ch.rasc.s4ws.snake.Snake.java Source code

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Here is the source code for ch.rasc.s4ws.snake.Snake.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package ch.rasc.s4ws.snake;

import java.io.IOException;
import java.util.ArrayDeque;
import java.util.Collection;
import java.util.Deque;

import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;

public class Snake {

    private static final int DEFAULT_LENGTH = 5;

    private final int id;

    private final WebSocketSession session;

    private Direction direction;

    private int length = DEFAULT_LENGTH;

    private Location head;

    private final Deque<Location> tail = new ArrayDeque<>();

    private final String hexColor;

    public Snake(int id, WebSocketSession session) {
        this.id = id;
        this.session = session;
        this.hexColor = SnakeUtils.getRandomHexColor();
        resetState();
    }

    private void resetState() {
        this.direction = Direction.NONE;
        this.head = SnakeUtils.getRandomLocation();
        this.tail.clear();
        this.length = DEFAULT_LENGTH;
    }

    private synchronized void kill() {
        resetState();
        sendMessage("{\"type\": \"dead\"}");
    }

    private synchronized void reward() {
        this.length++;
        sendMessage("{\"type\": \"kill\"}");
    }

    protected void sendMessage(String msg) {

        try {
            this.session.sendMessage(new TextMessage(msg));
        } catch (IOException ioe) {
            try {
                this.session.close(CloseStatus.NO_CLOSE_FRAME);
            } catch (IOException ioe2) {
                // Ignore
            }
        }
    }

    public synchronized void update(Collection<Snake> snakes) {
        Location nextLocation = this.head.getAdjacentLocation(this.direction);
        if (nextLocation.x >= SnakeUtils.PLAYFIELD_WIDTH) {
            nextLocation.x = 0;
        }
        if (nextLocation.y >= SnakeUtils.PLAYFIELD_HEIGHT) {
            nextLocation.y = 0;
        }
        if (nextLocation.x < 0) {
            nextLocation.x = SnakeUtils.PLAYFIELD_WIDTH;
        }
        if (nextLocation.y < 0) {
            nextLocation.y = SnakeUtils.PLAYFIELD_HEIGHT;
        }
        if (this.direction != Direction.NONE) {
            this.tail.addFirst(this.head);
            if (this.tail.size() > this.length) {
                this.tail.removeLast();
            }
            this.head = nextLocation;
        }

        handleCollisions(snakes);
    }

    private void handleCollisions(Collection<Snake> snakes) {
        for (Snake snake : snakes) {
            boolean headCollision = this.id != snake.id && snake.getHead().equals(this.head);
            boolean tailCollision = snake.getTail().contains(this.head);
            if (headCollision || tailCollision) {
                kill();
                if (this.id != snake.id) {
                    snake.reward();
                }
            }
        }
    }

    public synchronized Location getHead() {
        return this.head;
    }

    public synchronized Collection<Location> getTail() {
        return this.tail;
    }

    public synchronized void setDirection(Direction direction) {
        this.direction = direction;
    }

    public synchronized String getLocationsJson() {
        StringBuilder sb = new StringBuilder();
        sb.append(String.format("{\"x\": %d, \"y\": %d}", Integer.valueOf(this.head.x),
                Integer.valueOf(this.head.y)));
        for (Location location : this.tail) {
            sb.append(',');
            sb.append(String.format("{\"x\": %d, \"y\": %d}", Integer.valueOf(location.x),
                    Integer.valueOf(location.y)));
        }
        return String.format("{\"id\":%d,\"body\":[%s]}", Integer.valueOf(this.id), sb.toString());
    }

    public int getId() {
        return this.id;
    }

    public String getHexColor() {
        return this.hexColor;
    }
}