next-chat/app/components/markdown.tsx

import ReactMarkdown from "react-markdown";
import "katex/dist/katex.min.css";
import RemarkMath from "remark-math";
import RemarkBreaks from "remark-breaks";
import RehypeKatex from "rehype-katex";
import RemarkGfm from "remark-gfm";
import RehypeHighlight from "rehype-highlight";
import { useRef, useState, RefObject, useEffect, useMemo } from "react";
import { copyToClipboard } from "../utils";
import mermaid from "mermaid";

import LoadingIcon from "../icons/three-dots.svg";
import React from "react";
import { useDebouncedCallback } from "use-debounce";
import { showImageModal } from "./ui-lib";
import { nanoid } from "nanoid";

export function Mermaid(props: { code: string }) {
  const ref = useRef<HTMLDivElement>(null);
  const [hasError, setHasError] = useState(false);

  useEffect(() => {
    if (props.code && ref.current) {
      mermaid
        .run({
          nodes: [ref.current],
          suppressErrors: true,
        })
        .catch((e) => {
          setHasError(true);
          console.error("[Mermaid] ", e.message);
        });
    }
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [props.code]);

  function viewSvgInNewWindow() {
    const svg = ref.current?.querySelector("svg");
    if (!svg) return;
    const text = new XMLSerializer().serializeToString(svg);
    const blob = new Blob([text], { type: "image/svg+xml" });
    showImageModal(URL.createObjectURL(blob));
  }

  if (hasError) {
    return null;
  }

  return (
    <div
      className="no-dark mermaid"
      style={{
        cursor: "pointer",
        overflow: "auto",
      }}
      ref={ref}
      onClick={() => viewSvgInNewWindow()}
    >
      {props.code}
    </div>
  );
}

export function HTMLPreview(props: { code: string }) {
  const ref = useRef<HTMLDivElement>(null);
  const frameId = useRef<string>(nanoid());
  const [height, setHeight] = useState(600);
  /*
   * https://stackoverflow.com/questions/19739001/what-is-the-difference-between-srcdoc-and-src-datatext-html-in-an
   * 1. using srcdoc
   * 2. using src with dataurl:
   *    easy to share
   *    length limit (Data URIs cannot be larger than 32,768 characters.)
   */

  useEffect(() => {
    window.addEventListener("message", (e) => {
      const { id, height } = e.data;
      if (id == frameId.current) {
        console.log("setHeight", height);
        if (height < 600) {
          setHeight(height + 40);
        }
      }
    });
  }, []);

  const script = encodeURIComponent(
    `<script>new ResizeObserver((entries) => parent.postMessage({id: '${frameId.current}', height: entries[0].target.clientHeight}, '*')).observe(document.body)</script>`,
  );

  return (
    <div
      className="no-dark html"
      style={{
        cursor: "pointer",
        overflow: "auto",
      }}
      onClick={(e) => e.stopPropagation()}
    >
      <iframe
        id={frameId.current}
        ref={ref}
        frameBorder={0}
        sandbox="allow-forms allow-modals allow-scripts"
        style={{ width: "100%", height }}
        src={`data:text/html,${encodeURIComponent(props.code)}${script}`}
        // srcDoc={props.code + script}
      ></iframe>
    </div>
  );
}

export function PreCode(props: { children: any }) {
  const ref = useRef<HTMLPreElement>(null);
  const refText = ref.current?.innerText;
  const [mermaidCode, setMermaidCode] = useState("");
  const [htmlCode, setHtmlCode] = useState("");

  const renderArtifacts = useDebouncedCallback(() => {
    if (!ref.current) return;
    const mermaidDom = ref.current.querySelector("code.language-mermaid");
    if (mermaidDom) {
      setMermaidCode((mermaidDom as HTMLElement).innerText);
    }
    const htmlDom = ref.current.querySelector("code.language-html");
    if (htmlDom) {
      setHtmlCode((htmlDom as HTMLElement).innerText);
    }
  }, 600);

  useEffect(() => {
    setTimeout(renderArtifacts, 1);
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [refText]);

  return (
    <>
      <pre ref={ref}>
        <span
          className="copy-code-button"
          onClick={() => {
            if (ref.current) {
              const code = ref.current.innerText;
              copyToClipboard(code);
            }
          }}
        ></span>
        {props.children}
      </pre>
      {mermaidCode.length > 0 && (
        <Mermaid code={mermaidCode} key={mermaidCode} />
      )}
      {htmlCode.length > 0 && <HTMLPreview code={htmlCode} key={htmlCode} />}
    </>
  );
}

function escapeDollarNumber(text: string) {
  let escapedText = "";

  for (let i = 0; i < text.length; i += 1) {
    let char = text[i];
    const nextChar = text[i + 1] || " ";

    if (char === "$" && nextChar >= "0" && nextChar <= "9") {
      char = "\\$";
    }

    escapedText += char;
  }

  return escapedText;
}

function escapeBrackets(text: string) {
  const pattern =
    /(```[\s\S]*?```|`.*?`)|\\\[([\s\S]*?[^\\])\\\]|\\\((.*?)\\\)/g;
  return text.replace(
    pattern,
    (match, codeBlock, squareBracket, roundBracket) => {
      if (codeBlock) {
        return codeBlock;
      } else if (squareBracket) {
        return `$$${squareBracket}$$`;
      } else if (roundBracket) {
        return `$${roundBracket}$`;
      }
      return match;
    },
  );
}

function _MarkDownContent(props: { content: string }) {
  const escapedContent = useMemo(() => {
    return escapeBrackets(escapeDollarNumber(props.content));
  }, [props.content]);

  return (
    <ReactMarkdown
      remarkPlugins={[RemarkMath, RemarkGfm, RemarkBreaks]}
      rehypePlugins={[
        RehypeKatex,
        [
          RehypeHighlight,
          {
            detect: false,
            ignoreMissing: true,
          },
        ],
      ]}
      components={{
        pre: PreCode,
        p: (pProps) => <p {...pProps} dir="auto" />,
        a: (aProps) => {
          const href = aProps.href || "";
          const isInternal = /^\/#/i.test(href);
          const target = isInternal ? "_self" : aProps.target ?? "_blank";
          return <a {...aProps} target={target} />;
        },
      }}
    >
      {escapedContent}
    </ReactMarkdown>
  );
}

export const MarkdownContent = React.memo(_MarkDownContent);

export function Markdown(
  props: {
    content: string;
    loading?: boolean;
    fontSize?: number;
    parentRef?: RefObject<HTMLDivElement>;
    defaultShow?: boolean;
  } & React.DOMAttributes<HTMLDivElement>,
) {
  const mdRef = useRef<HTMLDivElement>(null);

  return (
    <div
      className="markdown-body"
      style={{
        fontSize: `${props.fontSize ?? 14}px`,
      }}
      ref={mdRef}
      onContextMenu={props.onContextMenu}
      onDoubleClickCapture={props.onDoubleClickCapture}
      dir="auto"
    >
      {props.loading ? (
        <LoadingIcon />
      ) : (
        <MarkdownContent content={props.content} />
      )}
    </div>
  );
}