md-wechat/src/assets/scripts/renderers/wx-renderer.js

import marked, { Renderer } from "marked";
import hljs from "highlight.js";
import markedKatex from "marked-katex-extension";

marked.use(markedKatex({
  throwOnError: false,
  output: `html`
}));

class WxRenderer {
  constructor(opts) {
    this.opts = opts;
    let footnotes = [];
    let footnoteIndex = 0;
    let styleMapping = new Map();

    let merge = (base, extend) => Object.assign({}, base, extend);

    this.buildTheme = (themeTpl) => {
      let mapping = {};
      let base = merge(themeTpl.BASE, {
        "font-family": this.opts.fonts,
        "font-size": this.opts.size,
      });
      for (let ele in themeTpl.inline) {
        if (themeTpl.inline.hasOwnProperty(ele)) {
          let style = themeTpl.inline[ele];
          mapping[ele] = merge(themeTpl.BASE, style);
        }
      }

      let base_block = merge(base, {});
      for (let ele in themeTpl.block) {
        if (themeTpl.block.hasOwnProperty(ele)) {
          let style = themeTpl.block[ele];
          mapping[ele] = merge(base_block, style);
        }
      }
      return mapping;
    };

    let getStyles = (tokenName, addition) => {
      let arr = [];
      let dict = styleMapping[tokenName];
      if (!dict) return "";
      for (const key in dict) {
        arr.push(key + ":" + dict[key]);
      }
      return `style="${arr.join(";") + (addition || "")}"`;
    };

    let addFootnote = (title, link) => {
      footnotes.push([++footnoteIndex, title, link]);
      return footnoteIndex;
    };

    this.buildFootnotes = () => {
      let footnoteArray = footnotes.map((x) => {
        if (x[1] === x[2]) {
          return `<code style="font-size: 90%; opacity: 0.6;">[${x[0]}]</code>: <i>${x[1]}</i><br/>`;
        }
        return `<code style="font-size: 90%; opacity: 0.6;">[${x[0]}]</code> ${x[1]}: <i>${x[2]}</i><br/>`;
      });
      if (!footnoteArray.length) {
        return "";
      }
      return `<h4 ${getStyles("h4")}>引用链接</h4><p ${getStyles(
        "footnotes"
      )}>${footnoteArray.join("\n")}</p>`;
    };

    this.buildAddition = () => {
      return `
            <style>
            .preview-wrapper pre::before {
                position: absolute;
                top: 0;
                right: 0;
                color: #ccc;
                text-align: center;
                font-size: 0.8em;
                padding: 5px 10px 0;
                line-height: 15px;
                height: 15px;
                font-weight: 600;
            }
            </style>
        `;
    };

    this.setOptions = (newOpts) => {
      this.opts = merge(this.opts, newOpts);
    };

    this.hasFootnotes = () => footnotes.length !== 0;

    this.getRenderer = (status) => {
      footnotes = [];
      footnoteIndex = 0;

      styleMapping = this.buildTheme(this.opts.theme);
      let renderer = new Renderer();

      renderer.heading = (text, level) => {
        switch (level) {
          case 1:
            return `<h1 ${getStyles("h1")}>${text}</h1>`;
          case 2:
            return `<h2 ${getStyles("h2")}>${text}</h2>`;
          case 3:
            return `<h3 ${getStyles("h3")}>${text}</h3>`;
          default:
            return `<h4 ${getStyles("h4")}>${text}</h4>`;
        }
      };
      renderer.paragraph = (text) => {
        if (text.indexOf("<figure") != -1 && text.indexOf("<img") != -1) {
          return text;
        }
        return text.replace(/ /g, "") === ""
          ? ""
          : `<p ${getStyles("p")}>${text}</p>`;
      };

      renderer.blockquote = (text) => {
        text = text.replace(/<p.*?>/g, `<p ${getStyles("blockquote_p")}>`);
        return `<blockquote ${getStyles("blockquote")}>${text}</blockquote>`;
      };
      renderer.code = (text, lang = "") => {
        if (lang.startsWith("mermaid")) {
          setTimeout(() => {
            window.mermaid?.run();
          }, 0);
          return `<center><pre class="mermaid">${text}</pre></center>`;
        }
        lang = hljs.getLanguage(lang) ? lang : "plaintext";

        text = hljs.highlight(text, { language: lang }).value;

        text = text
          .replace(/\r\n/g, "<br/>")
          .replace(/\n/g, "<br/>")
          .replace(/(>[^<]+)|(^[^<]+)/g, function (str) {
            return str.replace(/\s/g, "&nbsp;");
          });

        return `<pre class="hljs code__pre" ${getStyles(
          "code_pre"
        )}><code class="prettyprint language-${lang}" ${getStyles(
          "code"
        )}>${text}</code></pre>`;
      };
      renderer.codespan = (text, lang) =>
        `<code ${getStyles("codespan")}>${text}</code>`;
      renderer.listitem = (text) =>
        `<li ${getStyles("listitem")}><span><%s/></span>${text}</li>`;

      renderer.list = (text, ordered, start) => {
        text = text.replace(/<\/*p .*?>/g, "").replace(/<\/*p>/g, "");
        let segments = text.split(`<%s/>`);
        if (!ordered) {
          text = segments.join("• ");
          return `<ul ${getStyles("ul")}>${text}</ul>`;
        }
        text = segments[0];
        for (let i = 1; i < segments.length; i++) {
          text = text + i + ". " + segments[i];
        }
        return `<ol ${getStyles("ol")}>${text}</ol>`;
      };
      renderer.image = (href, title, text) => {
        let subText = "";
        if (text) {
          subText = `<figcaption ${getStyles(
            "figcaption"
          )}>${text}</figcaption>`;
        }
        let figureStyles = getStyles("figure");
        let imgStyles = getStyles("image");
        return `<figure ${figureStyles}><img ${imgStyles} src="${href}" title="${title}" alt="${text}"/>${subText}</figure>`;
      };
      renderer.link = (href, title, text) => {
        if (href.startsWith("https://mp.weixin.qq.com")) {
          return `<a href="${href}" title="${title || text}" ${getStyles(
            "wx_link"
          )}>${text}</a>`;
        }
        if (href === text) {
          return text;
        }
        if (status) {
          let ref = addFootnote(title || text, href);
          return `<span ${getStyles("link")}>${text}<sup>[${ref}]</sup></span>`;
        }
        return `<span ${getStyles("link")}>${text}</span>`;
      };
      renderer.strong = (text) =>
        `<strong ${getStyles("strong")}>${text}</strong>`;
      renderer.em = (text) =>
        `<span style="font-style: italic;">${text}</span>`;
      renderer.table = (header, body) =>
        `<section style="padding:0 8px;"><table class="preview-table"><thead ${getStyles(
          "thead"
        )}>${header}</thead><tbody>${body}</tbody></table></section>`;
      renderer.tablecell = (text, flags) =>
        `<td ${getStyles("td")}>${text}</td>`;
      renderer.hr = () => `<hr ${getStyles("hr")}>`;
      return renderer;
    };
  }
}
export default WxRenderer;