Calendar/src/utils/TimeFormatter.ts

/**
 * TimeFormatter - Centralized time formatting with timezone support
 * Now uses DateService internally for all date/time operations
 * 
 * Handles conversion from UTC/Zulu time to configured timezone (default: Europe/Copenhagen)
 * Supports both 12-hour and 24-hour format configuration
 * 
 * All events in the system are stored in UTC and must be converted to local timezone
 */

import { DateService } from './DateService';

export interface TimeFormatSettings {
  timezone: string;
  use24HourFormat: boolean;
  locale: string;
  dateFormat: 'locale' | 'technical';
  showSeconds: boolean;
}

export class TimeFormatter {
  private static settings: TimeFormatSettings = {
    timezone: 'Europe/Copenhagen',  // Default to Denmark
    use24HourFormat: true,          // 24-hour format standard in Denmark
    locale: 'da-DK',                // Danish locale
    dateFormat: 'technical',        // Use technical format yyyy-mm-dd hh:mm:ss
    showSeconds: false              // Don't show seconds by default
  };

  // DateService will be initialized lazily to avoid circular dependency with CalendarConfig
  private static dateService: DateService | null = null;

  private static getDateService(): DateService {
    if (!TimeFormatter.dateService) {
      // Create a minimal config object for DateService
      const config = {
        getTimezone: () => TimeFormatter.settings.timezone
      };
      TimeFormatter.dateService = new DateService(config as any);
    }
    return TimeFormatter.dateService;
  }

  /**
   * Configure time formatting settings
   */
  static configure(settings: Partial<TimeFormatSettings>): void {
    TimeFormatter.settings = { ...TimeFormatter.settings, ...settings };
    // Reset DateService to pick up new timezone
    TimeFormatter.dateService = null;
  }

  /**
   * Convert UTC date to configured timezone (internal helper)
   * @param utcDate - Date in UTC (or ISO string)
   * @returns Date object adjusted to configured timezone
   */
  private static convertToLocalTime(utcDate: Date | string): Date {
    if (typeof utcDate === 'string') {
      return TimeFormatter.getDateService().fromUTC(utcDate);
    }

    // If it's already a Date object, convert to UTC string first, then back to local
    const utcString = utcDate.toISOString();
    return TimeFormatter.getDateService().fromUTC(utcString);
  }

  /**
   * Format time in 24-hour format using DateService (internal helper)
   * @param date - Date to format
   * @returns Formatted time string (e.g., "09:00")
   */
  private static format24Hour(date: Date): string {
    const localDate = TimeFormatter.convertToLocalTime(date);
    return TimeFormatter.getDateService().formatTime(localDate, TimeFormatter.settings.showSeconds);
  }

  /**
   * Format time according to current configuration
   * @param date - Date to format
   * @returns Formatted time string
   */
  static formatTime(date: Date): string {
    // Always use 24-hour format (12-hour support removed as unused)
    return TimeFormatter.format24Hour(date);
  }

  /**
   * Format time range (start - end) using DateService
   * @param startDate - Start date
   * @param endDate - End date
   * @returns Formatted time range string (e.g., "09:00 - 10:30")
   */
  static formatTimeRange(startDate: Date, endDate: Date): string {
    const localStart = TimeFormatter.convertToLocalTime(startDate);
    const localEnd = TimeFormatter.convertToLocalTime(endDate);
    return TimeFormatter.getDateService().formatTimeRange(localStart, localEnd);
  }
}