spike: pagination data utils

packages/ember/src/-private/pagination-state.ts

@@ -0,0 +1,91 @@
+import { cached, tracked } from '@glimmer/tracking';
+
+import type {
+  Future,
+  ImmutableRequestInfo,
+  ResponseInfo,
+  StructuredDocument,
+  StructuredErrorDocument,
+} from '@ember-data/request';
+import type { Document } from '@ember-data/store';
+
+import type { RequestState } from './request-state';
+import { getRequestState } from './request-state';
+
+const RequestCache = new WeakMap<Future<unknown>, PaginationState>();
+
+type FirstLink<T, RT> = {
+  prev: null;
+  self: RequestState<T, RT>;
+  next: Link<T, RT> | PlaceholderLink<T, RT> | null;
+  isVirtual: false;
+};
+
+type Link<T, RT> = {
+  prev: Link<T, RT> | PlaceholderLink<T, RT> | FirstLink<T, RT>;
+  self: RequestState<T, RT>;
+  next: Link<T, RT> | PlaceholderLink<T, RT> | null;
+  isVirtual: false;
+};
+
+type PlaceholderLink<T, RT> = {
+  prev: Link<T, RT> | FirstLink<T, RT>;
+  self: null;
+  next: Link<T, RT>;
+  isVirtual: true;
+};
+
+class PaginationState<T = unknown, RT extends Document<T[]> = Document<T[]>> {
+  #pageList!: FirstLink<T>;
+
+  @tracked pages: Document<T[]>[] = [];
+  @tracked data: T[] = [];
+
+  constructor(request: Future<RT>) {
+    this.#pageList = {
+      prev: null,
+      self: getRequestState(request),
+      next: null,
+      isVirtual: false,
+    };
+  }
+
+  @cached
+  get isLoading() {
+    return this.pages.some((page) => page.isLoading);
+  }
+
+  @cached
+  get isSuccess() {
+    return !this.isError;
+  }
+
+  @cached
+  get isError() {
+    return this.pages.some((page) => page.isError);
+  }
+
+  #addPage(page: Document<T[]>) {
+    this.pages.push(page);
+    this.data = this.data.concat(page.data!);
+  }
+
+  async next() {
+    const page = this.pages.at(-1);
+    const result = await page?.next();
+    if (result) {
+      this.#addPage(result);
+    }
+  }
+}
+
+export function getPaginationState<T, RT extends Document<T[]>>(future: Future<RT>): PaginationState<T, RT> {
+  let state = RequestCache.get(future) as PaginationState<T, RT> | undefined;
+
+  if (!state) {
+    state = new PaginationState(future);
+    RequestCache.set(future, state);
+  }
+
+  return state;
+}