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

import { ICalendarEvent, IEventBus } from '../../types/CalendarTypes';
import { EventService } from '../../storage/events/EventService';
import { DateService } from '../../core/DateService';
import { IGridConfig } from '../../core/IGridConfig';
import { calculateEventPosition } from '../../utils/PositionUtils';
import { CoreEvents } from '../../constants/CoreEvents';
import { IDragColumnChangePayload } from '../../types/DragTypes';

/**
 * 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 {
  constructor(
    private eventService: EventService,
    private dateService: DateService,
    private gridConfig: IGridConfig,
    private eventBus: IEventBus
  ) {
    this.setupDragListeners();
  }

  /**
   * Setup listeners for drag-drop events
   */
  private setupDragListeners(): void {
    this.eventBus.on(CoreEvents.EVENT_DRAG_COLUMN_CHANGE, (e) => {
      const payload = (e as CustomEvent<IDragColumnChangePayload>).detail;
      this.handleColumnChange(payload);
    });
  }

  /**
   * Handle event moving to a new column during drag
   */
  private handleColumnChange(payload: IDragColumnChangePayload): void {
    const eventsLayer = payload.newColumn.querySelector('swp-events-layer');
    if (!eventsLayer) return;

    // Move element to new column
    eventsLayer.appendChild(payload.element);

    // Preserve Y position
    payload.element.style.top = `${payload.currentY}px`;
  }

  /**
   * Render events for visible dates into day columns
   * @param container - Calendar container element
   * @param filter - Filter with 'date' and optionally 'resource' arrays
   */
  async render(container: HTMLElement, filter: Record<string, string[]>): Promise<void> {
    const visibleDates = filter['date'] || [];

    if (visibleDates.length === 0) return;

    // 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);

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

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

    // Render events into each column based on data attributes
    columns.forEach(column => {
      const dateKey = (column as HTMLElement).dataset.date;
      const columnResourceId = (column as HTMLElement).dataset.resourceId;

      if (!dateKey) return;

      // Filter events for this column
      const columnEvents = events.filter(event => {
        // Must match date
        if (this.dateService.getDateKey(event.start) !== dateKey) return false;

        // If column has resourceId, event must match
        if (columnResourceId && event.resourceId !== columnResourceId) return false;

        // If no resourceId on column but resources in filter, show all
        // (this handles 'simple' view without resources)

        return true;
      });

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

  /**
   * 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>${this.dateService.formatTimeRange(event.start, event.end)}</swp-event-time>
      <swp-event-title>${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;
  }
}