/**
 * Time-related utility functions
 */
import { GcpMcpError } from './error.js';

/**
 * Parses a relative time string into a Date object
 * 
 * @param timeString A string representing a relative time (e.g., "1h", "2d", "30m")
 * @returns A Date object representing the time
 */
export function parseRelativeTime(timeString: string): Date {
  // If it's an ISO date string, parse it directly
  if (timeString.includes('T') && timeString.includes(':')) {
    const date = new Date(timeString);
    if (!isNaN(date.getTime())) {
      return date;
    }
  }
  
  // Parse relative time format (e.g., "1h", "2d", "30m")
  const match = timeString.match(/^(\d+)([smhdw])$/);
  if (!match) {
    throw new GcpMcpError(
      `Invalid time format: ${timeString}. Use format like "30s", "5m", "2h", "1d", or "1w".`,
      'INVALID_ARGUMENT',
      400
    );
  }
  
  const value = parseInt(match[1]);
  const unit = match[2];
  const now = new Date();
  
  switch (unit) {
    case 's': // seconds
      return new Date(now.getTime() - value * 1000);
    case 'm': // minutes
      return new Date(now.getTime() - value * 60 * 1000);
    case 'h': // hours
      return new Date(now.getTime() - value * 60 * 60 * 1000);
    case 'd': // days
      return new Date(now.getTime() - value * 24 * 60 * 60 * 1000);
    case 'w': // weeks
      return new Date(now.getTime() - value * 7 * 24 * 60 * 60 * 1000);
    default:
      throw new GcpMcpError(
        `Invalid time unit: ${unit}. Use s, m, h, d, or w.`,
        'INVALID_ARGUMENT',
        400
      );
  }
}