Add drag & drop support for effects between different sheets

Also refactor some effect related functionality into the DS4ActiveEffect class

src/module/active-effect.ts

@@ -4,6 +4,7 @@
 
 import { DS4Actor } from "./actor/actor";
 import { getGame } from "./helpers";
+import { DS4Item } from "./item/item";
 
 declare global {
     interface DocumentClassConfig {
@@ -12,6 +13,7 @@ declare global {
 }
 
 type PromisedType<T> = T extends Promise<infer U> ? U : T;
+
 export class DS4ActiveEffect extends ActiveEffect {
     /**
      * A fallback icon that can be used if no icon is defined for the effect.
@@ -23,6 +25,38 @@ export class DS4ActiveEffect extends ActiveEffect {
      */
     protected source: PromisedType<ReturnType<typeof fromUuid>> | undefined = undefined;
 
+    /**
+     * Whether or not this effect is currently surpressed.
+     */
+    get isSurpressed(): boolean {
+        const originatingItem = this.originatingItem;
+        if (!originatingItem) {
+            return false;
+        }
+        return originatingItem.isNonEquippedEuipable();
+    }
+
+    /**
+     * The item which this effect originates from if it has been transferred from an item to an actor.
+     */
+    get originatingItem(): DS4Item | undefined {
+        if (!(this.parent instanceof DS4Actor)) {
+            return;
+        }
+        const [, , , itemId] = this.data.origin?.split(".") ?? [];
+        if (!itemId) {
+            return;
+        }
+        return this.parent.items.get(itemId);
+    }
+
+    /**
+     * The number of times this effect should be applied.
+     */
+    get factor(): number {
+        return this.originatingItem?.activeEffectFactor ?? 1;
+    }
+
     /** @override */
     apply(actor: DS4Actor, change: foundry.data.ActiveEffectData["changes"][number]): unknown {
         change.value = Roll.replaceFormulaData(change.value, actor.data);
@@ -54,4 +88,21 @@ export class DS4ActiveEffect extends ActiveEffect {
         }
         return this.source;
     }
+
+    /**
+     * Create a new {@link DS4ActiveEffect} using default data.
+     *
+     * @param context The context for the creation of the effect, requiring a parent {@link DS4Actor} or {@link DS4Item}.
+     * @returns A promise that resolved to the created effect or udifined of the creation was prevented.
+     */
+    static async createDefault(
+        context: DocumentModificationContext & { parent: DS4Actor | DS4Item },
+    ): Promise<DS4ActiveEffect | undefined> {
+        const createData = {
+            label: getGame().i18n.localize(`DS4.NewEffectLabel`),
+            icon: this.FALLBACK_ICON,
+        };
+
+        return this.create(createData, context);
+    }
 }