package tutorial.jdo;

import java.util.*;
import javax.jdo.*;

/**
 * A snake is an animal that is likely to eat rabbits.
 * This class will be used in Chapter V.
 */
public class Snake
    extends Animal {

    // the resale price of a snake
    public static final float RESALE_PRICE = 150.0f;

    // member variable declarations go here
    private short length = 0;
    // This list will be persisted into the database as 
    // a one-to-many relation.
    private Set giTract = new HashSet();

    /**
     * Constructor.
     *
     * @param name the name of this snake
     * @param feet the length of the snake, in feet
     */
    public Snake(String name, short feet) {
        super(name, RESALE_PRICE);
        length = feet;
    }

    public String toString(boolean detailed) {
        StringBuffer buf = new StringBuffer(1024);
        buf.append("Snake ").append(getName());

        if (detailed) {
            buf.append(" (").append(length).append(" feet long) sells for ");
            buf.append(getPrice()).append(" dollars.");
            buf.append("  Its gastrointestinal tract contains:\n");
            for (Iterator iter = giTract.iterator(); iter.hasNext();)
                buf.append("\t").append(iter.next()).append("\n");
        } else
            buf.append("; ate " + giTract.size() + " rabbits.");

        return buf.toString();
    }

    /**
     * Kills the specified rabbit and eats it.
     */
    public void eat(Rabbit dinner) {
        // Consume the rabbit.
        dinner.kill();
        dinner.eater = this;
        giTract.add(dinner);
        System.out.println("Snake " + getName() + " ate rabbit " 
            + dinner.getName() + ".");
    }

    /**
     * Locates the specified snake and tells it to eat a rabbit.
     */
    public static void eat(String filter) {
        PersistenceManagerFactory pmf = JDOHelper.getPersistenceManagerFactory 
            ("META-INF/jdo.properties");
        PersistenceManager pm = pmf.getPersistenceManager();
        Transaction transaction = pm.currentTransaction();
        transaction.begin();

        // Find the desired snake(s) in the data store.
        Query query = pm.newQuery(Snake.class, filter);
        List results = (List) query.execute();
        if (results.isEmpty()) {
            System.out.println("No snakes matching '" + filter + "' found");
            return;
        }

        Query uneatenQuery = pm.newQuery(Rabbit.class, "isDead == false");
        Random random = new Random();
        for (Iterator iter = results.iterator(); iter.hasNext();) {
            // Run a query for a rabbit whose 'isDead' field indicates
            // that it is alive.
            List menu = (List) uneatenQuery.execute();
            if (menu.isEmpty()) {
                System.out.println("No live rabbits in DB.");
                break;
            }

            // Select a random rabbit from the list.
            Rabbit dinner = (Rabbit) menu.get(random.nextInt(menu.size()));
   
            // Perform the eating.
            Snake snake = (Snake) iter.next();
            System.out.println(snake + " is eating:");
            snake.eat(dinner);
        }

        transaction.commit();
        pm.close();
        pmf.close();
    }

    public static void main(String[] args) {
        if (args.length == 2 && args[0].equals("eat")) {
            eat(args[1]);
            return;
        }

        // If we get here, something went wrong.
        System.out.println("Usage:");
        System.out.println("  java tutorial.Snake eat \"snakequery\"");
    }
}