// Grid structure management

import { eventBus } from '../core/EventBus';
import { calendarConfig } from '../core/CalendarConfig';
import { EventTypes } from '../constants/EventTypes';
import { DateUtils } from '../utils/DateUtils';

/**
 * Grid position interface
 */
interface GridPosition {
  minutes: number;
  time: string;
  y: number;
}

/**
 * Manages the calendar grid structure
 */
export class GridManager {
  private container: HTMLElement | null = null;
  private timeAxis: HTMLElement | null = null;
  private weekHeader: HTMLElement | null = null;
  private timeGrid: HTMLElement | null = null;
  private dayColumns: HTMLElement | null = null;
  private scrollableContent: HTMLElement | null = null;
  private currentWeek: Date | null = null;
  
  constructor() {
    this.init();
  }

  private init(): void {
    this.findElements();
    this.subscribeToEvents();
    this.setupScrollSync();
  }

  private findElements(): void {
    this.container = document.querySelector('swp-calendar-container');
    this.timeAxis = document.querySelector('swp-time-axis');
    this.weekHeader = document.querySelector('swp-week-header');
    this.timeGrid = document.querySelector('swp-time-grid');
    this.scrollableContent = document.querySelector('swp-scrollable-content');
  }

  private subscribeToEvents(): void {
    // Re-render grid on config changes
    eventBus.on(EventTypes.CONFIG_UPDATE, (e: Event) => {
      const detail = (e as CustomEvent).detail;
      if (['dayStartHour', 'dayEndHour', 'hourHeight', 'view', 'weekDays'].includes(detail.key)) {
        this.render();
      }
    });

    // Re-render on view change
    eventBus.on(EventTypes.VIEW_CHANGE, () => {
      this.render();
    });

    // Re-render on period change
    eventBus.on(EventTypes.PERIOD_CHANGE, (e: Event) => {
      const detail = (e as CustomEvent).detail;
      this.currentWeek = detail.week;
      this.renderHeaders();
    });

    // Handle week changes from NavigationManager
    eventBus.on(EventTypes.WEEK_CHANGED, (e: Event) => {
      const detail = (e as CustomEvent).detail;
      this.currentWeek = detail.weekStart;
      this.render();
    });

    // Handle new week container creation
    eventBus.on(EventTypes.WEEK_CONTAINER_CREATED, (e: Event) => {
      const detail = (e as CustomEvent).detail;
      this.renderGridForContainer(detail.container, detail.weekStart);
    });

    // Handle grid clicks
    this.setupGridInteractions();
  }

  /**
   * Render the complete grid structure
   */
  render(): void {
    this.renderTimeAxis();
    this.renderHeaders();
    this.renderGrid();
    this.renderGridLines();
    
    // Emit grid rendered event
    eventBus.emit(EventTypes.GRID_RENDERED);
  }

  /**
   * Render time axis (left side hours)
   */
  private renderTimeAxis(): void {
    if (!this.timeAxis) return;

    const startHour = calendarConfig.get('dayStartHour');
    const endHour = calendarConfig.get('dayEndHour');
    
    this.timeAxis.innerHTML = '';
    
    for (let hour = startHour; hour <= endHour; hour++) {
      const marker = document.createElement('swp-hour-marker');
      marker.textContent = this.formatHour(hour);
      (marker as any).dataset.hour = hour;
      this.timeAxis.appendChild(marker);
    }
  }

  /**
   * Render week headers
   */
  private renderHeaders(): void {
    if (!this.weekHeader || !this.currentWeek) return;

    const view = calendarConfig.get('view');
    const weekDays = calendarConfig.get('weekDays');
    
    this.weekHeader.innerHTML = '';

    if (view === 'week') {
      const dates = this.getWeekDates(this.currentWeek);
      const daysToShow = dates.slice(0, weekDays);
      
      daysToShow.forEach((date, index) => {
        const header = document.createElement('swp-day-header');
        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);
        (header as any).dataset.dayIndex = index;
        
        // Mark today
        if (this.isToday(date)) {
          (header as any).dataset.today = 'true';
        }
        
        this.weekHeader!.appendChild(header);
      });
    }
  }

  /**
   * Render the main grid structure
   */
  private renderGrid(): void {
    if (!this.timeGrid) return;

    // Clear existing columns
    let dayColumns = this.timeGrid.querySelector('swp-day-columns');
    if (!dayColumns) {
      dayColumns = document.createElement('swp-day-columns');
      this.timeGrid.appendChild(dayColumns);
    }
    
    dayColumns.innerHTML = '';
    
    const view = calendarConfig.get('view');
    const columnsCount = view === 'week' ? calendarConfig.get('weekDays') : 1;
    
    // Create columns
    for (let i = 0; i < columnsCount; i++) {
      const column = document.createElement('swp-day-column');
      (column as any).dataset.columnIndex = i;
      
      if (this.currentWeek) {
        const dates = this.getWeekDates(this.currentWeek);
        if (dates[i]) {
          (column as any).dataset.date = this.formatDate(dates[i]);
        }
      }
      
      // Add events container
      const eventsLayer = document.createElement('swp-events-layer');
      column.appendChild(eventsLayer);
      
      dayColumns.appendChild(column);
    }

    this.dayColumns = dayColumns as HTMLElement;
    this.updateGridStyles();
  }

  /**
   * Render grid lines
   */
  private renderGridLines(): void {
    if (!this.timeGrid) return;

    let gridLines = this.timeGrid.querySelector('swp-grid-lines');
    if (!gridLines) {
      gridLines = document.createElement('swp-grid-lines');
      this.timeGrid.insertBefore(gridLines, this.timeGrid.firstChild);
    }

    const totalHours = calendarConfig.totalHours;
    const hourHeight = calendarConfig.get('hourHeight');
    
    // Set CSS variables
    this.timeGrid.style.setProperty('--total-hours', totalHours.toString());
    this.timeGrid.style.setProperty('--hour-height', `${hourHeight}px`);
    
    // Grid lines are handled by CSS
  }

  /**
   * Update grid CSS variables
   */
  private updateGridStyles(): void {
    const root = document.documentElement;
    const config = calendarConfig.getAll();
    
    // Set CSS variables
    root.style.setProperty('--hour-height', `${config.hourHeight}px`);
    root.style.setProperty('--minute-height', `${config.hourHeight / 60}px`);
    root.style.setProperty('--snap-interval', config.snapInterval.toString());
    root.style.setProperty('--day-start-hour', config.dayStartHour.toString());
    root.style.setProperty('--day-end-hour', config.dayEndHour.toString());
    root.style.setProperty('--work-start-hour', config.workStartHour.toString());
    root.style.setProperty('--work-end-hour', config.workEndHour.toString());
    
    // Set grid height
    const totalHeight = calendarConfig.totalHours * config.hourHeight;
    if (this.timeGrid) {
      this.timeGrid.style.height = `${totalHeight}px`;
    }
  }

  /**
   * Setup grid interaction handlers
   */
  private setupGridInteractions(): void {
    if (!this.timeGrid) return;

    // Click handler
    this.timeGrid.addEventListener('click', (e: MouseEvent) => {
      // Ignore if clicking on an event
      if ((e.target as Element).closest('swp-event')) return;
      
      const column = (e.target as Element).closest('swp-day-column') as HTMLElement;
      if (!column) return;

      const position = this.getClickPosition(e, column);
      
      eventBus.emit(EventTypes.GRID_CLICK, {
        date: (column as any).dataset.date,
        time: position.time,
        minutes: position.minutes,
        columnIndex: parseInt((column as any).dataset.columnIndex)
      });
    });

    // Double click handler
    this.timeGrid.addEventListener('dblclick', (e: MouseEvent) => {
      // Ignore if clicking on an event
      if ((e.target as Element).closest('swp-event')) return;
      
      const column = (e.target as Element).closest('swp-day-column') as HTMLElement;
      if (!column) return;

      const position = this.getClickPosition(e, column);
      
      eventBus.emit(EventTypes.GRID_DBLCLICK, {
        date: (column as any).dataset.date,
        time: position.time,
        minutes: position.minutes,
        columnIndex: parseInt((column as any).dataset.columnIndex)
      });
    });
  }

  /**
   * Get click position in grid
   */
  private getClickPosition(event: MouseEvent, column: HTMLElement): GridPosition {
    const rect = column.getBoundingClientRect();
    const y = event.clientY - rect.top + (this.scrollableContent?.scrollTop || 0);
    
    const minuteHeight = calendarConfig.minuteHeight;
    const snapInterval = calendarConfig.get('snapInterval');
    const dayStartHour = calendarConfig.get('dayStartHour');
    
    // Calculate minutes from start of day
    let minutes = Math.floor(y / minuteHeight);
    
    // Snap to interval
    minutes = Math.round(minutes / snapInterval) * snapInterval;
    
    // Add day start offset
    const totalMinutes = (dayStartHour * 60) + minutes;
    
    return {
      minutes: totalMinutes,
      time: this.minutesToTime(totalMinutes),
      y: minutes * minuteHeight
    };
  }

  /**
   * Utility methods
   */
  
  private formatHour(hour: number): string {
    const period = hour >= 12 ? 'PM' : 'AM';
    const displayHour = hour > 12 ? hour - 12 : (hour === 0 ? 12 : hour);
    return `${displayHour} ${period}`;
  }

  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()];
  }

  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 minutesToTime(totalMinutes: number): string {
    const hours = Math.floor(totalMinutes / 60);
    const minutes = totalMinutes % 60;
    const period = hours >= 12 ? 'PM' : 'AM';
    const displayHour = hours > 12 ? hours - 12 : (hours === 0 ? 12 : hours);
    
    return `${displayHour}:${minutes.toString().padStart(2, '0')} ${period}`;
  }

  /**
   * Scroll to specific hour
   */
  scrollToHour(hour: number): void {
    if (!this.scrollableContent) return;
    
    const hourHeight = calendarConfig.get('hourHeight');
    const dayStartHour = calendarConfig.get('dayStartHour');
    const scrollTop = (hour - dayStartHour) * hourHeight;
    
    this.scrollableContent.scrollTop = scrollTop;
  }

  /**
   * Render grid for a specific container (used during navigation transitions)
   */
  private renderGridForContainer(container: HTMLElement, weekStart: Date): void {
    // Find the week header and scrollable content within this container
    const weekHeader = container.querySelector('swp-week-header');
    const scrollableContent = container.querySelector('swp-scrollable-content');
    const timeGrid = container.querySelector('swp-time-grid');
    
    if (!weekHeader || !scrollableContent || !timeGrid) {
      console.warn('GridManager: Required elements not found in container');
      return;
    }

    // Render week header for this container
    this.renderWeekHeaderForContainer(weekHeader as HTMLElement, weekStart);
    
    // Render grid content for this container - pass weekStart
    this.renderGridForSpecificContainer(container, weekStart);
    this.renderGridLinesForContainer(timeGrid as HTMLElement);
    this.setupGridInteractionsForContainer(container);
    
    // Setup scroll sync for this new container
    this.setupScrollSyncForContainer(scrollableContent as HTMLElement);
  }

  /**
   * Render week header for a specific container
   */
  private renderWeekHeaderForContainer(weekHeader: HTMLElement, weekStart: Date): void {
    const days = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];
    
    weekHeader.innerHTML = '';
    
    for (let i = 0; i < 7; i++) {
      const date = new Date(weekStart);
      date.setDate(date.getDate() + i);
      
      const header = document.createElement('swp-day-header');
      if (this.isToday(date)) {
        (header as any).dataset.today = 'true';
      }
      
      header.innerHTML = `
        <swp-day-name>${days[date.getDay()]}</swp-day-name>
        <swp-day-date>${date.getDate()}</swp-day-date>
      `;
      (header as any).dataset.date = this.formatDate(date);
      
      weekHeader.appendChild(header);
    }
  }

  /**
   * Render grid structure for a specific container
   */
  private renderGridForSpecificContainer(container: HTMLElement, weekStart?: Date): void {
    const timeGrid = container.querySelector('swp-time-grid');
    if (!timeGrid) {
      console.warn('GridManager: No time-grid found in container');
      return;
    }

    // Use the weekStart parameter or fall back to currentWeek
    const targetWeek = weekStart || this.currentWeek;
    if (!targetWeek) {
      console.warn('GridManager: No target week available');
      return;
    }

    // Clear existing columns
    let dayColumns = timeGrid.querySelector('swp-day-columns');
    if (!dayColumns) {
      dayColumns = document.createElement('swp-day-columns');
      timeGrid.appendChild(dayColumns);
    }
    
    dayColumns.innerHTML = '';
    
    const view = calendarConfig.get('view');
    const columnsCount = view === 'week' ? calendarConfig.get('weekDays') : 1;
    
    // Create columns using the target week
    for (let i = 0; i < columnsCount; i++) {
      const column = document.createElement('swp-day-column');
      (column as any).dataset.columnIndex = i;
      
      const dates = this.getWeekDates(targetWeek);
      if (dates[i]) {
        (column as any).dataset.date = this.formatDate(dates[i]);
      }
      
      // Add events container
      const eventsLayer = document.createElement('swp-events-layer');
      column.appendChild(eventsLayer);
      
      dayColumns.appendChild(column);
    }

    // Update grid styles for this container
    const totalHeight = calendarConfig.totalHours * calendarConfig.get('hourHeight');
    (timeGrid as HTMLElement).style.height = `${totalHeight}px`;
  }

  /**
   * Render grid lines for a specific time grid
   */
  private renderGridLinesForContainer(timeGrid: HTMLElement): void {
    let gridLines = timeGrid.querySelector('swp-grid-lines');
    if (!gridLines) {
      gridLines = document.createElement('swp-grid-lines');
      timeGrid.insertBefore(gridLines, timeGrid.firstChild);
    }

    const totalHours = calendarConfig.totalHours;
    const hourHeight = calendarConfig.get('hourHeight');
    
    // Set CSS variables
    timeGrid.style.setProperty('--total-hours', totalHours.toString());
    timeGrid.style.setProperty('--hour-height', `${hourHeight}px`);
  }

  /**
   * Setup grid interactions for a specific container
   */
  private setupGridInteractionsForContainer(container: HTMLElement): void {
    const timeGrid = container.querySelector('swp-time-grid');
    if (!timeGrid) return;

    // Click handler
    timeGrid.addEventListener('click', (e: Event) => {
      const mouseEvent = e as MouseEvent;
      // Ignore if clicking on an event
      if ((mouseEvent.target as Element).closest('swp-event')) return;
      
      const column = (mouseEvent.target as Element).closest('swp-day-column') as HTMLElement;
      if (!column) return;

      const position = this.getClickPositionForContainer(mouseEvent, column, container);
      
      eventBus.emit(EventTypes.GRID_CLICK, {
        date: (column as any).dataset.date,
        time: position.time,
        minutes: position.minutes,
        columnIndex: parseInt((column as any).dataset.columnIndex)
      });
    });

    // Double click handler
    timeGrid.addEventListener('dblclick', (e: Event) => {
      const mouseEvent = e as MouseEvent;
      // Ignore if clicking on an event
      if ((mouseEvent.target as Element).closest('swp-event')) return;
      
      const column = (mouseEvent.target as Element).closest('swp-day-column') as HTMLElement;
      if (!column) return;

      const position = this.getClickPositionForContainer(mouseEvent, column, container);
      
      eventBus.emit(EventTypes.GRID_DBLCLICK, {
        date: (column as any).dataset.date,
        time: position.time,
        minutes: position.minutes,
        columnIndex: parseInt((column as any).dataset.columnIndex)
      });
    });
  }

  /**
   * Get click position for a specific container
   */
  private getClickPositionForContainer(event: MouseEvent, column: HTMLElement, container: HTMLElement): GridPosition {
    const rect = column.getBoundingClientRect();
    const scrollableContent = container.querySelector('swp-scrollable-content') as HTMLElement;
    const y = event.clientY - rect.top + (scrollableContent?.scrollTop || 0);
    
    const minuteHeight = calendarConfig.minuteHeight;
    const snapInterval = calendarConfig.get('snapInterval');
    const dayStartHour = calendarConfig.get('dayStartHour');
    
    // Calculate minutes from start of day
    let minutes = Math.floor(y / minuteHeight);
    
    // Snap to interval
    minutes = Math.round(minutes / snapInterval) * snapInterval;
    
    // Add day start offset
    const totalMinutes = (dayStartHour * 60) + minutes;
    
    return {
      minutes: totalMinutes,
      time: this.minutesToTime(totalMinutes),
      y: minutes * minuteHeight
    };
  }

  /**
   * Setup scroll synchronization between time-axis and scrollable content
   */
  private setupScrollSync(): void {
    if (!this.scrollableContent || !this.timeAxis) return;

    // Sync time-axis scroll with scrollable content
    this.scrollableContent.addEventListener('scroll', () => {
      if (this.timeAxis) {
        this.timeAxis.scrollTop = this.scrollableContent!.scrollTop;
      }
    });
  }

  /**
   * Setup scroll synchronization for a specific container's scrollable content
   */
  private setupScrollSyncForContainer(scrollableContent: HTMLElement): void {
    if (!this.timeAxis) return;

    // Sync time-axis scroll with this container's scrollable content
    scrollableContent.addEventListener('scroll', () => {
      if (this.timeAxis) {
        this.timeAxis.scrollTop = scrollableContent.scrollTop;
      }
    });
  }
}