docusaurus/lib/server/readMetadata.js

/**
 * Copyright (c) 2017-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */

const CWD = process.cwd();

const path = require("path");
const fs = require("fs");
const os = require("os");
let languages;
if (fs.existsSync(CWD + "/languages.js")) {
  languages = require(CWD + "/languages.js");
} else {
  languages = [
    {
      enabled: true,
      name: "English",
      tag: "en"
    }
  ];
}
const glob = require("glob");

function splitHeader(content) {
  const lines = content.split(os.EOL);
  let i = 1;
  for (; i < lines.length - 1; ++i) {
    if (lines[i] === "---") {
      break;
    }
  }
  return {
    header: lines.slice(1, i + 1).join("\n"),
    content: lines.slice(i + 1).join("\n")
  };
}

// Extract markdown metadata header
function extractMetadata(content) {
  const metadata = {};
  const both = splitHeader(content);
  const lines = both.header.split("\n");
  for (let i = 0; i < lines.length - 1; ++i) {
    const keyvalue = lines[i].split(":");
    const key = keyvalue[0].trim();
    let value = keyvalue.slice(1).join(":").trim();
    // Handle the case where you have "Community #10"
    try {
      value = JSON.parse(value);
    } catch (e) {}
    metadata[key] = value;
  }
  return { metadata, rawContent: both.content };
}

function processMetadata(file) {
  const result = extractMetadata(fs.readFileSync(file, "utf8"));

  const regexSubFolder = /docs\/(.*)\/.*/;

  let language = "en";
  const match = regexSubFolder.exec(file);
  if (match) {
    language = match[1];
  }

  const metadata = result.metadata;
  const rawContent = result.rawContent;
  metadata.source = path.basename(file);

  // in permalink replace /en/ language with localized folder
  metadata.permalink = metadata.permalink.replace(
    /\/en\//g,
    "/" + language + "/"
  );
  // change ids previous, next
  metadata.localized_id = metadata.id;
  metadata.id = language + "-" + metadata.id;
  if (metadata.previous) {
    metadata.previous_id = metadata.previous;
    metadata.previous = language + "-" + metadata.previous;
  }
  if (metadata.next) {
    metadata.next_id = metadata.next;
    metadata.next = language + "-" + metadata.next;
  }
  metadata.language = language;

  return { metadata, rawContent: rawContent };
}

function generateDocsMetadata() {
  const regexSubFolder = /docs\/(.*)\/.*/;

  const enabledLanguages = [];
  languages.filter(lang => lang.enabled).map(lang => {
    enabledLanguages.push(lang.tag);
  });

  const metadatas = [];

  const files = glob.sync(CWD + "/../docs/**");
  files.forEach(file => {
    let language = "en";
    const match = regexSubFolder.exec(file);
    if (match) {
      language = match[1];
    }

    if (enabledLanguages.indexOf(language) === -1) {
      return;
    }

    const extension = path.extname(file);

    if (extension === ".md" || extension === ".markdown") {
      const res = processMetadata(file);
      const metadata = res.metadata;
      metadatas.push(metadata);
    }
  });

  fs.writeFileSync(
    __dirname + "/../core/metadata.js",
    "/**\n" +
      " * @generated\n" +
      " */\n" +
      "module.exports = " +
      JSON.stringify(metadatas, null, 2) +
      ";"
  );
}

function generateBlogMetadata() {
  const metadatas = [];

  let files = glob.sync(CWD + "/../blog/**/*.*");
  files.sort().reverse().forEach(file => {
    // Transform
    //   2015-08-13-blog-post-name-0.5.md
    // into
    //   2015/08/13/blog-post-name-0-5.html
    const filePath = path
      .basename(file)
      .replace("-", "/")
      .replace("-", "/")
      .replace("-", "/")
      // react-middleware is broken with files that contains multiple .
      // like react-0.14.js
      .replace(/\./g, "-")
      .replace(/\-md$/, ".html");
    const result = extractMetadata(fs.readFileSync(file, { encoding: "utf8" }));
    const rawContent = result.rawContent;
    const metadata = Object.assign(
      { path: filePath, content: rawContent },
      result.metadata
    );
    metadata.id = metadata.title;
    metadatas.push(metadata);
  });

  fs.writeFileSync(
    __dirname + "/../core/MetadataBlog.js",
    "/**\n" +
      " * @generated\n" +
      " */\n" +
      "module.exports = " +
      JSON.stringify(metadatas, null, 2) +
      ";"
  );
}

module.exports.extractMetadata = extractMetadata;
module.exports.processMetadata = processMetadata;
module.exports.generateDocsMetadata = generateDocsMetadata;
module.exports.generateBlogMetadata = generateBlogMetadata;