/**
 * Parse a time string, which can be either an ISO date or a relative time like -30m, -1h, -1d
 * @param timeStr Time string to parse
 * @returns Timestamp in milliseconds
 */
export function parseTimeString(timeStr?: string): number | undefined {
  if (!timeStr) {
    return undefined;
  }
  
  // Current time
  const now = new Date();
  
  // If it's a relative time (e.g., -30m, -1h, -1d)
  if (timeStr.startsWith('-')) {
    // Extract the time value and unit
    const timeValue = timeStr.substring(1, timeStr.length - 1);
    const timeUnit = timeStr.charAt(timeStr.length - 1);
    const timeValueNum = parseInt(timeValue);
    
    if (isNaN(timeValueNum)) {
      throw new Error(`Invalid time value in ${timeStr}`);
    }
    
    // Calculate the time ago based on the unit
    switch (timeUnit) {
    case 'm': // minutes
      return now.getTime() - timeValueNum * 60 * 1000;
    case 'h': // hours
      return now.getTime() - timeValueNum * 60 * 60 * 1000;
    case 'd': // days
      return now.getTime() - timeValueNum * 24 * 60 * 60 * 1000;
    default:
      throw new Error(`Invalid time unit in ${timeStr}`);
    }
  } else {
    // It's an ISO date string
    const date = new Date(timeStr);
    if (isNaN(date.getTime())) {
      throw new Error(`Invalid date string: ${timeStr}`);
    }
    return date.getTime();
  }
}

/**
 * Get a date from a timestamp
 * @param timestamp Timestamp in milliseconds
 * @returns Date object
 */
export function getDateFromTimestamp(timestamp?: number): Date | undefined {
  if (!timestamp) {
    return undefined;
  }
  return new Date(timestamp);
}

/**
 * Format a timestamp as ISO string
 * @param timestamp Timestamp in milliseconds
 * @returns ISO string or undefined
 */
export function formatTimestamp(timestamp?: number): string | undefined {
  if (!timestamp) {
    return undefined;
  }
  return new Date(timestamp).toISOString();
}

/**
 * Get a default time range
 * @param defaultMinutesAgo Default minutes to go back
 * @returns Object with start and end timestamps
 */
export function getDefaultTimeRange(defaultMinutesAgo = 30): { startTime: number; endTime?: number } {
  const now = new Date();
  return {
    startTime: now.getTime() - defaultMinutesAgo * 60 * 1000,
    endTime: undefined // Current time
  };
}