Add PlayerInsertLecternBookEvent

paper-api/src/main/java/io/papermc/paper/event/player/PlayerInsertLecternBookEvent.java

@@ -0,0 +1,96 @@
+package io.papermc.paper.event.player;
+
+import com.google.common.base.Preconditions;
+import org.bukkit.block.Block;
+import org.bukkit.block.BlockState;
+import org.bukkit.block.Lectern;
+import org.bukkit.entity.Player;
+import org.bukkit.event.Cancellable;
+import org.bukkit.event.HandlerList;
+import org.bukkit.event.player.PlayerEvent;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.ApiStatus;
+import org.jspecify.annotations.NullMarked;
+
+/**
+ * This event is called when a player clicks on a lectern to insert a book.
+ * If this event is cancelled the player will keep the book and the lectern will remain empty.
+ */
+@NullMarked
+public class PlayerInsertLecternBookEvent extends PlayerEvent implements Cancellable {
+
+    private static final HandlerList HANDLER_LIST = new HandlerList();
+    private boolean cancelled = false;
+    private final Block block;
+    private ItemStack book;
+
+    @ApiStatus.Internal
+    public PlayerInsertLecternBookEvent(final Player player, final Block block, final ItemStack book) {
+        super(player);
+        this.block = block;
+        this.book = book;
+    }
+
+    /**
+     * Gets the block of the lectern involved in this event.
+     *
+     * @return the block of the lectern
+     */
+    public Block getBlock() {
+        return this.block;
+    }
+
+    /**
+     * Fetches the lectern block state that was part of this event.
+     * This method constructs a new snapshot {@link org.bukkit.block.BlockState}.
+     *
+     * @return a new lectern state snapshot of the involved lectern
+     * @throws IllegalStateException if the block at {@link #getBlock()} is no longer a lectern
+     */
+    public Lectern getLectern() {
+        final BlockState state = this.getBlock().getState();
+        Preconditions.checkState(state instanceof Lectern, "Block state of lectern block is no longer a lectern tile state!");
+        return (Lectern) state;
+    }
+
+    /**
+     * Returns the itemstack the player tried to insert. This is a copy of the item,
+     * changes made to this itemstack will not affect the book that is being placed in the lectern.
+     * If you want to mutate the item stack that ends up in the lectern, use {@link #setBook(ItemStack)}.
+     *
+     * @return the book that is being placed
+     */
+    public ItemStack getBook() {
+        return this.book.clone();
+    }
+
+    /**
+     * Sets the itemstack to insert into the lectern.
+     *
+     * @param book the book to insert (non book items will leave the lectern in a locked
+     *             state as the menu cannot be opened, preventing item extraction)
+     */
+    public void setBook(final ItemStack book) {
+        Preconditions.checkArgument(book != null, "Cannot set book to null");
+        this.book = book.clone();
+    }
+
+    @Override
+    public boolean isCancelled() {
+        return this.cancelled;
+    }
+
+    @Override
+    public void setCancelled(final boolean cancel) {
+        this.cancelled = cancel;
+    }
+
+    @Override
+    public HandlerList getHandlers() {
+        return HANDLER_LIST;
+    }
+
+    public static HandlerList getHandlerList() {
+        return HANDLER_LIST;
+    }
+}