const async = require('async');
const webpack = require('webpack');
const utils = require('../utils/utils');
const fs = require('../core/fs');
const constants = require('../constants');
const HardSourceWebpackPlugin = require('hard-source-webpack-plugin');
const ProcessWrapper = require('../process/processWrapper');

let webpackProcess;

class WebpackProcess extends ProcessWrapper {
  build(file, importsList, callback) {
    const self = this;
    let realCwd;

    async.waterfall([
      function findImports(next) {
        self.webpackRun(file.filename, {}, false, importsList, false, next);
      },

      function changeCwd(next) {
        realCwd = utils.pwd();
        process.chdir(fs.embarkPath(''));
        next();
      },

      function runWebpack(next) {
        self.webpackRun(file.filename, {}, true, importsList, true, next);
      },

      function changeCwdBack(next) {
        process.chdir(realCwd);
        next();
      }
    ], (err) => {
      process.chdir(realCwd);
      callback(err);
    });
  }


  webpackRun(filename, options, includeModules, importsList, detectErrors, callback) {
    let defaultOptions = {
      entry: fs.dappPath(filename),
      output: {
        libraryTarget: 'umd',
        path: fs.dappPath('.embark'),
        filename: filename
      },
      resolve: {
        alias: importsList,
        modules: [
          fs.embarkPath('node_modules'),
          fs.dappPath('node_modules')
        ]
      },
      externals: function (context, request, callback) {
        callback();
      },
      plugins: [new HardSourceWebpackPlugin()]
    };

    let webpackOptions = utils.recursiveMerge(defaultOptions, options);

    if (includeModules) {
      webpackOptions.module = {
        rules: [
          {
            test: /\.css$/,
            use: [{loader: "style-loader"}, {loader: "css-loader"}]
          },
          {
            test: /\.scss$/,
            use: [{loader: "style-loader"}, {loader: "css-loader"}]
          },
          {
            test: /\.(png|woff|woff2|eot|ttf|svg)$/,
            loader: 'url-loader?limit=100000'
          },
          {
            test: /\.js$/,
            loader: "babel-loader",
            exclude: /(node_modules|bower_components)/,
            options: {
              presets: ['babel-preset-es2016', 'babel-preset-es2017', 'babel-preset-react'].map(require.resolve),
              plugins: ["babel-plugin-webpack-aliases"].map(require.resolve),
              compact: false
            }
          }
        ]
      };
    }

    webpack(webpackOptions).run((err, stats) => {
      if (err) {
        console.error(err);
      }
      if (!detectErrors) {
        return callback();
      }

      if (stats.hasErrors()) {
        return callback(stats.toJson().errors.join("\n"));
      }
      callback();
    });
  }
}

process.on('message', (msg) => {
  if (msg.action === constants.pipeline.init) {
    webpackProcess = new WebpackProcess(msg.options);
    return process.send({result: constants.pipeline.initiated});
  }

  if (msg.action === constants.pipeline.build) {
    return webpackProcess.build(msg.file, msg.importsList, (err) => {
      process.send({result: constants.pipeline.built, error: err});
    });
  }
});