import { useState, useMemo, useRef, useEffect } from 'react';
import { searchHuggys, Huggy } from '../../data/huggys';

interface HuggyMenuProps {
  onSelectHuggy: (huggy: Huggy) => void;
  onClose: () => void;
}

const INITIAL_DISPLAY_COUNT = 12; // Show more initially to ensure scrolling
const LOAD_MORE_COUNT = 6;

export default function HuggyMenu({ onSelectHuggy, onClose }: HuggyMenuProps) {
  const [searchQuery, setSearchQuery] = useState('');
  const [displayCount, setDisplayCount] = useState(INITIAL_DISPLAY_COUNT);
  const [loadingImages, setLoadingImages] = useState<Set<string>>(new Set());
  const scrollContainerRef = useRef<HTMLDivElement>(null);

  // Filter Huggys based on search query
  const filteredHuggys = useMemo(() => searchHuggys(searchQuery), [searchQuery]);

  // Get the Huggys to display (limited by displayCount)
  const displayedHuggys = filteredHuggys.slice(0, displayCount);
  const hasMore = displayCount < filteredHuggys.length;

  // Check if content overflows, if not load more automatically
  useEffect(() => {
    const scrollContainer = scrollContainerRef.current;
    if (!scrollContainer || !hasMore) return;

    const checkOverflow = () => {
      const { scrollHeight, clientHeight } = scrollContainer;
      // If content doesn't overflow (no scrollbar), load more
      if (scrollHeight <= clientHeight && hasMore) {
        setDisplayCount(prev => Math.min(prev + LOAD_MORE_COUNT, filteredHuggys.length));
      }
    };

    // Check after images load
    const timer = setTimeout(checkOverflow, 100);
    return () => clearTimeout(timer);
  }, [displayCount, hasMore, filteredHuggys.length]);

  // Infinite scroll: load more when scrolled near bottom
  useEffect(() => {
    const scrollContainer = scrollContainerRef.current;
    if (!scrollContainer) return;

    const handleScroll = () => {
      const { scrollTop, scrollHeight, clientHeight } = scrollContainer;
      const scrollPercentage = (scrollTop + clientHeight) / scrollHeight;

      // Load more when scrolled to 80% of content
      if (scrollPercentage > 0.8 && hasMore) {
        setDisplayCount(prev => Math.min(prev + LOAD_MORE_COUNT, filteredHuggys.length));
      }
    };

    scrollContainer.addEventListener('scroll', handleScroll);
    return () => scrollContainer.removeEventListener('scroll', handleScroll);
  }, [hasMore, filteredHuggys.length]);

  const handleHuggyClick = (huggy: Huggy) => {
    onSelectHuggy(huggy);
    onClose();
  };

  const handleImageLoad = (huggyId: string) => {
    setLoadingImages(prev => {
      const newSet = new Set(prev);
      newSet.delete(huggyId);
      return newSet;
    });
  };

  const handleImageLoadStart = (huggyId: string) => {
    setLoadingImages(prev => new Set(prev).add(huggyId));
  };

  // Reset display count when search changes
  const handleSearchChange = (e: React.ChangeEvent<HTMLInputElement>) => {
    setSearchQuery(e.target.value);
    setDisplayCount(INITIAL_DISPLAY_COUNT);
  };

  return (
    <>
      {/* Backdrop */}
      <div
        className="fixed inset-0 z-10"
        onClick={onClose}
      />

      {/* Huggy Menu */}
      <div
        className="huggy-menu fixed left-[107px] top-[20px] z-20 w-[340px] bg-[#f8f9fa] border border-[#3faee6] rounded-[10px] flex flex-col overflow-hidden shadow-lg"
        onDragStart={(e) => {
          e.preventDefault();
          e.stopPropagation();
        }}
        onDrag={(e) => {
          e.preventDefault();
          e.stopPropagation();
        }}
        onDragOver={(e) => {
          e.preventDefault();
          e.stopPropagation();
        }}
      >
        {/* Search Bar */}
        <div className="border-b border-[#ebebeb] p-[5px]">
          <input
            type="text"
            placeholder="Search Huggy"
            value={searchQuery}
            onChange={handleSearchChange}
            className="w-full bg-transparent border-none outline-none text-[14px] text-[#999999] font-['Inter'] placeholder-[#999999]"
            autoFocus
          />
        </div>

        {/* Huggy Grid - Scrollable */}
        <div
          ref={scrollContainerRef}
          className="overflow-y-auto p-[5px]"
          style={{ maxHeight: '430px' }}
        >
          {filteredHuggys.length === 0 ? (
            <div className="text-center text-[#999999] text-[14px] py-8">
              No Huggys found
            </div>
          ) : (
            <div className="grid grid-cols-2 sm:grid-cols-2 md:grid-cols-2 lg:grid-cols-3 gap-[5px] p-[5px]">
              {displayedHuggys.map((huggy) => (
                <button
                  key={huggy.id}
                  onClick={() => handleHuggyClick(huggy)}
                  onDragStart={(e) => e.preventDefault()}
                  className="relative w-full aspect-square rounded-[5px] overflow-hidden hover:bg-[#e9ecef] transition-colors cursor-pointer border-none p-0"
                  title={huggy.name}
                >
                  {/* Shimmer Loading Placeholder */}
                  {loadingImages.has(huggy.id) && (
                    <div className="absolute inset-0 skeleton-shimmer"></div>
                  )}

                  {/* Huggy Image */}
                  <img
                    src={huggy.thumbnail}
                    alt={huggy.name}
                    className={`w-full h-full object-cover transition-opacity duration-200 ${loadingImages.has(huggy.id) ? 'opacity-0' : 'opacity-100'}`}
                    loading="lazy"
                    onLoadStart={() => handleImageLoadStart(huggy.id)}
                    onLoad={() => handleImageLoad(huggy.id)}
                    onError={() => handleImageLoad(huggy.id)}
                    draggable={false}
                  />
                </button>
              ))}
            </div>
          )}
        </div>

        {/* Summary Footer */}
        <div className="border-t border-[#ebebeb] p-[5px] text-center">
          <p className="text-[#999999] text-[12px]">
            Showing {displayedHuggys.length} of {filteredHuggys.length} Huggys
          </p>
        </div>
      </div>
    </>
  );
}