// Event rendering strategy interface and implementations

import { CalendarEvent } from '../types/CalendarTypes';
import { ALL_DAY_CONSTANTS } from '../core/CalendarConfig';
import { CalendarConfig } from '../core/CalendarConfig';
import { DateCalculator } from '../utils/DateCalculator';

/**
 * Interface for event rendering strategies
 */
export interface EventRendererStrategy {
  renderEvents(events: CalendarEvent[], container: HTMLElement, config: CalendarConfig): void;
  clearEvents(container?: HTMLElement): void;
}

/**
 * Base class for event renderers with common functionality
 */
export abstract class BaseEventRenderer implements EventRendererStrategy {
  protected dateCalculator: DateCalculator;

  constructor(config: CalendarConfig) {
    this.dateCalculator = new DateCalculator(config);
  }
  renderEvents(events: CalendarEvent[], container: HTMLElement, config: CalendarConfig): void {
    console.log('BaseEventRenderer: renderEvents called with', events.length, 'events');
    
    // NOTE: Removed clearEvents() to support sliding animation
    // With sliding animation, multiple grid containers exist simultaneously
    // clearEvents() would remove events from all containers, breaking the animation
    // Events are now rendered directly into the new container without clearing

    // Separate all-day events from regular events
    const allDayEvents = events.filter(event => event.allDay);
    const regularEvents = events.filter(event => !event.allDay);
    
    console.log(`BaseEventRenderer: Rendering ${allDayEvents.length} all-day events and ${regularEvents.length} regular events`);

    // Always call renderAllDayEvents to ensure height is set correctly (even to 0)
    this.renderAllDayEvents(allDayEvents, container, config);

    // Find columns in the specific container for regular events
    const columns = this.getColumns(container);
    console.log(`BaseEventRenderer: Found ${columns.length} columns in container`);

    columns.forEach(column => {
      const columnEvents = this.getEventsForColumn(column, regularEvents);
      console.log(`BaseEventRenderer: Rendering ${columnEvents.length} regular events in column`);
      
      const eventsLayer = column.querySelector('swp-events-layer');
      if (eventsLayer) {
        columnEvents.forEach(event => {
          console.log(`BaseEventRenderer: Rendering event "${event.title}" in events layer`);
          this.renderEvent(event, eventsLayer, config);
        });
        
        // Debug: Verify events were actually added
        const renderedEvents = eventsLayer.querySelectorAll('swp-event');
        console.log(`BaseEventRenderer: Events layer now has ${renderedEvents.length} events`);
      } else {
        console.warn('BaseEventRenderer: No events layer found in column');
      }
    });
  }

  // Abstract methods that subclasses must implement
  protected abstract getColumns(container: HTMLElement): HTMLElement[];
  protected abstract getEventsForColumn(column: HTMLElement, events: CalendarEvent[]): CalendarEvent[];

  /**
   * Render all-day events in the header row 2
   */
  protected renderAllDayEvents(allDayEvents: CalendarEvent[], container: HTMLElement, config: CalendarConfig): void {
    console.log(`BaseEventRenderer: Rendering ${allDayEvents.length} all-day events using nested grid`);
    
    // Find the calendar header
    const calendarHeader = container.querySelector('swp-calendar-header');
    if (!calendarHeader) {
      console.warn('BaseEventRenderer: No calendar header found for all-day events');
      return;
    }

    // Find the all-day container
    const allDayContainer = calendarHeader.querySelector('swp-allday-container') as HTMLElement;
    if (!allDayContainer) {
      console.warn('BaseEventRenderer: No swp-allday-container found - HeaderRenderer should create this');
      return;
    }

    // Clear existing events
    allDayContainer.innerHTML = '';

    if (allDayEvents.length === 0) {
      // No events - just return
      this.updateAllDayHeight(1);
      return;
    }

    // Build date to column mapping
    const dayHeaders = calendarHeader.querySelectorAll('swp-day-header');
    const dateToColumnMap = new Map<string, number>();
    
    dayHeaders.forEach((header, index) => {
      const dateStr = (header as any).dataset.date;
      if (dateStr) {
        dateToColumnMap.set(dateStr, index + 1); // 1-based column index
      }
    });

    // Calculate grid spans for all events
    const eventSpans = allDayEvents.map(event => ({
      event,
      span: this.calculateEventGridSpan(event, dateToColumnMap)
    })).filter(item => item.span.columnSpan > 0); // Remove events outside visible range

    // Simple row assignment using overlap detection
    const eventPlacements: Array<{ event: CalendarEvent, span: { startColumn: number, columnSpan: number }, row: number }> = [];
    
    eventSpans.forEach(eventItem => {
      let assignedRow = 1;
      
      // Find first row where this event doesn't overlap with any existing event
      while (true) {
        const rowEvents = eventPlacements.filter(item => item.row === assignedRow);
        const hasOverlap = rowEvents.some(rowEvent => 
          this.eventsOverlap(eventItem.span, rowEvent.span)
        );
        
        if (!hasOverlap) {
          break; // Found available row
        }
        assignedRow++;
      }
      
      eventPlacements.push({
        event: eventItem.event,
        span: eventItem.span,
        row: assignedRow
      });
    });

    // Get max row needed
    const maxRow = Math.max(...eventPlacements.map(item => item.row), 1);

    // Place events directly in the single container
    eventPlacements.forEach(({ event, span, row }) => {
      // Create the all-day event element
      const allDayEvent = document.createElement('swp-allday-event');
      allDayEvent.textContent = event.title;
      allDayEvent.setAttribute('data-event-id', event.id);
      allDayEvent.setAttribute('data-type', event.type || 'work');
      
      // Set grid position (column and row)
      (allDayEvent as HTMLElement).style.gridColumn = span.columnSpan > 1 
        ? `${span.startColumn} / span ${span.columnSpan}`
        : `${span.startColumn}`;
      (allDayEvent as HTMLElement).style.gridRow = row.toString();

      // Use event metadata for color if available
      if (event.metadata?.color) {
        (allDayEvent as HTMLElement).style.backgroundColor = event.metadata.color;
      }
      
      allDayContainer.appendChild(allDayEvent);
      
      console.log(`BaseEventRenderer: Placed "${event.title}" in row ${row}, columns ${span.startColumn} to ${span.startColumn + span.columnSpan - 1}`);
    });

    // Update height based on max row
    this.updateAllDayHeight(maxRow);
    
    console.log(`BaseEventRenderer: Created ${maxRow} rows with auto-expanding grid`);
  }

  protected renderEvent(event: CalendarEvent, container: Element, config: CalendarConfig): void {
    const eventElement = document.createElement('swp-event');
    eventElement.dataset.eventId = event.id;
    eventElement.dataset.type = event.type;

    // Calculate position based on time
    const position = this.calculateEventPosition(event, config);
    eventElement.style.position = 'absolute';
    eventElement.style.top = `${position.top + 1}px`;
    eventElement.style.height = `${position.height - 3}px`; //adjusted so bottom does not cover horizontal time lines.

    // Color is now handled by CSS classes based on data-type attribute

    // Format time for display
    const startTime = this.dateCalculator.formatTime(new Date(event.start));
    const endTime = this.dateCalculator.formatTime(new Date(event.end));

    // Create event content
    eventElement.innerHTML = `
        <swp-event-time>${startTime} - ${endTime}</swp-event-time>
        <swp-event-title>${event.title}</swp-event-title>
    `;

    container.appendChild(eventElement);
    
    console.log(`BaseEventRenderer: Created event element for "${event.title}":`, {
      top: eventElement.style.top,
      height: eventElement.style.height,
      dataType: eventElement.dataset.type,
      position: eventElement.style.position,
      innerHTML: eventElement.innerHTML
    });
  }

  protected calculateEventPosition(event: CalendarEvent, config: CalendarConfig): { top: number; height: number } {
    const startDate = new Date(event.start);
    const endDate = new Date(event.end);
    
    const gridSettings = config.getGridSettings();
    const dayStartHour = gridSettings.dayStartHour;
    const hourHeight = gridSettings.hourHeight;

    // Calculate minutes from visible day start
    const startMinutes = startDate.getHours() * 60 + startDate.getMinutes();
    const endMinutes = endDate.getHours() * 60 + endDate.getMinutes();
    const dayStartMinutes = dayStartHour * 60;

    // Calculate top position (subtract day start to align with time axis)
    const top = ((startMinutes - dayStartMinutes) / 60) * hourHeight;
    
    // Calculate height
    const durationMinutes = endMinutes - startMinutes;
    const height = (durationMinutes / 60) * hourHeight;

    console.log('Event positioning calculation:', {
      eventTime: `${startDate.getHours()}:${startDate.getMinutes()}`,
      startMinutes,
      endMinutes,
      dayStartMinutes,
      dayStartHour,
      hourHeight,
      top,
      height
    });

    return { top, height };
  }

  protected formatTime(isoString: string): string {
    const date = new Date(isoString);
    const hours = date.getHours();
    const minutes = date.getMinutes();
    const period = hours >= 12 ? 'PM' : 'AM';
    const displayHour = hours > 12 ? hours - 12 : (hours === 0 ? 12 : hours);
    
    return `${displayHour}:${minutes.toString().padStart(2, '0')} ${period}`;
  }

  /**
   * Update all-day row height and grid template based on number of rows
   */
  private updateAllDayHeight(maxRows: number): void {
    const root = document.documentElement;
    const eventHeight = parseInt(getComputedStyle(root).getPropertyValue('--allday-event-height') || '26');
    const calculatedHeight = maxRows * eventHeight;
    root.style.setProperty('--all-day-row-height', `${calculatedHeight}px`);
    
    // Update grid-template-rows for all swp-allday-containers
    const allDayContainers = document.querySelectorAll('swp-allday-container');
    allDayContainers.forEach(container => {
      const gridRows = `repeat(${maxRows}, var(--allday-event-height, 26px))`;
      (container as HTMLElement).style.gridTemplateRows = gridRows;
    });
    
    console.log(`BaseEventRenderer: Set all-day height to ${calculatedHeight}px and grid-template-rows to ${maxRows} rows`);
  }

  /**
   * Calculate grid column span for event
   */
  private calculateEventGridSpan(event: CalendarEvent, dateToColumnMap: Map<string, number>): { startColumn: number, columnSpan: number } {
    const startDate = new Date(event.start);
    const endDate = new Date(event.end);
    const startDateKey = this.dateCalculator.formatISODate(startDate);
    const startColumn = dateToColumnMap.get(startDateKey);
    
    if (!startColumn) {
      return { startColumn: 0, columnSpan: 0 }; // Event outside visible range
    }

    // Calculate span by checking each day
    let endColumn = startColumn;
    const currentDate = new Date(startDate);
    
    while (currentDate <= endDate) {
      currentDate.setDate(currentDate.getDate() + 1);
      const dateKey = this.dateCalculator.formatISODate(currentDate);
      const col = dateToColumnMap.get(dateKey);
      if (col) {
        endColumn = col;
      } else {
        break; // Event extends beyond visible range
      }
    }
    
    const columnSpan = endColumn - startColumn + 1;
    return { startColumn, columnSpan };
  }

  /**
   * Check if two events overlap in columns
   */
  private eventsOverlap(event1Span: { startColumn: number, columnSpan: number }, event2Span: { startColumn: number, columnSpan: number }): boolean {
    const event1End = event1Span.startColumn + event1Span.columnSpan - 1;
    const event2End = event2Span.startColumn + event2Span.columnSpan - 1;
    
    return !(event1End < event2Span.startColumn || event2End < event1Span.startColumn);
  }

  clearEvents(container?: HTMLElement): void {
    const selector = 'swp-event';
    const existingEvents = container 
      ? container.querySelectorAll(selector)
      : document.querySelectorAll(selector);
    
    if (existingEvents.length > 0) {
      console.log(`BaseEventRenderer: Clearing ${existingEvents.length} events`, 
        container ? 'from container' : 'globally');
    }
    existingEvents.forEach(event => event.remove());
  }
}

/**
 * Date-based event renderer
 */
export class DateEventRenderer extends BaseEventRenderer {
  protected getColumns(container: HTMLElement): HTMLElement[] {
    const columns = container.querySelectorAll('swp-day-column');
    console.log('DateEventRenderer: Found', columns.length, 'day columns in container');
    return Array.from(columns) as HTMLElement[];
  }

  protected getEventsForColumn(column: HTMLElement, events: CalendarEvent[]): CalendarEvent[] {
    const columnDate = column.dataset.date;
    if (!columnDate) {
      console.log(`DateEventRenderer: Column has no dataset.date`);
      return [];
    }

    const columnEvents = events.filter(event => {
      const eventDate = new Date(event.start);
      const eventDateStr = this.dateCalculator.formatISODate(eventDate);
      const matches = eventDateStr === columnDate;
      
      if (!matches) {
        if(event.title == 'Architecture Planning')
        console.log(`DateEventRenderer: Event ${event.title} (${eventDateStr}) does not match column (${columnDate})`);
      }
      
      return matches;
    });

    console.log(`DateEventRenderer: Column ${columnDate} has ${columnEvents.length} events from ${events.length} total`);
    return columnEvents;
  }
}

/**
 * Resource-based event renderer
 */
export class ResourceEventRenderer extends BaseEventRenderer {
  protected getColumns(container: HTMLElement): HTMLElement[] {
    const columns = container.querySelectorAll('swp-resource-column');
    console.log('ResourceEventRenderer: Found', columns.length, 'resource columns in container');
    return Array.from(columns) as HTMLElement[];
  }

  protected getEventsForColumn(column: HTMLElement, events: CalendarEvent[]): CalendarEvent[] {
    const resourceName = column.dataset.resource;
    if (!resourceName) return [];

    const columnEvents = events.filter(event => {
      return event.resource?.name === resourceName;
    });

    console.log(`ResourceEventRenderer: Resource ${resourceName} has ${columnEvents.length} events`);
    return columnEvents;
  }
}