components/messages.tsx

import { PreviewMessage, ThinkingMessage } from './message';
import { Greeting } from './greeting';
import { memo } from 'react';
import type { Vote } from '@/lib/db/schema';
import equal from 'fast-deep-equal';
import type { UseChatHelpers } from '@ai-sdk/react';
import { motion } from 'framer-motion';
import { useMessages } from '@/hooks/use-messages';
import type { ChatMessage } from '@/lib/types';
import { useDataStream } from './data-stream-provider';
import { Conversation, ConversationContent, ConversationScrollButton } from './elements/conversation';

interface MessagesProps {
  chatId: string;
  status: UseChatHelpers<ChatMessage>['status'];
  votes: Array<Vote> | undefined;
  messages: ChatMessage[];
  setMessages: UseChatHelpers<ChatMessage>['setMessages'];
  regenerate: UseChatHelpers<ChatMessage>['regenerate'];
  isReadonly: boolean;
  isArtifactVisible: boolean;
}

function PureMessages({
  chatId,
  status,
  votes,
  messages,
  setMessages,
  regenerate,
  isReadonly,
}: MessagesProps) {
  const {
    containerRef: messagesContainerRef,
    endRef: messagesEndRef,
    onViewportEnter,
    onViewportLeave,
    hasSentMessage,
  } = useMessages({
    chatId,
    status,
  });

  useDataStream();

  return (
    <div ref={messagesContainerRef} className="flex-1 overflow-y-auto">
      <Conversation className="flex flex-col min-w-0 gap-6 py-4 px-2 md:px-4">
        <ConversationContent className="flex flex-col gap-6">
          {messages.length === 0 && <Greeting />}

          {messages.map((message, index) => (
            <PreviewMessage
              key={message.id}
              chatId={chatId}
              message={message}
              isLoading={status === 'streaming' && messages.length - 1 === index}
              vote={
                votes
                  ? votes.find((vote) => vote.messageId === message.id)
                  : undefined
              }
              setMessages={setMessages}
              regenerate={regenerate}
              isReadonly={isReadonly}
              requiresScrollPadding={
                hasSentMessage && index === messages.length - 1
              }
            />
          ))}

          {status === 'submitted' &&
            messages.length > 0 &&
            messages[messages.length - 1].role === 'user' && <ThinkingMessage />}

          <motion.div
            ref={messagesEndRef}
            className="shrink-0 min-w-[24px] min-h-[24px]"
            onViewportLeave={onViewportLeave}
            onViewportEnter={onViewportEnter}
          />
        </ConversationContent>
        <ConversationScrollButton />
      </Conversation>
    </div>
  );
}

export const Messages = memo(PureMessages, (prevProps, nextProps) => {
  if (prevProps.isArtifactVisible && nextProps.isArtifactVisible) return true;

  if (prevProps.status !== nextProps.status) return false;
  if (prevProps.messages.length !== nextProps.messages.length) return false;
  if (!equal(prevProps.messages, nextProps.messages)) return false;
  if (!equal(prevProps.votes, nextProps.votes)) return false;

  return false;
});