import React, { useState, useEffect, useRef, useCallback } from 'react';
import { api } from '../../api/client';
import type { GifResult } from '@backspace/shared';

interface GifPickerProps {
  onGifSelect: (url: string) => void;
}

export function GifPicker({ onGifSelect }: GifPickerProps) {
  const [query, setQuery] = useState('');
  const [debouncedQuery, setDebouncedQuery] = useState('');
  const [results, setResults] = useState<GifResult[]>([]);
  const [loading, setLoading] = useState(true);
  const [nextPos, setNextPos] = useState('');
  const [loadingMore, setLoadingMore] = useState(false);
  const scrollRef = useRef<HTMLDivElement>(null);
  const debounceRef = useRef<ReturnType<typeof setTimeout>>();

  // Debounce search query
  useEffect(() => {
    if (debounceRef.current) clearTimeout(debounceRef.current);
    debounceRef.current = setTimeout(() => {
      setDebouncedQuery(query);
    }, 300);
    return () => {
      if (debounceRef.current) clearTimeout(debounceRef.current);
    };
  }, [query]);

  // Fetch results when debounced query changes
  useEffect(() => {
    let cancelled = false;
    setLoading(true);
    setResults([]);
    setNextPos('');

    const fetchGifs = async () => {
      try {
        const data = debouncedQuery.trim()
          ? await api.gif.search(debouncedQuery.trim(), 30)
          : await api.gif.trending(30);
        if (!cancelled) {
          setResults(data.results);
          setNextPos(data.next);
          setLoading(false);
        }
      } catch {
        if (!cancelled) setLoading(false);
      }
    };
    fetchGifs();
    return () => { cancelled = true; };
  }, [debouncedQuery]);

  // Infinite scroll
  const handleScroll = useCallback(() => {
    const el = scrollRef.current;
    if (!el || loadingMore || !nextPos) return;
    if (el.scrollTop + el.clientHeight >= el.scrollHeight - 100) {
      setLoadingMore(true);
      const fetchMore = async () => {
        try {
          const data = debouncedQuery.trim()
            ? await api.gif.search(debouncedQuery.trim(), 30, nextPos)
            : await api.gif.trending(30, nextPos);
          setResults((prev) => [...prev, ...data.results]);
          setNextPos(data.next);
        } finally {
          setLoadingMore(false);
        }
      };
      fetchMore();
    }
  }, [loadingMore, nextPos, debouncedQuery]);

  // Prevent keyboard events from bubbling
  const handleKeyDown = (e: React.KeyboardEvent) => {
    e.stopPropagation();
  };

  return (
    <div className="flex flex-col h-[390px]" onKeyDown={handleKeyDown}>
      {/* Search */}
      <div className="px-3 pt-2 pb-1.5">
        <input
          type="text"
          value={query}
          onChange={(e) => setQuery(e.target.value)}
          placeholder="Search GIFs"
          className="input-search w-full"
          autoFocus
        />
      </div>

      {/* Results grid */}
      <div
        ref={scrollRef}
        className="flex-1 overflow-y-auto scrollbar-thin px-2 pb-1"
        onScroll={handleScroll}
      >
        {loading ? (
          <div className="grid grid-cols-2 gap-1.5 p-1">
            {Array.from({ length: 6 }).map((_, i) => (
              <div
                key={i}
                className="bg-surface-elevated rounded-lg animate-pulse"
                style={{ height: 100 + Math.random() * 60 }}
              />
            ))}
          </div>
        ) : results.length === 0 ? (
          <div className="flex items-center justify-center h-full text-txt-tertiary text-sm">
            {debouncedQuery.trim() ? 'No GIFs found' : 'No trending GIFs'}
          </div>
        ) : (
          <div className="columns-2 gap-1.5 p-1">
            {results.map((gif) => (
              <button
                key={gif.id}
                onClick={() => onGifSelect(gif.url)}
                className="w-full mb-1.5 rounded-lg overflow-hidden hover:ring-2 hover:ring-accent-primary transition-all break-inside-avoid"
              >
                <img
                  src={gif.previewUrl}
                  alt={gif.title}
                  className="w-full object-cover rounded-lg"
                  loading="lazy"
                  style={{
                    aspectRatio: gif.width && gif.height ? `${gif.width}/${gif.height}` : undefined,
                  }}
                />
              </button>
            ))}
          </div>
        )}
        {loadingMore && (
          <div className="flex justify-center py-2">
            <div className="w-5 h-5 border-2 border-txt-tertiary border-t-transparent rounded-full animate-spin" />
          </div>
        )}
      </div>

      {/* Attribution */}
      <div className="px-3 py-1 text-[10px] text-txt-tertiary text-right">
        Powered by Klipy
      </div>
    </div>
  );
}