'use strict';

// Do this as the first thing so that any code reading it knows the right env.
process.env.NODE_ENV = 'production';

// Makes the script crash on unhandled rejections instead of silently
// ignoring them. In the future, promise rejections that are not handled will
// terminate the Node.js process with a non-zero exit code.
process.on('unhandledRejection', err => {
	throw err;
});

// Ensure environment variables are read.
require('../env');

const path = require('path');
const chalk = require('chalk');
const fs = require('fs-extra');
const webpack = require('webpack');
const config = require('../webpack.config.prod');
const paths = require('../paths');
const checkRequiredFiles = require('react-dev-utils/checkRequiredFiles');
const formatWebpackMessages = require('react-dev-utils/formatWebpackMessages');
const printHostingInstructions = require('react-dev-utils/printHostingInstructions');
const FileSizeReporter = require('react-dev-utils/FileSizeReporter');

const measureFileSizesBeforeBuild = FileSizeReporter.measureFileSizesBeforeBuild;
const printFileSizesAfterBuild = FileSizeReporter.printFileSizesAfterBuild;
const useYarn = fs.existsSync(paths.yarnLockFile);

// Warn and crash if required files are missing
if (!checkRequiredFiles([paths.appHtml, paths.appIndexJs])) {
	process.exit(1);
}

// First, read the current file sizes in build directory.
// This lets us display how much they changed later.
measureFileSizesBeforeBuild(paths.appBuild)
	.then(previousFileSizes => {
		// Remove all content but keep the directory so that
		// if you're in it, you don't end up in Trash
		fs.emptyDirSync(paths.appBuild);
		// Merge with the public folder
		copyPublicFolder();
		// Start the webpack build
		return build(previousFileSizes);
	})
	.then(
		({ stats, previousFileSizes, warnings }) => {
			if (warnings.length) {
				console.log(chalk.yellow('Compiled with warnings.\n'));
				console.log(warnings.join('\n\n'));
				console.log(
					'\nSearch for the ' +
						chalk.underline(chalk.yellow('keywords')) +
						' to learn more about each warning.'
				);
				console.log(
					'To ignore, add ' +
						chalk.cyan('// eslint-disable-next-line') +
						' to the line before.\n'
				);
			} else {
				console.log(chalk.green('Compiled successfully.\n'));
			}

			console.log('File sizes after gzip:\n');
			printFileSizesAfterBuild(stats, previousFileSizes);
			console.log();

			const appPackage = require(paths.appPackageJson);
			const publicUrl = paths.publicUrl;
			const publicPath = config.output.publicPath;
			const buildFolder = path.relative(process.cwd(), paths.appBuild);
			printHostingInstructions(
				appPackage,
				publicUrl,
				publicPath,
				buildFolder,
				useYarn
			);
		},
		err => {
			console.log(chalk.red('Failed to compile.\n'));
			console.log((err.message || err) + '\n');
			process.exit(1);
		}
	);

// Create the production build and print the deployment instructions.
function build(previousFileSizes) {
	console.log('Creating an optimized production build...');

	let compiler = webpack(config);
	return new Promise((resolve, reject) => {
		compiler.run((err, stats) => {
			if (err) {
				return reject(err);
			}
			const messages = formatWebpackMessages(stats.toJson({}, true));
			if (messages.errors.length) {
				return reject(new Error(messages.errors.join('\n\n')));
			}
			if (process.env.CI && messages.warnings.length) {
				console.log(
					chalk.yellow(
						'\nTreating warnings as errors because process.env.CI = true.\n' +
							'Most CI servers set it automatically.\n'
					)
				);
				return reject(new Error(messages.warnings.join('\n\n')));
			}
			return resolve({
				stats,
				previousFileSizes,
				warnings: messages.warnings,
			});
		});
	});
}

function copyPublicFolder() {
	fs.copySync(paths.appPublic, paths.appBuild, {
		dereference: true,
		filter: file => file !== paths.appHtml,
	});
}
