import { CalendarConfig } from '../core/CalendarConfig';
import { ResourceCalendarData } from '../types/CalendarTypes';
import { CalendarTypeFactory } from '../factories/CalendarTypeFactory';
import { HeaderRenderContext } from './HeaderRenderer';
import { ColumnRenderContext } from './ColumnRenderer';
import { eventBus } from '../core/EventBus';
/**
 * GridRenderer - Handles DOM rendering for the calendar grid
 * Separated from GridManager to follow Single Responsibility Principle
 */
export class GridRenderer {
  private config: CalendarConfig;
  private headerEventListener: ((event: Event) => void) | null = null;

  constructor(config: CalendarConfig) {
    this.config = config;
  }

  /**
   * Render the complete grid structure
   */
  public renderGrid(
    grid: HTMLElement, 
    currentWeek: Date, 
    resourceData: ResourceCalendarData | null
  ): void {
    
    if (!grid || !currentWeek) {
      return;
    }

    // Only clear and rebuild if grid is empty (first render)
    if (grid.children.length === 0) {
      // Create POC structure: header-spacer + time-axis + grid-container
      this.createHeaderSpacer(grid);
      this.createTimeAxis(grid);
      this.createGridContainer(grid, currentWeek, resourceData);
    } else {
      // Just update the calendar header for all-day events
      this.updateCalendarHeader(grid, currentWeek, resourceData);
    }
    
  }

  /**
   * Create header spacer to align time axis with week content
   */
  private createHeaderSpacer(grid: HTMLElement): void {
    const headerSpacer = document.createElement('swp-header-spacer');
    grid.appendChild(headerSpacer);
  }

  /**
   * Create time axis (positioned beside grid container)
   */
  private createTimeAxis(grid: HTMLElement): void {
    const timeAxis = document.createElement('swp-time-axis');
    const timeAxisContent = document.createElement('swp-time-axis-content');
    const gridSettings = this.config.getGridSettings();
    const startHour = gridSettings.dayStartHour;
    const endHour = gridSettings.dayEndHour;
    

    for (let hour = startHour; hour < endHour; hour++) {
      const marker = document.createElement('swp-hour-marker');
      const period = hour >= 12 ? 'PM' : 'AM';
      const displayHour = hour > 12 ? hour - 12 : (hour === 0 ? 12 : hour);
      marker.textContent = `${displayHour} ${period}`;
      timeAxisContent.appendChild(marker);
    }

    timeAxis.appendChild(timeAxisContent);
    grid.appendChild(timeAxis);
  }

  /**
   * Create grid container with header and scrollable content
   */
  private createGridContainer(
    grid: HTMLElement, 
    currentWeek: Date,
    resourceData: ResourceCalendarData | null
  ): void {
    const gridContainer = document.createElement('swp-grid-container');
    
    // Create calendar header using Strategy Pattern
    const calendarHeader = document.createElement('swp-calendar-header');
    this.renderCalendarHeader(calendarHeader, currentWeek, resourceData);
    gridContainer.appendChild(calendarHeader);
    
    // Create scrollable content
    const scrollableContent = document.createElement('swp-scrollable-content');
    const timeGrid = document.createElement('swp-time-grid');
    
    // Add grid lines
    const gridLines = document.createElement('swp-grid-lines');
    timeGrid.appendChild(gridLines);
    
    // Create column container using Strategy Pattern
    const columnContainer = document.createElement('swp-day-columns');
    this.renderColumnContainer(columnContainer, currentWeek, resourceData);
    timeGrid.appendChild(columnContainer);
    
    scrollableContent.appendChild(timeGrid);
    gridContainer.appendChild(scrollableContent);
    
    grid.appendChild(gridContainer);
  }

  /**
   * Render calendar header using Strategy Pattern
   */
  private renderCalendarHeader(
    calendarHeader: HTMLElement,
    currentWeek: Date,
    resourceData: ResourceCalendarData | null
  ): void {
    const calendarType = this.config.getCalendarMode();
    const headerRenderer = CalendarTypeFactory.getHeaderRenderer(calendarType);
    
    const context: HeaderRenderContext = {
      currentWeek: currentWeek,
      config: this.config,
      resourceData: resourceData
    };

    headerRenderer.render(calendarHeader, context);
    
    // Always ensure all-day containers exist for all days
    headerRenderer.ensureAllDayContainers(calendarHeader);
    
    // Setup event listener for mouseover detection
    this.setupHeaderEventListener(calendarHeader);
  }

  /**
   * Render column container using Strategy Pattern
   */
  private renderColumnContainer(
    columnContainer: HTMLElement,
    currentWeek: Date,
    resourceData: ResourceCalendarData | null
  ): void {
    const calendarType = this.config.getCalendarMode();
    const columnRenderer = CalendarTypeFactory.getColumnRenderer(calendarType);
    
    const context: ColumnRenderContext = {
      currentWeek: currentWeek,
      config: this.config,
      resourceData: resourceData
    };

    columnRenderer.render(columnContainer, context);
  }

  /**
   * Update only the calendar header without rebuilding entire grid
   */
  private updateCalendarHeader(
    grid: HTMLElement,
    currentWeek: Date,
    resourceData: ResourceCalendarData | null
  ): void {
    const calendarHeader = grid.querySelector('swp-calendar-header');
    if (!calendarHeader) return;

    // Clear existing content
    calendarHeader.innerHTML = '';

    // Re-render headers using Strategy Pattern - this will also re-attach the event listener
    this.renderCalendarHeader(calendarHeader as HTMLElement, currentWeek, resourceData);
  }

  /**
   * Setup or re-setup event delegation listener on calendar header
   */
  private setupHeaderEventListener(calendarHeader: HTMLElement): void {
    // Remove existing listener if any (stored reference approach)
    if (this.headerEventListener) {
      calendarHeader.removeEventListener('mouseover', this.headerEventListener);
    }

    // Create new listener function
    this.headerEventListener = (event) => {
      const target = event.target as HTMLElement;
      
      // Check what was hovered - could be day-header OR all-day-container
      const dayHeader = target.closest('swp-day-header');
      const allDayContainer = target.closest('swp-allday-container');
      
      if (dayHeader || allDayContainer) {
        let hoveredElement: HTMLElement;
        let targetDate: string | undefined;
        
        if (dayHeader) {
          hoveredElement = dayHeader as HTMLElement;
          targetDate = hoveredElement.dataset.date;
        } else if (allDayContainer) {
          // For all-day areas, we need to determine which day column we're over
          hoveredElement = allDayContainer as HTMLElement;
          
          // Calculate which day we're hovering over based on mouse position
          const headerRect = calendarHeader.getBoundingClientRect();
          const dayHeaders = calendarHeader.querySelectorAll('swp-day-header');
          const mouseX = (event as MouseEvent).clientX - headerRect.left;
          const dayWidth = headerRect.width / dayHeaders.length;
          const dayIndex = Math.floor(mouseX / dayWidth);
          
          const targetDayHeader = dayHeaders[dayIndex] as HTMLElement;
          targetDate = targetDayHeader?.dataset.date;
        } else {
          return; // No valid element found
        }
        
        
        // Get the header renderer for addToAllDay functionality
        const calendarType = this.config.getCalendarMode();
        const headerRenderer = CalendarTypeFactory.getHeaderRenderer(calendarType);
        
        eventBus.emit('header:mouseover', { 
          element: hoveredElement,
          targetDate,
          headerRenderer 
        });
      }
    };

    // Add the new listener
    calendarHeader.addEventListener('mouseover', this.headerEventListener);
  }
}