'use client';

import { useCallback, useEffect, useRef, useState } from 'react';

interface UseChatDragSelectionOptions {
  selectionMode: boolean;
  enterSelectionMode: (messageId: string) => void;
  addSelectedMessage: (messageId: string) => void;
}

export function useChatDragSelection({
  selectionMode,
  enterSelectionMode,
  addSelectedMessage
}: UseChatDragSelectionOptions) {
  const [isDragging, setIsDragging] = useState(false);
  const visitedRef = useRef<Set<string>>(new Set());

  const startDragSelection = useCallback(
    (messageId: string) => {
      setIsDragging(true);
      visitedRef.current = new Set([messageId]);
      if (!selectionMode) {
        enterSelectionMode(messageId);
      } else {
        addSelectedMessage(messageId);
      }
    },
    [addSelectedMessage, enterSelectionMode, selectionMode]
  );

  const handleDragEnterMessage = useCallback(
    (messageId: string) => {
      if (!isDragging || visitedRef.current.has(messageId)) return;
      visitedRef.current.add(messageId);
      addSelectedMessage(messageId);
    },
    [addSelectedMessage, isDragging]
  );

  const endDragSelection = useCallback(() => {
    setIsDragging(false);
    visitedRef.current.clear();
  }, []);

  useEffect(() => {
    window.addEventListener('mouseup', endDragSelection);
    return () => window.removeEventListener('mouseup', endDragSelection);
  }, [endDragSelection]);

  return {
    isDragging,
    startDragSelection,
    handleDragEnterMessage,
    endDragSelection
  };
}