OwnedBlock.java

package com.nicewuerfel.blockown;

import org.bukkit.Bukkit;
import org.bukkit.World;
import org.bukkit.block.Block;

import java.lang.ref.WeakReference;

public class OwnedBlock implements Ownable {

  private static final long serialVersionUID = 4996349639615230112L;

  private transient WeakReference<Block> blockRef = new WeakReference<>(null);

  private final int hashCode;
  private final String worldName;
  private final int x;
  private final int y;
  private final int z;
  private transient Material material = null;

  /**
   * Creates a new OwnedBlock instance holding a WeakReference to the given block.
   *
   * @param block the Block
   * @return the new OwnedBlock instance
   */
  public static OwnedBlock newInstance(Block block) {
    if (block == null) {
      throw new NullPointerException("Block can't be null");
    } else {
      return new OwnedBlock(block.getWorld().getName(), block.getX(), block.getY(), block.getZ(),
          new Material(block.getType()), block);
    }
  }

  /**
   * Creates a new OwnedBlock instance. The corresponding Block will be looked up when getBlock() is
   * called.
   *
   * @param worldName the world name
   * @param x         the x coordinate
   * @param y         the y coordinate
   * @param z         the z coordinate
   * @param material  the material
   * @return the new OwnedBlock instance
   */
  public static OwnedBlock newInstance(String worldName, int x, int y, int z, Material material) {
    if (worldName == null) {
      throw new NullPointerException("world name can't be null");
    }
    // it's ok if material is null
    return new OwnedBlock(worldName, x, y, z, material, null);
  }

  /**
   * Creates a new OwnedBlock instance. The corresponding Block and its Material will be looked up
   * when needed.
   *
   * @param worldName the world name
   * @param x         the x
   * @param y         the y
   * @param z         the z
   * @return the new OwnedBlock instance
   */
  public static OwnedBlock newInstance(String worldName, int x, int y, int z) {
    return newInstance(worldName, x, y, z, null);
  }

  private OwnedBlock(String worldName, int x, int y, int z, Material material, Block block) {
    this.worldName = worldName;
    this.x = x;
    this.y = y;
    this.z = z;
    this.material = material;
    this.blockRef = new WeakReference<>(block);
    this.hashCode = calcHashCode();
  }

  private int calcHashCode() {
    final int prime = 31;
    int result = 13;
    result = prime * result + worldName.hashCode();
    result = prime * result + x;
    result = prime * result + y;
    result = prime * result + z;
    return result;
  }

  public int getX() {
    return x;
  }

  public int getY() {
    return y;
  }

  public int getZ() {
    return z;
  }

  @Override
  public World getWorld() throws InvalidWorldNameException {
    World world = Bukkit.getServer().getWorld(worldName);
    if (world == null) {
      throw new InvalidWorldNameException("There is no world called " + worldName);
    }
    return world;
  }

  /**
   * Returns the Block at the location of this OwnedBlock. Never null.
   *
   * @return the Block
   * @throws InvalidWorldNameException if the world referenced by the world name doesn't exist
   */
  public Block getBlock() throws InvalidWorldNameException {
    if (blockRef == null) {
      blockRef = new WeakReference<>(null);
    }
    Block result = blockRef.get();
    if (result == null) {
      result = getWorld().getBlockAt(x, y, z);
      blockRef = new WeakReference<>(result);
    }
    return result;
  }

  @Override
  public String getWorldName() {
    return worldName;
  }

  @Override
  public Material getMaterial() throws InvalidWorldNameException {
    if (material == null) {
      material = new Material(getBlock().getType());
    }
    return material;
  }

  @Override
  public int hashCode() {
    return hashCode;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (!(obj instanceof OwnedBlock)) {
      return false;
    }
    OwnedBlock other = (OwnedBlock) obj;
    if (!worldName.equals(other.worldName)) {
      return false;
    }
    if (x != other.x) {
      return false;
    }
    if (y != other.y) {
      return false;
    }
    return z == other.z;
  }

  @Override
  public String toString() {
    return "OwnedBlock [block=" + getWorldName() + ":" + getX() + "," + getY() + "," + getZ() + "]";
  }
}