@adobe/eslint-config-helix/rules/header.js

Helix's ESLint config, based on Airbnb's style guide

/*
 * Copyright 2024 Adobe. All rights reserved.
 * This file is licensed to you under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License. You may obtain a copy
 * of the License at http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under
 * the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
 * OF ANY KIND, either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */

function headerLineMatches(expected, actual) {
  if (expected.pattern) {
    return new RegExp(expected.pattern).test(actual);
  }
  return expected === actual;
}

function headerMatches(expected, actual) {
  if (expected.length !== actual.length) {
    return false;
  }
  for (let i = 0; i < expected.length; i += 1) {
    if (!headerLineMatches(expected[i], actual[i])) {
      return false;
    }
  }
  return true;
}

/**
 * Returns the header comment.
 *
 * @param {Program} program program node
 * @param {import('eslint').Rule.RuleContext} context rule context
 * @returns header comment or null
 */
function getHeaderComment(program, context) {
  const comments = context.sourceCode.getCommentsBefore(program);
  if (!comments.length) {
    return null;
  }
  const startingIndex = comments[0].type === 'Shebang' ? 1 : 0;
  if (comments.length <= startingIndex) {
    return null;
  }
  if (comments[startingIndex].type === 'Block') {
    return comments[startingIndex].value.split('\n');
  }
  return null;
}

export default {
  rules: {
    /** @type {import('eslint').Rule.RuleModule} */
    header: {
      meta: {
        type: 'layout',
        docs: {
          description:
            'Verifies the content and format of a file\'s leading comment block.',
          recommended: false,
        },
        messages: {
          missingHeader: 'No header found.',
          headerContentMismatch: 'Header does not include expected content.',
        },
        fixable: 'code',
        schema: [
          {
            type: 'object',
            properties: {
              block: {
                type: 'array',
              },
            },
            required: ['block'],
          },
        ],
      },
      create: (context) => ({
        Program: (node) => {
          const headerComment = getHeaderComment(node, context);
          if (!headerComment) {
            context.report({
              node,
              messageId: 'missingHeader',
            });
            return;
          }
          const { options: [{ block }] } = context;
          if (!headerMatches(block, headerComment)) {
            context.report({
              node,
              messageId: 'headerContentMismatch',
            });
          }
        },
      }),
    },
  },
};