import { useEffect, useRef, useState } from 'react';
import { CreateLibrary, DeleteLibrary, ImportCSV, ListLibraries, SwitchLibrary } from 'wailsjs/go/main/App';
import type { handler } from 'wailsjs/go/models';

interface LibraryBarProps {
  activeName: string;
  onSwitch: (name: string) => void;
}

export default function LibraryBar({ activeName, onSwitch }: LibraryBarProps) {
  const [open, setOpen]       = useState(false);
  const [libs, setLibs]       = useState<handler.LibraryInfo[]>([]);
  const [creating, setCreating] = useState(false);
  const [newName, setNewName] = useState('');
  const [importing, setImporting] = useState(false);
  const [msg, setMsg]         = useState('');
  const ref = useRef<HTMLDivElement>(null);

  const load = async () => { setLibs(await ListLibraries()); };

  useEffect(() => {
    if (open) load();
  }, [open]);

  // Close on outside click
  useEffect(() => {
    const handler = (e: MouseEvent) => {
      if (ref.current && !ref.current.contains(e.target as Node)) setOpen(false);
    };
    document.addEventListener('mousedown', handler);
    return () => document.removeEventListener('mousedown', handler);
  }, []);

  const handleSwitch = async (name: string) => {
    await SwitchLibrary(name);
    onSwitch(name);
    setOpen(false);
  };

  const handleCreate = async () => {
    if (!newName.trim()) return;
    const err = await CreateLibrary(newName.trim(), '');
    if (!err) { onSwitch(newName.trim()); setNewName(''); setCreating(false); load(); }
    else setMsg(err);
  };

  const handleImport = async () => {
    setImporting(true); setMsg('');
    const result = await ImportCSV();
    setImporting(false);
    if (result.error && result.error !== '已取消') setMsg(result.error);
    else if (result.imported > 0) { setMsg(`✓ 导入了 ${result.imported} 条（跳过 ${result.skipped} 条）`); load(); }
    setTimeout(() => setMsg(''), 4000);
  };

  return (
    <div ref={ref} className="relative px-4 pb-2">
      {/* Button row */}
      <div className="flex items-center gap-2">
        <button onClick={() => setOpen(o => !o)}
          className="flex-1 flex items-center gap-2 px-3 py-1.5 rounded-xl
                     bg-white/5 hover:bg-white/10 border border-white/8 transition-all text-left">
          <span className="text-sm">📚</span>
          <span className="text-[12px] text-white/80 truncate flex-1">{activeName || '选择知识库'}</span>
          <span className="text-[10px] text-white/30">{open ? '▲' : '▾'}</span>
        </button>
        <button onClick={handleImport} disabled={importing} title="导入 CSV"
          className="px-2.5 py-1.5 rounded-xl bg-accent/15 text-accent-light border border-accent/25
                     hover:bg-accent/25 transition-all text-[11px] font-medium disabled:opacity-50">
          {importing ? '…' : '📥 导入'}
        </button>
      </div>

      {msg && <p className={`text-[10px] mt-1 ${msg.startsWith('✓') ? 'text-green-400' : 'text-red-400'}`}>{msg}</p>}

      {/* Dropdown */}
      {open && (
        <div className="absolute left-4 right-4 top-full mt-1 z-40
                        bg-[rgba(12,10,24,0.98)] border border-white/10 rounded-xl
                        shadow-2xl overflow-hidden animate-fade-in">
          <div className="max-h-48 overflow-y-auto results-scroll">
            {libs.map(lib => (
              <div key={lib.id}
                className={`flex items-center gap-2 px-3 py-2.5 cursor-pointer transition-colors
                  ${lib.is_active ? 'bg-accent/15 border-l-2 border-accent' : 'hover:bg-white/5'}`}
                onClick={() => handleSwitch(lib.name)}>
                <span className="text-sm">{lib.is_active ? '✅' : '📁'}</span>
                <div className="flex-1 min-w-0">
                  <p className="text-[12px] text-white/85 truncate">{lib.name}</p>
                  <p className="text-[10px] text-white/35">{lib.entry_count} 条记录</p>
                </div>
                {!lib.is_active && (
                  <button onClick={e => { e.stopPropagation(); DeleteLibrary(lib.name); load(); }}
                    className="text-white/20 hover:text-red-400 text-xs transition-colors">✕</button>
                )}
              </div>
            ))}
          </div>

          {/* Create new */}
          <div className="border-t border-white/8 p-2">
            {creating ? (
              <div className="flex gap-2">
                <input autoFocus className="flex-1 search-input text-[11px]" placeholder="知识库名称"
                  value={newName} onChange={e => setNewName(e.target.value)}
                  onKeyDown={e => e.key === 'Enter' && handleCreate()}
                  style={{ paddingLeft: '10px', paddingRight: '10px' }} />
                <button onClick={handleCreate}
                  className="px-3 py-1.5 rounded-lg bg-accent text-white text-[11px]">✓</button>
                <button onClick={() => setCreating(false)} className="text-white/30 text-xs">✕</button>
              </div>
            ) : (
              <button onClick={() => setCreating(true)}
                className="w-full flex items-center gap-2 px-2 py-1.5 rounded-lg
                           text-[11px] text-white/50 hover:text-white/70 hover:bg-white/5 transition-all">
                <span>+</span> 新建知识库
              </button>
            )}
          </div>
        </div>
      )}
    </div>
  );
}