/**
 * MultiSelect 필드 컴포넌트
 * 여러 항목을 동시에 선택 (태그 칩 형태로 표시)
 *
 * 저장값: string[] (예: ["CUT", "BEND", "WELD"])
 */

'use client';

import { useState, useRef, useEffect } from 'react';
import { X, ChevronDown } from 'lucide-react';
import { Label } from '@/components/ui/label';
import { Input } from '@/components/ui/input';
import { Badge } from '@/components/ui/badge';
import type { DynamicFieldRendererProps, MultiSelectConfig } from '../types';

// 옵션 정규화 (DropdownField와 동일 로직)
function normalizeOptions(rawOptions: unknown): Array<{ label: string; value: string }> {
  if (!rawOptions) return [];
  if (typeof rawOptions === 'string') {
    return rawOptions.split(',').map(o => {
      const trimmed = o.trim();
      return { label: trimmed, value: trimmed };
    });
  }
  if (Array.isArray(rawOptions)) {
    return rawOptions.map(item => {
      if (typeof item === 'object' && item !== null && 'value' in item) {
        return {
          label: String((item as Record<string, unknown>).label || (item as Record<string, unknown>).value),
          value: String((item as Record<string, unknown>).value),
        };
      }
      const str = String(item);
      return { label: str, value: str };
    });
  }
  return [];
}

export function MultiSelectField({
  field,
  value,
  onChange,
  error,
  disabled,
}: DynamicFieldRendererProps) {
  const fieldKey = field.field_key || `field_${field.id}`;
  const [isOpen, setIsOpen] = useState(false);
  const [searchTerm, setSearchTerm] = useState('');
  const containerRef = useRef<HTMLDivElement>(null);

  const config = (field.properties || {}) as MultiSelectConfig;
  const maxSelections = config.maxSelections;
  const allowCustom = config.allowCustom ?? false;

  // 현재 선택된 값 배열
  const selectedValues: string[] = Array.isArray(value) ? (value as string[]) : [];

  // 옵션 목록
  const options = normalizeOptions(field.options);
  const filteredOptions = options.filter(
    opt => opt.label.toLowerCase().includes(searchTerm.toLowerCase()) &&
           !selectedValues.includes(opt.value)
  );

  // 외부 클릭 감지
  useEffect(() => {
    const handleClickOutside = (e: MouseEvent) => {
      if (containerRef.current && !containerRef.current.contains(e.target as Node)) {
        setIsOpen(false);
      }
    };
    document.addEventListener('mousedown', handleClickOutside);
    return () => document.removeEventListener('mousedown', handleClickOutside);
  }, []);

  // 항목 추가
  const addValue = (val: string) => {
    if (maxSelections && selectedValues.length >= maxSelections) return;
    const newValues = [...selectedValues, val];
    onChange(newValues);
    setSearchTerm('');
  };

  // 항목 제거
  const removeValue = (val: string) => {
    onChange(selectedValues.filter(v => v !== val));
  };

  // 커스텀 입력 추가 (Enter)
  const handleKeyDown = (e: React.KeyboardEvent) => {
    if (e.key === 'Enter' && searchTerm.trim()) {
      e.preventDefault();
      if (allowCustom && !selectedValues.includes(searchTerm.trim())) {
        addValue(searchTerm.trim());
      } else {
        // 기존 옵션에서 일치하는 것 선택
        const match = filteredOptions[0];
        if (match) addValue(match.value);
      }
    }
    if (e.key === 'Backspace' && !searchTerm && selectedValues.length > 0) {
      removeValue(selectedValues[selectedValues.length - 1]);
    }
  };

  // 옵션 라벨 조회
  const getLabel = (val: string) => {
    const opt = options.find(o => o.value === val);
    return opt ? opt.label : val;
  };

  const isAtLimit = maxSelections ? selectedValues.length >= maxSelections : false;

  return (
    <div ref={containerRef}>
      <Label htmlFor={fieldKey}>
        {field.field_name}
        {field.is_required && <span className="text-red-500"> *</span>}
        {maxSelections && (
          <span className="text-muted-foreground font-normal ml-1">
            ({selectedValues.length}/{maxSelections})
          </span>
        )}
      </Label>
      <div
        className={`min-h-10 flex flex-wrap items-center gap-1 rounded-md border bg-background px-3 py-2 text-sm cursor-text ${
          error ? 'border-red-500' : 'border-input'
        } ${disabled ? 'opacity-50 cursor-not-allowed' : ''}`}
        onClick={() => !disabled && setIsOpen(true)}
      >
        {/* 선택된 칩들 */}
        {selectedValues.map(val => (
          <Badge key={val} variant="secondary" className="gap-1 pr-1">
            {getLabel(val)}
            {!disabled && (
              <button
                type="button"
                onClick={(e) => { e.stopPropagation(); removeValue(val); }}
                className="hover:text-destructive"
              >
                <X className="h-3 w-3" />
              </button>
            )}
          </Badge>
        ))}
        {/* 검색 입력 */}
        {!disabled && !isAtLimit && (
          <Input
            id={fieldKey}
            value={searchTerm}
            onChange={(e) => { setSearchTerm(e.target.value); setIsOpen(true); }}
            onFocus={() => setIsOpen(true)}
            onKeyDown={handleKeyDown}
            placeholder={selectedValues.length === 0 ? (field.placeholder || '선택하세요') : ''}
            className="border-0 shadow-none p-0 h-6 min-w-[60px] flex-1 focus-visible:ring-0"
          />
        )}
        <ChevronDown className="h-4 w-4 shrink-0 text-muted-foreground ml-auto" />
      </div>

      {/* 드롭다운 */}
      {isOpen && filteredOptions.length > 0 && (
        <div className="relative">
          <div className="absolute z-50 w-full mt-1 max-h-48 overflow-auto rounded-md border bg-popover shadow-md">
            {filteredOptions.map(opt => (
              <button
                key={opt.value}
                type="button"
                className="w-full text-left px-3 py-2 text-sm hover:bg-accent hover:text-accent-foreground"
                onClick={() => { addValue(opt.value); setIsOpen(false); }}
              >
                {opt.label}
              </button>
            ))}
          </div>
        </div>
      )}

      {error && (
        <p className="text-xs text-red-500 mt-1">{error}</p>
      )}
      {!error && field.description && (
        <p className="text-xs text-muted-foreground mt-1">
          * {field.description}
        </p>
      )}
    </div>
  );
}