testing

projects/common/src/pagination.ts

@@ -0,0 +1,73 @@
+import { NotFoundError } from "backend/src/error/not-found-error";
+import { Metadata } from "./types/metadata";
+
+export class Pagination<T> {
+  /**
+   * The amount of items per page.
+   * @private
+   */
+  private itemsPerPage: number = 0;
+
+  /**
+   * The amount of items in total.
+   * @private
+   */
+  private totalItems: number = 0;
+
+  /**
+   * The items to paginate.
+   * @private
+   */
+  private items: T[] = [];
+
+  /**
+   * Sets the number of items per page.
+   *
+   * @param itemsPerPage - The number of items per page.
+   * @returns the pagination
+   */
+  setItemsPerPage(itemsPerPage: number): Pagination<T> {
+    this.itemsPerPage = itemsPerPage;
+    return this;
+  }
+
+  /**
+   * Sets the items to paginate.
+   *
+   * @param items the items to paginate
+   * @returns the pagination
+   */
+  setItems(items: T[]): Pagination<T> {
+    this.items = items;
+    this.totalItems = items.length;
+    return this;
+  }
+
+  /**
+   * Gets a page of items.
+   *
+   * @param page the page number to retrieve.
+   * @returns the page of items.
+   * @throws throws an error if the page number is invalid.
+   */
+  getPage(page: number): Page<T> {
+    const totalPages = Math.ceil(this.totalItems / this.itemsPerPage);
+
+    if (page < 1 || page > totalPages) {
+      throw new NotFoundError("Invalid page number");
+    }
+
+    const items = this.items.slice((page - 1) * this.itemsPerPage, page * this.itemsPerPage);
+    return new Page<T>(items, new Metadata(totalPages, this.totalItems, page, this.itemsPerPage));
+  }
+}
+
+class Page<T> {
+  readonly items: T[];
+  readonly metadata: Metadata;
+
+  constructor(items: T[], metadata: Metadata) {
+    this.items = items;
+    this.metadata = metadata;
+  }
+}