up3

server/session/handler_book_edit.go

@@ -0,0 +1,76 @@
+package session
+
+import (
+	"fmt"
+	"github.com/df-mc/dragonfly/server/item"
+	"github.com/df-mc/dragonfly/server/world"
+	"github.com/sandertv/gophertunnel/minecraft/protocol/packet"
+)
+
+// BookEditHandler handles the BookEdit packet.
+type BookEditHandler struct{}
+
+// Handle ...
+func (b BookEditHandler) Handle(p packet.Packet, s *Session, _ *world.Tx, _ Controllable) error {
+	pk := p.(*packet.BookEdit)
+
+	it, err := s.inv.Item(int(pk.InventorySlot))
+	if err != nil {
+		return fmt.Errorf("invalid inventory slot index %v", pk.InventorySlot)
+	}
+	book, ok := it.Item().(item.BookAndQuill)
+	if !ok {
+		return fmt.Errorf("inventory slot %v does not contain a writable book", pk.InventorySlot)
+	}
+
+	page := int(pk.PageNumber)
+	if page >= 50 || page < 0 {
+		return fmt.Errorf("page number %v is out of bounds", pk.PageNumber)
+	}
+	if len(pk.Text) > 256 {
+		return fmt.Errorf("text can not be longer than 256 bytes")
+	}
+
+	slot := int(pk.InventorySlot)
+	switch pk.ActionType {
+	case packet.BookActionReplacePage:
+		book = book.SetPage(page, pk.Text)
+	case packet.BookActionAddPage:
+		if len(book.Pages) >= 50 {
+			return fmt.Errorf("unable to add page beyond 50")
+		}
+		if page >= len(book.Pages) && page <= len(book.Pages)+2 {
+			book = book.SetPage(page, "")
+			break
+		}
+		if _, ok := book.Page(page); !ok {
+			return fmt.Errorf("unable to insert page at %v", pk.PageNumber)
+		}
+		book = book.InsertPage(page, pk.Text)
+	case packet.BookActionDeletePage:
+		if _, ok := book.Page(page); !ok {
+			// We break here instead of returning an error because the client can be a page or two ahead in the UI then
+			// the actual pages representation server side. The client still sends the deletion indexes.
+			break
+		}
+		book = book.DeletePage(page)
+	case packet.BookActionSwapPages:
+		if pk.SecondaryPageNumber >= 50 {
+			return fmt.Errorf("page number out of bounds")
+		}
+		_, ok := book.Page(page)
+		_, ok2 := book.Page(int(pk.SecondaryPageNumber))
+		if !ok || !ok2 {
+			// We break here instead of returning an error because the client can try to swap pages that don't exist.
+			// This happens as a result of the client being a page or two ahead in the UI then the actual pages
+			// representation server side. The client still sends the swap indexes.
+			break
+		}
+		book = book.SwapPages(page, int(pk.SecondaryPageNumber))
+	case packet.BookActionSign:
+		_ = s.inv.SetItem(slot, it.WithItem(item.WrittenBook{Title: pk.Title, Author: pk.Author, Pages: book.Pages, Generation: item.OriginalGeneration()}))
+		return nil
+	}
+	_ = s.inv.SetItem(slot, it.WithItem(book))
+	return nil
+}