffer response = new StringBuffer();
	        URL obj = new URL(url);
	        String authHeaderValue = "Bearer " + authToken;

	        HttpURLConnection connection = (HttpURLConnection) obj.openConnection();
	        connection.setRequestMethod("GET");
	        connection.setRequestProperty("Authorization", authHeaderValue);
	        connection.setRequestProperty("Accept", "application/json");
	        connection.setRequestProperty("Content-type", "application/x-www-form-urlencoded");
	        connection.setRequestProperty("User-Agent", "Java Client");
	        int responseCode = connection.getResponseCode();

	        if (responseCode == HttpURLConnection.HTTP_OK) { //success
	        	response = getHttpResponse (connection.getInputStream());
	        } else {
	        	response = getHttpResponse (connection.getErrorStream());
	        }
	        connection.disconnect();
	        return response.toString();
	    }
	 	
	 	private static StringBuffer getHttpResponse(InputStream in) throws IOException{
	 		StringBuffer response = new StringBuffer();
        	BufferedReader bfr = new BufferedReader(new InputStreamReader(in));
            String inputLine;
            while ((inputLine = bfr.readLine()) != null) {
                response.append(inputLine);
            }
            bfr.close();
            return response;
	 	}
	 

}