const fs = require("fs");
const path = require("path");
const MFS = require("memory-fs");
const webpack = require("webpack");
const chokidar = require("chokidar");
const clientConfig = require("./webpack.client.config");
const serverConfig = require("./webpack.server.config");

/**
 * 读取文件
 */
const readFile = (fs, file) => {
  try {
    return fs.readFileSync(path.join(clientConfig.output.path, file), "utf-8");
  } catch (e) {}
};

module.exports = function setupDevServer(app, templatePath, cb) {
  let bundle;
  let template;
  let clientManifest;

  let ready;
  const readyPromise = new Promise((r) => {
    ready = r;
  });
  const update = () => {
    if (bundle && clientManifest) {
      ready();
      cb(bundle, {
        template,
        clientManifest,
      });
    }
  };

  // read template from disk and watch
  template = fs.readFileSync(templatePath, "utf-8");
  chokidar.watch(templatePath).on("change", () => {
    template = fs.readFileSync(templatePath, "utf-8");
    console.log("index.html template updated.");
    update();
  });

  // modify client config to work with hot middleware
  clientConfig.entry.app = [
    "webpack-hot-middleware/client",
    clientConfig.entry.app,
  ];
  clientConfig.output.filename = "[name].js";
  clientConfig.plugins.push(
    new webpack.HotModuleReplacementPlugin({
      // https://github.com/webpack/webpack/issues/6693
      multiStep: true,
    }),
    new webpack.NoEmitOnErrorsPlugin()
  );

  const clientCompiler = webpack(clientConfig);
  const devMiddleware = require("webpack-dev-middleware")(clientCompiler, {
    publicPath: clientConfig.output.publicPath,
  });

  // dev middleware
  app.use(devMiddleware);
  clientCompiler.hooks.done.tap("done", (stats) => {
    console.log("编译完成");
    stats = stats.toJson();
    stats.errors.forEach((err) => console.error(err));
    stats.warnings.forEach((err) => console.warn(err));
    if (stats.errors.length) return;
    clientManifest = JSON.parse(
      readFile(
        devMiddleware.context.outputFileSystem,
        "vue-ssr-client-manifest.json"
      )
    );
    update();
  });

  // hot middleware
  app.use(
    require("webpack-hot-middleware")(clientCompiler, { heartbeat: 5000 })
  );

  // watch and update server renderer
  const serverCompiler = webpack(serverConfig);
  const mfs = new MFS();
  serverCompiler.outputFileSystem = mfs;
  serverCompiler.watch({}, (err, stats) => {
    if (err) throw err;
    stats = stats.toJson();
    if (stats.errors.length) return;

    // read bundle generated by vue-ssr-webpack-plugin
    bundle = JSON.parse(readFile(mfs, "vue-ssr-server-bundle.json"));
    update();
  });

  return readyPromise;
};