import { Paper, Stack } from "@mantine/core";
import type { ChatMessage } from "gpt-tokenizer/GptEncoding";
import { Suspense, lazy, memo } from "react";

const FormattedMarkdown = lazy(() => import("./FormattedMarkdown"));

interface MessageListProps {
  messages: ChatMessage[];
}

interface MessageProps {
  message: ChatMessage;
  index: number;
}

const Message = memo(
  function Message({ message, index }: MessageProps) {
    return (
      <Paper
        key={`${message.role}-${index}`}
        shadow="xs"
        radius="xl"
        p="sm"
        maw="90%"
        style={{
          alignSelf: message.role === "user" ? "flex-end" : "flex-start",
        }}
      >
        <Suspense fallback={message.content}>
          <FormattedMarkdown>{message.content}</FormattedMarkdown>
        </Suspense>
      </Paper>
    );
  },
  (prevProps, nextProps) => {
    return (
      prevProps.message.content === nextProps.message.content &&
      prevProps.message.role === nextProps.message.role
    );
  },
);

const MessageList = memo(function MessageList({ messages }: MessageListProps) {
  if (messages.length <= 2) return null;

  return (
    <Stack gap="md">
      {messages
        .slice(2)
        .filter((message) => message.content.length > 0)
        .map((message, index) => (
          <Message
            key={`${message.role}-${index}`}
            message={message}
            index={index}
          />
        ))}
    </Stack>
  );
});

export default MessageList;