import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.NoSuchElementException;
import java.util.StringTokenizer;

/**
 * Example datafeed receiver.
 *
 * This is a functional example program that accepts real-time porting
 * changes from Paradigm.One. Porting changes are transmitted via a simple
 * text-based protocol over TCP/IP. Although any port can be used, port
 * 5000 is the default.
 * <p/>
 * Porting changes are transmitted from Paradigm.One's datafeed server
 * (referred to as the DatafeedSender) to the datafeed receiver (referred
 * to as the DatafeedReceiver).
 * <p/>
 * The DatafeedSender is responsible for maintaining the connection to the
 * DatafeedReceiver.
 * <p/>
 * Once the DatafeedSender has connected to the DatafeedReceiver, it will
 * start sending porting changes one at a time. Each porting change is line
 * of text terminated by a linefeed character. Once the DatafeedReceiver
 * has processed the porting change, it should send back an
 * acknowledgement. An acknowledgement is a line of text consisting of "OK"
 * (without the double quotes) followed by a linefeed character. On
 * receiving the acknowledgement the DatafeedSender sends the next porting
 * change. If no acknowledgement is received for whatever reason the
 * DatafeedSender will retry until an acknowledgement is received (in other
 * words, the delivery of porting changes is guaranteed).
 * <p/>
 * Each porting change consists of 3 fields separated by a pipe (|) symbol,
 * for example 0408975099|1411|20170518134525. The fields are:
 * <ul>
 * <li>Mobile Number: the number being ported</li>
 * <li>CAC: the carrier access code</li>
 * <li>Timestamp: the date and time the porting event was generated. The timestamp format is YYYYMMDDHHMISS (24-hour notation), e.g. "20170518134525". The timestamp is in AEST.</li>
 * </ul>
 *
 * (c) 2017 Paradigm One Pty Ltd.
 */
public class DatafeedReceiver {

    // Default port
    private int port = 5000;

    // The server socket
    private ServerSocket server = null;

    /**
     * Receives porting changes.
     */
    public void receive() throws IOException {

        try {
            // Create the server socket
            server = new ServerSocket(port);

            // Main loop
            System.out.println("DatafeedReceiver started on port " + port + "...");
            Socket client = null;
            while (true) {
                try {
                    client = server.accept();

                    // See who the connection is from
                    InetAddress inetAddress = client.getInetAddress();
                    System.out.println("Accepted connection from " + inetAddress.getHostAddress() + " (" + inetAddress.getHostName() + ")...");

                    // Receive the porting changes one at a time
                    receiveChanges(client);

                    System.out.println("Waiting for connection...");

                } finally {
                    if (client != null) {
                        client.close();
                        client = null;
                    }
                }
            }
        } finally {
            if (server != null) {
                server.close();
            }
        }
    }

    /**
     * Receives porting changes one at a time.
     */
    private void receiveChanges(Socket socket) throws IOException {

        BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        OutputStream out = socket.getOutputStream();

        String change;
        while ((change = in.readLine()) != null) {

            // Received a porting change
            System.out.println("Received porting change: " + change);

            // Parse the porting change into individual fields
            String mobileNumber = null;
            String cac          = null;
            String timestamp    = null;
            try {
                StringTokenizer strTok = new StringTokenizer(change, "|");
                mobileNumber = strTok.nextToken();
                cac          = strTok.nextToken();
                timestamp    = strTok.nextToken();
            } catch (NoSuchElementException e) {
                // Format not correct, but in this example continue anyway
            }
            System.out.println("Mobile Number : " + mobileNumber);
            System.out.println("CAC           : " + cac);
            System.out.println("Timestamp     : " + timestamp);

            // Acknowledge the porting change so the DatafeedSender sends the next one
            out.write("OK".getBytes());
            out.write(0x0A);
            out.flush();

        }

    }

    /**
     * The entry point into this program.
     */
    public static void main(String[] args) throws IOException {
        DatafeedReceiver datafeedReceiver = new DatafeedReceiver();
        datafeedReceiver.receive();
    }
}