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package robot;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.logging.Level;
import java.util.logging.Logger;

/** Class Robot
 * Contains main method and creates new thread for each robot
 *
 * @author beata
 */
public class Robot {
    private static final Logger logger = Logger.getLogger(ClientHandler.class.getName());
    // thread pool
    private static final ScheduledExecutorService executor = Executors.newScheduledThreadPool(10);

    /**
     *
     * @param args
     */
    public static void main(String[] args) {
        try {
            ServerSocket serverSocket = new ServerSocket(Integer.parseInt(args[0]));
            while (true) {
                // waiting for client to be connected
                Socket socket = serverSocket.accept(); // waiting for client to be connected
                executor.execute(new ClientHandler(socket)); // new thread
            }
        } catch (IOException ex) {
            logger.log(Level.SEVERE, null, ex);
        }
    }
}


/** Class ClientHandler
 * Handles connection and communication with robot
 *
 * @author beata
 */
class ClientHandler implements Runnable {
    private static final Logger logger = Logger.getLogger(ClientHandler.class.getName());

    private boolean closed = false;

    private final Socket socket;
    private final PrintWriter output;
    private final BufferedInputStream input;

    public ClientHandler(Socket socket) throws IOException {
        this.socket = socket;
        this.output = new PrintWriter(socket.getOutputStream(), true);
        this.input = new BufferedInputStream(socket.getInputStream());
    }

    /** Reading until new line
     * Returns string of line
     *
     * @return returns string (line)
     */
    public String readUntilNewLine() {
        int character;
        String word = "";
        try {
            while ((character = input.read()) != -1) {
                if (character != '\n') {
                    word += Character.toString((char)character);
                } else {
                    if (word.charAt(word.length() - 1) == '\r') {
                        return word.substring(0, word.length() - 1);
                    } else {
                        word += Character.toString((char)character);
                    }
                }
            }
        } catch (IOException ex) {
            logger.log(Level.SEVERE, null, ex);
        }
        return word;
    }

    /** Login validation
     * Gets username and password and returns true if correct
     *
     * @param username
     * @param password
     * @return returns true if correct, false if not
     */
    public boolean validateLogin(String username, String password) {
        String checkUsername = "";
        for (int i = 0; i < 5; i++) {
            checkUsername += username.charAt(i);
        }
        if (!checkUsername.equals("Robot")) {
            return false;
        }

        int intUsername = 0;
        for (int i = 0; i < username.length(); i++) {
            intUsername += (int)username.charAt(i);
        }

        try{
            int intPassword = Integer.parseInt(password);
            if (intUsername == intPassword) {
                return true;
            }
        } catch (NumberFormatException ex) {
            logger.log(Level.SEVERE, null, ex);
        }

        return false;
    }

    /** Photo validation
 Returns OK if valid, saves photo to photoXXX.png, if dataCounter of Bytes is less than 1, returns SYNTAX_ERROR,
 if check sum is not equal, returns BAD_CHECKSUM
     *
     * @return String OK if valid,
     */
    public String validatePhoto() {
        // FOTO 8 ABCDEFGH\x00\x00\x02\x24
        String result = "";
        int character;
        int checkSumFirst = 0;
        int checkSumSecond = 0;
        int numberOfBytes = 0;
        String numberOfBytesString = "";
        try {
            // dataCounter of Bytes
            while ((char)(character = input.read()) != ' ') {
                numberOfBytesString += (char)character;
            }
            numberOfBytes = Integer.parseInt(numberOfBytesString);

            if (numberOfBytes < 1) {
                result = "SYNTAX_ERROR";
            }

            // data, check sum
            for (int i = 0; i < numberOfBytes; i++) {
                character = input.read();
                checkSumFirst += character;
            }

            // last 4 control bytes, check sum
            for (int i = 0; i < 4; i++) {
                character = input.read();
                System.out.println("Character: " + character);
                checkSumSecond += character * Math.pow(16, 2 * (3 - i));
            }

            // printing
            System.out.println("---------------------");
            System.out.println("Number of bytes: " + numberOfBytes);
            System.out.println("First check sum: " + checkSumFirst);
            System.out.println("Second check sum: " + checkSumSecond);
        } catch (IOException ex) {
            logger.log(Level.SEVERE, null, ex);
        }
        return result;
    }

    /** Comparing two strings
     * If they are equal, returns true, else false
     *
     * @param first First string
     * @param second Second string
     * @return returns true if equal, else false
     */
    public boolean compareStrings(String first, String second) {
        if (first.length() < second.length()) {
            for (int i = 0; i < first.length(); i++) {
                if (first.charAt(i) != second.charAt(i)) {
                    return false;
                }
            }
        } else {
            for (int i = 0; i < second.length(); i++) {
                if (first.charAt(i) != second.charAt(i)) {
                    return false;
                }
            }
        }
        return true;
    }

    /** Closing connection
     * Closes the connection
     */
    public void closeConnection() {
        if (closed == false) {
            try {
                socket.close();
            } catch (IOException ex) {
                logger.log(Level.SEVERE, null, ex);
            }
        }
    }

    @Override
    public void run() {

        try {
            // Login
            output.printf(Messages.LOGIN);
            String username = readUntilNewLine();
            output.printf(Messages.PASSWORD);
            String password = readUntilNewLine();


            // Login validation
            if (validateLogin(username, password) == true) {
                output.printf(Messages.OK);
            } else {
                output.printf(Messages.LOGIN_FAILED);
                closeConnection();
                closed = true;
            }


            // Messages
            int character;
            int counter = 0;
            String word = "";
            while (true) {
                while ((character = input.read()) != -1 && counter != 5) {
                    word += Character.toString((char)character);
                    // Info message
                    if (word.startsWith("I")) {
                        if (compareStrings(word, "INFO ") == false) {
                            output.printf(Messages.SYNTAX_ERROR);
                            closeConnection();
                            closed = true;
                        }
                    // Foto message
                    } else if (word.startsWith("F")) {
                        if (compareStrings(word, "FOTO ") == false) {
                            output.printf(Messages.SYNTAX_ERROR);
                            closeConnection();
                            closed = true;
                        }
                    } else {
                        output.printf(Messages.SYNTAX_ERROR);
                        closeConnection();
                        closed = true;
                    }
                    if (counter == 4) {
                        break;
                    }
                    counter++;
                }
                if (word.equals("INFO ")) {
                    word = readUntilNewLine();
                    output.printf(Messages.OK);
                } else if (word.equals("FOTO ")) {
                    String result = validatePhoto();
                }
            }
        } catch (IOException ex) {
            logger.log(Level.SEVERE, null, ex);
        }

    }
}

/** Class Messages
 * Holds messages to be sent to robot
 *
 * @author beata
 */
class Messages {
    public static final String LOGIN = "200 LOGIN\r\n";
    public static final String PASSWORD = "201 PASSWORD\r\n";
    public static final String OK = "202 OK\r\n";
    public static final String BAD_CHECKSUM = "300 BAD CHECKSUM\r\n";
    public static final String LOGIN_FAILED = "500 LOGIN FAILED\r\n";
    public static final String SYNTAX_ERROR = "501 SYNTAX ERROR\r\n";
    public static final String TIMEOUT = "502 TIMEOUT\r\n";
}