MCP Time Server Node

import { addYears } from 'date-fns'; import { toZonedTime, fromZonedTime } from 'date-fns-tz'; import type { RecurrencePattern, YearlyParams } from '../../types/recurrence'; export class YearlyRecurrence implements RecurrencePattern { calculate(from: Date, params: YearlyParams): Date { const timezone = params.timezone ?? 'UTC'; const hasSpecificDate = params.month !== undefined && params.dayOfMonth !== undefined; if (hasSpecificDate) { return this.calculateSpecificDate(from, params, timezone); } return this.calculateSameDate(from, params, timezone); } private calculateSameDate(from: Date, params: YearlyParams, timezone: string): Date { const targetTime = params.time; if (timezone === 'UTC') { const nextDate = addYears(from, 1); // If time is specified, update it if (targetTime) { const [hours, minutes] = targetTime.split(':').map(Number); nextDate.setUTCHours(hours, minutes, 0, 0); } return nextDate; } // Timezone-aware calculation const fromInTz = toZonedTime(from, timezone); const nextDate = addYears(fromInTz, 1); // If time is specified, update it if (targetTime) { const [hours, minutes] = targetTime.split(':').map(Number); nextDate.setHours(hours, minutes, 0, 0); } return fromZonedTime(nextDate, timezone); } private calculateSpecificDate(from: Date, params: YearlyParams, timezone: string): Date { const targetMonth = params.month ?? 0; // Default to January if not specified const targetDay = params.dayOfMonth ?? 1; // Default to 1st if not specified const targetTime = params.time; if (timezone === 'UTC') { return this.calculateSpecificDateUTC(from, targetMonth, targetDay, targetTime); } return this.calculateSpecificDateTZ(from, targetMonth, targetDay, targetTime, timezone); } private calculateSpecificDateUTC( from: Date, targetMonth: number, targetDay: number, targetTime?: string, ): Date { const fromYear = from.getUTCFullYear(); let targetDate = this.createUTCDate(fromYear, targetMonth, targetDay); // Set time if specified if (targetTime) { const [hours, minutes] = targetTime.split(':').map(Number); targetDate.setUTCHours(hours, minutes, 0, 0); } // If the target date has passed, advance to next year if (targetDate <= from) { targetDate = this.createUTCDate(fromYear + 1, targetMonth, targetDay); if (targetTime) { const [hours, minutes] = targetTime.split(':').map(Number); targetDate.setUTCHours(hours, minutes, 0, 0); } } return targetDate; } private calculateSpecificDateTZ( from: Date, targetMonth: number, targetDay: number, targetTime: string | undefined, timezone: string, ): Date { const fromInTz = toZonedTime(from, timezone); const fromYear = fromInTz.getFullYear(); let targetDate = this.createTimezoneDate(fromYear, targetMonth, targetDay, timezone); // Set time if specified if (targetTime) { const [hours, minutes] = targetTime.split(':').map(Number); const dateInTz = toZonedTime(targetDate, timezone); dateInTz.setHours(hours, minutes, 0, 0); targetDate = fromZonedTime(dateInTz, timezone); } // If the target date has passed, advance to next year if (targetDate <= from) { targetDate = this.createTimezoneDate(fromYear + 1, targetMonth, targetDay, timezone); if (targetTime) { const [hours, minutes] = targetTime.split(':').map(Number); const dateInTz = toZonedTime(targetDate, timezone); dateInTz.setHours(hours, minutes, 0, 0); targetDate = fromZonedTime(dateInTz, timezone); } } return targetDate; } private createUTCDate(year: number, month: number, requestedDay: number): Date { if (requestedDay === -1) { // Last day of month return new Date(Date.UTC(year, month + 1, 0)); } // Handle month-end overflow const lastDay = new Date(Date.UTC(year, month + 1, 0)).getUTCDate(); const actualDay = Math.min(requestedDay, lastDay); return new Date(Date.UTC(year, month, actualDay)); } private createTimezoneDate( year: number, month: number, requestedDay: number, timezone: string, ): Date { let actualDay: number; if (requestedDay === -1) { // Last day of month actualDay = new Date(year, month + 1, 0).getDate(); } else { // Handle month-end overflow const lastDay = new Date(year, month + 1, 0).getDate(); actualDay = Math.min(requestedDay, lastDay); } // Create date in timezone context return fromZonedTime(new Date(year, month, actualDay), timezone); } }