Add PlayerBookEditEvent. Adds BUKKIT-1995

Event related to book & quill and written book items.

By: Des Herriott <des.herriott@gmail.com>

paper-api/src/main/java/org/bukkit/event/player/PlayerEditBookEvent.java

@@ -0,0 +1,125 @@
+package org.bukkit.event.player;
+
+import org.apache.commons.lang.Validate;
+import org.bukkit.Bukkit;
+import org.bukkit.entity.Player;
+import org.bukkit.event.Cancellable;
+import org.bukkit.event.HandlerList;
+import org.bukkit.inventory.meta.BookMeta;
+
+/**
+ * Called when a player edits or signs a book and quill item.  If the event
+ * is cancelled, no changes are made to the BookMeta
+ */
+public class PlayerEditBookEvent extends PlayerEvent implements Cancellable {
+    private static final HandlerList handlers = new HandlerList();
+
+    private final BookMeta previousBookMeta;
+    private final int slot;
+    private BookMeta newBookMeta;
+    private boolean isSigning;
+    private boolean cancel;
+
+    public PlayerEditBookEvent(Player who, int slot, BookMeta previousBookMeta, BookMeta newBookMeta, boolean isSigning) {
+        super(who);
+
+        Validate.isTrue(slot >= 0 && slot <=8, "Slot must be in range 0-8 inclusive");
+        Validate.notNull(previousBookMeta, "Previous book meta must not be null");
+        Validate.notNull(newBookMeta, "New book meta must not be null");
+
+        Bukkit.getItemFactory().equals(previousBookMeta, newBookMeta);
+
+        this.previousBookMeta = previousBookMeta;
+        this.newBookMeta = newBookMeta;
+        this.slot = slot;
+        this.isSigning = isSigning;
+        this.cancel = false;
+    }
+
+    /**
+     * Gets the book meta currently on the book.
+     * <p>
+     * Note: this is a copy of the book meta.  You cannot use this object to
+     * change the existing book meta.
+     *
+     * @return the book meta currently on the book
+     */
+    public BookMeta getPreviousBookMeta() {
+        return previousBookMeta.clone();
+    }
+
+    /**
+     * Gets the book meta that the player is attempting to add to
+     * the book.
+     * <p>
+     * Note: this is a copy of the proposed new book meta. Use {@link
+     * #setNewBookMeta(BookMeta)} to change what will actually be
+     * added to the book.
+     *
+     * @return the book meta that the player is attempting to add
+     */
+    public BookMeta getNewBookMeta() {
+        return newBookMeta.clone();
+    }
+
+    /**
+     * Gets the inventory slot number for the book item that triggered this
+     * event.
+     * <p>
+     * This is a slot number on the player's hotbar in the range 0-8.
+     *
+     * @return the inventory slot number that the book item occupies
+     */
+    public int getSlot() {
+        return slot;
+    }
+
+    /**
+     * Sets the book meta that will actually be added to the book.
+     *
+     * @param bookMeta new book meta
+     * @throws IllegalArgumentException if the new book meta is null
+     */
+    public void setNewBookMeta(BookMeta newBookMeta) throws IllegalArgumentException {
+        Validate.notNull(newBookMeta, "New book meta must not be null");
+        Bukkit.getItemFactory().equals(newBookMeta, null);
+        this.newBookMeta = newBookMeta.clone();
+    }
+
+    /**
+     * Gets whether or not the book is being signed. If a book is signed the
+     * Material changes from BOOK_AND_QUILL to WRITTEN_BOOK.
+     *
+     * @return true if the book is being signed
+     */
+    public boolean isSigning() {
+        return isSigning;
+    }
+
+    /**
+     * Sets whether or not the book is being signed. If a book is signed the
+     * Material changes from BOOK_AND_QUILL to WRITTEN_BOOK.
+     *
+     * @param signing whether or not the book is being signed.
+     */
+    public void setSigning(boolean signing) {
+        isSigning = signing;
+    }
+
+    @Override
+    public HandlerList getHandlers() {
+        return handlers;
+    }
+
+    public static HandlerList getHandlerList() {
+        return handlers;
+    }
+
+    public boolean isCancelled() {
+        return cancel;
+    }
+
+    public void setCancelled(boolean cancel) {
+        this.cancel = cancel;
+    }
+}