import { IEventBus } from '../types/CalendarTypes.js';
import { DateUtils } from '../utils/DateUtils.js';
import { EventTypes } from '../constants/EventTypes.js';

/**
 * NavigationManager handles calendar navigation (prev/next/today buttons)
 * with simplified CSS Grid approach
 */
export class NavigationManager {
  private eventBus: IEventBus;
  private currentWeek: Date;
  private targetWeek: Date;
  private animationQueue: number = 0;

  constructor(eventBus: IEventBus) {
    console.log('🧭 NavigationManager: Constructor called');
    this.eventBus = eventBus;
    this.currentWeek = DateUtils.getWeekStart(new Date(), 0); // Sunday start like POC
    this.targetWeek = new Date(this.currentWeek);
    this.init();
  }

  private init(): void {
    this.setupEventListeners();
    // Don't update week info immediately - wait for DOM to be ready
    console.log('NavigationManager: Waiting for CALENDAR_INITIALIZED before updating DOM');
  }

  private setupEventListeners(): void {
    // Initial DOM update when calendar is initialized
    this.eventBus.on(EventTypes.CALENDAR_INITIALIZED, () => {
      console.log('NavigationManager: Received CALENDAR_INITIALIZED, updating week info');
      this.updateWeekInfo();
    });

    // Listen for navigation button clicks
    document.addEventListener('click', (e) => {
      const target = e.target as HTMLElement;
      const navButton = target.closest('[data-action]') as HTMLElement;
      
      if (!navButton) return;
      
      const action = navButton.dataset.action;
      
      switch (action) {
        case 'prev':
          this.navigateToPreviousWeek();
          break;
        case 'next':
          this.navigateToNextWeek();
          break;
        case 'today':
          this.navigateToToday();
          break;
      }
    });

    // Listen for external navigation requests
    this.eventBus.on(EventTypes.NAVIGATE_TO_DATE, (event: Event) => {
      const customEvent = event as CustomEvent;
      const targetDate = new Date(customEvent.detail.date);
      this.navigateToDate(targetDate);
    });
  }

  private navigateToPreviousWeek(): void {
    this.targetWeek.setDate(this.targetWeek.getDate() - 7);
    const weekToShow = new Date(this.targetWeek);
    this.animationQueue++;
    this.animateTransition('prev', weekToShow);
  }

  private navigateToNextWeek(): void {
    this.targetWeek.setDate(this.targetWeek.getDate() + 7);
    const weekToShow = new Date(this.targetWeek);
    this.animationQueue++;
    this.animateTransition('next', weekToShow);
  }

  private navigateToToday(): void {
    const today = new Date();
    const todayWeekStart = DateUtils.getWeekStart(today, 0);
    
    // Reset to today
    this.targetWeek = new Date(todayWeekStart);
    
    const currentTime = this.currentWeek.getTime();
    const targetTime = todayWeekStart.getTime();
    
    if (currentTime < targetTime) {
      this.animationQueue++;
      this.animateTransition('next', todayWeekStart);
    } else if (currentTime > targetTime) {
      this.animationQueue++;
      this.animateTransition('prev', todayWeekStart);
    }
  }

  private navigateToDate(date: Date): void {
    const weekStart = DateUtils.getWeekStart(date, 0);
    this.targetWeek = new Date(weekStart);
    
    const currentTime = this.currentWeek.getTime();
    const targetTime = weekStart.getTime();
    
    if (currentTime < targetTime) {
      this.animationQueue++;
      this.animateTransition('next', weekStart);
    } else if (currentTime > targetTime) {
      this.animationQueue++;
      this.animateTransition('prev', weekStart);
    }
  }

  /**
   * POC-style animation transition - creates new grid container and slides it in
   */
  private animateTransition(direction: 'prev' | 'next', targetWeek: Date): void {
    const container = document.querySelector('swp-calendar-container');
    const currentGrid = container?.querySelector('swp-grid-container');
    
    if (!container || !currentGrid) {
      console.warn('NavigationManager: Required DOM elements not found');
      return;
    }

    console.log(`NavigationManager: Starting ${direction} animation to ${targetWeek.toDateString()}`);

    // Create new grid container (POC approach)
    const newGrid = document.createElement('swp-grid-container');
    newGrid.innerHTML = `
      <swp-calendar-header></swp-calendar-header>
      <swp-scrollable-content>
        <swp-time-grid>
          <swp-grid-lines></swp-grid-lines>
          <swp-day-columns></swp-day-columns>
        </swp-time-grid>
      </swp-scrollable-content>
    `;

    // Position new grid off-screen (POC positioning)
    newGrid.style.position = 'absolute';
    newGrid.style.top = '0';
    newGrid.style.left = '0';
    newGrid.style.width = '100%';
    newGrid.style.height = '100%';
    newGrid.style.transform = direction === 'next' ? 'translateX(100%)' : 'translateX(-100%)';

    // Add to container
    container.appendChild(newGrid);

    // Render new content for target week
    this.renderWeekContent(newGrid, targetWeek);

    // Animate transition (POC animation)
    requestAnimationFrame(() => {
      // Slide out current grid
      (currentGrid as HTMLElement).style.transform = direction === 'next' ? 'translateX(-100%)' : 'translateX(100%)';
      (currentGrid as HTMLElement).style.opacity = '0.5';
      
      // Cleanup: Remove all old grids except the new one after animation
      setTimeout(() => {
        const allGrids = container.querySelectorAll('swp-grid-container');
        // Keep only the newest grid (last one), remove all others
        for (let i = 0; i < allGrids.length - 1; i++) {
          allGrids[i].remove();
        }
      }, 450);
      
      // Slide in new grid
      newGrid.style.transform = 'translateX(0)';
      
      // Wait for new grid animation to complete before updating state
      setTimeout(() => {
        newGrid.style.position = 'relative';
        
        // Only now is the animation truly complete
        this.currentWeek = new Date(targetWeek);
        this.animationQueue--;
        
        // If this was the last queued animation, ensure we're in sync
        if (this.animationQueue === 0) {
          this.currentWeek = new Date(this.targetWeek);
        }
        
        // Update week info and notify other managers
        this.updateWeekInfo();
        this.eventBus.emit(EventTypes.WEEK_CHANGED, {
          weekStart: this.currentWeek,
          weekEnd: DateUtils.addDays(this.currentWeek, 6)
        });
        
        console.log(`NavigationManager: Completed ${direction} animation`);
      }, 400); // Wait for slide-in animation to complete
    });
  }

  /**
   * Render week content in the new grid container
   */
  private renderWeekContent(gridContainer: HTMLElement, weekStart: Date): void {
    const header = gridContainer.querySelector('swp-calendar-header');
    const dayColumns = gridContainer.querySelector('swp-day-columns');
    
    if (!header || !dayColumns) return;

    // Clear existing content
    header.innerHTML = '';
    dayColumns.innerHTML = '';

    // Render headers for target week
    const days = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];
    for (let i = 0; i < 7; i++) {
      const date = new Date(weekStart);
      date.setDate(date.getDate() + i);
      
      const headerElement = document.createElement('swp-day-header');
      if (this.isToday(date)) {
        headerElement.dataset.today = 'true';
      }
      
      headerElement.innerHTML = `
        <swp-day-name>${days[date.getDay()]}</swp-day-name>
        <swp-day-date>${date.getDate()}</swp-day-date>
      `;
      headerElement.dataset.date = this.formatDate(date);
      
      header.appendChild(headerElement);
    }
    
    // Render day columns for target week
    for (let i = 0; i < 7; i++) {
      const column = document.createElement('swp-day-column');
      const date = new Date(weekStart);
      date.setDate(date.getDate() + i);
      column.dataset.date = this.formatDate(date);
      
      const eventsLayer = document.createElement('swp-events-layer');
      column.appendChild(eventsLayer);
      
      dayColumns.appendChild(column);
    }

    // NOTE: Removed POC event emission to prevent interference with production code
    // POC events should not trigger production event rendering
    // this.eventBus.emit(EventTypes.WEEK_CONTENT_RENDERED, { ... });
  }

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

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

  private updateWeekInfo(): void {
    const weekNumber = DateUtils.getWeekNumber(this.currentWeek);
    const weekEnd = DateUtils.addDays(this.currentWeek, 6);
    const dateRange = DateUtils.formatDateRange(this.currentWeek, weekEnd);
    
    // Update week info in DOM
    const weekNumberElement = document.querySelector('swp-week-number');
    const dateRangeElement = document.querySelector('swp-date-range');
    
    if (weekNumberElement) {
      weekNumberElement.textContent = `Week ${weekNumber}`;
      console.log('NavigationManager: Updated week number:', `Week ${weekNumber}`);
    } else {
      console.warn('NavigationManager: swp-week-number element not found in DOM');
    }
    
    if (dateRangeElement) {
      dateRangeElement.textContent = dateRange;
      console.log('NavigationManager: Updated date range:', dateRange);
    } else {
      console.warn('NavigationManager: swp-date-range element not found in DOM');
    }
    
    // Notify other managers about week info update
    this.eventBus.emit(EventTypes.WEEK_INFO_UPDATED, {
      weekNumber,
      dateRange,
      weekStart: this.currentWeek,
      weekEnd
    });
  }

  /**
   * Get current week start date
   */
  getCurrentWeek(): Date {
    return new Date(this.currentWeek);
  }

  /**
   * Get target week (where navigation is heading)
   */
  getTargetWeek(): Date {
    return new Date(this.targetWeek);
  }

  /**
   * Check if navigation animation is in progress
   */
  isAnimating(): boolean {
    return this.animationQueue > 0;
  }

  /**
   * Force navigation to specific week without animation
   */
  setWeek(weekStart: Date): void {
    this.currentWeek = new Date(weekStart);
    this.targetWeek = new Date(weekStart);
    this.updateWeekInfo();
    
    this.eventBus.emit(EventTypes.WEEK_CHANGED, {
      weekStart: this.currentWeek,
      weekEnd: DateUtils.addDays(this.currentWeek, 6)
    });
  }
}