import { basename, resolve } from 'path';
import { cacheLoader, getExposeLoaders } from './webpack-helpers';
import BundleTracker from 'webpack4-bundle-tracker';
import CleanCss from 'clean-css';
import HtmlWebpackPlugin from 'html-webpack-plugin';
import MiniCssExtractPlugin from 'mini-css-extract-plugin';
import OptimizeCssAssetsPlugin from 'optimize-css-assets-webpack-plugin';
import TerserPlugin from 'terser-webpack-plugin';
// The devServer member of webpack.Configuration is managed by the
// webpack-dev-server package. We are only importing the type here.
import _webpackDevServer from 'webpack-dev-server';
import webpack from 'webpack';

const assets = require('./webpack.assets.json');

export default (env?: string): webpack.Configuration[] => {
    const production: boolean = env === "production";
    const publicPath = production ? '/static/webpack-bundles/' : '/webpack/';
    const config: webpack.Configuration = {
        name: "frontend",
        mode: production ? "production" : "development",
        context: resolve(__dirname, "../"),
        entry: assets,
        module: {
            rules: [
                // Generate webfont
                {
                    test: /\.font\.js$/,
                    use: [
                        MiniCssExtractPlugin.loader,
                        'css-loader',
                        {
                            loader: 'webfonts-loader',
                            options: {
                                fileName: production ? 'files/[fontname].[chunkhash].[ext]' : 'files/[fontname].[ext]',
                                publicPath,
                            },
                        },
                    ],
                },
                // Transpile .js and .ts files with Babel
                {
                    test: /\.(js|ts)$/,
                    include: [
                        resolve(__dirname, '../static/shared/js'),
                        resolve(__dirname, '../static/js'),
                    ],
                    loader: 'babel-loader',
                },
                // Uses script-loader on minified files so we don't change global variables in them.
                // Also has the effect of making processing these files fast
                // Currently the source maps don't work with these so use unminified files
                // if debugging is required.
                {
                    // We dont want to match admin.js
                    test: /(\.min|min\.|zxcvbn)\.js/,
                    use: [cacheLoader, 'script-loader'],
                },
                // regular css files
                {
                    test: /\.css$/,
                    use: [
                        {
                            loader: MiniCssExtractPlugin.loader,
                            options: {
                                hmr: !production,
                            },
                        },
                        cacheLoader,
                        {
                            loader: 'css-loader',
                            options: {
                                sourceMap: true,
                            },
                        },
                    ],
                },
                // scss loader
                {
                    test: /\.scss$/,
                    include: resolve(__dirname, '../static/styles'),
                    use: [
                        {
                            loader: MiniCssExtractPlugin.loader,
                            options: {
                                hmr: !production,
                            },
                        },
                        cacheLoader,
                        {
                            loader: 'css-loader',
                            options: {
                                importLoaders: 1,
                                sourceMap: true,
                            },
                        },
                        {
                            loader: 'postcss-loader',
                            options: {
                                sourceMap: true,
                            },
                        },
                    ],
                },
                {
                    test: /\.hbs$/,
                    loader: 'handlebars-loader',
                    options: {
                        // Tell webpack not to explicitly require these.
                        knownHelpers: ['if', 'unless', 'each', 'with',
                            // The ones below are defined in static/js/templates.js
                            'plural', 'eq', 'and', 'or', 'not',
                            't', 'tr'],
                        preventIndent: true,
                    },
                },
                // load fonts and files
                {
                    test: /\.(woff(2)?|ttf|eot|svg|otf|png)$/,
                    use: [{
                        loader: 'file-loader',
                        options: {
                            name: production ? '[name].[hash].[ext]' : '[name].[ext]',
                            outputPath: 'files/',
                        },
                    }],
                },
            ],
        },
        output: {
            path: resolve(__dirname, '../static/webpack-bundles'),
            publicPath,
            filename: production ? '[name].[contenthash].js' : '[name].js',
            chunkFilename: production ? '[contenthash].js' : '[id].js',
        },
        resolve: {
            extensions: [".ts", ".js"],
        },
        // We prefer cheap-module-source-map over any eval-** options
        // because the eval-options currently don't support being
        // source mapped in error stack traces
        // We prefer it over eval since eval has trouble setting
        // breakpoints in chrome.
        devtool: production ? 'source-map' : 'cheap-module-source-map',
        optimization: {
            minimizer: [
                // Based on a comment in NMFR/optimize-css-assets-webpack-plugin#10.
                // Can be simplified when NMFR/optimize-css-assets-webpack-plugin#87
                // is fixed.
                new OptimizeCssAssetsPlugin({
                    cssProcessor: {
                        process: async (css, options) => {
                            const filename = basename(options.to);
                            const result = await new CleanCss(options).minify({
                                [filename]: {
                                    styles: css,
                                    sourceMap: options.map.prev,
                                },
                            });
                            for (const warning of result.warnings) {
                                console.warn(warning);
                            }
                            return {
                                css: result.styles + `\n/*# sourceMappingURL=${filename}.map */`,
                                map: result.sourceMap,
                            };
                        },
                    },
                    cssProcessorOptions: {
                        map: {},
                        returnPromise: true,
                        sourceMap: true,
                        sourceMapInlineSources: true,
                    },
                }),
                new TerserPlugin({
                    cache: true,
                    parallel: true,
                    sourceMap: true,
                }),
            ],
            splitChunks: {
                chunks: "all",
                // webpack/examples/many-pages suggests 20 requests for HTTP/2
                maxAsyncRequests: 20,
                maxInitialRequests: 20,
            },
        },
        plugins: [
            new BundleTracker({
                filename: production
                    ? 'webpack-stats-production.json'
                    : 'var/webpack-stats-dev.json',
            }),
            ...production
                ? []
                : [
                    // Better logging from console for hot reload
                    new webpack.NamedModulesPlugin(),
                    // script-loader should load sourceURL in dev
                    new webpack.LoaderOptionsPlugin({debug: true}),
                ],
            // Extract CSS from files
            new MiniCssExtractPlugin({
                filename: production ? "[name].[contenthash].css" : "[name].css",
                chunkFilename: production ? "[contenthash].css" : "[id].css",
            }),
            new HtmlWebpackPlugin({
                filename: "5xx.html",
                template: "static/html/5xx.html",
                chunks: ["error-styles"],
            }),
        ],
    };

    // Expose Global variables for third party libraries to webpack modules
    // Use the unminified versions of jquery and underscore so that
    // Good error messages show up in production and development in the source maps
    var exposeOptions = [
        { path: "blueimp-md5/js/md5.js" },
        { path: "clipboard/dist/clipboard.js", name: "ClipboardJS" },
        { path: "xdate/src/xdate.js", name: "XDate" },
        { path: "simplebar/dist/simplebar.js"},
        { path: "../static/third/marked/lib/marked.js" },
        { path: "../static/generated/emoji/emoji_codes.js" },
        { path: "../static/generated/pygments_data.js" },
        { path: "../static/js/debug.js" },
        { path: "../static/js/blueslip.js" },
        { path: "../static/js/common.js" },
        { path: "jquery/dist/jquery.js", name: ['$', 'jQuery'] },
        { path: "underscore/underscore.js", name: '_' },
        { path: "handlebars/dist/cjs/handlebars.runtime.js", name: 'Handlebars' },
        { path: "to-markdown/dist/to-markdown.js", name: 'toMarkdown' },
        { path: "sortablejs/Sortable.js"},
        { path: "winchan/winchan.js", name: 'WinChan'},
    ];
    config.module.rules.unshift(...getExposeLoaders(exposeOptions));

    if (!production) {
        // Out JS debugging tools
        for (const name of Object.keys(config.entry)) {
            config.entry[name].push('./static/js/debug.js');
        }
        config.devServer = {
            clientLogLevel: "error",
            stats: "errors-only",
        };
    }

    const serverConfig: webpack.Configuration = {
        mode: production ? "production" : "development",
        target: "node",
        context: resolve(__dirname, "../"),
        entry: {
            "katex-cli": "shebang-loader!katex/cli",
        },
        output: {
            path: resolve(__dirname, "../static/webpack-bundles"),
            filename: "[name].js",
        },
    };

    return [config, serverConfig];
};