feat: implement Advent of Code scheduler to automate daily post creation in Discord forum

Author: wiktoriavh

src/util/advent-scheduler.ts

@@ -0,0 +1,156 @@
+import { ChannelType, type Client, type ForumChannel } from 'discord.js';
+import * as cron from 'node-cron';
+import { promises as fs } from 'node:fs';
+
+const TRACKER_FILE = 'advent-of-code-tracker.json';
+
+type TrackerData = {
+  [year: string]: number[];
+};
+
+/**
+ * Load the tracker file to see which days have already been posted
+ */
+async function loadTracker(): Promise<TrackerData> {
+  try {
+    const data = await fs.readFile(TRACKER_FILE, 'utf-8');
+    return JSON.parse(data);
+  } catch (_error) {
+    // If file doesn't exist or can't be read, return empty object
+    return {};
+  }
+}
+
+/**
+ * Save the tracker file with updated data
+ */
+async function saveTracker(data: TrackerData): Promise<void> {
+  await fs.writeFile(TRACKER_FILE, JSON.stringify(data, null, 2), 'utf-8');
+}
+
+/**
+ * Check if a specific day has already been posted for a given year
+ */
+async function isDayPosted(year: number, day: number): Promise<boolean> {
+  const tracker = await loadTracker();
+  const yearData = tracker[year.toString()];
+  return yearData ? yearData.includes(day) : false;
+}
+
+/**
+ * Mark a day as posted for a given year
+ */
+async function markDayAsPosted(year: number, day: number): Promise<void> {
+  const tracker = await loadTracker();
+  const yearKey = year.toString();
+
+  if (!tracker[yearKey]) {
+    tracker[yearKey] = [];
+  }
+
+  if (!tracker[yearKey].includes(day)) {
+    tracker[yearKey].push(day);
+    tracker[yearKey].sort((a, b) => a - b);
+    await saveTracker(tracker);
+  }
+}
+
+/**
+ * Create a forum post for a specific Advent of Code day
+ */
+async function createAdventPost(
+  client: Client,
+  channelId: string,
+  year: number,
+  day: number
+): Promise<boolean> {
+  try {
+    const channel = await client.channels.fetch(channelId);
+
+    if (!channel) {
+      console.error(`❌ Advent of Code channel not found: ${channelId}`);
+      return false;
+    }
+
+    if (channel.type !== ChannelType.GuildForum) {
+      console.error(`❌ Advent of Code channel is not a forum channel. Type: ${channel.type}`);
+      return false;
+    }
+
+    const forumChannel = channel as ForumChannel;
+    const title = `Day ${day}, ${year}`;
+    const content = `https://adventofcode.com/${year}/day/${day}`;
+
+    await forumChannel.threads.create({
+      name: title,
+      message: {
+        content: content,
+      },
+    });
+
+    console.log(`✅ Created Advent of Code post: ${title}`);
+    return true;
+  } catch (error) {
+    console.error(`❌ Failed to create Advent of Code post for day ${day}:`, error);
+    return false;
+  }
+}
+
+/**
+ * Check if today is during Advent of Code (December 1-25) and create post if needed
+ */
+async function checkAndCreateTodaysPost(client: Client, channelId: string): Promise<void> {
+  const now = new Date();
+  const month = now.getUTCMonth(); // 0-indexed, so December is 11
+  const day = now.getUTCDate();
+  const year = now.getUTCFullYear();
+
+  // Only run during December (month 11)
+  if (month !== 10) {
+    return;
+  }
+
+  // Only run for days 1-25
+  if (day < 1 || day > 25) {
+    return;
+  }
+
+  // Check if we've already posted for this day this year
+  const alreadyPosted = await isDayPosted(year, day);
+  if (alreadyPosted) {
+    console.log(`ℹ️ Advent of Code post for ${year} day ${day} already exists`);
+    return;
+  }
+
+  // Create the post
+  const success = await createAdventPost(client, channelId, year, day);
+
+  // Mark as posted if successful
+  if (success) {
+    await markDayAsPosted(year, day);
+  }
+}
+
+/**
+ * Initialize the Advent of Code scheduler
+ * Runs every day at midnight UTC and checks if we should create a post
+ */
+export function initializeAdventScheduler(client: Client, channelId: string): void {
+  console.log('🎄 Initializing Advent of Code scheduler...');
+
+  // Run immediately on startup to check if we need to post today
+  checkAndCreateTodaysPost(client, channelId).catch((error) => {
+    console.error('❌ Error checking for Advent of Code post on startup:', error);
+  });
+
+  // Schedule to run every day at midnight UTC
+  // Cron pattern: '0 5 * * *' = At 05:00 UTC every day (midnight UTC-5)
+  cron.schedule('0 5 * * *', () => {
+    console.log('⏰ Running scheduled Advent of Code check...');
+    checkAndCreateTodaysPost(client, channelId).catch((error) => {
+      console.error('❌ Error in scheduled Advent of Code check:', error);
+    });
+  });
+
+  console.log('✅ Advent of Code scheduler initialized (runs daily at midnight UTC)');
+}