refactor: extract "extract note from request" logic into separate function

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

backend/src/api/utils/extract-note-from-request.spec.ts

@@ -0,0 +1,87 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import { Mock } from 'ts-mockery';
+
+import { Note } from '../../notes/note.entity';
+import { NotesService } from '../../notes/notes.service';
+import { extractNoteFromRequest } from './extract-note-from-request';
+import { CompleteRequest } from './request.type';
+
+describe('extract note from request', () => {
+  const mockNoteIdOrAlias1 = 'mockNoteIdOrAlias1';
+  const mockNoteIdOrAlias2 = 'mockNoteIdOrAlias2';
+
+  const mockNote1 = Mock.of<Note>({ id: 1 });
+  const mockNote2 = Mock.of<Note>({ id: 2 });
+
+  let notesService: NotesService;
+
+  beforeEach(() => {
+    notesService = Mock.of<NotesService>({
+      getNoteByIdOrAlias: async (id) => {
+        if (id === mockNoteIdOrAlias1) {
+          return mockNote1;
+        } else if (id === mockNoteIdOrAlias2) {
+          return mockNote2;
+        } else {
+          throw new Error('unknown note id');
+        }
+      },
+    });
+  });
+
+  function createRequest(
+    parameterValue: string | undefined,
+    headerValue: string | string[] | undefined,
+  ): CompleteRequest {
+    return Mock.of<CompleteRequest>({
+      params: parameterValue
+        ? {
+            noteIdOrAlias: parameterValue,
+          }
+        : {},
+      headers: headerValue
+        ? {
+            // eslint-disable-next-line @typescript-eslint/naming-convention
+            'hedgedoc-note': headerValue,
+          }
+        : {},
+    });
+  }
+
+  it('will return undefined if no id is present', async () => {
+    const request = createRequest(undefined, undefined);
+    expect(await extractNoteFromRequest(request, notesService)).toBe(undefined);
+  });
+
+  it('can extract an id from parameters', async () => {
+    const request = createRequest(mockNoteIdOrAlias1, undefined);
+    expect(await extractNoteFromRequest(request, notesService)).toBe(mockNote1);
+  });
+
+  it('can extract an id from headers if no parameter is given', async () => {
+    const request = createRequest(undefined, mockNoteIdOrAlias1);
+    expect(await extractNoteFromRequest(request, notesService)).toBe(mockNote1);
+  });
+
+  it('can extract the first id from multiple id headers', async () => {
+    const request = createRequest(undefined, [
+      mockNoteIdOrAlias1,
+      mockNoteIdOrAlias2,
+    ]);
+    expect(await extractNoteFromRequest(request, notesService)).toBe(mockNote1);
+  });
+
+  it('will return undefined if no parameter and empty id header array', async () => {
+    const request = createRequest(undefined, []);
+    expect(await extractNoteFromRequest(request, notesService)).toBe(undefined);
+  });
+
+  it('will prefer the parameter over the header', async () => {
+    const request = createRequest(mockNoteIdOrAlias1, mockNoteIdOrAlias2);
+    expect(await extractNoteFromRequest(request, notesService)).toBe(mockNote1);
+  });
+});

backend/src/api/utils/extract-note-from-request.ts

@@ -0,0 +1,33 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import { isArray } from 'class-validator';
+
+import { Note } from '../../notes/note.entity';
+import { NotesService } from '../../notes/notes.service';
+import { CompleteRequest } from './request.type';
+
+export async function extractNoteFromRequest(
+  request: CompleteRequest,
+  noteService: NotesService,
+): Promise<Note | undefined> {
+  const noteIdOrAlias = extractNoteIdOrAlias(request);
+  if (noteIdOrAlias === undefined) {
+    return undefined;
+  }
+  return await noteService.getNoteByIdOrAlias(noteIdOrAlias);
+}
+
+function extractNoteIdOrAlias(request: CompleteRequest): string | undefined {
+  const noteIdOrAlias =
+    request.params['noteIdOrAlias'] || request.headers['hedgedoc-note'];
+  if (noteIdOrAlias === undefined) {
+    return undefined;
+  } else if (isArray(noteIdOrAlias)) {
+    return noteIdOrAlias[0];
+  } else {
+    return noteIdOrAlias;
+  }
+}

backend/src/api/utils/get-note.interceptor.ts

@@ -11,8 +11,8 @@ import {
 } from '@nestjs/common';
 import { Observable } from 'rxjs';
 
-import { Note } from '../../notes/note.entity';
 import { NotesService } from '../../notes/notes.service';
+import { extractNoteFromRequest } from './extract-note-from-request';
 import { CompleteRequest } from './request.type';
 
 /**
@@ -28,15 +28,10 @@ export class GetNoteInterceptor implements NestInterceptor {
     next: CallHandler,
   ): Promise<Observable<T>> {
     const request: CompleteRequest = context.switchToHttp().getRequest();
-    const noteIdOrAlias = request.params['noteIdOrAlias'];
-    request.note = await getNote(this.noteService, noteIdOrAlias);
+    const note = await extractNoteFromRequest(request, this.noteService);
+    if (note !== undefined) {
+      request.note = note;
+    }
     return next.handle();
   }
 }
-
-export async function getNote(
-  noteService: NotesService,
-  noteIdOrAlias: string,
-): Promise<Note> {
-  return await noteService.getNoteByIdOrAlias(noteIdOrAlias);
-}