utils.js

import url from "url";
import path from "path";

function getDefaultSassImplementation() {
  let sassImplPkg = "sass";

  try {
    require.resolve("sass");
  } catch (ignoreError) {
    try {
      require.resolve("node-sass");
      sassImplPkg = "node-sass";
    } catch (_ignoreError) {
      try {
        require.resolve("sass-embedded");
        sassImplPkg = "sass-embedded";
      } catch (__ignoreError) {
        sassImplPkg = "sass";
      }
    }
  }

  // eslint-disable-next-line import/no-dynamic-require, global-require
  return require(sassImplPkg);
}

/**
 * This function is not Webpack-specific and can be used by tools wishing to mimic `sass-loader`'s behaviour, so its signature should not be changed.
 */
function getSassImplementation(loaderContext, implementation) {
  let resolvedImplementation = implementation;

  if (!resolvedImplementation) {
    resolvedImplementation = getDefaultSassImplementation();
  }

  if (typeof resolvedImplementation === "string") {
    // eslint-disable-next-line import/no-dynamic-require, global-require
    resolvedImplementation = require(resolvedImplementation);
  }

  const { info } = resolvedImplementation;

  if (!info) {
    throw new Error("Unknown Sass implementation.");
  }

  const infoParts = info.split("\t");

  if (infoParts.length < 2) {
    throw new Error(`Unknown Sass implementation "${info}".`);
  }

  const [implementationName] = infoParts;

  if (implementationName === "dart-sass") {
    // eslint-disable-next-line consistent-return
    return resolvedImplementation;
  } else if (implementationName === "node-sass") {
    // eslint-disable-next-line consistent-return
    return resolvedImplementation;
  } else if (implementationName === "sass-embedded") {
    // eslint-disable-next-line consistent-return
    return resolvedImplementation;
  }

  throw new Error(`Unknown Sass implementation "${implementationName}".`);
}

/**
 * @param {any} loaderContext
 * @returns {boolean}
 */
function isProductionLikeMode(loaderContext) {
  return loaderContext.mode === "production" || !loaderContext.mode;
}

function proxyCustomImporters(importers, loaderContext) {
  return [].concat(importers).map(
    (importer) =>
      function proxyImporter(...args) {
        const self = { ...this, webpackLoaderContext: loaderContext };

        return importer.apply(self, args);
      }
  );
}

function isSupportedFibers() {
  const [nodeVersion] = process.versions.node.split(".");

  return Number(nodeVersion) < 16;
}

/**
 * Derives the sass options from the loader context and normalizes its values with sane defaults.
 *
 * @param {object} loaderContext
 * @param {object} loaderOptions
 * @param {string} content
 * @param {object} implementation
 * @param {boolean} useSourceMap
 * @returns {Object}
 */
async function getSassOptions(
  loaderContext,
  loaderOptions,
  content,
  implementation,
  useSourceMap
) {
  const options = loaderOptions.sassOptions
    ? typeof loaderOptions.sassOptions === "function"
      ? loaderOptions.sassOptions(loaderContext) || {}
      : loaderOptions.sassOptions
    : {};
  const sassOptions = {
    ...options,
    data: loaderOptions.additionalData
      ? typeof loaderOptions.additionalData === "function"
        ? await loaderOptions.additionalData(content, loaderContext)
        : `${loaderOptions.additionalData}\n${content}`
      : content,
  };

  if (!sassOptions.logger) {
    const needEmitWarning = loaderOptions.warnRuleAsWarning !== false;
    const logger = loaderContext.getLogger("sass-loader");
    const formatSpan = (span) =>
      `${span.url || "-"}:${span.start.line}:${span.start.column}: `;
    const formatDebugSpan = (span) =>
      `[debug:${span.start.line}:${span.start.column}] `;

    sassOptions.logger = {
      debug(message, loggerOptions) {
        let builtMessage = "";

        if (loggerOptions.span) {
          builtMessage = formatDebugSpan(loggerOptions.span);
        }

        builtMessage += message;

        logger.debug(builtMessage);
      },
      warn(message, loggerOptions) {
        let builtMessage = "";

        if (loggerOptions.deprecation) {
          builtMessage += "Deprecation ";
        }

        if (loggerOptions.span && !loggerOptions.stack) {
          builtMessage = formatSpan(loggerOptions.span);
        }

        builtMessage += message;

        if (loggerOptions.stack) {
          builtMessage += `\n\n${loggerOptions.stack}`;
        }

        if (needEmitWarning) {
          const warning = new Error(builtMessage);

          warning.name = "SassWarning";
          warning.stack = null;

          loaderContext.emitWarning(warning);
        } else {
          logger.warn(builtMessage);
        }
      },
    };
  }

  const isModernAPI = loaderOptions.api === "modern";
  const { resourcePath } = loaderContext;

  if (isModernAPI) {
    sassOptions.url = url.pathToFileURL(resourcePath);

    // opt.outputStyle
    if (!sassOptions.style && isProductionLikeMode(loaderContext)) {
      sassOptions.style = "compressed";
    }

    if (useSourceMap) {
      sassOptions.sourceMap = true;
    }

    // If we are compiling sass and indentedSyntax isn't set, automatically set it.
    if (typeof sassOptions.syntax === "undefined") {
      const ext = path.extname(resourcePath);

      if (ext && ext.toLowerCase() === ".scss") {
        sassOptions.syntax = "scss";
      } else if (ext && ext.toLowerCase() === ".sass") {
        sassOptions.syntax = "indented";
      } else if (ext && ext.toLowerCase() === ".css") {
        sassOptions.syntax = "css";
      }
    }

    sassOptions.importers = sassOptions.importers
      ? Array.isArray(sassOptions.importers)
        ? sassOptions.importers.slice()
        : [sassOptions.importers]
      : [];
  } else {
    sassOptions.file = resourcePath;

    const isDartSass = implementation.info.includes("dart-sass");

    if (isDartSass && isSupportedFibers()) {
      const shouldTryToResolveFibers =
        !sassOptions.fiber && sassOptions.fiber !== false;

      if (shouldTryToResolveFibers) {
        let fibers;

        try {
          fibers = require.resolve("fibers");
        } catch (_error) {
          // Nothing
        }

        if (fibers) {
          // eslint-disable-next-line global-require, import/no-dynamic-require
          sassOptions.fiber = require(fibers);
        }
      } else if (sassOptions.fiber === false) {
        // Don't pass the `fiber` option for `sass` (`Dart Sass`)
        delete sassOptions.fiber;
      }
    } else {
      // Don't pass the `fiber` option for `node-sass`
      delete sassOptions.fiber;
    }

    // opt.outputStyle
    if (!sassOptions.outputStyle && isProductionLikeMode(loaderContext)) {
      sassOptions.outputStyle = "compressed";
    }

    if (useSourceMap) {
      // Deliberately overriding the sourceMap option here.
      // node-sass won't produce source maps if the data option is used and options.sourceMap is not a string.
      // In case it is a string, options.sourceMap should be a path where the source map is written.
      // But since we're using the data option, the source map will not actually be written, but
      // all paths in sourceMap.sources will be relative to that path.
      // Pretty complicated... :(
      sassOptions.sourceMap = true;
      sassOptions.outFile = path.join(
        loaderContext.rootContext,
        "style.css.map"
      );
      sassOptions.sourceMapContents = true;
      sassOptions.omitSourceMapUrl = true;
      sassOptions.sourceMapEmbed = false;
    }

    const ext = path.extname(resourcePath);

    // If we are compiling sass and indentedSyntax isn't set, automatically set it.
    if (
      ext &&
      ext.toLowerCase() === ".sass" &&
      typeof sassOptions.indentedSyntax === "undefined"
    ) {
      sassOptions.indentedSyntax = true;
    } else {
      sassOptions.indentedSyntax = Boolean(sassOptions.indentedSyntax);
    }

    // Allow passing custom importers to `sass`/`node-sass`. Accepts `Function` or an array of `Function`s.
    sassOptions.importer = sassOptions.importer
      ? proxyCustomImporters(
          Array.isArray(sassOptions.importer)
            ? sassOptions.importer.slice()
            : [sassOptions.importer],
          loaderContext
        )
      : [];

    sassOptions.includePaths = []
      .concat(process.cwd())
      .concat(
        // We use `includePaths` in context for resolver, so it should be always absolute
        (sassOptions.includePaths ? sassOptions.includePaths.slice() : []).map(
          (includePath) =>
            path.isAbsolute(includePath)
              ? includePath
              : path.join(process.cwd(), includePath)
        )
      )
      .concat(
        process.env.SASS_PATH
          ? process.env.SASS_PATH.split(
              process.platform === "win32" ? ";" : ":"
            )
          : []
      );

    if (typeof sassOptions.charset === "undefined") {
      sassOptions.charset = true;
    }
  }

  return sassOptions;
}

const MODULE_REQUEST_REGEX = /^[^?]*~/;

// Examples:
// - ~package
// - ~package/
// - ~@org
// - ~@org/
// - ~@org/package
// - ~@org/package/
const IS_MODULE_IMPORT =
  /^~([^/]+|[^/]+\/|@[^/]+[/][^/]+|@[^/]+\/?|@[^/]+[/][^/]+\/)$/;

/**
 * When `sass`/`node-sass` tries to resolve an import, it uses a special algorithm.
 * Since the `sass-loader` uses webpack to resolve the modules, we need to simulate that algorithm.
 * This function returns an array of import paths to try.
 * The last entry in the array is always the original url to enable straight-forward webpack.config aliases.
 *
 * We don't need emulate `dart-sass` "It's not clear which file to import." errors (when "file.ext" and "_file.ext" files are present simultaneously in the same directory).
 * This reduces performance and `dart-sass` always do it on own side.
 *
 * @param {string} url
 * @param {boolean} forWebpackResolver
 * @param {boolean} fromImport
 * @returns {Array<string>}
 */
function getPossibleRequests(
  // eslint-disable-next-line no-shadow
  url,
  forWebpackResolver = false,
  fromImport = false
) {
  let request = url;

  // In case there is module request, send this to webpack resolver
  if (forWebpackResolver) {
    if (MODULE_REQUEST_REGEX.test(url)) {
      request = request.replace(MODULE_REQUEST_REGEX, "");
    }

    if (IS_MODULE_IMPORT.test(url)) {
      request = request[request.length - 1] === "/" ? request : `${request}/`;

      return [...new Set([request, url])];
    }
  }

  // Keep in mind: ext can also be something like '.datepicker' when the true extension is omitted and the filename contains a dot.
  // @see https://github.com/webpack-contrib/sass-loader/issues/167
  const extension = path.extname(request).toLowerCase();

  // Because @import is also defined in CSS, Sass needs a way of compiling plain CSS @imports without trying to import the files at compile time.
  // To accomplish this, and to ensure SCSS is as much of a superset of CSS as possible, Sass will compile any @imports with the following characteristics to plain CSS imports:
  //  - imports where the URL ends with .css.
  //  - imports where the URL begins http:// or https://.
  //  - imports where the URL is written as a url().
  //  - imports that have media queries.
  //
  // The `node-sass` package sends `@import` ending on `.css` to importer, it is bug, so we skip resolve
  if (extension === ".css") {
    return [];
  }

  const dirname = path.dirname(request);
  const normalizedDirname = dirname === "." ? "" : `${dirname}/`;
  const basename = path.basename(request);
  const basenameWithoutExtension = path.basename(request, extension);

  return [
    ...new Set(
      []
        .concat(
          fromImport
            ? [
                `${normalizedDirname}_${basenameWithoutExtension}.import${extension}`,
                `${normalizedDirname}${basenameWithoutExtension}.import${extension}`,
              ]
            : []
        )
        .concat([
          `${normalizedDirname}_${basename}`,
          `${normalizedDirname}${basename}`,
        ])
        .concat(forWebpackResolver ? [url] : [])
    ),
  ];
}

function promiseResolve(callbackResolve) {
  return (context, request) =>
    new Promise((resolve, reject) => {
      callbackResolve(context, request, (error, result) => {
        if (error) {
          reject(error);
        } else {
          resolve(result);
        }
      });
    });
}

async function startResolving(resolutionMap) {
  if (resolutionMap.length === 0) {
    return Promise.reject();
  }

  const [{ possibleRequests }] = resolutionMap;

  if (possibleRequests.length === 0) {
    return Promise.reject();
  }

  const [{ resolve, context }] = resolutionMap;

  try {
    return await resolve(context, possibleRequests[0]);
  } catch (_ignoreError) {
    const [, ...tailResult] = possibleRequests;

    if (tailResult.length === 0) {
      const [, ...tailResolutionMap] = resolutionMap;

      return startResolving(tailResolutionMap);
    }

    // eslint-disable-next-line no-param-reassign
    resolutionMap[0].possibleRequests = tailResult;

    return startResolving(resolutionMap);
  }
}

const IS_SPECIAL_MODULE_IMPORT = /^~[^/]+$/;
// `[drive_letter]:\` + `\\[server]\[sharename]\`
const IS_NATIVE_WIN32_PATH = /^[a-z]:[/\\]|^\\\\/i;

/**
 * @public
 * Create the resolve function used in the custom Sass importer.
 *
 * Can be used by external tools to mimic how `sass-loader` works, for example
 * in a Jest transform. Such usages will want to wrap `resolve.create` from
 * [`enhanced-resolve`]{@link https://github.com/webpack/enhanced-resolve} to
 * pass as the `resolverFactory` argument.
 *
 * @param {Function} resolverFactory - A factory function for creating a Webpack
 *   resolver.
 * @param {Object} implementation - The imported Sass implementation, both
 *   `sass` (Dart Sass) and `node-sass` are supported.
 * @param {string[]} [includePaths] - The list of include paths passed to Sass.
 *
 * @throws If a compatible Sass implementation cannot be found.
 */
function getWebpackResolver(
  resolverFactory,
  implementation,
  includePaths = []
) {
  const isDartSass =
    implementation && implementation.info.includes("dart-sass");
  // We only have one difference with the built-in sass resolution logic and out resolution logic:
  // First, we look at the files starting with `_`, then without `_` (i.e. `_name.sass`, `_name.scss`, `_name.css`, `name.sass`, `name.scss`, `name.css`),
  // although `sass` look together by extensions (i.e. `_name.sass`/`name.sass`/`_name.scss`/`name.scss`/`_name.css`/`name.css`).
  // It shouldn't be a problem because `sass` throw errors:
  // - on having `_name.sass` and `name.sass` (extension can be `sass`, `scss` or `css`) in the same directory
  // - on having `_name.sass` and `_name.scss` in the same directory
  //
  // Also `sass` prefer `sass`/`scss` over `css`.
  const sassModuleResolve = promiseResolve(
    resolverFactory({
      alias: [],
      aliasFields: [],
      conditionNames: [],
      descriptionFiles: [],
      extensions: [".sass", ".scss", ".css"],
      exportsFields: [],
      mainFields: [],
      mainFiles: ["_index", "index"],
      modules: [],
      restrictions: [/\.((sa|sc|c)ss)$/i],
      preferRelative: true,
    })
  );
  const sassImportResolve = promiseResolve(
    resolverFactory({
      alias: [],
      aliasFields: [],
      conditionNames: [],
      descriptionFiles: [],
      extensions: [".sass", ".scss", ".css"],
      exportsFields: [],
      mainFields: [],
      mainFiles: ["_index.import", "_index", "index.import", "index"],
      modules: [],
      restrictions: [/\.((sa|sc|c)ss)$/i],
      preferRelative: true,
    })
  );
  const webpackModuleResolve = promiseResolve(
    resolverFactory({
      dependencyType: "sass",
      conditionNames: ["sass", "style", "..."],
      mainFields: ["sass", "style", "main", "..."],
      mainFiles: ["_index", "index", "..."],
      extensions: [".sass", ".scss", ".css"],
      restrictions: [/\.((sa|sc|c)ss)$/i],
      preferRelative: true,
    })
  );
  const webpackImportResolve = promiseResolve(
    resolverFactory({
      dependencyType: "sass",
      conditionNames: ["sass", "style", "..."],
      mainFields: ["sass", "style", "main", "..."],
      mainFiles: ["_index.import", "_index", "index.import", "index", "..."],
      extensions: [".sass", ".scss", ".css"],
      restrictions: [/\.((sa|sc|c)ss)$/i],
      preferRelative: true,
    })
  );

  return (context, request, fromImport) => {
    // See https://github.com/webpack/webpack/issues/12340
    // Because `node-sass` calls our importer before `1. Filesystem imports relative to the base file.`
    // custom importer may not return `{ file: '/path/to/name.ext' }` and therefore our `context` will be relative
    if (!isDartSass && !path.isAbsolute(context)) {
      return Promise.reject();
    }

    const originalRequest = request;
    const isFileScheme = originalRequest.slice(0, 5).toLowerCase() === "file:";

    if (isFileScheme) {
      try {
        // eslint-disable-next-line no-param-reassign
        request = url.fileURLToPath(originalRequest);
      } catch (ignoreError) {
        // eslint-disable-next-line no-param-reassign
        request = request.slice(7);
      }
    }

    let resolutionMap = [];

    const needEmulateSassResolver =
      // `sass` doesn't support module import
      !IS_SPECIAL_MODULE_IMPORT.test(request) &&
      // We need improve absolute paths handling.
      // Absolute paths should be resolved:
      // - Server-relative URLs - `<context>/path/to/file.ext` (where `<context>` is root context)
      // - Absolute path - `/full/path/to/file.ext` or `C:\\full\path\to\file.ext`
      !isFileScheme &&
      !originalRequest.startsWith("/") &&
      !IS_NATIVE_WIN32_PATH.test(originalRequest);

    if (includePaths.length > 0 && needEmulateSassResolver) {
      // The order of import precedence is as follows:
      //
      // 1. Filesystem imports relative to the base file.
      // 2. Custom importer imports.
      // 3. Filesystem imports relative to the working directory.
      // 4. Filesystem imports relative to an `includePaths` path.
      // 5. Filesystem imports relative to a `SASS_PATH` path.
      //
      // `sass` run custom importers before `3`, `4` and `5` points, we need to emulate this behavior to avoid wrong resolution.
      const sassPossibleRequests = getPossibleRequests(
        request,
        false,
        fromImport
      );

      // `node-sass` calls our importer before `1. Filesystem imports relative to the base file.`, so we need emulate this too
      if (!isDartSass) {
        resolutionMap = resolutionMap.concat({
          resolve: fromImport ? sassImportResolve : sassModuleResolve,
          context: path.dirname(context),
          possibleRequests: sassPossibleRequests,
        });
      }

      resolutionMap = resolutionMap.concat(
        // eslint-disable-next-line no-shadow
        includePaths.map((context) => {
          return {
            resolve: fromImport ? sassImportResolve : sassModuleResolve,
            context,
            possibleRequests: sassPossibleRequests,
          };
        })
      );
    }

    const webpackPossibleRequests = getPossibleRequests(
      request,
      true,
      fromImport
    );

    resolutionMap = resolutionMap.concat({
      resolve: fromImport ? webpackImportResolve : webpackModuleResolve,
      context: path.dirname(context),
      possibleRequests: webpackPossibleRequests,
    });

    return startResolving(resolutionMap);
  };
}

const MATCH_CSS = /\.css$/i;

function getModernWebpackImporter() {
  return {
    async canonicalize() {
      return null;
    },
    load() {
      // TODO implement
    },
  };
}

function getWebpackImporter(loaderContext, implementation, includePaths) {
  const resolve = getWebpackResolver(
    loaderContext.getResolve,
    implementation,
    includePaths
  );

  return function importer(originalUrl, prev, done) {
    const { fromImport } = this;

    resolve(prev, originalUrl, fromImport)
      .then((result) => {
        // Add the result as dependency.
        // Although we're also using stats.includedFiles, this might come in handy when an error occurs.
        // In this case, we don't get stats.includedFiles from node-sass/sass.
        loaderContext.addDependency(path.normalize(result));

        // By removing the CSS file extension, we trigger node-sass to include the CSS file instead of just linking it.
        done({ file: result.replace(MATCH_CSS, "") });
      })
      // Catch all resolving errors, return the original file and pass responsibility back to other custom importers
      .catch(() => {
        done({ file: originalUrl });
      });
  };
}

let nodeSassJobQueue = null;

/**
 * Verifies that the implementation and version of Sass is supported by this loader.
 *
 * @param {Object} implementation
 * @param {Object} options
 * @returns {Function}
 */
function getCompileFn(implementation, options) {
  const isNewSass =
    implementation.info.includes("dart-sass") ||
    implementation.info.includes("sass-embedded");

  if (isNewSass) {
    if (options.api === "modern") {
      return (sassOptions) => {
        const { data, ...rest } = sassOptions;

        return implementation.compileStringAsync(data, rest);
      };
    }

    return (sassOptions) =>
      new Promise((resolve, reject) => {
        implementation.render(sassOptions, (error, result) => {
          if (error) {
            reject(error);

            return;
          }

          resolve(result);
        });
      });
  }

  if (options.api === "modern") {
    throw new Error("Modern API is not supported for 'node-sass'");
  }

  // There is an issue with node-sass when async custom importers are used
  // See https://github.com/sass/node-sass/issues/857#issuecomment-93594360
  // We need to use a job queue to make sure that one thread is always available to the UV lib
  if (nodeSassJobQueue === null) {
    const threadPoolSize = Number(process.env.UV_THREADPOOL_SIZE || 4);
    // Only used for `node-sass`, so let's load it lazily
    // eslint-disable-next-line global-require
    const async = require("neo-async");

    nodeSassJobQueue = async.queue(
      implementation.render.bind(implementation),
      threadPoolSize - 1
    );
  }

  return (sassOptions) =>
    new Promise((resolve, reject) => {
      nodeSassJobQueue.push.bind(nodeSassJobQueue)(
        sassOptions,
        (error, result) => {
          if (error) {
            reject(error);

            return;
          }

          resolve(result);
        }
      );
    });
}

const ABSOLUTE_SCHEME = /^[A-Za-z0-9+\-.]+:/;

/**
 * @param {string} source
 * @returns {"absolute" | "scheme-relative" | "path-absolute" | "path-absolute"}
 */
function getURLType(source) {
  if (source[0] === "/") {
    if (source[1] === "/") {
      return "scheme-relative";
    }

    return "path-absolute";
  }

  if (IS_NATIVE_WIN32_PATH.test(source)) {
    return "path-absolute";
  }

  return ABSOLUTE_SCHEME.test(source) ? "absolute" : "path-relative";
}

function normalizeSourceMap(map, rootContext) {
  const newMap = map;

  // result.map.file is an optional property that provides the output filename.
  // Since we don't know the final filename in the webpack build chain yet, it makes no sense to have it.
  // eslint-disable-next-line no-param-reassign
  if (typeof newMap.file !== "undefined") {
    delete newMap.file;
  }

  // eslint-disable-next-line no-param-reassign
  newMap.sourceRoot = "";

  // node-sass returns POSIX paths, that's why we need to transform them back to native paths.
  // This fixes an error on windows where the source-map module cannot resolve the source maps.
  // @see https://github.com/webpack-contrib/sass-loader/issues/366#issuecomment-279460722
  // eslint-disable-next-line no-param-reassign
  newMap.sources = newMap.sources.map((source) => {
    const sourceType = getURLType(source);

    // Do no touch `scheme-relative`, `path-absolute` and `absolute` types (except `file:`)
    if (sourceType === "absolute" && /^file:/i.test(source)) {
      return url.fileURLToPath(source);
    } else if (sourceType === "path-relative") {
      return path.resolve(rootContext, path.normalize(source));
    }

    return source;
  });

  return newMap;
}

function errorFactory(error) {
  let message;

  if (error.formatted) {
    message = error.formatted.replace(/^Error: /, "");
  } else {
    // Keep original error if `sassError.formatted` is unavailable
    ({ message } = error);
  }

  const obj = new Error(message, { cause: error });

  obj.stack = null;

  return obj;
}

export {
  getSassImplementation,
  getSassOptions,
  getModernWebpackImporter,
  getWebpackResolver,
  getWebpackImporter,
  getCompileFn,
  normalizeSourceMap,
  isSupportedFibers,
  errorFactory,
};