Add move item functionality to Settings.

source/settings/settings.ts

@@ -59,6 +59,32 @@ export class Settings {
     });
   }
 
+  public async moveQueueItem(
+    id: number,
+    direction: Queue.MoveDirection,
+  ): Promise<void> {
+    const targetItem = this.queue.find((item) => item.id === id);
+    if (targetItem === undefined) {
+      throw new Error(`Failed to move item with ID: ${id}`);
+    }
+
+    const previousIndex = targetItem.sortIndex;
+    if (direction === 'down') {
+      targetItem.sortIndex += 1;
+    } else if (direction === 'up') {
+      targetItem.sortIndex -= 1;
+    }
+
+    const existingItem = this.queue.find(
+      (item) => item.sortIndex === targetItem.sortIndex,
+    );
+    if (existingItem !== undefined) {
+      existingItem.sortIndex = previousIndex;
+    }
+
+    await this.save();
+  }
+
   public newQueueItemId(): number {
     const item = this.queue.sort((a, b) => b.id - a.id)[0];
     return item === undefined ? 1 : item.id + 1;

source/types.d.ts

@@ -26,5 +26,7 @@ declare global {
       text: string;
       url: string;
     };
+
+    type MoveDirection = 'up' | 'down';
   }
 }