MCP Time Server Node

import { addDays, addWeeks, getDay } from 'date-fns'; import { toZonedTime } from 'date-fns-tz'; import type { RecurrencePattern, WeeklyParams } from '../../types/recurrence'; import { isTimeInFuture, setTimeInTimezone } from './TimezoneDateBuilder'; export class WeeklyRecurrence implements RecurrencePattern { calculate(from: Date, params: WeeklyParams): Date { const timezone = params.timezone ?? 'UTC'; const { time, dayOfWeek } = params; // Get the target day of week const targetDay = this.getTargetDay(from, dayOfWeek, timezone); // Calculate days until target const daysToAdd = this.calculateDaysToAdd(from, targetDay, timezone); if (daysToAdd === 0) { return this.handleSameDay(from, time, timezone); } // Add days to reach target day const targetDate = addDays(from, daysToAdd); // Set time if specified if (time) { const [hours, minutes] = time.split(':').map(Number); return setTimeInTimezone(targetDate, hours, minutes, timezone); } return targetDate; } private getTargetDay(from: Date, dayOfWeek: number | undefined, timezone: string): number { if (dayOfWeek !== undefined) { return dayOfWeek; } // Default to same day of week if (timezone === '' || timezone === 'UTC') { return getDay(from); } const zonedFrom = toZonedTime(from, timezone); return getDay(zonedFrom); } private calculateDaysToAdd(from: Date, targetDay: number, timezone: string): number { let currentDay: number; if (timezone === '' || timezone === 'UTC') { currentDay = getDay(from); } else { const zonedFrom = toZonedTime(from, timezone); currentDay = getDay(zonedFrom); } return (targetDay - currentDay + 7) % 7; } private handleSameDay(from: Date, time: string | undefined, timezone: string): Date { if (!time) { // No specific time, force next week return addWeeks(from, 1); } // Parse time string const [hours, minutes] = time.split(':').map(Number); // Check if time has passed const withTime = setTimeInTimezone(from, hours, minutes, timezone); if (isTimeInFuture(withTime, from)) { // Time hasn't passed, use today return withTime; } // Time has passed, go to next week const nextWeek = addWeeks(from, 1); return setTimeInTimezone(nextWeek, hours, minutes, timezone); } }