Items.java

package com.ev3.item;

import java.time.Instant;
import java.util.Collection;

import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

@Stateless
public class Items {

	public void findFirstEmptySpace()
	{
		Collection<Item> items = findAllItems();
	}

    @PersistenceContext
    private EntityManager em;

    public Item createItem(String title, int coorX, int coorY, direction d) {
        // EntityManager em = emf.createEntityManager();
        Item newItem = new Item.Builder().id(ItemId.generate()).title(title)
                .created(Instant.now().toEpochMilli()).coorX(coorX).coorY(coorY).dir(d).build();
        em.persist(newItem);
        return newItem;
    }

    public Item findItem(String id) {
        // EntityManager em = emf.createEntityManager();
        return em.find(Item.class, id);
    }

    public Collection<Item> findAllItems() {
        // EntityManager em = emf.createEntityManager();
        Query q = em.createQuery("SELECT i FROM Item i");
        return q.getResultList();
    }

    public boolean CheckFreeLocation(int row, int col, direction dir)
    {
    	String r = Integer.toString(row);
    	String c = Integer.toString(col);
    	String d = Integer.toString(dir.ordinal());

    	Query q = em.createQuery("SELECT i FROM Item i WHERE coorX = '" + r + "' AND coorY = '" + c + "' AND dir = '" + d + "'");

    	return q.getResultList().isEmpty();
    }

    public Location GetFreeLocation()
    {
    	// Hardcoded storage size.
    	int rows = 4;
    	int cols = 4;

    	if (findAllItems().size() != rows * cols)
    	{
        	int r = rows/2;
        	int c = cols/2;

        	for (int i = 1; i <= r; i++)
        	{
        	    for (int j = 1; j <= c; j++)
        	    {
    	    		if (CheckFreeLocation(i, -j, direction.down))
    	    		{
    	    			return new Location(i, -j, direction.down);
    	    		}

    	    		else if(CheckFreeLocation(i, j, direction.down))
    	    		{
    	    			return new Location(i, j, direction.down);
    	    		}

    	    		else if (CheckFreeLocation(i, -j, direction.up))
    	    		{
    	    			return new Location(i, -j, direction.up);
    	    		}

    	    		else if (CheckFreeLocation(i, j, direction.up))
    	    		{
    	    			return new Location(i, j, direction.up);
    	    		}
        	    }
        	}
    	}

    	return null;
    }

    public Location AddItem(String title)
    {
    	Location loc = GetFreeLocation();

    	if (loc != null)
    	{
    		createItem(title, loc.getRow(), loc.getCol(), loc.getDirection());
    		return loc;
    	}

    	return null;
    }

    public boolean EditItem(String id, String title)
    {
        try
        {
            Item item = findItem(id);

            if (item != null)
            {
                item.setTitle(title);
                return true;
            }
            else
            {
                return false;
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
            return false;
        }
    }

    public void RemoveItem(String id)
    {
        try
        {
            Item item = findItem(id);

            if (item != null)
            {
                em.remove(item);
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }

    public void ClearDatabase()
    {
        if (findAllItems().size() > 0)
        {
            em.createQuery("DELETE FROM Item").executeUpdate();
        }
    }
}