generateRuleExamples.ts

import {nodeFs} from './convertEsmToCjs.js';
import * as rulesTests from './spec/rules/index.js';

const {readFileSync, writeFileSync} = nodeFs;

const startMarker = '<!-- begin auto-generated examples -->';
const endMarker = '<!-- end auto-generated examples -->';

type File = Readonly<{codes: string[]; filename: string; output: string | undefined}>;

for (const [ruleName, ruleTests] of Object.entries(rulesTests)) {
  const invalidFiles: File[] = [];
  const invalidFilesHash: Record<string, File> = {};
  const validFiles: File[] = [];
  const validFilesHash: Record<string, File> = {};

  for (const {code, comment, filename, hideInDocs, output, showFixInDocs} of ruleTests.invalid) {
    if (hideInDocs === true) {
      continue;
    }

    if (comment?.includes('\n') === true) {
      throw new Error(`Comment for "${code}" is multi-line: ${comment}`);
    }

    const fullCode = comment === undefined ? code : `// ${comment}\n${code}`;

    if (code.includes('\n') || showFixInDocs === true) {
      invalidFiles.push({
        codes: [fullCode],
        filename,
        output: showFixInDocs === true ? output : undefined,
      });

      continue;
    }

    let file = invalidFilesHash[filename];

    if (file === undefined) {
      file = {codes: [], filename, output: undefined};
      invalidFiles.push(file);
      invalidFilesHash[filename] = file;
    }

    file.codes.push(fullCode);
  }

  for (const {code, comment, filename, hideInDocs} of ruleTests.valid) {
    if (hideInDocs === true) {
      continue;
    }

    if (comment?.includes('\n') === true) {
      throw new Error(`Comment for "${code}" is multi-line: ${comment}`);
    }

    const fullCode = comment === undefined ? code : `// ${comment}\n${code}`;

    if (code.includes('\n')) {
      validFiles.push({codes: [fullCode], filename, output: undefined});

      continue;
    }

    let file = validFilesHash[filename];

    if (file === undefined) {
      file = {codes: [], filename, output: undefined};
      validFiles.push(file);
      validFilesHash[filename] = file;
    }

    file.codes.push(fullCode);
  }

  const incorrectText =
    '### ❌ Incorrect\n\n' +
    invalidFiles
      .map(
        ({codes, filename, output}) =>
          '```ts\n' +
          `// ${filename}\n\n` +
          codes.join('\n\n') +
          '\n```' +
          (output === undefined
            ? ''
            : `\n\n<details>\n<summary>Fixed</summary>\n\n` +
              '```ts\n' +
              output +
              '\n```\n\n</details>'),
      )
      .join('\n\n');

  const correctText =
    '### ✅ Correct\n\n' +
    validFiles
      .map(({codes, filename}) => '```ts\n' + `// ${filename}\n\n` + codes.join('\n\n') + '\n```')
      .join('\n\n');

  const filePath = `./docs/rules/${ruleName}.md`;
  const fileContent = readFileSync(filePath, {encoding: 'utf8'});

  const startIndex = fileContent.indexOf(startMarker) + startMarker.length;
  const endIndex = fileContent.indexOf(endMarker);

  if (startIndex < startMarker.length) {
    throw new Error(`Cannot find start marker ${startMarker} in ${filePath}`);
  }

  if (endIndex < 0) {
    throw new Error(`Cannot find end marker ${endMarker} in ${filePath}`);
  }

  const newFileContent =
    fileContent.slice(0, startIndex) +
    `\n\n${incorrectText}\n\n${correctText}\n\n` +
    fileContent.slice(endIndex);

  writeFileSync(filePath, newFileContent);
}