'use strict';

const errorOverlayMiddleware = require('react-dev-utils/errorOverlayMiddleware');
const evalSourceMapMiddleware = require('react-dev-utils/evalSourceMapMiddleware');
const noopServiceWorkerMiddleware = require('react-dev-utils/noopServiceWorkerMiddleware');
const ignoredFiles = require('react-dev-utils/ignoredFiles');
const paths = require('./paths');
const fs = require('fs');

const protocol = process.env.HTTPS === 'true' ? 'https' : 'http';
const host = process.env.HOST || '0.0.0.0';

module.exports = function(proxy, allowedHost) {
	return {
		// WebpackDevServer 2.4.3 introduced a security fix that prevents remote
		// websites from potentially accessing local content through DNS rebinding:
		// https://github.com/webpack/webpack-dev-server/issues/887
		// https://medium.com/webpack/webpack-dev-server-middleware-security-issues-1489d950874a
		// However, it made several existing use cases such as development in cloud
		// environment or subdomains in development significantly more complicated:
		// https://github.com/facebook/create-react-app/issues/2271
		// https://github.com/facebook/create-react-app/issues/2233
		// While we're investigating better solutions, for now we will take a
		// compromise. Since our WDS configuration only serves files in the `public`
		// folder we won't consider accessing them a vulnerability. However, if you
		// use the `proxy` feature, it gets more dangerous because it can expose
		// remote code execution vulnerabilities in backends like Django and Rails.
		// So we will disable the host check normally, but enable it if you have
		// specified the `proxy` setting. Finally, we let you override it if you
		// really know what you're doing with a special environment variable.
		disableHostCheck:
      !proxy || process.env.DANGEROUSLY_DISABLE_HOST_CHECK === 'true',
		// Enable gzip compression of generated files.
		compress: true,
		// Silence WebpackDevServer's own logs since they're generally not useful.
		// It will still show compile warnings and errors with this setting.
		clientLogLevel: 'none',
		// By default WebpackDevServer serves physical files from current directory
		// in addition to all the virtual build products that it serves from memory.
		// This is confusing because those files won’t automatically be available in
		// production build folder unless we copy them. However, copying the whole
		// project directory is dangerous because we may expose sensitive files.
		// Instead, we establish a convention that only files in `public` directory
		// get served. Our build script will copy `public` into the `build` folder.
		// In `index.html`, you can get URL of `public` folder with %PUBLIC_URL%:
		// <link rel="icon" href="%PUBLIC_URL%/favicon.ico">
		// In JavaScript code, you can access it with `process.env.PUBLIC_URL`.
		// Note that we only recommend to use `public` folder as an escape hatch
		// for files like `favicon.ico`, `manifest.json`, and libraries that are
		// for some reason broken when imported through Webpack. If you just want to
		// use an image, put it in `src` and `import` it from JavaScript instead.
		contentBase: paths.appPublic,
		// By default files from `contentBase` will not trigger a page reload.
		watchContentBase: true,
		// Enable hot reloading server. It will provide /sockjs-node/ endpoint
		// for the WebpackDevServer client so it can learn when the files were
		// updated. The WebpackDevServer client is included as an entry point
		// in the Webpack development configuration. Note that only changes
		// to CSS are currently hot reloaded. JS changes will refresh the browser.
		hot: true,
		// Use 'ws' instead of 'sockjs-node' on server since we're using native
		// websockets in `webpackHotDevClient`.
		transportMode: 'ws',
		// Prevent a WS client from getting injected as we're already including
		// `webpackHotDevClient`.
		injectClient: false,
		// It is important to tell WebpackDevServer to use the same "root" path
		// as we specified in the config. In development, we always serve from /.
		publicPath: '/',
		// WebpackDevServer is noisy by default so we emit custom message instead
		// by listening to the compiler events with `compiler.hooks[...].tap` calls above.
		quiet: true,
		// Reportedly, this avoids CPU overload on some systems.
		// https://github.com/facebook/create-react-app/issues/293
		// src/node_modules is not ignored to support absolute imports
		// https://github.com/facebook/create-react-app/issues/1065
		watchOptions: {
			ignored: ignoredFiles(paths.appSrc),
		},
		// Enable HTTPS if the HTTPS environment variable is set to 'true'
		https: protocol === 'https',
		host,
		overlay: false,
		historyApiFallback: {
			// Paths with dots should still use the history fallback.
			// See https://github.com/facebook/create-react-app/issues/387.
			disableDotRule: true,
		},
		public: allowedHost,
		proxy,
		before(app, server) {
			if (fs.existsSync(paths.proxySetup)) {
				// This registers user provided middleware for proxy reasons
				require(paths.proxySetup)(app);
			}

			// This lets us fetch source contents from webpack for the error overlay
			app.use(evalSourceMapMiddleware(server));
			// This lets us open files from the runtime error overlay.
			app.use(errorOverlayMiddleware());

			// This service worker file is effectively a 'no-op' that will reset any
			// previous service worker registered for the same host:port combination.
			// We do this in development to avoid hitting the production cache if
			// it used the same host and port.
			// https://github.com/facebook/create-react-app/issues/2272#issuecomment-302832432
			app.use(noopServiceWorkerMiddleware());
		},
	};
};