Refactor Cron scheduler

package.json

@@ -58,6 +58,7 @@
   "devDependencies": {
     "@eslint/js": "^9.2.0",
     "@types/express": "^4.17.17",
+    "@types/node-cron": "^3.0.11",
     "eslint": "^8.57.0",
     "globals": "^15.1.0",
     "prettier": "3.0.3",

src/modules/cron-tasks/cron.service.ts

@@ -0,0 +1,72 @@
+import { Client, TextChannel } from 'discord.js';
+import BirthdayShoutoutTask from './tasks/birthday-shoutout.task';
+import { Inject, Injectable } from '@nestjs/common';
+import WakeUpTask from './tasks/wake-up.task';
+import * as cron from 'node-cron';
+import { BirthdayEntryService } from '../models/birthday/service/birthday-entry.service';
+import { TaskEntry } from './interfaces/task-entry.interface';
+import { DiscordService } from '../discord/discord.service';
+
+@Injectable()
+export class CronService {
+  private static instance: CronService;
+  private tasks: TaskEntry[];
+
+  constructor(
+    @Inject(BirthdayEntryService)
+    private readonly birthdayService: BirthdayEntryService,
+    @Inject(DiscordService)
+    private readonly discordService: DiscordService,
+  ) {
+    if (CronService.instance) {
+      throw new Error(`ERROR: An instance has already been created.`);
+    }
+
+    CronService.instance = this;
+  }
+
+  static getInstance(): CronService {
+    return CronService.instance;
+  }
+
+  public init() {
+    this.tasks = [
+      {
+        name: 'birthday-shoutout',
+        schedule: '0 10 * * *',
+        task: new BirthdayShoutoutTask(
+          this.discordService.client.channels.cache.find(
+            (channel) => channel.id === '447554141724737548',
+          ) as TextChannel,
+          this.birthdayService,
+        ),
+      },
+      {
+        name: 'first-of-the-month',
+        schedule: '0 12 1 * *',
+        task: new WakeUpTask(
+          this.discordService.client.channels.cache.find(
+            (channel) => channel.id === '447554141724737548',
+          ) as TextChannel,
+        ),
+      },
+    ];
+    this.registerTasks();
+  }
+
+  registerTasks(): void {
+    this.tasks.forEach((task) => {
+      if (!cron.validate(task.schedule)) {
+        throw new Error(
+          `ERROR: Invalid cron schedule expression for task '${task.name}'`,
+        );
+      }
+
+      cron
+        .schedule(task.schedule, async () => {
+          await task.task.execute();
+        })
+        .start();
+    });
+  }
+}

src/modules/cron-tasks/interfaces/task-entry.interface.ts

@@ -0,0 +1,7 @@
+import { ITask } from '../tasks/interfaces/task.interface';
+
+export interface TaskEntry {
+  name: string;
+  schedule: string;
+  task: ITask;
+}

src/modules/cron-tasks/task.module.ts

@@ -1,12 +1,11 @@
-import { Module } from "@nestjs/common";
-import { BirthdayEntryModule } from "../models/birthday/module/birthday-entry.module";
-
+import { Module } from '@nestjs/common';
+import { BirthdayEntryModule } from '../models/birthday/module/birthday-entry.module';
+import { CronService } from './cron.service';
+import { DiscordModule } from '../discord/discord.module';
 
 @Module({
-  imports: [
-    BirthdayEntryModule,
-  ],
-  providers: [],
-  exports: [],
+  imports: [DiscordModule, BirthdayEntryModule],
+  providers: [CronService],
+  exports: [CronService],
 })
 export class TaskModule {}

src/modules/discord/discord.service.ts

@@ -1,27 +1,19 @@
 import { Injectable } from '@nestjs/common';
 import { Client, GatewayIntentBits } from 'discord.js';
 import { AppConfigService } from '../../config/config.service';
-import { CronScheduler } from '../cron-tasks/cron-scheduler';
-import { BirthdayEntryService } from '../models/birthday/service/birthday-entry.service';
 
 @Injectable()
 export class DiscordService {
   public readonly client: Client<boolean>;
-  public cronScheduler: CronScheduler;
 
-  constructor(configService: AppConfigService, private readonly birthdayService: BirthdayEntryService) {
+  constructor(configService: AppConfigService) {
     this.client = new Client({
       intents: [
         GatewayIntentBits.Guilds,
         GatewayIntentBits.GuildMessages,
         GatewayIntentBits.MessageContent,
       ],
     });
-
     this.client.login(configService.botToken);
-    this.client.on('ready', () => {
-      this.cronScheduler = new CronScheduler(this.client, birthdayService);
-      this.cronScheduler.registerTasks();
-    });
   }
 }

src/modules/event/event.module.ts

@@ -6,9 +6,10 @@ import { MessageEvent } from './services/messageEvent';
 import { DiscordModule } from '../discord/discord.module';
 import { CommandModule } from '../command/command.module';
 import { PollModule } from '../models/poll/module/poll.module';
+import { TaskModule } from '../cron-tasks/task.module';
 
 @Module({
-  imports: [DiscordModule, CommandModule, PollModule],
+  imports: [DiscordModule, TaskModule, CommandModule, PollModule],
   providers: [EventService, ClientReady, Interaction, MessageEvent],
   exports: [EventService],
 })

src/modules/event/services/clientReady.ts

@@ -1,14 +1,21 @@
 import { Injectable } from '@nestjs/common';
 import { ClientEvents, Events } from 'discord.js';
 import { AEvent } from '../event.abstract';
+import { CronService } from '../../cron-tasks/cron.service';
 
 @Injectable()
 export class ClientReady extends AEvent {
+  constructor(private readonly cronService: CronService) {
+    super();
+  }
+
   event: keyof ClientEvents = Events.ClientReady;
   once: boolean = true;
 
   async execute(args: ClientEvents[Events.ClientReady]) {
     console.log('Successfully connected to Discord');
     console.log(`logged in as ${args[0].user.username}`);
+
+    this.cronService.init();
   }
 }