import { type IBlock } from './wysiwyg.types.js';

export class WysiwygDragDropHandler {
  private component: any;
  private draggedBlockId: string | null = null;
  private dragOverBlockId: string | null = null;
  private dragOverPosition: 'before' | 'after' | null = null;

  constructor(component: any) {
    this.component = component;
  }

  /**
   * Gets the current drag state
   */
  get dragState() {
    return {
      draggedBlockId: this.draggedBlockId,
      dragOverBlockId: this.dragOverBlockId,
      dragOverPosition: this.dragOverPosition
    };
  }

  /**
   * Handles drag start
   */
  handleDragStart(e: DragEvent, block: IBlock): void {
    if (!e.dataTransfer) return;
    
    this.draggedBlockId = block.id;
    e.dataTransfer.effectAllowed = 'move';
    e.dataTransfer.setData('text/plain', block.id);
    
    // Update UI state
    this.updateComponentState();
    
    // Add slight delay to show dragging state
    setTimeout(() => {
      this.component.requestUpdate();
    }, 10);
  }

  /**
   * Handles drag end
   */
  handleDragEnd(): void {
    this.draggedBlockId = null;
    this.dragOverBlockId = null;
    this.dragOverPosition = null;
    this.updateComponentState();
    this.component.requestUpdate();
  }

  /**
   * Handles drag over
   */
  handleDragOver(e: DragEvent, block: IBlock): void {
    e.preventDefault();
    if (!e.dataTransfer || !this.draggedBlockId || this.draggedBlockId === block.id) return;
    
    e.dataTransfer.dropEffect = 'move';
    
    const rect = (e.currentTarget as HTMLElement).getBoundingClientRect();
    const midpoint = rect.top + rect.height / 2;
    
    this.dragOverBlockId = block.id;
    this.dragOverPosition = e.clientY < midpoint ? 'before' : 'after';
    this.updateComponentState();
    this.component.requestUpdate();
  }

  /**
   * Handles drag leave
   */
  handleDragLeave(block: IBlock): void {
    if (this.dragOverBlockId === block.id) {
      this.dragOverBlockId = null;
      this.dragOverPosition = null;
      this.updateComponentState();
      this.component.requestUpdate();
    }
  }

  /**
   * Handles drop
   */
  handleDrop(e: DragEvent, targetBlock: IBlock): void {
    e.preventDefault();
    
    if (!this.draggedBlockId || this.draggedBlockId === targetBlock.id) return;
    
    const blocks = [...this.component.blocks];
    const draggedIndex = blocks.findIndex(b => b.id === this.draggedBlockId);
    const targetIndex = blocks.findIndex(b => b.id === targetBlock.id);
    
    if (draggedIndex === -1 || targetIndex === -1) return;
    
    // Remove the dragged block
    const [draggedBlock] = blocks.splice(draggedIndex, 1);
    
    // Calculate the new index
    let newIndex = targetIndex;
    if (this.dragOverPosition === 'after') {
      newIndex = draggedIndex < targetIndex ? targetIndex : targetIndex + 1;
    } else {
      newIndex = draggedIndex < targetIndex ? targetIndex - 1 : targetIndex;
    }
    
    // Insert at new position
    blocks.splice(newIndex, 0, draggedBlock);
    
    // Update blocks
    this.component.blocks = blocks;
    this.component.updateValue();
    this.handleDragEnd();
    
    // Focus the moved block
    setTimeout(() => {
      const blockOps = this.component.blockOperations;
      if (draggedBlock.type !== 'divider') {
        blockOps.focusBlock(draggedBlock.id);
      }
    }, 100);
  }

  /**
   * Updates component drag state
   */
  private updateComponentState(): void {
    this.component.draggedBlockId = this.draggedBlockId;
    this.component.dragOverBlockId = this.dragOverBlockId;
    this.component.dragOverPosition = this.dragOverPosition;
  }

  /**
   * Checks if a block is being dragged
   */
  isDragging(blockId: string): boolean {
    return this.draggedBlockId === blockId;
  }

  /**
   * Checks if a block has drag over state
   */
  isDragOver(blockId: string): boolean {
    return this.dragOverBlockId === blockId;
  }

  /**
   * Gets drag over CSS classes for a block
   */
  getDragOverClasses(blockId: string): string {
    if (!this.isDragOver(blockId)) return '';
    return this.dragOverPosition === 'before' ? 'drag-over-before' : 'drag-over-after';
  }
}