MCP Time Server Node

import { differenceInCalendarDays } from 'date-fns'; import { toZonedTime } from 'date-fns-tz'; import { ValidationError, TimezoneError, DateParsingError } from '../adapters/mcp-sdk'; import { CacheTTL } from '../cache/timeCache'; import type { DaysUntilParams, DaysUntilResult } from '../types'; import { getConfig } from '../utils/config'; import { debug } from '../utils/debug'; import { parseTimeInput } from '../utils/parseTimeInput'; import { resolveTimezone as resolveTimezoneUtil } from '../utils/timezoneUtils'; import { validateTimezone, validateStringLength, LIMITS } from '../utils/validation'; import { withCache } from '../utils/withCache'; /** * Parse target date from various formats */ export function parseTargetDate(target_date: string | number, timezone?: string): Date { // Convert to string first for parseTimeInput const input = String(target_date); return parseTimeInput(input, timezone).date; } /** * Convert date to specified timezone */ export function convertToTimezone(date: Date, timezone: string): Date { return timezone === 'UTC' ? date : toZonedTime(date, timezone); } /** * Format days until as human-readable string */ export function formatDaysUntil(days: number): string { if (days === 0) return 'Today'; if (days === 1) return 'Tomorrow'; if (days === -1) return 'Yesterday'; if (days > 0) return `in ${days} days`; return `${Math.abs(days)} days ago`; } /** * Get appropriate cache TTL based on days until */ export function getCacheTTL(daysUntil: number): number { return Math.abs(daysUntil) === 0 ? CacheTTL.CURRENT_TIME : CacheTTL.CALCULATIONS; } /** * Calculate days until a target date * @param params - The parameters for the calculation * @returns Number of days or formatted string */ // eslint-disable-next-line max-lines-per-function export function daysUntil(params: DaysUntilParams): DaysUntilResult { debug.timing('daysUntil called with params: %O', params); // Validate required parameter if (!params.target_date) { debug.error('target_date is required'); throw new ValidationError('target_date is required', { field: 'target_date' }); } // Validate string length first (general limit for very long strings) if (typeof params.target_date === 'string') { validateStringLength(params.target_date, LIMITS.MAX_STRING_LENGTH, 'target_date'); } const { target_date, timezone: userTimezone, format_result = false } = params; const { defaultTimezone } = getConfig(); const timezone = resolveTimezoneUtil(userTimezone, defaultTimezone); debug.timezone('Resolved timezone: %s', timezone); // Use withCache wrapper with CacheTTL.CALCULATIONS (since TTL depends on result) return withCache( `days_until:${target_date}:${timezone}:${format_result}`, CacheTTL.CALCULATIONS, () => { // Validate timezone if provided if (userTimezone !== undefined && !validateTimezone(timezone)) { debug.error('Invalid timezone: %s', timezone); throw new TimezoneError(`Invalid timezone: ${timezone}`, timezone); } // Parse target date let targetDate: Date; debug.parse('Parsing target_date: %s', target_date); try { targetDate = parseTargetDate(target_date, timezone); debug.parse('Parsed date: %s', targetDate.toISOString()); } catch (error) { debug.error( 'Invalid target_date format: %s, error: %s', target_date, error instanceof Error ? error.message : String(error) ); throw new DateParsingError(`Invalid target_date format: ${target_date}`, { target_date, error: error instanceof Error ? error.message : String(error), }); } // Get current date in the specified timezone const now = new Date(); debug.timing('Current time: %s', now.toISOString()); // Convert both dates to the specified timezone for calendar day comparison const nowInTimezone = convertToTimezone(now, timezone); const targetInTimezone = convertToTimezone(targetDate, timezone); debug.timezone('Now in timezone: %s', nowInTimezone.toISOString()); debug.timezone('Target in timezone: %s', targetInTimezone.toISOString()); // Calculate calendar days difference const daysUntil = differenceInCalendarDays(targetInTimezone, nowInTimezone); debug.timing('Days until: %d', daysUntil); let result: DaysUntilResult; if (format_result) { // Format the result as a human-readable string result = formatDaysUntil(daysUntil); debug.timing('Formatted result: %s', result); } else { // Return just the number result = daysUntil; } return result; } ); }