'use client';

import { useState, useEffect, useRef } from 'react';
import { Search, X } from 'lucide-react';
import Fuse from 'fuse.js';
import { Input } from '@/components/ui/input';
import { Button } from '@/components/ui/button';
import {
  getAllMeasures,
  getUnitsForMeasure,
  getUnitInfo,
  formatMeasureName,
  getCategoryColor,
  getCategoryColorHex,
  type Measure,
  type UnitInfo,
} from '@/lib/units';
import { cn } from '@/lib/utils';

interface SearchResult {
  unitInfo: UnitInfo;
  measure: Measure;
}

interface SearchUnitsProps {
  onSelectUnit: (unit: string, measure: Measure) => void;
}

export default function SearchUnits({ onSelectUnit }: SearchUnitsProps) {
  const [query, setQuery] = useState('');
  const [results, setResults] = useState<SearchResult[]>([]);
  const [isOpen, setIsOpen] = useState(false);
  const inputRef = useRef<HTMLInputElement>(null);
  const containerRef = useRef<HTMLDivElement>(null);

  // Build search index
  const searchIndex = useRef<Fuse<SearchResult> | null>(null);

  useEffect(() => {
    // Build comprehensive search data
    const allData: SearchResult[] = [];
    const measures = getAllMeasures();

    for (const measure of measures) {
      const units = getUnitsForMeasure(measure);

      for (const unit of units) {
        const unitInfo = getUnitInfo(unit);
        if (unitInfo) {
          allData.push({
            unitInfo,
            measure,
          });
        }
      }
    }

    // Initialize Fuse.js for fuzzy search
    searchIndex.current = new Fuse(allData, {
      keys: [
        { name: 'unitInfo.abbr', weight: 2 },
        { name: 'unitInfo.singular', weight: 1.5 },
        { name: 'unitInfo.plural', weight: 1.5 },
        { name: 'measure', weight: 1 },
      ],
      threshold: 0.3,
      includeScore: true,
    });
  }, []);

  // Perform search
  useEffect(() => {
    if (!query.trim() || !searchIndex.current) {
      setResults([]);
      setIsOpen(false);
      return;
    }

    const searchResults = searchIndex.current.search(query);
    setResults(searchResults.map(r => r.item).slice(0, 10));
    setIsOpen(true);
  }, [query]);

  // Handle click outside
  useEffect(() => {
    function handleClickOutside(event: MouseEvent) {
      if (
        containerRef.current &&
        !containerRef.current.contains(event.target as Node)
      ) {
        setIsOpen(false);
      }
    }

    document.addEventListener('mousedown', handleClickOutside);
    return () => document.removeEventListener('mousedown', handleClickOutside);
  }, []);

  // Keyboard shortcut: / to focus search
  useEffect(() => {
    function handleKeyDown(e: KeyboardEvent) {
      if (e.key === '/' && !e.ctrlKey && !e.metaKey) {
        const activeElement = document.activeElement;
        if (
          activeElement?.tagName !== 'INPUT' &&
          activeElement?.tagName !== 'TEXTAREA'
        ) {
          e.preventDefault();
          inputRef.current?.focus();
        }
      }

      if (e.key === 'Escape') {
        setIsOpen(false);
        inputRef.current?.blur();
      }
    }

    document.addEventListener('keydown', handleKeyDown);
    return () => document.removeEventListener('keydown', handleKeyDown);
  }, []);

  const handleSelectUnit = (unit: string, measure: Measure) => {
    onSelectUnit(unit, measure);
    setQuery('');
    setIsOpen(false);
    inputRef.current?.blur();
  };

  const clearSearch = () => {
    setQuery('');
    setIsOpen(false);
  };

  return (
    <div ref={containerRef} className="relative w-full max-w-md">
      <div className="relative">
        <Search className="absolute left-3 top-1/2 -translate-y-1/2 h-4 w-4 text-muted-foreground" />
        <Input
          ref={inputRef}
          type="text"
          placeholder="Search units (press / to focus)"
          value={query}
          onChange={(e) => setQuery(e.target.value)}
          onFocus={() => query && setIsOpen(true)}
          className="pl-10 pr-10"
        />
        {query && (
          <Button
            variant="ghost"
            size="icon"
            className="absolute right-1 top-1/2 -translate-y-1/2 h-8 w-8"
            onClick={clearSearch}
          >
            <X className="h-4 w-4" />
          </Button>
        )}
      </div>

      {/* Results dropdown */}
      {isOpen && results.length > 0 && (
        <div className="absolute z-50 w-full mt-2 bg-popover border rounded-lg shadow-lg max-h-80 overflow-y-auto">
          {results.map((result, index) => (
            <button
              key={`${result.measure}-${result.unitInfo.abbr}`}
              onClick={() => handleSelectUnit(result.unitInfo.abbr, result.measure)}
              className={cn(
                'w-full px-4 py-3 text-left hover:bg-accent transition-colors',
                'flex items-center justify-between gap-4',
                index !== 0 && 'border-t'
              )}
            >
              <div className="flex-1 min-w-0">
                <div className="font-medium truncate">
                  {result.unitInfo.plural}
                </div>
                <div className="text-sm text-muted-foreground flex items-center gap-2">
                  <span className="truncate">{result.unitInfo.abbr}</span>
                  <span>•</span>
                  <span className="truncate">{formatMeasureName(result.measure)}</span>
                </div>
              </div>
              <div
                className="w-3 h-3 rounded-full flex-shrink-0"
                style={{
                  backgroundColor: getCategoryColorHex(result.measure),
                }}
              />
            </button>
          ))}
        </div>
      )}

      {isOpen && query && results.length === 0 && (
        <div className="absolute z-50 w-full mt-2 bg-popover border rounded-lg shadow-lg p-4 text-center text-muted-foreground">
          No units found for "{query}"
        </div>
      )}
    </div>
  );
}