import { useState, useRef, useEffect, useMemo } from 'react';
import { motion, AnimatePresence } from 'motion/react';
import { ChevronDown, X, AlertTriangle } from 'lucide-react';

interface Props {
  allPlates: string[];
  selected: string[];
  onChange: (plates: string[]) => void;
  placeholder?: string;
}

function parseInput(text: string): string[] {
  return text
    .split(/[\s,;，；、]+/)
    .map(s => s.trim())
    .filter(Boolean);
}

export default function PlateMultiSelect({ allPlates, selected, onChange, placeholder = '按车牌（可多选/粘贴）' }: Props) {
  const [isOpen, setIsOpen] = useState(false);
  const [text, setText] = useState('');
  const [search, setSearch] = useState('');
  const [unmatched, setUnmatched] = useState<string[]>([]);
  const wrapRef = useRef<HTMLDivElement>(null);

  const allSet = useMemo(() => new Set(allPlates), [allPlates]);

  useEffect(() => {
    if (!isOpen) return;
    const handler = (e: MouseEvent) => {
      if (wrapRef.current && !wrapRef.current.contains(e.target as Node)) setIsOpen(false);
    };
    document.addEventListener('mousedown', handler);
    return () => document.removeEventListener('mousedown', handler);
  }, [isOpen]);

  const filtered = useMemo(() => {
    if (!search) return allPlates.slice(0, 200);
    const q = search.toLowerCase();
    return allPlates.filter(p => p.toLowerCase().includes(q)).slice(0, 200);
  }, [allPlates, search]);

  const selectedSet = useMemo(() => new Set(selected), [selected]);

  const apply = (input: string) => {
    const tokens = parseInput(input);
    if (tokens.length === 0) return;
    const matched: string[] = [];
    const missed: string[] = [];
    const seen = new Set(selected);
    for (const t of tokens) {
      if (allSet.has(t)) {
        if (!seen.has(t)) {
          matched.push(t);
          seen.add(t);
        }
      } else {
        missed.push(t);
      }
    }
    if (matched.length > 0) onChange([...selected, ...matched]);
    setUnmatched(missed);
    setText('');
  };

  const togglePlate = (plate: string) => {
    if (selectedSet.has(plate)) {
      onChange(selected.filter(p => p !== plate));
    } else {
      onChange([...selected, plate]);
    }
  };

  const removePlate = (plate: string) => {
    onChange(selected.filter(p => p !== plate));
  };

  const clearAll = () => {
    onChange([]);
    setUnmatched([]);
    setText('');
  };

  const display = selected.length === 0
    ? placeholder
    : selected.length === 1
      ? selected[0]
      : `${selected[0]} 等 ${selected.length} 个车牌`;

  return (
    <div className="relative" ref={wrapRef}>
      <div
        onClick={() => setIsOpen(o => !o)}
        className={`w-full bg-slate-50 rounded-lg py-1.5 px-2 text-[10px] font-bold cursor-pointer flex items-center justify-between gap-1 ${selected.length > 0 ? 'text-blue-600 ring-1 ring-blue-200' : 'text-slate-600'}`}
      >
        <span className="truncate">{display}</span>
        <ChevronDown size={10} className="text-slate-400 flex-shrink-0" />
      </div>

      <AnimatePresence>
        {isOpen && (
          <motion.div
            initial={{ opacity: 0, y: -5 }}
            animate={{ opacity: 1, y: 0 }}
            exit={{ opacity: 0, y: -5 }}
            className="absolute z-50 right-0 mt-1 bg-white border border-slate-100 rounded-xl shadow-xl"
            style={{ width: 'min(280px, calc(100vw - 24px))', minWidth: '100%' }}
          >
            <div className="p-2 space-y-2">
              <textarea
                value={text}
                onChange={(e) => setText(e.target.value)}
                placeholder="粘贴或输入车牌&#10;支持换行/逗号/空格分隔，回车或点添加确认"
                className="w-full bg-slate-50 border-none rounded-lg p-2 text-[11px] text-slate-700 outline-none focus:ring-1 focus:ring-blue-500/30 resize-none"
                rows={3}
                onKeyDown={(e) => {
                  if (e.key === 'Enter' && (e.metaKey || e.ctrlKey)) {
                    e.preventDefault();
                    apply(text);
                  }
                }}
              />
              <div className="flex justify-between items-center">
                <span className="text-[10px] text-slate-400">已选 <span className="font-bold text-blue-600">{selected.length}</span> 个</span>
                <div className="flex gap-1">
                  <button
                    onClick={() => apply(text)}
                    disabled={!text.trim()}
                    className="px-2 py-1 bg-blue-600 text-white rounded-md text-[10px] font-bold disabled:bg-slate-200 disabled:text-slate-400"
                  >添加</button>
                  <button
                    onClick={clearAll}
                    className="px-2 py-1 bg-slate-100 text-slate-500 rounded-md text-[10px] font-bold"
                  >清空</button>
                </div>
              </div>

              {unmatched.length > 0 && (
                <div className="bg-amber-50 border border-amber-200 rounded-lg p-2 space-y-1">
                  <div className="flex items-center gap-1 text-amber-700">
                    <AlertTriangle size={10} />
                    <span className="text-[10px] font-bold">{unmatched.length} 个车牌未匹配</span>
                    <button
                      onClick={() => setUnmatched([])}
                      className="ml-auto text-amber-500 hover:text-amber-700"
                    ><X size={10} /></button>
                  </div>
                  <div className="text-[10px] text-amber-600 break-all max-h-16 overflow-y-auto leading-relaxed">
                    {unmatched.join('，')}
                  </div>
                </div>
              )}

              {selected.length > 0 && (
                <div className="flex flex-wrap gap-1 max-h-20 overflow-y-auto p-1 bg-slate-50 rounded-lg">
                  {selected.map(p => (
                    <span key={p} className="inline-flex items-center gap-0.5 px-1.5 py-0.5 bg-white border border-blue-100 text-blue-600 rounded text-[10px] font-bold">
                      {p}
                      <button onClick={() => removePlate(p)} className="text-blue-400 hover:text-blue-700"><X size={9} /></button>
                    </span>
                  ))}
                </div>
              )}

              <div className="border-t border-slate-100 pt-2">
                <input
                  type="text"
                  value={search}
                  onChange={(e) => setSearch(e.target.value)}
                  placeholder="搜索车牌"
                  className="w-full bg-slate-50 border-none rounded-lg py-1.5 px-2 text-[10px] text-slate-700 outline-none focus:ring-1 focus:ring-blue-500/30"
                />
                <div className="mt-1 max-h-40 overflow-y-auto">
                  {filtered.map(p => (
                    <div
                      key={p}
                      onClick={() => togglePlate(p)}
                      className={`px-2 py-1 text-[10px] font-bold cursor-pointer flex items-center gap-1.5 rounded ${selectedSet.has(p) ? 'bg-blue-50 text-blue-600' : 'text-slate-600 hover:bg-slate-50'}`}
                    >
                      <span className={`w-3 h-3 rounded border ${selectedSet.has(p) ? 'bg-blue-600 border-blue-600' : 'border-slate-300'} flex items-center justify-center`}>
                        {selectedSet.has(p) && <span className="text-white text-[8px] leading-none">✓</span>}
                      </span>
                      {p}
                    </div>
                  ))}
                  {filtered.length === 0 && (
                    <div className="px-2 py-1 text-[10px] text-slate-300 italic">无匹配项</div>
                  )}
                </div>
              </div>
            </div>
          </motion.div>
        )}
      </AnimatePresence>
    </div>
  );
}