30-seconds-of-code/node_modules/gatsby-plugin-netlify/build-headers-program.js

"use strict";

var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");

exports.__esModule = true;
exports.default = buildHeadersProgram;

var _lodash = _interopRequireDefault(require("lodash"));

var _fsExtra = require("fs-extra");

var _path = require("path");

var _kebabHash = _interopRequireDefault(require("kebab-hash"));

var _constants = require("./constants");

function validHeaders(headers) {
  if (!headers || !_lodash.default.isObject(headers)) {
    return false;
  }

  return _lodash.default.every(headers, (headersList, path) => _lodash.default.isArray(headersList) && _lodash.default.every(headersList, header => _lodash.default.isString(header)));
}

function linkTemplate(assetPath, type = `script`) {
  return `Link: <${assetPath}>; rel=preload; as=${type}`;
}

function pathChunkName(path) {
  const name = path === `/` ? `index` : (0, _kebabHash.default)(path);
  return `path---${name}`;
}

function createScriptHeaderGenerator(manifest, pathPrefix) {
  return script => {
    const chunk = manifest[script];

    if (!chunk) {
      return null;
    } // convert to array if it's not already


    const chunks = _lodash.default.isArray(chunk) ? chunk : [chunk];
    return chunks.filter(script => {
      const parsed = (0, _path.parse)(script); // handle only .js, .css content is inlined already
      // and doesn't need to be pushed

      return parsed.ext === `.js`;
    }).map(script => linkTemplate(`${pathPrefix}/${script}`)).join(`\n  `);
  };
}

function linkHeaders(scripts, manifest, pathPrefix) {
  return _lodash.default.compact(scripts.map(createScriptHeaderGenerator(manifest, pathPrefix)));
}

function headersPath(pathPrefix, path) {
  return `${pathPrefix}${path}`;
}

function preloadHeadersByPage(pages, manifest, pathPrefix) {
  let linksByPage = {};
  pages.forEach(page => {
    const scripts = [..._constants.COMMON_BUNDLES, pathChunkName(page.path), page.componentChunkName];
    const pathKey = headersPath(pathPrefix, page.path);
    linksByPage[pathKey] = linkHeaders(scripts, manifest, pathPrefix);
  });
  return linksByPage;
}

function defaultMerge(...headers) {
  function unionMerge(objValue, srcValue) {
    if (_lodash.default.isArray(objValue)) {
      return _lodash.default.union(objValue, srcValue);
    } else {
      return undefined; // opt into default merge behavior
    }
  }

  return _lodash.default.mergeWith({}, ...headers, unionMerge);
}

function transformLink(manifest, publicFolder, pathPrefix) {
  return header => header.replace(_constants.LINK_REGEX, (__, prefix, file, suffix) => {
    const hashed = manifest[file];

    if (hashed) {
      return `${prefix}${pathPrefix}${hashed}${suffix}`;
    } else if ((0, _fsExtra.existsSync)(publicFolder(file))) {
      return `${prefix}${pathPrefix}${file}${suffix}`;
    } else {
      throw new Error(`Could not find the file specified in the Link header \`${header}\`.` + `The gatsby-plugin-netlify is looking for a matching file (with or without a ` + `webpack hash). Check the public folder and your gatsby-config.js to ensure you are ` + `pointing to a public file.`);
    }
  });
} // Writes out headers file format, with two spaces for indentation
// https://www.netlify.com/docs/headers-and-basic-auth/


function stringifyHeaders(headers) {
  return _lodash.default.reduce(headers, (text, headerList, path) => {
    const headersString = _lodash.default.reduce(headerList, (accum, header) => `${accum}  ${header}\n`, ``);

    return `${text}${path}\n${headersString}`;
  }, ``);
} // program methods


const validateUserOptions = pluginOptions => headers => {
  if (!validHeaders(headers)) {
    throw new Error(`The "headers" option to gatsby-plugin-netlify is in the wrong shape. ` + `You should pass in a object with string keys (representing the paths) and an array ` + `of strings as the value (representing the headers). ` + `Check your gatsby-config.js.`);
  }

  ;
  [`mergeSecurityHeaders`, `mergeLinkHeaders`, `mergeCachingHeaders`].forEach(mergeOption => {
    if (!_lodash.default.isBoolean(pluginOptions[mergeOption])) {
      throw new Error(`The "${mergeOption}" option to gatsby-plugin-netlify must be a boolean. ` + `Check your gatsby-config.js.`);
    }
  });

  if (!_lodash.default.isFunction(pluginOptions.transformHeaders)) {
    throw new Error(`The "transformHeaders" option to gatsby-plugin-netlify must be a function ` + `that returns a array of header strings.` + `Check your gatsby-config.js.`);
  }

  return headers;
};

const mapUserLinkHeaders = ({
  manifest,
  pathPrefix,
  publicFolder
}) => headers => _lodash.default.mapValues(headers, headerList => _lodash.default.map(headerList, transformLink(manifest, publicFolder, pathPrefix)));

const mapUserLinkAllPageHeaders = (pluginData, {
  allPageHeaders
}) => headers => {
  if (!allPageHeaders) {
    return headers;
  }

  const {
    pages,
    manifest,
    publicFolder,
    pathPrefix
  } = pluginData;

  const headersList = _lodash.default.map(allPageHeaders, transformLink(manifest, publicFolder, pathPrefix));

  const duplicateHeadersByPage = {};
  pages.forEach(page => {
    const pathKey = headersPath(pathPrefix, page.path);
    duplicateHeadersByPage[pathKey] = headersList;
  });
  return defaultMerge(headers, duplicateHeadersByPage);
};

const applyLinkHeaders = (pluginData, {
  mergeLinkHeaders
}) => headers => {
  if (!mergeLinkHeaders) {
    return headers;
  }

  const {
    pages,
    manifest,
    pathPrefix
  } = pluginData;
  const perPageHeaders = preloadHeadersByPage(pages, manifest, pathPrefix);
  return defaultMerge(headers, perPageHeaders);
};

const applySecurityHeaders = ({
  mergeSecurityHeaders
}) => headers => {
  if (!mergeSecurityHeaders) {
    return headers;
  }

  return defaultMerge(headers, _constants.SECURITY_HEADERS);
};

const applyCachingHeaders = (pluginData, {
  mergeCachingHeaders
}) => headers => {
  if (!mergeCachingHeaders) {
    return headers;
  }

  const chunks = Array.from(pluginData.pages.values()).map(page => page.componentChunkName);
  chunks.push(`pages-manifest`, `app`);
  const files = [].concat(...chunks.map(chunk => pluginData.manifest[chunk]));
  const cachingHeaders = {};
  files.forEach(file => {
    cachingHeaders[`/` + file] = [_constants.IMMUTABLE_CACHING_HEADER];
  });
  return defaultMerge(headers, cachingHeaders, _constants.CACHING_HEADERS);
};

const applyTransfromHeaders = ({
  transformHeaders
}) => headers => _lodash.default.mapValues(headers, transformHeaders);

const transformToString = headers => `${_constants.HEADER_COMMENT}\n\n${stringifyHeaders(headers)}`;

const writeHeadersFile = ({
  publicFolder
}) => contents => (0, _fsExtra.writeFile)(publicFolder(_constants.NETLIFY_HEADERS_FILENAME), contents);

function buildHeadersProgram(pluginData, pluginOptions) {
  return _lodash.default.flow(validateUserOptions(pluginOptions), mapUserLinkHeaders(pluginData), applySecurityHeaders(pluginOptions), applyCachingHeaders(pluginData, pluginOptions), mapUserLinkAllPageHeaders(pluginData, pluginOptions), applyLinkHeaders(pluginData, pluginOptions), applyTransfromHeaders(pluginOptions), transformToString, writeHeadersFile(pluginData))(pluginOptions.headers);
}