// Header rendering strategy interface and implementations

import { CalendarConfig } from '../core/CalendarConfig';
import { ResourceCalendarData } from '../types/CalendarTypes';

/**
 * Interface for header rendering strategies
 */
export interface HeaderRenderer {
  render(calendarHeader: HTMLElement, context: HeaderRenderContext): void;
}

/**
 * Context for header rendering
 */
export interface HeaderRenderContext {
  currentWeek: Date;
  config: CalendarConfig;
  allDayEvents?: any[];
  resourceData?: ResourceCalendarData | null;
}

/**
 * Date-based header renderer (original functionality)
 */
export class DateHeaderRenderer implements HeaderRenderer {
  render(calendarHeader: HTMLElement, context: HeaderRenderContext): void {
    const { currentWeek, config, allDayEvents = [] } = context;
    
    const dates = this.getWeekDates(currentWeek);
    const weekDays = config.get('weekDays');
    const daysToShow = dates.slice(0, weekDays);

    daysToShow.forEach((date) => {
      const header = document.createElement('swp-day-header');
      if (this.isToday(date)) {
        (header as any).dataset.today = 'true';
      }
      
      header.innerHTML = `
        <swp-day-name>${this.getDayName(date)}</swp-day-name>
        <swp-day-date>${date.getDate()}</swp-day-date>
      `;
      (header as any).dataset.date = this.formatDate(date);
      
      calendarHeader.appendChild(header);
    });

    // Render all-day events in row 2
    this.renderAllDayEvents(calendarHeader, context);
  }

  private renderAllDayEvents(calendarHeader: HTMLElement, context: HeaderRenderContext): void {
    const { currentWeek, config, allDayEvents = [] } = context;
    
    const dates = this.getWeekDates(currentWeek);
    const weekDays = config.get('weekDays');
    const daysToShow = dates.slice(0, weekDays);

    // Process each all-day event to calculate its span
    allDayEvents.forEach(event => {
      const startDate = new Date(event.start);
      const endDate = new Date(event.end);
      
      // Find start and end column indices
      let startColumnIndex = -1;
      let endColumnIndex = -1;
      
      daysToShow.forEach((date, index) => {
        const dateStr = this.formatDate(date);
        const startDateStr = this.formatDate(startDate);
        
        if (dateStr === startDateStr) {
          startColumnIndex = index;
        }
        
        // For end date, we need to check if the event spans to this day
        if (date <= endDate) {
          endColumnIndex = index;
        }
      });
      
      // Only render if the event starts within the visible week
      if (startColumnIndex >= 0) {
        // If end column is not found or is before start, default to single day
        if (endColumnIndex < startColumnIndex) {
          endColumnIndex = startColumnIndex;
        }
        
        const allDayEvent = document.createElement('swp-allday-event');
        allDayEvent.textContent = event.title;
        
        // Set grid column span: start column (1-based) to end column + 1 (1-based)
        const gridColumnStart = startColumnIndex + 1;
        const gridColumnEnd = endColumnIndex + 2;
        allDayEvent.style.gridColumn = `${gridColumnStart} / ${gridColumnEnd}`;
        allDayEvent.style.backgroundColor = event.metadata?.color || '#ff9800';
        
        calendarHeader.appendChild(allDayEvent);
      }
    });
  }

  private getWeekDates(weekStart: Date): Date[] {
    const dates: Date[] = [];
    for (let i = 0; i < 7; i++) {
      const date = new Date(weekStart);
      date.setDate(weekStart.getDate() + i);
      dates.push(date);
    }
    return dates;
  }

  private isToday(date: Date): boolean {
    const today = new Date();
    return date.toDateString() === today.toDateString();
  }

  private formatDate(date: Date): string {
    return `${date.getFullYear()}-${String(date.getMonth() + 1).padStart(2, '0')}-${String(date.getDate()).padStart(2, '0')}`;
  }

  private getDayName(date: Date): string {
    const days = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];
    return days[date.getDay()];
  }
}

/**
 * Resource-based header renderer
 */
export class ResourceHeaderRenderer implements HeaderRenderer {
  render(calendarHeader: HTMLElement, context: HeaderRenderContext): void {
    const { resourceData } = context;
    
    if (!resourceData) {
      console.warn('ResourceHeaderRenderer: No resource data available for resource headers');
      return;
    }

    resourceData.resources.forEach((resource) => {
      const header = document.createElement('swp-resource-header');
      header.setAttribute('data-resource', resource.name);
      header.setAttribute('data-employee-id', resource.employeeId);
      
      header.innerHTML = `
        <swp-resource-avatar>
          <img src="${resource.avatarUrl}" alt="${resource.displayName}" onerror="this.style.display='none'">
        </swp-resource-avatar>
        <swp-resource-name>${resource.displayName}</swp-resource-name>
      `;
      
      calendarHeader.appendChild(header);
    });

    console.log(`ResourceHeaderRenderer: Rendered ${resourceData.resources.length} resource headers`);
  }
}