professor/components/chat/MessageList.tsx

'use client';

import { useEffect, useRef } from 'react';
import ReactMarkdown from 'react-markdown';
import remarkGfm from 'remark-gfm';
import { Prism as SyntaxHighlighter } from 'react-syntax-highlighter';
import { vscDarkPlus } from 'react-syntax-highlighter/dist/esm/styles/prism';
import type { Message } from '@/types';
import MessageBubble from './MessageBubble';

interface Props {
  messages: Message[];
  isStreaming: boolean;
  streamingContent: string;
  emptyText?: string;
}

export default function MessageList({ messages, isStreaming, streamingContent, emptyText }: Props) {
  const bottomRef = useRef<HTMLDivElement>(null);

  useEffect(() => {
    bottomRef.current?.scrollIntoView({ behavior: 'smooth' });
  }, [messages, streamingContent]);

  if (messages.length === 0 && !isStreaming) {
    return (
      <div className="flex flex-1 items-center justify-center p-6 text-center">
        <p className="text-sm text-zinc-500">
          {emptyText ?? 'Run your code or submit it for review — or ask me anything about the task.'}
        </p>
      </div>
    );
  }

  return (
    <div className="flex-1 overflow-y-auto p-4 space-y-3">
      {messages.map((msg) => (
        <MessageBubble key={msg.id} message={msg} />
      ))}

      {/* Live streaming bubble */}
      {isStreaming && streamingContent && (
        <div className="flex justify-start">
          <div className="max-w-[92%] rounded-2xl rounded-tl-sm bg-zinc-800 px-4 py-3 text-sm text-zinc-200">
            <ReactMarkdown
              remarkPlugins={[remarkGfm]}
              components={{
                code({ className, children, ...rest }) {
                  const match = /language-(\w+)/.exec(className ?? '');
                  return match ? (
                    <SyntaxHighlighter
                      style={vscDarkPlus as Record<string, React.CSSProperties>}
                      language={match[1]}
                      PreTag="div"
                      customStyle={{ margin: '0.5rem 0', borderRadius: '0.375rem', fontSize: '0.8rem' }}
                    >
                      {String(children).replace(/\n$/, '')}
                    </SyntaxHighlighter>
                  ) : (
                    <code className="rounded bg-zinc-700 px-1 py-0.5 text-xs font-mono text-zinc-200" {...rest}>
                      {children}
                    </code>
                  );
                },
                p: ({ children }) => <p className="mb-2 last:mb-0 leading-relaxed">{children}</p>,
              }}
            >
              {streamingContent}
            </ReactMarkdown>
          </div>
        </div>
      )}

      {/* Typing indicator when streaming but no content yet */}
      {isStreaming && !streamingContent && (
        <div className="flex justify-start">
          <div className="rounded-2xl rounded-tl-sm bg-zinc-800 px-4 py-3">
            <div className="flex items-center gap-1">
              <div className="h-2 w-2 animate-bounce rounded-full bg-zinc-500 [animation-delay:-0.3s]" />
              <div className="h-2 w-2 animate-bounce rounded-full bg-zinc-500 [animation-delay:-0.15s]" />
              <div className="h-2 w-2 animate-bounce rounded-full bg-zinc-500" />
            </div>
          </div>
        </div>
      )}

      <div ref={bottomRef} />
    </div>
  );
}