fix: calendar reminder timezone handling

src/cron/__tests__/schedule-google-calendar.test.js

@@ -0,0 +1,100 @@
+/**
+ * Tests for timezone-aware cron expression generation
+ * Issue: Calendar reminder is not taking in consideration the time zone
+ * https://github.com/TeamNovaSoft/novabot/issues/109
+ */
+
+/**
+ * Converts a date to a CRON expression in the specified timezone.
+ * This ensures the cron expression matches the intended time in the event's timezone,
+ * preventing timezone offset issues when the server is in a different timezone.
+ *
+ * @param {Date} date - The date to convert.
+ * @param {string} timeZone - The IANA timezone identifier.
+ * @returns {string} A CRON expression derived from the provided date in the specified timezone.
+ */
+const dateToCronExpressionInTimezone = (date, timeZone) => {
+  const options = {
+    timeZone,
+    minute: 'numeric',
+    hour: 'numeric',
+    day: 'numeric',
+    month: 'numeric',
+    year: 'numeric',
+    hour12: false,
+  };
+
+  // Get date components in the target timezone
+  const formatter = new Intl.DateTimeFormat('en-US', options);
+  const parts = formatter.formatToParts(date);
+
+  const getPart = (type) =>
+    parseInt(parts.find((p) => p.type === type)?.value, 10);
+
+  const minutes = getPart('minute');
+  const hours = getPart('hour');
+  const day = getPart('day');
+  const month = getPart('month');
+
+  return `${minutes} ${hours} ${day} ${month} *`;
+};
+
+describe('dateToCronExpressionInTimezone', () => {
+  test('should generate correct cron for Argentina timezone event', () => {
+    // Event at 1:00 PM Argentina time
+    const eventDate = new Date('2025-03-15T13:00:00-03:00'); // 1pm ART
+    const timeZone = 'America/Argentina/Buenos_Aires';
+
+    const cron = dateToCronExpressionInTimezone(eventDate, timeZone);
+
+    // Should be 13:00 (1pm) in cron format
+    expect(cron).toBe('0 13 15 3 *');
+  });
+
+  test('should generate same cron expression regardless of server timezone', () => {
+    // Same event time, but let's verify it's consistent
+    // 1pm Argentina = 11am Colombia (2 hour difference)
+    const argentinaEvent = new Date('2025-03-15T13:00:00-03:00');
+    const argentinaTz = 'America/Argentina/Buenos_Aires';
+
+    // Generate cron for Argentina timezone
+    const argentinaCron = dateToCronExpressionInTimezone(
+      argentinaEvent,
+      argentinaTz
+    );
+
+    // The cron should reflect 13:00 (1pm) in Argentina time
+    expect(argentinaCron).toBe('0 13 15 3 *');
+  });
+
+  test('should handle reminder offset correctly', () => {
+    // Event at 1:00 PM Argentina, with 10-minute reminder
+    const eventDate = new Date('2025-03-15T13:00:00-03:00');
+    const reminderDate = new Date(eventDate.getTime() - 10 * 60 * 1000); // 12:50 PM
+    const timeZone = 'America/Argentina/Buenos_Aires';
+
+    const cron = dateToCronExpressionInTimezone(reminderDate, timeZone);
+
+    // Should be 12:50 (10 min before 1pm) in cron format
+    expect(cron).toBe('50 12 15 3 *');
+  });
+
+  test('should handle different timezones correctly', () => {
+    // Same UTC moment, different timezone representations
+    const utcDate = new Date('2025-03-15T16:00:00Z'); // 4pm UTC
+
+    // In Colombia (UTC-5), this is 11:00 AM
+    const colombiaCron = dateToCronExpressionInTimezone(
+      utcDate,
+      'America/Bogota'
+    );
+    expect(colombiaCron).toBe('0 11 15 3 *');
+
+    // In Argentina (UTC-3), this is 1:00 PM
+    const argentinaCron = dateToCronExpressionInTimezone(
+      utcDate,
+      'America/Argentina/Buenos_Aires'
+    );
+    expect(argentinaCron).toBe('0 13 15 3 *');
+  });
+});

src/cron/schedule-google-calendar.js

@@ -2,7 +2,6 @@ const { CronJob } = require('cron');
 const { listEvents } = require('../../calendar');
 const { EmbedBuilder } = require('discord.js');
 const { translateLanguage } = require('../languages');
-const dateToCronExpression = require('../utils/date-to-cron-expression');
 const convertCronToText = require('../utils/cron-to-text-parser');
 const {
   FIREBASE_CONFIG,
@@ -14,6 +13,45 @@ let activeCronJobs = [];
 
 const minutesBeforeEvent = 10;
 
+/**
+ * Converts a date to a CRON expression in the specified timezone.
+ * This ensures the cron expression matches the intended time in the event's timezone,
+ * preventing timezone offset issues when the server is in a different timezone.
+ *
+ * @param {Date} date - The date to convert.
+ * @param {string} timeZone - The IANA timezone identifier (e.g., 'America/Argentina/Buenos_Aires').
+ * @returns {string} A CRON expression derived from the provided date in the specified timezone.
+ *
+ * @example
+ * dateToCronExpressionInTimezone(new Date('2025-01-22T15:30:00'), 'America/Bogota');
+ * // Returns '30 15 22 1 *'
+ */
+const dateToCronExpressionInTimezone = (date, timeZone) => {
+  const options = {
+    timeZone,
+    minute: 'numeric',
+    hour: 'numeric',
+    day: 'numeric',
+    month: 'numeric',
+    year: 'numeric',
+    hour12: false,
+  };
+
+  // Get date components in the target timezone
+  const formatter = new Intl.DateTimeFormat('en-US', options);
+  const parts = formatter.formatToParts(date);
+
+  const getPart = (type) =>
+    parseInt(parts.find((p) => p.type === type)?.value, 10);
+
+  const minutes = getPart('minute');
+  const hours = getPart('hour');
+  const day = getPart('day');
+  const month = getPart('month');
+
+  return `${minutes} ${hours} ${day} ${month} *`;
+};
+
 const clearAllCronJobs = () => {
   activeCronJobs.forEach((job) => job.stop());
   activeCronJobs = [];
@@ -74,7 +112,12 @@ const scheduleEventNotification = async ({ client, event }) => {
   const startDate = new Date(event.start.dateTime);
   startDate.setMinutes(startDate.getMinutes() - minutesBeforeEvent);
 
-  const cronExpression = dateToCronExpression(startDate);
+  // Use timezone-aware cron expression to ensure correct scheduling
+  // regardless of the server's local timezone
+  const cronExpression = dateToCronExpressionInTimezone(
+    startDate,
+    event.start.timeZone
+  );
   const job = new CronJob(
     cronExpression,
     async () => {