index.js

const path = require("path");
const os = require("os");

const { validate } = require("schema-utils");

const {
  throttleAll,
  memoize,
  terserMinify,
  uglifyJsMinify,
  swcMinify,
  esbuildMinify,
} = require("./utils");

const schema = require("./options.json");
const { minify } = require("./minify");

/** @typedef {import("schema-utils/declarations/validate").Schema} Schema */
/** @typedef {import("webpack").Compiler} Compiler */
/** @typedef {import("webpack").Compilation} Compilation */
/** @typedef {import("webpack").WebpackError} WebpackError */
/** @typedef {import("webpack").Asset} Asset */
/** @typedef {import("./utils.js").TerserECMA} TerserECMA */
/** @typedef {import("./utils.js").TerserOptions} TerserOptions */
/** @typedef {import("jest-worker").Worker} JestWorker */
/** @typedef {import("@jridgewell/trace-mapping").SourceMapInput} SourceMapInput */
/** @typedef {import("@jridgewell/trace-mapping").TraceMap} TraceMap */

/** @typedef {RegExp | string} Rule */
/** @typedef {Rule[] | Rule} Rules */

/**
 * @callback ExtractCommentsFunction
 * @param {any} astNode
 * @param {{ value: string, type: 'comment1' | 'comment2' | 'comment3' | 'comment4', pos: number, line: number, col: number }} comment
 * @returns {boolean}
 */

/**
 * @typedef {boolean | 'all' | 'some' | RegExp | ExtractCommentsFunction} ExtractCommentsCondition
 */

/**
 * @typedef {string | ((fileData: any) => string)} ExtractCommentsFilename
 */

/**
 * @typedef {boolean | string | ((commentsFile: string) => string)} ExtractCommentsBanner
 */

/**
 * @typedef {Object} ExtractCommentsObject
 * @property {ExtractCommentsCondition} [condition]
 * @property {ExtractCommentsFilename} [filename]
 * @property {ExtractCommentsBanner} [banner]
 */

/**
 * @typedef {ExtractCommentsCondition | ExtractCommentsObject} ExtractCommentsOptions
 */

/**
 * @typedef {Object} MinimizedResult
 * @property {string} code
 * @property {SourceMapInput} [map]
 * @property {Array<Error | string>} [errors]
 * @property {Array<Error | string>} [warnings]
 * @property {Array<string>} [extractedComments]
 */

/**
 * @typedef {{ [file: string]: string }} Input
 */

/**
 * @typedef {{ [key: string]: any }} CustomOptions
 */

/**
 * @template T
 * @typedef {T extends infer U ? U : CustomOptions} InferDefaultType
 */

/**
 * @typedef {Object} PredefinedOptions
 * @property {boolean} [module]
 * @property {TerserECMA} [ecma]
 */

/**
 * @template T
 * @typedef {PredefinedOptions & InferDefaultType<T>} MinimizerOptions
 */

/**
 * @template T
 * @callback BasicMinimizerImplementation
 * @param {Input} input
 * @param {SourceMapInput | undefined} sourceMap
 * @param {MinimizerOptions<T>} minifyOptions
 * @param {ExtractCommentsOptions | undefined} extractComments
 * @returns {Promise<MinimizedResult>}
 */

/**
 * @typedef {object} MinimizeFunctionHelpers
 * @property {() => string | undefined} [getMinimizerVersion]
 */

/**
 * @template T
 * @typedef {BasicMinimizerImplementation<T> & MinimizeFunctionHelpers} MinimizerImplementation
 */

/**
 * @template T
 * @typedef {Object} InternalOptions
 * @property {string} name
 * @property {string} input
 * @property {SourceMapInput | undefined} inputSourceMap
 * @property {ExtractCommentsOptions | undefined} extractComments
 * @property {{ implementation: MinimizerImplementation<T>, options: MinimizerOptions<T> }} minimizer
 */

/**
 * @template T
 * @typedef {JestWorker & { transform: (options: string) => MinimizedResult, minify: (options: InternalOptions<T>) => MinimizedResult }} MinimizerWorker
 */

/**
 * @typedef {undefined | boolean | number} Parallel
 */

/**
 * @typedef {Object} BasePluginOptions
 * @property {Rules} [test]
 * @property {Rules} [include]
 * @property {Rules} [exclude]
 * @property {ExtractCommentsOptions} [extractComments]
 * @property {Parallel} [parallel]
 */

/**
 * @template T
 * @typedef {T extends TerserOptions ? { minify?: MinimizerImplementation<T> | undefined, terserOptions?: MinimizerOptions<T> | undefined } : { minify: MinimizerImplementation<T>, terserOptions?: MinimizerOptions<T> | undefined }} DefinedDefaultMinimizerAndOptions
 */

/**
 * @template T
 * @typedef {BasePluginOptions & { minimizer: { implementation: MinimizerImplementation<T>, options: MinimizerOptions<T> } }} InternalPluginOptions
 */

const getTraceMapping = memoize(() =>
  // eslint-disable-next-line global-require
  require("@jridgewell/trace-mapping")
);
const getSerializeJavascript = memoize(() =>
  // eslint-disable-next-line global-require
  require("serialize-javascript")
);

/**
 * @template [T=TerserOptions]
 */
class TerserPlugin {
  /**
   * @param {BasePluginOptions & DefinedDefaultMinimizerAndOptions<T>} [options]
   */
  constructor(options) {
    validate(/** @type {Schema} */ (schema), options || {}, {
      name: "Terser Plugin",
      baseDataPath: "options",
    });

    // TODO make `minimizer` option instead `minify` and `terserOptions` in the next major release, also rename `terserMinify` to `terserMinimize`
    const {
      minify = /** @type {MinimizerImplementation<T>} */ (terserMinify),
      terserOptions = /** @type {MinimizerOptions<T>} */ ({}),
      test = /\.[cm]?js(\?.*)?$/i,
      extractComments = true,
      parallel = true,
      include,
      exclude,
    } = options || {};

    /**
     * @private
     * @type {InternalPluginOptions<T>}
     */
    this.options = {
      test,
      extractComments,
      parallel,
      include,
      exclude,
      minimizer: {
        implementation: minify,
        options: terserOptions,
      },
    };
  }

  /**
   * @private
   * @param {any} input
   * @returns {boolean}
   */
  static isSourceMap(input) {
    // All required options for `new TraceMap(...options)`
    // https://github.com/jridgewell/trace-mapping#usage
    return Boolean(
      input &&
        input.version &&
        input.sources &&
        Array.isArray(input.sources) &&
        typeof input.mappings === "string"
    );
  }

  /**
   * @private
   * @param {unknown} warning
   * @param {string} file
   * @returns {Error}
   */
  static buildWarning(warning, file) {
    /**
     * @type {Error & { hideStack: true, file: string }}
     */
    // @ts-ignore
    const builtWarning = new Error(warning.toString());

    builtWarning.name = "Warning";
    builtWarning.hideStack = true;
    builtWarning.file = file;

    return builtWarning;
  }

  /**
   * @private
   * @param {any} error
   * @param {string} file
   * @param {TraceMap} [sourceMap]
   * @param {Compilation["requestShortener"]} [requestShortener]
   * @returns {Error}
   */
  static buildError(error, file, sourceMap, requestShortener) {
    /**
     * @type {Error & { file?: string }}
     */
    let builtError;

    if (typeof error === "string") {
      builtError = new Error(`${file} from Terser plugin\n${error}`);
      builtError.file = file;

      return builtError;
    }

    if (error.line) {
      const original =
        sourceMap &&
        getTraceMapping().originalPositionFor(sourceMap, {
          line: error.line,
          column: error.col,
        });

      if (original && original.source && requestShortener) {
        builtError = new Error(
          `${file} from Terser plugin\n${
            error.message
          } [${requestShortener.shorten(original.source)}:${original.line},${
            original.column
          }][${file}:${error.line},${error.col}]${
            error.stack
              ? `\n${error.stack.split("\n").slice(1).join("\n")}`
              : ""
          }`
        );
        builtError.file = file;

        return builtError;
      }

      builtError = new Error(
        `${file} from Terser plugin\n${error.message} [${file}:${error.line},${
          error.col
        }]${
          error.stack ? `\n${error.stack.split("\n").slice(1).join("\n")}` : ""
        }`
      );
      builtError.file = file;

      return builtError;
    }

    if (error.stack) {
      builtError = new Error(
        `${file} from Terser plugin\n${
          typeof error.message !== "undefined" ? error.message : ""
        }\n${error.stack}`
      );
      builtError.file = file;

      return builtError;
    }

    builtError = new Error(`${file} from Terser plugin\n${error.message}`);
    builtError.file = file;

    return builtError;
  }

  /**
   * @private
   * @param {Parallel} parallel
   * @returns {number}
   */
  static getAvailableNumberOfCores(parallel) {
    // In some cases cpus() returns undefined
    // https://github.com/nodejs/node/issues/19022
    const cpus = os.cpus() || { length: 1 };

    return parallel === true
      ? cpus.length - 1
      : Math.min(Number(parallel) || 0, cpus.length - 1);
  }

  /**
   * @private
   * @param {Compiler} compiler
   * @param {Compilation} compilation
   * @param {Record<string, import("webpack").sources.Source>} assets
   * @param {{availableNumberOfCores: number}} optimizeOptions
   * @returns {Promise<void>}
   */
  async optimize(compiler, compilation, assets, optimizeOptions) {
    const cache = compilation.getCache("TerserWebpackPlugin");
    let numberOfAssets = 0;
    const assetsForMinify = await Promise.all(
      Object.keys(assets)
        .filter((name) => {
          const { info } = /** @type {Asset} */ (compilation.getAsset(name));

          if (
            // Skip double minimize assets from child compilation
            info.minimized ||
            // Skip minimizing for extracted comments assets
            info.extractedComments
          ) {
            return false;
          }

          if (
            !compiler.webpack.ModuleFilenameHelpers.matchObject.bind(
              // eslint-disable-next-line no-undefined
              undefined,
              this.options
            )(name)
          ) {
            return false;
          }

          return true;
        })
        .map(async (name) => {
          const { info, source } = /** @type {Asset} */ (
            compilation.getAsset(name)
          );

          const eTag = cache.getLazyHashedEtag(source);
          const cacheItem = cache.getItemCache(name, eTag);
          const output = await cacheItem.getPromise();

          if (!output) {
            numberOfAssets += 1;
          }

          return { name, info, inputSource: source, output, cacheItem };
        })
    );

    if (assetsForMinify.length === 0) {
      return;
    }

    /** @type {undefined | (() => MinimizerWorker<T>)} */
    let getWorker;
    /** @type {undefined | MinimizerWorker<T>} */
    let initializedWorker;
    /** @type {undefined | number} */
    let numberOfWorkers;

    if (optimizeOptions.availableNumberOfCores > 0) {
      // Do not create unnecessary workers when the number of files is less than the available cores, it saves memory
      numberOfWorkers = Math.min(
        numberOfAssets,
        optimizeOptions.availableNumberOfCores
      );
      // eslint-disable-next-line consistent-return
      getWorker = () => {
        if (initializedWorker) {
          return initializedWorker;
        }

        // eslint-disable-next-line global-require
        const { Worker } = require("jest-worker");

        initializedWorker =
          /** @type {MinimizerWorker<T>} */
          (
            new Worker(require.resolve("./minify"), {
              numWorkers: numberOfWorkers,
              enableWorkerThreads: true,
            })
          );

        // https://github.com/facebook/jest/issues/8872#issuecomment-524822081
        const workerStdout = initializedWorker.getStdout();

        if (workerStdout) {
          workerStdout.on("data", (chunk) => process.stdout.write(chunk));
        }

        const workerStderr = initializedWorker.getStderr();

        if (workerStderr) {
          workerStderr.on("data", (chunk) => process.stderr.write(chunk));
        }

        return initializedWorker;
      };
    }

    const { SourceMapSource, ConcatSource, RawSource } =
      compiler.webpack.sources;

    /** @typedef {{ extractedCommentsSource : import("webpack").sources.RawSource, commentsFilename: string }} ExtractedCommentsInfo */
    /** @type {Map<string, ExtractedCommentsInfo>} */
    const allExtractedComments = new Map();
    const scheduledTasks = [];

    for (const asset of assetsForMinify) {
      scheduledTasks.push(async () => {
        const { name, inputSource, info, cacheItem } = asset;
        let { output } = asset;

        if (!output) {
          let input;
          /** @type {SourceMapInput | undefined} */
          let inputSourceMap;

          const { source: sourceFromInputSource, map } =
            inputSource.sourceAndMap();

          input = sourceFromInputSource;

          if (map) {
            if (!TerserPlugin.isSourceMap(map)) {
              compilation.warnings.push(
                /** @type {WebpackError} */
                (new Error(`${name} contains invalid source map`))
              );
            } else {
              inputSourceMap = /** @type {SourceMapInput} */ (map);
            }
          }

          if (Buffer.isBuffer(input)) {
            input = input.toString();
          }

          /**
           * @type {InternalOptions<T>}
           */
          const options = {
            name,
            input,
            inputSourceMap,
            minimizer: {
              implementation: this.options.minimizer.implementation,
              // @ts-ignore https://github.com/Microsoft/TypeScript/issues/10727
              options: { ...this.options.minimizer.options },
            },
            extractComments: this.options.extractComments,
          };

          if (typeof options.minimizer.options.module === "undefined") {
            if (typeof info.javascriptModule !== "undefined") {
              options.minimizer.options.module = info.javascriptModule;
            } else if (/\.mjs(\?.*)?$/i.test(name)) {
              options.minimizer.options.module = true;
            } else if (/\.cjs(\?.*)?$/i.test(name)) {
              options.minimizer.options.module = false;
            }
          }

          if (typeof options.minimizer.options.ecma === "undefined") {
            options.minimizer.options.ecma = TerserPlugin.getEcmaVersion(
              compiler.options.output.environment || {}
            );
          }

          try {
            output = await (getWorker
              ? getWorker().transform(getSerializeJavascript()(options))
              : minify(options));
          } catch (error) {
            const hasSourceMap =
              inputSourceMap && TerserPlugin.isSourceMap(inputSourceMap);

            compilation.errors.push(
              /** @type {WebpackError} */
              (
                TerserPlugin.buildError(
                  error,
                  name,
                  hasSourceMap
                    ? new (getTraceMapping().TraceMap)(
                        /** @type {SourceMapInput} */ (inputSourceMap)
                      )
                    : // eslint-disable-next-line no-undefined
                      undefined,
                  // eslint-disable-next-line no-undefined
                  hasSourceMap ? compilation.requestShortener : undefined
                )
              )
            );

            return;
          }

          if (typeof output.code === "undefined") {
            compilation.errors.push(
              /** @type {WebpackError} */
              (
                new Error(
                  `${name} from Terser plugin\nMinimizer doesn't return result`
                )
              )
            );

            return;
          }

          if (output.warnings && output.warnings.length > 0) {
            output.warnings = output.warnings.map(
              /**
               * @param {Error | string} item
               */
              (item) => TerserPlugin.buildWarning(item, name)
            );
          }

          if (output.errors && output.errors.length > 0) {
            const hasSourceMap =
              inputSourceMap && TerserPlugin.isSourceMap(inputSourceMap);

            output.errors = output.errors.map(
              /**
               * @param {Error | string} item
               */
              (item) =>
                TerserPlugin.buildError(
                  item,
                  name,
                  hasSourceMap
                    ? new (getTraceMapping().TraceMap)(
                        /** @type {SourceMapInput} */ (inputSourceMap)
                      )
                    : // eslint-disable-next-line no-undefined
                      undefined,
                  // eslint-disable-next-line no-undefined
                  hasSourceMap ? compilation.requestShortener : undefined
                )
            );
          }

          let shebang;

          if (
            /** @type {ExtractCommentsObject} */
            (this.options.extractComments).banner !== false &&
            output.extractedComments &&
            output.extractedComments.length > 0 &&
            output.code.startsWith("#!")
          ) {
            const firstNewlinePosition = output.code.indexOf("\n");

            shebang = output.code.substring(0, firstNewlinePosition);
            output.code = output.code.substring(firstNewlinePosition + 1);
          }

          if (output.map) {
            output.source = new SourceMapSource(
              output.code,
              name,
              output.map,
              input,
              /** @type {SourceMapInput} */ (inputSourceMap),
              true
            );
          } else {
            output.source = new RawSource(output.code);
          }

          if (output.extractedComments && output.extractedComments.length > 0) {
            const commentsFilename =
              /** @type {ExtractCommentsObject} */
              (this.options.extractComments).filename ||
              "[file].LICENSE.txt[query]";

            let query = "";
            let filename = name;

            const querySplit = filename.indexOf("?");

            if (querySplit >= 0) {
              query = filename.slice(querySplit);
              filename = filename.slice(0, querySplit);
            }

            const lastSlashIndex = filename.lastIndexOf("/");
            const basename =
              lastSlashIndex === -1
                ? filename
                : filename.slice(lastSlashIndex + 1);
            const data = { filename, basename, query };

            output.commentsFilename = compilation.getPath(
              commentsFilename,
              data
            );

            let banner;

            // Add a banner to the original file
            if (
              /** @type {ExtractCommentsObject} */
              (this.options.extractComments).banner !== false
            ) {
              banner =
                /** @type {ExtractCommentsObject} */
                (this.options.extractComments).banner ||
                `For license information please see ${path
                  .relative(path.dirname(name), output.commentsFilename)
                  .replace(/\\/g, "/")}`;

              if (typeof banner === "function") {
                banner = banner(output.commentsFilename);
              }

              if (banner) {
                output.source = new ConcatSource(
                  shebang ? `${shebang}\n` : "",
                  `/*! ${banner} */\n`,
                  output.source
                );
              }
            }

            const extractedCommentsString = output.extractedComments
              .sort()
              .join("\n\n");

            output.extractedCommentsSource = new RawSource(
              `${extractedCommentsString}\n`
            );
          }

          await cacheItem.storePromise({
            source: output.source,
            errors: output.errors,
            warnings: output.warnings,
            commentsFilename: output.commentsFilename,
            extractedCommentsSource: output.extractedCommentsSource,
          });
        }

        if (output.warnings && output.warnings.length > 0) {
          for (const warning of output.warnings) {
            compilation.warnings.push(/** @type {WebpackError} */ (warning));
          }
        }

        if (output.errors && output.errors.length > 0) {
          for (const error of output.errors) {
            compilation.errors.push(/** @type {WebpackError} */ (error));
          }
        }

        /** @type {Record<string, any>} */
        const newInfo = { minimized: true };
        const { source, extractedCommentsSource } = output;

        // Write extracted comments to commentsFilename
        if (extractedCommentsSource) {
          const { commentsFilename } = output;

          newInfo.related = { license: commentsFilename };

          allExtractedComments.set(name, {
            extractedCommentsSource,
            commentsFilename,
          });
        }

        compilation.updateAsset(name, source, newInfo);
      });
    }

    const limit =
      getWorker && numberOfAssets > 0
        ? /** @type {number} */ (numberOfWorkers)
        : scheduledTasks.length;
    await throttleAll(limit, scheduledTasks);

    if (initializedWorker) {
      await initializedWorker.end();
    }

    /** @typedef {{ source: import("webpack").sources.Source, commentsFilename: string, from: string }} ExtractedCommentsInfoWIthFrom */
    await Array.from(allExtractedComments)
      .sort()
      .reduce(
        /**
         * @param {Promise<unknown>} previousPromise
         * @param {[string, ExtractedCommentsInfo]} extractedComments
         * @returns {Promise<ExtractedCommentsInfoWIthFrom>}
         */
        async (previousPromise, [from, value]) => {
          const previous =
            /** @type {ExtractedCommentsInfoWIthFrom | undefined} **/ (
              await previousPromise
            );
          const { commentsFilename, extractedCommentsSource } = value;

          if (previous && previous.commentsFilename === commentsFilename) {
            const { from: previousFrom, source: prevSource } = previous;
            const mergedName = `${previousFrom}|${from}`;
            const name = `${commentsFilename}|${mergedName}`;
            const eTag = [prevSource, extractedCommentsSource]
              .map((item) => cache.getLazyHashedEtag(item))
              .reduce((previousValue, currentValue) =>
                cache.mergeEtags(previousValue, currentValue)
              );

            let source = await cache.getPromise(name, eTag);

            if (!source) {
              source = new ConcatSource(
                Array.from(
                  new Set([
                    .../** @type {string}*/ (prevSource.source()).split("\n\n"),
                    .../** @type {string}*/ (
                      extractedCommentsSource.source()
                    ).split("\n\n"),
                  ])
                ).join("\n\n")
              );

              await cache.storePromise(name, eTag, source);
            }

            compilation.updateAsset(commentsFilename, source);

            return { source, commentsFilename, from: mergedName };
          }

          const existingAsset = compilation.getAsset(commentsFilename);

          if (existingAsset) {
            return {
              source: existingAsset.source,
              commentsFilename,
              from: commentsFilename,
            };
          }

          compilation.emitAsset(commentsFilename, extractedCommentsSource, {
            extractedComments: true,
          });

          return { source: extractedCommentsSource, commentsFilename, from };
        },
        /** @type {Promise<unknown>} */ (Promise.resolve())
      );
  }

  /**
   * @private
   * @param {any} environment
   * @returns {TerserECMA}
   */
  static getEcmaVersion(environment) {
    // ES 6th
    if (
      environment.arrowFunction ||
      environment.const ||
      environment.destructuring ||
      environment.forOf ||
      environment.module
    ) {
      return 2015;
    }

    // ES 11th
    if (environment.bigIntLiteral || environment.dynamicImport) {
      return 2020;
    }

    return 5;
  }

  /**
   * @param {Compiler} compiler
   * @returns {void}
   */
  apply(compiler) {
    const pluginName = this.constructor.name;
    const availableNumberOfCores = TerserPlugin.getAvailableNumberOfCores(
      this.options.parallel
    );

    compiler.hooks.compilation.tap(pluginName, (compilation) => {
      const hooks =
        compiler.webpack.javascript.JavascriptModulesPlugin.getCompilationHooks(
          compilation
        );
      const data = getSerializeJavascript()({
        minimizer:
          typeof this.options.minimizer.implementation.getMinimizerVersion !==
          "undefined"
            ? this.options.minimizer.implementation.getMinimizerVersion() ||
              "0.0.0"
            : "0.0.0",
        options: this.options.minimizer.options,
      });

      hooks.chunkHash.tap(pluginName, (chunk, hash) => {
        hash.update("TerserPlugin");
        hash.update(data);
      });

      compilation.hooks.processAssets.tapPromise(
        {
          name: pluginName,
          stage:
            compiler.webpack.Compilation.PROCESS_ASSETS_STAGE_OPTIMIZE_SIZE,
          additionalAssets: true,
        },
        (assets) =>
          this.optimize(compiler, compilation, assets, {
            availableNumberOfCores,
          })
      );

      compilation.hooks.statsPrinter.tap(pluginName, (stats) => {
        stats.hooks.print
          .for("asset.info.minimized")
          .tap("terser-webpack-plugin", (minimized, { green, formatFlag }) =>
            minimized
              ? /** @type {Function} */ (green)(
                  /** @type {Function} */ (formatFlag)("minimized")
                )
              : ""
          );
      });
    });
  }
}

TerserPlugin.terserMinify = terserMinify;
TerserPlugin.uglifyJsMinify = uglifyJsMinify;
TerserPlugin.swcMinify = swcMinify;
TerserPlugin.esbuildMinify = esbuildMinify;

module.exports = TerserPlugin;