const fs = require('fs')
const path = require('path')

const MODULES_PATH = path.join(__dirname, '/modules')

// Generate a hash of entry points, including modules
const entryPoints = {}
if (fs.existsSync(MODULES_PATH)) {
  fs.readdirSync(MODULES_PATH).reduce((acc, module) => {
    const entryPath = path.join(MODULES_PATH, module, '/public/es/index.js')
    if (fs.existsSync(entryPath)) {
      acc[module] = entryPath
    }
    return acc
  }, entryPoints)
}

// If no entry points are found, silently exit
if (!Object.keys(entryPoints).length) {
  console.warn('No entry points found, exiting')
  process.exit(0)
}

module.exports = {
  // Defines the "entry point(s)" for the application - i.e. the file which
  // bootstraps the application
  entry: entryPoints,

  // Define where and how the bundle will be output to disk
  // Note: webpack-dev-server does not write the bundle to disk, instead it is
  // kept in memory for speed
  output: {
    path: path.join(__dirname, '/public/js/es'),

    filename: '[name].js',

    // Output as UMD bundle (allows main JS to import with CJS, AMD or global
    // style code bundles
    libraryTarget: 'umd',
    // Name the exported variable from output bundle
    library: ['Frontend', '[name]']
  },

  // Define how file types are handled by webpack
  module: {
    rules: [
      {
        // Pass application JS files through babel-loader, compiling to ES5
        test: /\.js$/,
        // Only compile application files (dependencies are in ES5 already)
        exclude: /node_modules/,
        use: [
          {
            loader: 'babel-loader',
            options: {
              // Configure babel-loader to cache compiled output so that
              // subsequent compile runs are much faster
              cacheDirectory: true
            }
          }
        ]
      },
      {
        // These options are neccesary for handlebars to have access to helper
        // methods
        test: /\.handlebars$/,
        loader: 'handlebars-loader',
        options: {
          compat: true,
          knownHelpersOnly: false,
          runtimePath: 'handlebars/runtime'
        }
      }
    ]
  },
  resolve: {
    alias: {
      // makes handlebars globally accessible to backbone
      handlebars: 'handlebars/dist/handlebars.min.js',
      jquery: path.join(__dirname, 'node_modules/jquery/dist/jquery')
    }
  }
}