✨ Add utils for url slug in workbook (#2020)

Author: KATO-Hiro

src/lib/utils/workbook.ts

@@ -1,8 +1,11 @@
 import { error } from '@sveltejs/kit';
 
 import type { WorkBook } from '$lib/types/workbook';
+
 import * as userCrud from '$lib/services/users';
 import * as workBookCrud from '$lib/services/workbooks';
+
+import { isValidUrlSlug } from '$lib/utils/url';
 import { BAD_REQUEST, NOT_FOUND } from '$lib/constants/http-response-status-codes';
 
 // See:
@@ -11,25 +14,71 @@ import { BAD_REQUEST, NOT_FOUND } from '$lib/constants/http-response-status-code
 export async function getWorkbookWithAuthor(
   slug: string,
 ): Promise<{ workBook: WorkBook; isExistingAuthor: boolean }> {
-  const id = parseInt(slug);
+  const workBookId = parseWorkBookId(slug);
+  const workBookUrlSlug = parseWorkBookUrlSlug(slug);
 
-  if (Number.isNaN(id)) {
+  if (workBookId === null && workBookUrlSlug === null) {
     error(BAD_REQUEST, '不正な問題集idです。');
   }
 
-  const workBook = await workBookCrud.getWorkBook(id);
+  let workBook: WorkBook | null = null;
+
+  if (workBookId) {
+    workBook = await workBookCrud.getWorkBook(workBookId);
+  } else if (workBookUrlSlug) {
+    workBook = await workBookCrud.getWorkBookByUrlSlug(workBookUrlSlug);
+  }
 
-  if (!workBook) {
-    error(NOT_FOUND, `問題集id: ${id} は見つかりませんでした。`);
+  if (workBook === null) {
+    error(NOT_FOUND, `問題集id: ${slug} は見つかりませんでした。`);
   }
 
-  // ユーザが問題集を作成したあとに、アカウントが削除されていないかを確認
+  // Validate if the author of the workbook exists after the workbook has been created.
   const workbookAuthor = await userCrud.getUserById(workBook.authorId);
   const isExistingAuthor = workbookAuthor ? true : false;
 
   return { workBook: workBook, isExistingAuthor: isExistingAuthor };
 }
 
+/**
+ * Finds a workbook ID from a given slug string.
+ *
+ * This function first attempts to parse the slug as a direct workbook ID.
+ * If that fails, it tries to parse it as a workbook URL slug and looks up
+ * the corresponding workbook in the database.
+ *
+ * @param slug - The slug string to search for, can be either a numeric ID or URL slug
+ * @returns A Promise that resolves to the workbook ID if found, or null if not found
+ *
+ * @example
+ * ```typescript
+ * // Using numeric ID
+ * const id1 = await findWorkBookIdFrom("123");
+ *
+ * // Using URL slug
+ * const id2 = await findWorkBookIdFrom("union-find");
+ * ```
+ */
+export async function findWorkBookIdFrom(slug: string): Promise<number | null> {
+  const workBookId = parseWorkBookId(slug);
+
+  if (workBookId !== null) {
+    return workBookId;
+  }
+
+  const workBookUrlSlug = parseWorkBookUrlSlug(slug);
+
+  if (workBookUrlSlug !== null) {
+    const workBook = await workBookCrud.getWorkBookByUrlSlug(slug);
+
+    if (workBook !== null && workBook.id !== null) {
+      return workBook.id;
+    }
+  }
+
+  return null;
+}
+
 export function parseWorkBookId(slug: string): number | null {
   const isOnlyDigits = (id: string) => /^\d+$/.test(id);
   const id = Number(slug);
@@ -42,3 +91,7 @@ export function parseWorkBookId(slug: string): number | null {
 
   return id;
 }
+
+export function parseWorkBookUrlSlug(slug: string): string | null {
+  return isValidUrlSlug(slug) ? slug : null;
+}