implement resolver.resolveCollectionItems

3 files changed, 86 insertions, 26 deletions

diff --git a/packages/backend/src/core/activitypub/ApResolverService.ts b/packages/backend/src/core/activitypub/ApResolverService.ts
index a7c5125928..74050f456b 100644
--- a/packages/backend/src/core/activitypub/ApResolverService.ts
+++ b/packages/backend/src/core/activitypub/ApResolverService.ts
@@ -19,11 +19,12 @@ import { ApLogService, calculateDurationSince, extractObjectContext } from '@/co
 import { ApUtilityService } from '@/core/activitypub/ApUtilityService.js';
 import { SystemAccountService } from '@/core/SystemAccountService.js';
 import { IdentifiableError } from '@/misc/identifiable-error.js';
-import { getApId, getNullableApId, IObjectWithId, isCollectionOrOrderedCollection } from './type.js';
+import { toArray } from '@/misc/prelude/array.js';
+import { AnyCollection, getApId, getNullableApId, IObjectWithId, isCollection, isCollectionOrOrderedCollection, isCollectionPage, isOrderedCollection, isOrderedCollectionPage } from './type.js';
 import { ApDbResolverService } from './ApDbResolverService.js';
 import { ApRendererService } from './ApRendererService.js';
 import { ApRequestService } from './ApRequestService.js';
-import type { IObject, ICollection, IOrderedCollection, ApObject } from './type.js';
+import type { IObject, ApObject } from './type.js';
 
 export class Resolver {
 	private history: Set<string>;
@@ -78,6 +79,65 @@ export class Resolver {
 		}
 	}
 
+	@bindThis
+	public async resolveCollectionItems(value: string | IObject, limit?: number, allowAnonymousItems?: boolean): Promise<IObjectWithId[]> {
+		const items: IObjectWithId[] = [];
+
+		const collection = await this.resolveCollection(value);
+		await this.resolveCollectionItemsTo(collection, limit, allowAnonymousItems, collection.id, items);
+
+		return items;
+	}
+
+	private async resolveCollectionItemsTo(current: AnyCollection | null, limit: number | undefined, allowAnonymousItems: boolean | undefined, sourceUri: string | undefined, destination: IObjectWithId[]): Promise<void> {
+		// This is pulled up to avoid code duplication below
+		const iterate = async(items: ApObject): Promise<void> => {
+			for (const item of toArray(items)) {
+				// Stop when we reach the fetch limit
+				if (this.history.size > this.recursionLimit) break;
+
+				// Stop when we reach the item limit
+				if (limit != null && limit < 1) break;
+
+				// Use secureResolve whenever possible, to avoid re-fetching items that were included inline.
+				const resolved = (sourceUri && !allowAnonymousItems)
+					? await this.secureResolve(item, sourceUri)
+					: await this.resolve(getApId(item), allowAnonymousItems);
+				destination.push(resolved);
+
+				// Decrement the outer variable directly, because the code below checks it too
+				if (limit != null) limit--;
+			}
+		};
+
+		while (current != null) {
+			// Iterate all items in the current page
+			if (current.items) {
+				await iterate(current.items);
+			}
+			if (current.orderedItems) {
+				await iterate(current.orderedItems);
+			}
+
+			if (this.history.size >= this.recursionLimit) {
+				// Stop when we reach the fetch limit
+				current = null;
+			} else if (limit != null && limit < 1) {
+				// Stop when we reach the item limit
+				current = null;
+			} else if (isCollection(current) || isOrderedCollection(current)) {
+				// Continue to first page
+				current = current.first ? await this.resolveCollection(current.first, true) : null;
+			} else if (isCollectionPage(current) || isOrderedCollectionPage(current)) {
+				// Continue to next page
+				current = current.next ? await this.resolveCollection(current.next, true) : null;
+			} else {
+				// Stop in all other conditions
+				current = null;
+			}
+		}
+	}
+
 	/**
 	 * Securely resolves an AP object or URL that has been sent from another instance.
 	 * An input object is trusted if and only if its ID matches the authority of sentFromUri.
diff --git a/packages/backend/src/core/activitypub/type.ts b/packages/backend/src/core/activitypub/type.ts
index 281733d484..e33dec18d7 100644
--- a/packages/backend/src/core/activitypub/type.ts
+++ b/packages/backend/src/core/activitypub/type.ts
@@ -125,48 +125,46 @@ export interface IActivity extends IObject {
 	};
 }
 
-export interface ICollection extends IObject {
-	type: 'Collection';
-	totalItems: number;
+export interface CollectionBase extends IObject {
+	totalItems?: number;
 	first?: IObject | string;
 	last?: IObject | string;
 	current?: IObject | string;
+	partOf?: IObject | string;
+	next?: IObject | string;
+	prev?: IObject | string;
 	items?: ApObject;
+	orderedItems?: ApObject;
 }
 
-export interface IOrderedCollection extends IObject {
+export interface ICollection extends CollectionBase {
+	type: 'Collection';
+	totalItems: number;
+	items?: ApObject;
+	orderedItems?: undefined;
+}
+
+export interface IOrderedCollection extends CollectionBase {
 	type: 'OrderedCollection';
 	totalItems: number;
-	first?: IObject | string;
-	last?: IObject | string;
-	current?: IObject | string;
+	items?: undefined;
 	orderedItems?: ApObject;
 }
 
-export interface ICollectionPage extends IObject {
+export interface ICollectionPage extends CollectionBase {
 	type: 'CollectionPage';
-	totalItems: number;
-	first?: IObject | string;
-	last?: IObject | string;
-	current?: IObject | string;
-	partOf?: IObject | string;
-	next?: IObject | string;
-	prev?: IObject | string;
 	items?: ApObject;
+	orderedItems?: undefined;
 }
 
-export interface IOrderedCollectionPage extends IObject {
+export interface IOrderedCollectionPage extends CollectionBase {
 	type: 'OrderedCollectionPage';
-	totalItems: number;
-	first?: IObject | string;
-	last?: IObject | string;
-	current?: IObject | string;
-	partOf?: IObject | string;
-	next?: IObject | string;
-	prev?: IObject | string;
+	items?: undefined;
 	orderedItems?: ApObject;
 }
 
+export type AnyCollection = ICollection | IOrderedCollection | ICollectionPage | IOrderedCollectionPage;
+
 export const validPost = ['Note', 'Question', 'Article', 'Audio', 'Document', 'Image', 'Page', 'Video', 'Event'];
 
 export const isPost = (object: IObject): object is IPost => {
@@ -269,7 +267,7 @@ export const isCollectionPage = (object: IObject): object is ICollectionPage =>
 export const isOrderedCollectionPage = (object: IObject): object is IOrderedCollectionPage =>
 	getApType(object) === 'OrderedCollectionPage';
 
-export const isCollectionOrOrderedCollection = (object: IObject): object is ICollection | IOrderedCollection =>
+export const isCollectionOrOrderedCollection = (object: IObject): object is AnyCollection =>
 	isCollection(object) || isOrderedCollection(object) || isCollectionPage(object) || isOrderedCollectionPage(object);
 
 export interface IApPropertyValue extends IObject {
diff --git a/packages/misskey-js/src/autogen/types.ts b/packages/misskey-js/src/autogen/types.ts
index 55302960dc..678e980892 100644
--- a/packages/misskey-js/src/autogen/types.ts
+++ b/packages/misskey-js/src/autogen/types.ts
@@ -12918,6 +12918,8 @@ export type operations = {
       content: {
         'application/json': {
           uri: string;
+          expandCollectionItems?: boolean;
+          allowAnonymous?: boolean;
         };
       };
     };