kourendlibrary: Show a hint arrow above target book

This commit adds a configuration to the Kourend library plugin to
display a hint arrow above the target bookcase. (when it is known)

Co-authored-by: Jordan Atwood <jordan.atwood423@gmail.com>

runelite-client/src/main/java/net/runelite/client/plugins/kourendlibrary/KourendLibraryConfig.java

@@ -72,4 +72,14 @@ public interface KourendLibraryConfig extends Config
 	{
 		return true;
 	}
+
+	@ConfigItem(
+		keyName = "showTargetHintArrow",
+		name = "Show target book arrow",
+		description = "Show a hint arrow pointing to the target bookcase"
+	)
+	default boolean showTargetHintArrow()
+	{
+		return true;
+	}
 }

runelite-client/src/main/java/net/runelite/client/plugins/kourendlibrary/KourendLibraryPlugin.java

@@ -199,6 +199,15 @@ public class KourendLibraryPlugin extends Plugin
 				}
 			});
 		}
+		else if (ev.getKey().equals("showTargetHintArrow"))
+		{
+			if (client.getLocalPlayer() == null || client.getLocalPlayer().getWorldLocation().getRegionID() != REGION)
+			{
+				return;
+			}
+
+			updateBookcaseHintArrow();
+		}
 	}
 
 	@Subscribe
@@ -227,7 +236,7 @@ public class KourendLibraryPlugin extends Plugin
 			if (event.getMessage().equals("You don't find anything useful here."))
 			{
 				library.mark(lastBookcaseAnimatedOn, null);
-				panel.update();
+				updateBooksPanel();
 				lastBookcaseAnimatedOn = null;
 			}
 		}
@@ -277,7 +286,7 @@ public class KourendLibraryPlugin extends Plugin
 				if (book != null)
 				{
 					library.mark(lastBookcaseAnimatedOn, book);
-					panel.update();
+					updateBooksPanel();
 					lastBookcaseAnimatedOn = null;
 				}
 			}
@@ -302,12 +311,12 @@ public class KourendLibraryPlugin extends Plugin
 					}
 
 					library.setCustomer(npcHead.getModelId(), book);
-					panel.update();
+					updateBooksPanel();
 				}
 				else if (text.contains("You can have this other book") || text.contains("please accept a token of my thanks.") || text.contains("Thanks, I'll get on with reading it."))
 				{
 					library.setCustomer(-1, null);
-					panel.update();
+					updateBooksPanel();
 				}
 			}
 		}
@@ -361,6 +370,49 @@ public class KourendLibraryPlugin extends Plugin
 		}
 	}
 
+	private void updateBooksPanel()
+	{
+		panel.update();
+		updateBookcaseHintArrow();
+	}
+
+	private void updateBookcaseHintArrow()
+	{
+		final Book customerBook = library.getCustomerBook();
+		final SolvedState state = library.getState();
+
+		// Clear the hint arrow if the player has no book requested of them
+		// or if the player is already holding the correct book
+		// or if this plugin is configured not to show the target book hint arrow
+		if (customerBook == null || doesPlayerContainBook(customerBook) || !config.showTargetHintArrow())
+		{
+			client.clearHintArrow();
+		}
+		else if (state == SolvedState.COMPLETE && client.getHintArrowPoint() == null)
+		{
+			// Show a hint arrow pointing toward the target book if all book locations are known
+			// and a hint arrow is not already being displayed
+			for (Bookcase bookcase : library.getBookcases())
+			{
+				final Set<Book> books = bookcase.getPossibleBooks();
+
+				if (!books.isEmpty())
+				{
+					final Book book = books.iterator().next();
+
+					// Each bookcase in a complete solved state will contain only one book. If that book is the book
+					// the customer wants, mark the bookcase which contains it with a hint arrow.
+					if (book == customerBook)
+					{
+						WorldPoint correctLocation = bookcase.getLocation();
+						client.setHintArrow(correctLocation);
+						break;
+					}
+				}
+			}
+		}
+	}
+
 	static boolean isLibraryCustomer(int npcId)
 	{
 		return npcId == NpcID.VILLIA || npcId == NpcID.PROFESSOR_GRACKLEBONE || npcId == NpcID.SAM_7049;