import { useEffect, useRef, useState, type ReactNode } from 'react';
import { Search, Check, Loader2, ChevronsUpDown } from 'lucide-react';
import { cn } from '@/lib/utils';
import { Input } from './input';
import { Typography } from './typography';

// 서버검색 콤보박스 — 목록(options)은 부모가 쿼리에 맞춰 조회해 넘기고, 검색어 디바운스는 이 컴포넌트가 처리한다.
// variant: 'field'(트리거+팝오버, 단일선택 폼용) / 'inline'(검색창+리스트 상시노출, 다중 체크리스트용).
export type ComboOption = {
  id: string;
  label: string;        // 검색결과에 없을 때 선택 표시용 텍스트
  node?: ReactNode;     // 커스텀 행(미지정 시 label 렌더)
  disabled?: boolean;
};

type ComboboxProps = {
  options: ComboOption[];
  onQueryChange: (q: string) => void; // 내부 디바운스 후 호출
  loading?: boolean;
  placeholder?: string;
  searchPlaceholder?: string;
  emptyText?: string;
  debounceMs?: number;
  id?: string;
  className?: string;
  maxListHeight?: string; // tailwind, default max-h-56
  variant?: 'field' | 'inline';
  multiple?: boolean;
  // single
  value?: string;
  selectedLabel?: ReactNode;
  onSelect?: (opt: ComboOption) => void;
  // multi
  values?: string[];
  onToggle?: (opt: ComboOption) => void;
};

export function Combobox({
  options,
  onQueryChange,
  loading,
  placeholder = '선택...',
  searchPlaceholder = '검색...',
  emptyText = '결과가 없습니다',
  debounceMs = 300,
  id,
  className,
  maxListHeight = 'max-h-56',
  variant = 'field',
  multiple = false,
  value,
  selectedLabel,
  onSelect,
  values = [],
  onToggle,
}: ComboboxProps) {
  const [text, setText] = useState('');
  const [open, setOpen] = useState(false);
  const rootRef = useRef<HTMLDivElement>(null);
  const popoverRef = useRef<HTMLDivElement>(null);

  // 검색어 디바운스 → onQueryChange. 콜백은 ref로 잡아 text 변화에만 반응.
  const qcRef = useRef(onQueryChange);
  qcRef.current = onQueryChange;
  useEffect(() => {
    const t = setTimeout(() => qcRef.current(text.trim()), debounceMs);
    return () => clearTimeout(t);
  }, [text, debounceMs]);

  // field 팝오버 바깥 클릭 시 닫기.
  useEffect(() => {
    if (variant === 'inline') return;
    const onDoc = (e: MouseEvent) => {
      if (rootRef.current && !rootRef.current.contains(e.target as Node)) setOpen(false);
    };
    document.addEventListener('mousedown', onDoc);
    return () => document.removeEventListener('mousedown', onDoc);
  }, [variant]);

  // field 팝오버가 열리면 스크롤 컨테이너(모달 등) 안에서 잘리지 않게 뷰로 끌어온다.
  // 로딩→목록 로 높이가 커질 때도 다시 당겨온다(이미 보이면 scrollIntoView 는 no-op).
  useEffect(() => {
    if (variant === 'inline' || !open) return;
    popoverRef.current?.scrollIntoView({ block: 'nearest', behavior: 'smooth' });
  }, [open, variant, loading, options.length]);

  const isSelected = (oid: string) => (multiple ? values.includes(oid) : value === oid);

  const handlePick = (opt: ComboOption) => {
    if (opt.disabled) return;
    if (multiple) onToggle?.(opt);
    else {
      onSelect?.(opt);
      setOpen(false);
    }
  };

  const searchInput = (
    <div className="relative">
      <Search size={13} className="absolute left-2 top-1/2 -translate-y-1/2 text-muted-foreground" />
      <Input
        id={id}
        type="text"
        value={text}
        onChange={(e) => setText(e.target.value)}
        placeholder={searchPlaceholder}
        className="pl-7 text-xs"
        autoComplete="off"
      />
      {loading && <Loader2 size={13} className="absolute right-2 top-1/2 -translate-y-1/2 animate-spin text-muted-foreground" />}
    </div>
  );

  const list = (
    <div className={cn('border border-border rounded bg-background overflow-y-auto', maxListHeight)}>
      {loading && options.length === 0 ? (
        <div className="flex items-center gap-2 p-3 text-muted-foreground text-[11px]">
          <Loader2 size={13} className="animate-spin" />
          <Typography as="span" variant="small" className="text-[11px]">불러오는 중…</Typography>
        </div>
      ) : options.length === 0 ? (
        <Typography as="p" variant="small" className="p-3 text-muted-foreground text-[11px]">{emptyText}</Typography>
      ) : (
        options.map((opt) => {
          const sel = isSelected(opt.id);
          return (
            <button
              key={opt.id}
              type="button"
              disabled={opt.disabled}
              onClick={() => handlePick(opt)}
              className={cn(
                'w-full flex items-center justify-between gap-2 p-2 text-left border-b border-border last:border-b-0 hover:bg-muted/40 disabled:opacity-40 disabled:cursor-not-allowed cursor-pointer transition-colors',
                sel && 'bg-primary/5',
              )}
            >
              <span className="min-w-0 flex-1">
                {opt.node ?? <Typography as="span" variant="small">{opt.label}</Typography>}
              </span>
              {multiple ? (
                <input type="checkbox" checked={sel} readOnly className="accent-primary h-3.5 w-3.5 shrink-0" />
              ) : (
                sel && <Check size={14} className="text-primary shrink-0" />
              )}
            </button>
          );
        })
      )}
    </div>
  );

  if (variant === 'inline') {
    return (
      <div ref={rootRef} className={cn('space-y-1.5', className)}>
        {searchInput}
        {list}
      </div>
    );
  }

  // field: 트리거(선택 요약) + 팝오버(검색창 + 리스트)
  const hasSelection = multiple ? values.length > 0 : !!value;
  const summary = multiple
    ? (values.length ? `${values.length}개 선택됨` : placeholder)
    : (value ? selectedLabel ?? '선택됨' : placeholder);

  return (
    <div ref={rootRef} className={cn('relative', className)}>
      <button
        type="button"
        id={id}
        onClick={() => setOpen((o) => !o)}
        className="w-full flex items-center justify-between gap-2 p-2 bg-background border border-border rounded text-xs text-left hover:bg-muted/20 cursor-pointer"
      >
        <span className={cn('truncate', !hasSelection && 'text-muted-foreground')}>{summary}</span>
        <ChevronsUpDown size={14} className="text-muted-foreground shrink-0" />
      </button>
      {open && (
        <div ref={popoverRef} className="absolute z-50 mt-1 w-full rounded border border-border bg-card shadow-lg p-1.5 space-y-1.5">
          {searchInput}
          {list}
        </div>
      )}
    </div>
  );
}