import { useState, useRef } from 'react';
import { Terminal, Image, Play, FileText, ArrowUp, X, Paperclip } from 'lucide-react';

const SLASH_COMMANDS = [
  { cmd: '/run', desc: '执行 pipeline 阶段', icon: Play },
  { cmd: '/status', desc: '查看管线进度', icon: Terminal },
  { cmd: '/images', desc: '生成图片', icon: Image },
  { cmd: '/list', desc: '列出可用账号', icon: FileText },
  { cmd: '/help', desc: '显示帮助', icon: Terminal },
];

export interface ImageAttachment {
  data: string;
  mimeType: string;
  preview: string;
}

export function ChatInput({ onSend, disabled, connecting }: { onSend: (content: string, images?: Array<{ data: string; mimeType: string }>) => void; disabled?: boolean; connecting?: boolean }) {
  const [input, setInput] = useState('');
  const [showCmds, setShowCmds] = useState(false);
  const [cmdIdx, setCmdIdx] = useState(0);
  const [images, setImages] = useState<ImageAttachment[]>([]);
  const [dragging, setDragging] = useState(false);
  const fileRef = useRef<HTMLInputElement>(null);
  const textRef = useRef<HTMLTextAreaElement>(null);

  const matchingCmds = input.startsWith('/')
    ? SLASH_COMMANDS.filter((c) => c.cmd.startsWith(input.split(' ')[0]))
    : [];

  const readFiles = (files: File[]) => {
    if (files.length === 0) return;
    let loaded = 0;
    const results: ImageAttachment[] = [];
    files.forEach((file, i) => {
      const reader = new FileReader();
      reader.onload = () => {
        const base64 = (reader.result as string).split(',')[1];
        results[i] = { data: base64, mimeType: file.type, preview: reader.result as string };
        loaded++;
        if (loaded === files.length) {
          setImages((prev) => [...prev, ...results]);
        }
      };
      reader.readAsDataURL(file);
    });
  };

  const handleFileChange = (e: React.ChangeEvent<HTMLInputElement>) => {
    if (e.target.files) readFiles(Array.from(e.target.files));
    e.target.value = '';
  };

  const handleDragOver = (e: React.DragEvent) => {
    e.preventDefault();
    if (!dragging) setDragging(true);
  };

  const handleDragLeave = (e: React.DragEvent) => {
    e.preventDefault();
    setDragging(false);
  };

  const handleDrop = (e: React.DragEvent) => {
    e.preventDefault();
    setDragging(false);
    const imageFiles = Array.from(e.dataTransfer.files).filter((f) => f.type.startsWith('image/'));
    if (imageFiles.length > 0) readFiles(imageFiles);
  };

  const removeImage = (idx: number) => {
    setImages((prev) => prev.filter((_, i) => i !== idx));
  };

  const handleSend = () => {
    const text = input.trim();
    if ((!text && images.length === 0) || disabled) return;
    const imgs = images.length > 0 ? images.map(({ data, mimeType }) => ({ data, mimeType })) : undefined;
    onSend(text || '(图片)', imgs);
    setInput('');
    setImages([]);
    setShowCmds(false);
    textRef.current?.focus();
  };

  const handleKeyDown = (e: React.KeyboardEvent) => {
    if (showCmds && matchingCmds.length > 0) {
      if (e.key === 'Tab') { e.preventDefault(); setInput(matchingCmds[cmdIdx % matchingCmds.length].cmd + ' '); setShowCmds(false); return; }
      if (e.key === 'ArrowDown') { e.preventDefault(); setCmdIdx((i) => (i + 1) % matchingCmds.length); return; }
      if (e.key === 'ArrowUp') { e.preventDefault(); setCmdIdx((i) => (i - 1 + matchingCmds.length) % matchingCmds.length); return; }
    }
    if (e.key === 'Escape') { setShowCmds(false); return; }
    if (e.key === 'Enter' && !e.shiftKey) {
      e.preventDefault();
      handleSend();
    }
  };

  const canSend = (input.trim().length > 0 || images.length > 0) && !disabled;

  return (
    <div className="relative">
      {/* Slash command menu */}
      {showCmds && matchingCmds.length > 0 && (
        <div className="mx-6 mb-1 bg-white border border-zinc-200 rounded-2xl shadow-xl shadow-zinc-200/50 overflow-hidden animate-in slide-in-from-bottom-2">
          {matchingCmds.map((c, i) => {
            const Icon = c.icon;
            return (
              <button
                key={c.cmd}
                onClick={() => { setInput(c.cmd + ' '); setShowCmds(false); textRef.current?.focus(); }}
                className={`w-full flex items-center gap-3 px-4 py-2.5 text-sm transition-colors ${
                  i === (cmdIdx % matchingCmds.length) ? 'bg-zinc-50 text-zinc-900' : 'text-zinc-500 hover:bg-zinc-50'
                }`}
              >
                <Icon size={15} className="text-zinc-400" />
                <span className="font-mono font-medium text-xs">{c.cmd}</span>
                <span className="text-zinc-400 text-xs">{c.desc}</span>
              </button>
            );
          })}
        </div>
      )}

      {/* Input area */}
      <div
        className="px-5 pb-5 pt-3"
        onDragOver={handleDragOver}
        onDragLeave={handleDragLeave}
        onDrop={handleDrop}
      >
        <div className={`
          bg-white rounded-3xl border transition-all duration-300 relative
          ${dragging
            ? 'border-zinc-400 shadow-xl shadow-zinc-200/60'
            : disabled
              ? 'border-zinc-100 opacity-50'
              : 'border-zinc-200/80 shadow-lg shadow-zinc-100/50 focus-within:border-zinc-300 focus-within:shadow-xl focus-within:shadow-zinc-200/40'
          }
        `}>
          {/* Drop overlay */}
          {dragging && (
            <div className="absolute inset-0 rounded-3xl bg-zinc-50/80 backdrop-blur-sm z-10 flex items-center justify-center pointer-events-none">
              <span className="text-sm text-zinc-400 font-medium">松开以添加图片</span>
            </div>
          )}
          {/* Image preview strip */}
          {images.length > 0 && (
            <div className="flex flex-wrap gap-2.5 px-5 pt-4">
              {images.map((img, i) => (
                <div key={i} className="relative group/att">
                  <img src={img.preview} alt="" className="w-20 h-20 object-cover rounded-2xl shadow-sm" />
                  <button
                    onClick={() => removeImage(i)}
                    className="absolute -top-2 -right-2 w-5 h-5 bg-zinc-900 text-white rounded-full flex items-center justify-center opacity-0 group-hover/att:opacity-100 transition-all duration-200 scale-75 group-hover/att:scale-100"
                  >
                    <X size={10} strokeWidth={3} />
                  </button>
                </div>
              ))}
            </div>
          )}

          {/* Input row */}
          <div className="flex items-end gap-1 px-3 py-3">
            {/* Attachment button */}
            <button
              onClick={() => fileRef.current?.click()}
              disabled={disabled}
              className="flex-shrink-0 w-10 h-10 rounded-2xl flex items-center justify-center text-zinc-300 hover:text-zinc-500 hover:bg-zinc-50 active:scale-95 transition-all duration-200 disabled:opacity-40"
            >
              <Paperclip size={20} strokeWidth={1.8} />
            </button>
            <input
              ref={fileRef}
              type="file"
              accept="image/*"
              multiple
              onChange={handleFileChange}
              className="hidden"
            />

            <textarea
              ref={textRef}
              value={input}
              onChange={(e) => setInput(e.target.value)}
              onKeyDown={handleKeyDown}
              rows={1}
              placeholder={disabled ? (connecting ? '连接中...' : '等待回复中...') : '输入消息...'}
              className="flex-1 bg-transparent text-[15px] resize-none outline-none placeholder:text-zinc-300 text-zinc-800 min-h-[40px] max-h-[140px] py-2 leading-relaxed"
              disabled={disabled}
              style={{ height: 'auto' }}
              onInput={(e) => {
                const el = e.currentTarget;
                el.style.height = 'auto';
                el.style.height = Math.min(el.scrollHeight, 140) + 'px';
              }}
            />

            {/* Send button */}
            <button
              onClick={handleSend}
              disabled={!canSend}
              className={`
                flex-shrink-0 w-10 h-10 rounded-2xl flex items-center justify-center transition-all duration-200
                ${canSend
                  ? 'bg-zinc-900 text-white hover:bg-zinc-800 active:scale-90'
                  : 'bg-zinc-100 text-zinc-300'}
              `}
            >
              <ArrowUp size={18} strokeWidth={2.5} />
            </button>
          </div>
        </div>
      </div>
    </div>
  );
}
