add: database abstraction

src/server/databases/database.ts

@@ -0,0 +1,54 @@
+import type System from './entities/system';
+import type User from './entities/user';
+
+type Undefined = null | undefined | 0 | '';
+
+/**
+ * `id` of T or T.
+ *
+ * @template T - The specific type that can be used in place of id string.
+ */
+type Identity<T> = string | T;
+
+export { Undefined, Identity };
+
+/**
+ * Abstract class for database operations.
+ * Provides methods to connect, disconnect, and interact with system and user data.
+ *
+ * **Note:** This class does not handle errors directly. Error handling should be implemented in the API methods
+ * that use this class. The methods here should not throw errors themselves but should rely on the consuming code
+ * to manage any exceptions or failures.
+ */
+export default abstract class DatabaseProvider {
+  /**
+   * Connects to the database.
+   */
+  abstract connect(): Promise<void>;
+  /**
+   * Disconnects from the database.
+   */
+  abstract disconnect(): Promise<void>;
+
+  /**
+   * Retrieves system data from the database.
+   * @returns {Promise<System | Undefined>} The system data or null if not found.
+   */
+  abstract getSystem(): Promise<System | Undefined>;
+
+  /**
+   * Retrieves a user by their ID or by User structure from the database.
+   * @param {Identity<User>} id - The ID of the user or a user.
+   * @returns {Promise<User | Undefined>} The user data or null if not found.
+   */
+  abstract getUser(id: Identity<User>): Promise<User | Undefined>;
+
+  /**
+   * Creates or Updates a user in the database.
+   * @param {User} user - The user to be saved.
+   *
+   * **Note:** If the user already exists, this method will update their details.
+   * If the user does not exist, it will create a new user entry.
+   */
+  abstract saveUser(user: User): Promise<void>;
+}

src/server/databases/entities/system.ts

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+/**
+ * Representing the WireGuard network configuration data structure of a computer interface system.
+ */
+type System = {
+  privateKey: string;
+  publicKey: string;
+  address: string;
+};
+
+export default System;

src/server/databases/entities/user.ts

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+export type ROLE = 'ADMIN';
+
+/**
+ * Representing a user data structure.
+ */
+type User = {
+  id: string;
+  roles: Array<ROLE>;
+  name: string;
+  address: string;
+  privateKey: string;
+  publicKey: string;
+  preSharedKey: string;
+  createdAt: string;
+  updatedAt: string;
+  enabled: boolean;
+};
+
+export default User;

src/server/databases/providers/inmemory.ts

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+import DatabaseProvider, { type Identity } from '../database';
+import type System from '../entities/system';
+import type User from '../entities/user';
+import debug from 'debug';
+
+const INMDP_DEBUG = debug('InMemoryDP');
+
+// Represent in-memory data structure
+type InMemoryData = {
+  system?: System;
+  users: Array<User>;
+};
+
+// In-Memory Database Provider
+export class InMemoryDP extends DatabaseProvider {
+  private data: InMemoryData = { users: [] };
+
+  async connect() {
+    // No connection needed for in-memory
+  }
+
+  async disconnect() {
+    // No disconnection needed for in-memory
+  }
+
+  async getSystem() {
+    INMDP_DEBUG('Get System');
+    return this.data.system || null;
+  }
+
+  async saveSystem(system: System) {
+    INMDP_DEBUG('Save System');
+    this.data.system = system;
+  }
+
+  async getUser(id: Identity<User>) {
+    INMDP_DEBUG('Get User');
+    if (typeof id === 'string') {
+      return this.data.users.find((user) => user.id === id);
+    }
+    return this.data.users.find((user) => user.id === id.id);
+  }
+
+  async saveUser(user: User) {
+    let _user = await this.getUser(user);
+    if (_user) {
+      INMDP_DEBUG('Update User');
+      _user = user;
+    } else {
+      INMDP_DEBUG('New User');
+      this.data.users.push(user);
+    }
+  }
+}