import { eventBus } from '../core/EventBus';
import { CoreEvents } from '../constants/CoreEvents';
import { calendarConfig } from '../core/CalendarConfig';

export class ResizeHandleManager {
  private resizeZoneHeight = 15; // Must match CSS ::after height
  private cachedEvents: HTMLElement[] = [];

  // Resize state
  private isResizing = false;
  private resizingElement: HTMLElement | null = null;
  private initialHeight = 0;
  private initialMouseY = 0;
  private targetHeight = 0;
  private currentHeight = 0;
  private animationFrameId: number | null = null;

  // Snap configuration
  private snapIntervalMinutes = 15;
  private hourHeightPx: number;

  constructor() {
    const gridSettings = calendarConfig.getGridSettings();
    this.hourHeightPx = gridSettings.hourHeight;
    this.snapIntervalMinutes = gridSettings.snapInterval;
  }

  public initialize(): void {
    this.refreshEventCache();
    this.setupEventListeners();
  }

  private refreshEventCache(): void {
    this.cachedEvents = Array.from(
      document.querySelectorAll<HTMLElement>('swp-day-columns swp-event')
    );
  }

  private setupEventListeners(): void {
    // Hover detection (only when not resizing and mouse button is up)
    document.addEventListener('mousemove', (e: MouseEvent) => {
      if (!this.isResizing) {
        // Only check for resize zones when mouse button is up
        if (e.buttons === 0) {
          this.handleGlobalMouseMove(e);
        }
      } else {
        this.handleMouseMove(e);
      }
    });

    // Resize mouse handling
    document.addEventListener('mousedown', (e: MouseEvent) => {
      this.handleMouseDown(e);
    });

    document.addEventListener('mouseup', (e: MouseEvent) => {
      this.handleMouseUp(e);
    });

    // Cache refresh
    eventBus.on(CoreEvents.GRID_RENDERED, () => this.refreshEventCache());
    eventBus.on(CoreEvents.EVENTS_RENDERED, () => this.refreshEventCache());
    eventBus.on(CoreEvents.EVENT_CREATED, () => this.refreshEventCache());
    eventBus.on(CoreEvents.EVENT_UPDATED, () => this.refreshEventCache());
    eventBus.on(CoreEvents.EVENT_DELETED, () => this.refreshEventCache());
  }

  private handleGlobalMouseMove(e: MouseEvent): void {
    // Check all cached events to see if mouse is in their resize zone
    const events = this.cachedEvents;

    events.forEach(eventElement => {
      // Skip the element we're currently resizing
      if (this.resizingElement === eventElement) {
        return;
      }

      const rect = eventElement.getBoundingClientRect();
      const mouseY = e.clientY;
      const mouseX = e.clientX;

      // Check if mouse is within element bounds horizontally
      const isInHorizontalBounds = mouseX >= rect.left && mouseX <= rect.right;

      // Check if mouse is in bottom resize zone of the element
      const distanceFromBottom = rect.bottom - mouseY;
      const isInResizeZone = distanceFromBottom >= 0 && distanceFromBottom <= this.resizeZoneHeight;

      if (isInHorizontalBounds && isInResizeZone) {
        this.showResizeIndicator(eventElement);
        console.log(`✅ In resize zone - bottom ${this.resizeZoneHeight}px`);
      } else {
        this.hideResizeIndicator(eventElement);
      }
    });
  }

  private showResizeIndicator(eventElement: HTMLElement): void {
    // Check if indicator already exists
    let indicator = eventElement.querySelector<HTMLElement>('swp-resize-indicator');

    if (!indicator) {
      indicator = document.createElement('swp-resize-indicator');
      eventElement.appendChild(indicator);
    }

    eventElement.setAttribute('data-resize-hover', 'true');
  }

  private hideResizeIndicator(eventElement: HTMLElement): void {
    const indicator = eventElement.querySelector<HTMLElement>('swp-resize-indicator');
    if (indicator) {
      indicator.remove();
    }
    eventElement.removeAttribute('data-resize-hover');
  }

  private handleMouseDown(e: MouseEvent): void {
    const target = e.target as HTMLElement;
    const eventElement = target.closest<HTMLElement>('swp-event[data-resize-hover="true"]');

    if (!eventElement) return;

    // Check if click is in bottom resize zone
    const rect = eventElement.getBoundingClientRect();
    const distanceFromBottom = rect.bottom - e.clientY;

    if (distanceFromBottom >= 0 && distanceFromBottom <= this.resizeZoneHeight) {
      // START RESIZE
      e.stopPropagation(); // Prevent DragDropManager from handling
      e.preventDefault();

      this.isResizing = true;
      this.resizingElement = eventElement;
      this.initialHeight = eventElement.offsetHeight;
      this.initialMouseY = e.clientY;

      // Set high z-index on event-group if exists, otherwise on event itself
      const eventGroup = eventElement.closest<HTMLElement>('swp-event-group');
      if (eventGroup) {
        eventGroup.style.zIndex = '1000';
      } else {
        eventElement.style.zIndex = '1000';
      }

      console.log('🔄 Resize started', this.initialHeight);
    }
  }

  private handleMouseMove(e: MouseEvent): void {
    if (!this.isResizing || !this.resizingElement) return;

    const deltaY = e.clientY - this.initialMouseY;
    const rawHeight = this.initialHeight + deltaY;

    // Apply minimum height
    this.targetHeight = Math.max(30, rawHeight);

    // Start animation loop if not already running
    if (this.animationFrameId === null) {
      this.currentHeight = this.resizingElement.offsetHeight;
      this.animate();
    }
  }

  private animate(): void {
    if (!this.isResizing || !this.resizingElement) {
      this.animationFrameId = null;
      return;
    }

    // Smooth interpolation towards target
    const diff = this.targetHeight - this.currentHeight;
    const step = diff * 0.3; // 30% of distance per frame

    // Update if difference is significant
    if (Math.abs(diff) > 0.5) {
      this.currentHeight += step;

      const swpEvent = this.resizingElement as any;
      if (swpEvent.updateHeight) {
        swpEvent.updateHeight(this.currentHeight);
      }

      this.animationFrameId = requestAnimationFrame(() => this.animate());
    } else {
      // Close enough - snap to target
      this.currentHeight = this.targetHeight;
      const swpEvent = this.resizingElement as any;
      if (swpEvent.updateHeight) {
        swpEvent.updateHeight(this.currentHeight);
      }
      this.animationFrameId = null;
    }
  }

  private handleMouseUp(e: MouseEvent): void {
    if (!this.isResizing || !this.resizingElement) return;

    // Cancel animation
    if (this.animationFrameId !== null) {
      cancelAnimationFrame(this.animationFrameId);
      this.animationFrameId = null;
    }

    // Snap to grid on mouse up
    const snapDistancePx = (this.snapIntervalMinutes / 60) * this.hourHeightPx;
    const currentHeight = this.resizingElement.offsetHeight;
    const snappedHeight = Math.round(currentHeight / snapDistancePx) * snapDistancePx;
    const finalHeight = Math.max(30, snappedHeight);

    const swpEvent = this.resizingElement as any;
    if (swpEvent.updateHeight) {
      swpEvent.updateHeight(finalHeight);
    }

    console.log('✅ Resize ended', finalHeight);

    // Clear z-index on event-group if exists, otherwise on event itself
    const eventGroup = this.resizingElement.closest<HTMLElement>('swp-event-group');
    if (eventGroup) {
      eventGroup.style.zIndex = '';
    } else {
      this.resizingElement.style.zIndex = '';
    }

    // Cleanup state
    this.isResizing = false;
    this.resizingElement = null;

    // Refresh cache for future operations
    this.refreshEventCache();
  }
}