const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const CssMinimizerPlugin = require('css-minimizer-webpack-plugin');
const CopyWebpackPlugin = require('copy-webpack-plugin');

module.exports = (env, argv) => {
  const isProd = argv.mode === 'production';

  return {
    entry: {
      sheet: './fabula-ultima-sheet.js',
      // Imports the shared CSS so HtmlWebpackPlugin can inject it into the book page
      book: './book.js',
    },
    output: {
      filename: isProd ? '[name].[contenthash].js' : '[name].js',
      path: path.resolve(__dirname, 'dist'),
      clean: true,
      // Disable IIFE wrapping so onclick= handlers can reach global functions
      iife: false,
    },
    module: {
      rules: [
        {
          test: /\.css$/,
          use: [
            isProd ? MiniCssExtractPlugin.loader : 'style-loader',
            'css-loader',
          ],
        },
      ],
    },
    plugins: [
      ...(isProd
        ? [new MiniCssExtractPlugin({ filename: '[name].[contenthash].css' })]
        : []),
      new HtmlWebpackPlugin({
        template: './fabula-ultima-sheet.html',
        filename: 'index.html',
        chunks: ['sheet'],
        scriptLoading: 'blocking',
      }),
      new HtmlWebpackPlugin({
        template: './html/index.html',
        filename: 'book/index.html',
        chunks: ['book'],
        scriptLoading: 'blocking',
      }),
      // Copy book pages to dist/book/ (excluding index.html, managed by HtmlWebpackPlugin)
      new CopyWebpackPlugin({
        patterns: [
          {
            from: 'html',
            to: 'book',
            globOptions: { ignore: ['**/index.html'] },
          },
        ],
      }),
    ],
    optimization: {
      minimizer: ['...', new CssMinimizerPlugin()],
      splitChunks: {
        cacheGroups: {
          // Merge CSS from all entries into a single shared file
          styles: {
            name: 'styles',
            type: 'css/mini-extract',
            chunks: 'all',
            enforce: true,
          },
        },
      },
    },
    devServer: {
      static: [
        { directory: path.resolve(__dirname, 'dist') },
        // Serve raw html/ pages at /book in dev so they don't need to be copied
        { directory: path.resolve(__dirname, 'html'), publicPath: '/book' },
      ],
      port: 8080,
      open: true,
      historyApiFallback: {
        rewrites: [
          // /book (no trailing slash) → /book/index.html
          { from: /^\/book$/, to: '/book/index.html' },
        ],
      },
    },
  };
};