var fs = require('fs')
var path = require('path')
var utils = require('./utils')
var webpack = require('webpack')
var config = require('../config')
var merge = require('webpack-merge')
var baseWebpackConfig = require('./webpack.base.conf')
var CopyWebpackPlugin = require('copy-webpack-plugin')
var HtmlWebpackPlugin = require('html-webpack-plugin')
var ExtractTextPlugin = require('extract-text-webpack-plugin')
var FriendlyErrorsPlugin = require('friendly-errors-webpack-plugin')

module.exports = merge(baseWebpackConfig, {
  watch: true,
  module: {
    rules: utils.styleLoaders({
      sourceMap: config.dev.produceSourceMap,
      extract: true
    })
  },
  devtool: '#cheap-module-eval-source-map',
  output: {
    path: config.dev.assetsRoot,
    filename: utils.assetsPath('js/[name].[chunkhash].js'),
    chunkFilename: utils.assetsPath('js/[id].[chunkhash].js')
  },
  plugins: [
    new webpack.NoEmitOnErrorsPlugin(),
    new FriendlyErrorsPlugin(),
    new webpack.DefinePlugin({
      'process.env': config.dev.env
    }),
    // extract css into its own file
    new ExtractTextPlugin({
      filename: utils.assetsPath('css/[name].[contenthash].css')
    }),
    // generate dist index.html with correct asset hash for caching.
    // you can customize output by editing /index.html
    // see https://github.com/ampedandwired/html-webpack-plugin
    new HtmlWebpackPlugin({
      filename: config.dev.index,
      template: 'index.html',
      inject: true,
      // necessary to consistently work with multiple chunks via CommonsChunkPlugin
      chunksSortMode: 'dependency',
      serviceWorkerLoader: `<script>${fs.readFileSync(path.join(__dirname,
        './service-worker-dev.js'), 'utf-8')}</script>`
    }),
    // split vendor js into its own file
    new webpack.optimize.CommonsChunkPlugin({
      name: 'vendor',
      minChunks: function (module, count) {
        // any required modules inside node_modules are extracted to vendor
        return (
          module.resource &&
          /\.js$/.test(module.resource) &&
          module.resource.indexOf(
            path.join(__dirname, '../node_modules')
          ) === 0
        )
      }
    }),
    // extract webpack runtime and module manifest to its own file in order to
    // prevent vendor hash from being updated whenever app bundle is updated
    new webpack.optimize.CommonsChunkPlugin({
      name: 'manifest',
      chunks: ['vendor']
    }),
    // copy custom static assets
    new CopyWebpackPlugin([
      {
        from: path.resolve(__dirname, '../static'),
        to: config.dev.assetsSubDirectory,
        ignore: ['.*']
      }
    ])
  ]
})