gulpfile.cjs

const gulp = require("gulp");
const terser = require("gulp-terser");
const glob = require("glob");
const fs = require("fs");
const path = require("path");

gulp.task(
  "move-build", async () => {
    // delete distributed build directory prior to creation of a new one
    fs.rmdirSync('./app/dist/build', { recursive: true });
    // move files to productionb build path
    return await fs.rename('./app/build', './app/dist/build', () => { return true;});
  }
);

gulp.task(
  "terser", () => {
    // now work on all the other files
    gulp.src('./app/dist/build/es6/**/*.js')
      .pipe(terser({
        ecma: 2017,
        keep_fnames: true,
        mangle: false,
        module: true,
      }))
      .pipe(gulp.dest('./app/dist/build/es6/'));
    // now work on all the other files
    return gulp.src('./app/dist/build/es6-amd/**/*.js')
      .pipe(terser({
        keep_fnames: true,
        mangle: false,
        module: true,
        safari10: true,
      }))
      .pipe(gulp.dest('./app/dist/build/es6-amd/'));
  }
);

gulp.task("wc-autoloader", async () => {
  glob(path.join("./app/dist/build/es6/node_modules/**/*.js"), (er, files) => {
    let elements = {};
    // async loop over files
    files.forEach((file) => {
      // grab the name of the file
      if (fs.existsSync(file)) {
        let fLocation = file.replace("app/dist/build/es6/node_modules/", "");
        const contents = fs.readFileSync(file, "utf8");
        // This Regex is looking for tags that are defined by string values
        // this will work for customElements.define("local-time",s))
        // This will NOT work for customElements.define(LocalTime.tagName,s))
        const defineStatements = /customElements\.define\(["|'|`](.*?)["|'|`]/gm.exec(
          contents
        );
        // basic
        if (defineStatements) {
          elements[defineStatements[1]] = fLocation;
        }
        // .tag calls
        else {
          const hasDefine = /customElements\.define\((.*?),(.*?)\)/gm.exec(
            contents
          );
          // check for a define still
          if (hasDefine && hasDefine[1] && hasDefine[1].includes('.tag')) {
            const tagStatements = /static get tag\(\){return"(.*?)"}/gm.exec(
              contents
            );
            if (tagStatements) {
              elements[tagStatements[1]] = fLocation;
            }
          }
          else if (hasDefine && hasDefine[1] && hasDefine[1].includes('.is')) {
            const tagStatements = /static get is\(\){return"(.*?)"}/gm.exec(
              contents
            );
            if (tagStatements) {
              elements[tagStatements[1]] = fLocation;
            }
          }
          else {
            if (!hasDefine) {
              // support for polymer legacy class housing
              const PolymerLegacy = /\,is\:\"(.*?)\",/gm.exec(
                contents
              );
              if (PolymerLegacy && PolymerLegacy[1]) {
                elements[PolymerLegacy[1]] = fLocation;
              }
              else {
                // if we got here, it wasn't a file w/ a custom element definition
                // so it's not an entry point
              }
            }
          }
        }
      }
    });

    // write entries to file
    fs.writeFileSync(
      path.join(__dirname, "app/dist/wc-registry.json"),
      JSON.stringify(elements),
      "utf8"
    );
  });
});