fix(repository): Move backend code into subdirectory

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

backend/src/authors/author.entity.ts

@@ -0,0 +1,69 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import {
+  Column,
+  Entity,
+  ManyToOne,
+  OneToMany,
+  PrimaryGeneratedColumn,
+} from 'typeorm';
+
+import { Edit } from '../revisions/edit.entity';
+import { Session } from '../users/session.entity';
+import { User } from '../users/user.entity';
+
+export type AuthorColor = number;
+
+/**
+ * The author represents a single user editing a note.
+ * A 'user' can either be a registered and logged-in user or a browser session identified by its cookie.
+ * All edits of one user in a note must belong to the same author, so that the same color can be displayed.
+ */
+@Entity()
+export class Author {
+  @PrimaryGeneratedColumn()
+  id: number;
+
+  /**
+   * The id of the color of this author
+   * The application maps the id to an actual color
+   */
+  @Column({ type: 'int' })
+  color: AuthorColor;
+
+  /**
+   * A list of (browser) sessions this author has
+   * Only contains sessions for anonymous users, which don't have a user set
+   */
+  @OneToMany(() => Session, (session) => session.author)
+  sessions: Promise<Session[]>;
+
+  /**
+   * User that this author corresponds to
+   * Only set when the user was identified (by a browser session) as a registered user at edit-time
+   */
+  @ManyToOne(() => User, (user) => user.authors, { nullable: true })
+  user: Promise<User | null>;
+
+  /**
+   * List of edits that this author created
+   * All edits must belong to the same note
+   */
+  @OneToMany(() => Edit, (edit) => edit.author)
+  edits: Promise<Edit[]>;
+
+  // eslint-disable-next-line @typescript-eslint/no-empty-function
+  private constructor() {}
+
+  public static create(color: number): Omit<Author, 'id'> {
+    const newAuthor = new Author();
+    newAuthor.color = color;
+    newAuthor.sessions = Promise.resolve([]);
+    newAuthor.user = Promise.resolve(null);
+    newAuthor.edits = Promise.resolve([]);
+    return newAuthor;
+  }
+}

backend/src/authors/authors.module.ts

@@ -0,0 +1,14 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import { Module } from '@nestjs/common';
+import { TypeOrmModule } from '@nestjs/typeorm';
+
+import { Author } from './author.entity';
+
+@Module({
+  imports: [TypeOrmModule.forFeature([Author])],
+})
+export class AuthorsModule {}