MarkdownDictPlugin.ts

import fs from 'node:fs/promises';
import path from 'node:path';
import matter from 'gray-matter';
import type { Compiler, WebpackPluginInstance } from 'webpack';
import VirtualModulesPlugin from 'webpack-virtual-modules';

interface MarkdownDictPluginOptions {
  dir: string;
  modulePath?: string; // e.g. 'node_modules/virtual/markdown-dict.js'
}

export class MarkdownDictPlugin implements WebpackPluginInstance {
  constructor(private readonly options: MarkdownDictPluginOptions) {}

  apply(compiler: Compiler) {
    const virtualPath =
      this.options.modulePath ?? 'node_modules/virtual/markdown-dict.js';

    const virtualModules = new VirtualModulesPlugin();

    virtualModules.apply(compiler);

    compiler.hooks.beforeCompile.tapPromise('MarkdownDictPlugin', async () => {
      const files = await fs.readdir(this.options.dir);

      const imports = new Set(['import { createElement } from "react";']);

      const code: string[] = ['export default ['];

      for (const file of files) {
        if (!file.endsWith('.md')) {
          continue;
        }

        const fullPath = path.join(this.options.dir, file);
        const { data } = matter(await fs.readFile(fullPath, 'utf-8'));

        const match = /^(\w+)\.(\w\w)\.md$/.exec(file);

        if (!match) {
          throw new Error('invalid filename ' + file);
        }

        if ('icon' in data) {
          imports.add(
            `import { ${data.icon} } from 'react-icons/${data.icon.slice(0, 2).toLowerCase()}';`,
          );
        }

        const fields: string[] = [`key: "${match[1]}"`, `lang: "${match[2]}"`];

        if ('title' in data) {
          fields.push(`title: ${JSON.stringify(data.title)}`);
        }

        if ('listed' in data) {
          fields.push(`listed: ${data.listed}`);
        }

        if ('icon' in data) {
          fields.push(`icon: createElement(${data.icon})`);
        }

        if ('order' in data) {
          fields.push(`order: ${data.order}`);
        }

        code.push(`{ ${fields.join(', ')} },`);
      }

      code.push('];');

      virtualModules.writeModule(virtualPath, [...imports, ...code].join('\n'));
    });
  }
}