Calendar/src/v2/features/event/EventRenderer.ts

import { ICalendarEvent } from '../../types/CalendarTypes';
import { EventService } from '../../storage/events/EventService';
import { calculateEventPosition, getDateKey, formatTimeRange, GridConfig } from '../../utils/PositionUtils';

/**
 * EventRenderer - Renders calendar events to the DOM
 *
 * CLEAN approach:
 * - Only data-id attribute on event element
 * - innerHTML contains only visible content
 * - Event data retrieved via EventService when needed
 */
export class EventRenderer {
  private readonly gridConfig: GridConfig = {
    dayStartHour: 6,
    dayEndHour: 18,
    hourHeight: 64
  };

  constructor(private eventService: EventService) {}

  /**
   * Render events for visible dates into day columns
   */
  async render(container: HTMLElement, visibleDates: string[]): Promise<void> {
    // Get date range for query
    const startDate = new Date(visibleDates[0]);
    const endDate = new Date(visibleDates[visibleDates.length - 1]);
    endDate.setHours(23, 59, 59, 999);

    // Fetch events from IndexedDB
    const events = await this.eventService.getByDateRange(startDate, endDate);

    // Group events by date
    const eventsByDate = this.groupEventsByDate(events);

    // Find day columns
    const dayColumns = container.querySelector('swp-day-columns');
    if (!dayColumns) return;

    const columns = dayColumns.querySelectorAll('swp-day-column');

    // Render events into columns
    columns.forEach((column, index) => {
      const dateKey = visibleDates[index];
      const dateEvents = eventsByDate.get(dateKey) || [];

      // Get or create events layer
      let eventsLayer = column.querySelector('swp-events-layer');
      if (!eventsLayer) {
        eventsLayer = document.createElement('swp-events-layer');
        column.appendChild(eventsLayer);
      }

      // Clear existing events
      eventsLayer.innerHTML = '';

      // Render each event
      dateEvents.forEach(event => {
        if (!event.allDay) {
          const eventElement = this.createEventElement(event);
          eventsLayer!.appendChild(eventElement);
        }
      });
    });
  }

  /**
   * Group events by their date key
   */
  private groupEventsByDate(events: ICalendarEvent[]): Map<string, ICalendarEvent[]> {
    const map = new Map<string, ICalendarEvent[]>();

    events.forEach(event => {
      const dateKey = getDateKey(event.start);
      const existing = map.get(dateKey) || [];
      existing.push(event);
      map.set(dateKey, existing);
    });

    return map;
  }

  /**
   * Create a single event element
   *
   * CLEAN approach:
   * - Only data-id for lookup
   * - Visible content in innerHTML only
   */
  private createEventElement(event: ICalendarEvent): HTMLElement {
    const element = document.createElement('swp-event');

    // Only essential data attribute
    element.dataset.id = event.id;

    // Calculate position
    const position = calculateEventPosition(event.start, event.end, this.gridConfig);
    element.style.top = `${position.top}px`;
    element.style.height = `${position.height}px`;

    // Color class based on event type
    const colorClass = this.getColorClass(event);
    if (colorClass) {
      element.classList.add(colorClass);
    }

    // Visible content only
    element.innerHTML = `
      <swp-event-time>${formatTimeRange(event.start, event.end)}</swp-event-time>
      <swp-event-title>${this.escapeHtml(event.title)}</swp-event-title>
      ${event.description ? `<swp-event-description>${this.escapeHtml(event.description)}</swp-event-description>` : ''}
    `;

    return element;
  }

  /**
   * Get color class based on event type
   */
  private getColorClass(event: ICalendarEvent): string {
    const typeColors: Record<string, string> = {
      'customer': 'is-blue',
      'vacation': 'is-green',
      'break': 'is-amber',
      'meeting': 'is-purple',
      'blocked': 'is-red'
    };
    return typeColors[event.type] || 'is-blue';
  }

  /**
   * Escape HTML to prevent XSS
   */
  private escapeHtml(text: string): string {
    const div = document.createElement('div');
    div.textContent = text;
    return div.innerHTML;
  }
}