src/net/lightstone/model/ChunkManager.java

package net.lightstone.model;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import net.lightstone.io.ChunkIoService;
import net.lightstone.world.WorldGenerator;

/**
 * A class which manages the {@link Chunk}s currently loaded in memory.
 * @author Graham Edgecombe
 */
public final class ChunkManager {

    /**
     * The chunk I/O service used to read chunks from the disk and write them to
     * the disk.
     */
	private final ChunkIoService service;

    /**
     * The world generator used to generate new chunks.
     */
	private final WorldGenerator generator;

    /**
     * A map of chunks currently loaded in memory.
     */
	private final Map<Chunk.Key, Chunk> chunks = new HashMap<Chunk.Key, Chunk>();

    /**
     * Creates a new chunk manager with the specified I/O service and world
     * generator.
     * @param service The I/O service.
     * @param generator The world generator.
     */
	public ChunkManager(ChunkIoService service, WorldGenerator generator) {
		this.service = service;
		this.generator = generator;
	}

    /**
     * Gets the chunk at the specified X and Z coordinates, loading it from the
     * disk or generating it if necessary.
     * @param x The X coordinate.
     * @param z The Z coordinate.
     * @return The chunk.
     */
	public Chunk getChunk(int x, int z) {
		Chunk.Key key = new Chunk.Key(x, z);
		Chunk chunk = chunks.get(key);
		if (chunk == null) {
			try {
				chunk = service.read(x, z);
			} catch (IOException e) {
				chunk = null;
			}

			if (chunk == null) {
				chunk = generator.generate(x, z);
			}

			chunks.put(key, chunk);
		}
		return chunk;
	}

}