const { src, dest, watch, parallel } = require('gulp');
const ts = require('gulp-typescript');
const fs = require('fs');
const sourcemaps = require('gulp-sourcemaps');
const minimist = require('minimist');
const tsConfig = require('./tsconfig.json');
const webpack = require('webpack-stream');
const webpackConfig = require('./webpack.config');

const argv = minimist(process.argv);
const tsProject = ts.createProject('tsconfig.json');

function buildFrontend() {
  let config = webpackConfig;
  if (argv.dev) {
    config = { ...config, ...{ mode: 'development' } };
  }
  if (argv.watch) {
    config = { ...config, ...{ watch: true } };
  }

  return src(config.entry)
    .pipe(webpack(config))
    .pipe(dest(config.output.path));
}

function copyIndexHtml(cb) {
  let indexHtml = 'index.prod.html';
  if (argv.dev) {
    indexHtml = 'index.dev.html';
  }
  fs.copyFileSync(indexHtml, 'index.html');
  cb();
}

function transpileTypescript() {
  return tsProject
    .src()
    .pipe(sourcemaps.init())
    .pipe(tsProject())
    .pipe(sourcemaps.write('.'))
    .pipe(dest('.'));
}

function build(cb) {
  if (argv.watch) {
    watch(tsConfig.include, { ignoreInitial: false }, transpileTypescript);
    watch('index.*.html', { ignoreInitial: false }, copyIndexHtml);
    buildFrontend();
  } else {
    parallel(transpileTypescript, copyIndexHtml, buildFrontend)(cb);
  }
}
build.flags = {
  '--dev': 'builds in development mode',
  '--watch': 'watches the files',
};

exports.build = build;