import path from "path";
import { readdirSync } from "fs";
import { Compilation, sources } from "webpack";
import type {
  Configuration,
  RuleSetRule,
  Compiler,
  EntryObject,
} from "webpack";

interface FindReplacePluginOptions {
  replace: { from: RegExp; to: string }[];
}

/**
 * Simple find and replace in assets plugin for Webpack
 */
class FindReplacePlugin {
  options: FindReplacePluginOptions;

  constructor(options: FindReplacePluginOptions) {
    this.options = options;
  }

  apply(compiler: Compiler) {
    const pluginName = FindReplacePlugin.name;
    const logger = compiler.getInfrastructureLogger(pluginName);

    compiler.hooks.compilation.tap({ name: pluginName }, (compilation) => {
      compilation.hooks.processAssets.tap(
        {
          name: pluginName,
          stage: Compilation.PROCESS_ASSETS_STAGE_ANALYSE,
        },
        (assets) => {
          Object.entries(assets).forEach(([pathname, source]) => {
            if (path.extname(pathname) !== ".js") return;

            let replaced = source.source().toString();

            // For every regex pattern, replace it in the source content
            for (const { from, to } of this.options.replace) {
              const matches = replaced.match(from);

              if (matches) {
                logger.info(`${from} | Found ${matches.length} matches`);
              }

              replaced = replaced.replace(from, to);
            }

            const newSource = new sources.RawSource(replaced);

            const previousSize = source.size();
            compilation.updateAsset(pathname, newSource);
            const newSize = newSource.size();

            if (newSize !== previousSize) {
              logger.info(
                `Found and replaced in ${pathname}: ${previousSize} -> ${newSize}`,
              );
            }
          });
        },
      );
    });
  }
}

const babelRule: RuleSetRule = {
  test: /\.(ts|js|mjs)$/,
  // https://webpack.js.org/loaders/babel-loader/#exclude-libraries-that-should-not-be-transpiled
  exclude: [
    // \\ for Windows, / for macOS and Linux
    /node_modules[\\/]core-js/,
  ],
  use: {
    loader: "babel-loader",
    options: {
      targets: "defaults",
      sourceType: "unambiguous",
      presets: [
        // Parse TypeScript
        ["@babel/preset-typescript"],
        [
          "@babel/preset-env",
          {
            // Use this to cover the lowest possible syntax requirement for QtScript
            // See: https://browsersl.ist/
            targets: "cover 100%",
            // Adds at the top of each file imports of polyfills only for features used in the current and not supported by target environments
            useBuiltIns: "usage",
            corejs: "3.46.0",
          },
        ],
      ],
    },
  },
};

/**
 * Dynamically returns an object of script entries from src/scripts/*.ts files
 */
function getScriptsEntryObject(): EntryObject {
  const entries: EntryObject = {};
  const scriptsPath = path.resolve(__dirname, "src", "scripts");
  const scripts = readdirSync(scriptsPath).filter((file) =>
    file.endsWith(".ts"),
  );

  scripts.forEach((script) => {
    entries[path.parse(script).name] = path.resolve(scriptsPath, script);
  });

  return entries;
}

const config: Configuration = {
  mode: "production",
  module: {
    rules: [babelRule],
  },
  entry: getScriptsEntryObject(),
  resolve: {
    extensions: [".ts", ".js", ".mjs"],
    // Explicitly define where node_modules is in this project for corejs imports
    // See: https://stackoverflow.com/a/62129649
    modules: [path.resolve(__dirname, "node_modules")],
  },
  output: {
    filename: "[name].js",
    path: path.resolve(__dirname, "dist"),
    environment: { arrowFunction: false },
  },
  plugins: [
    new FindReplacePlugin({
      replace: [
        /**
         * Replaces reserved words as property names
         * For example obj.for = 0 -> obj["for"] = 0
         */
        { from: /\.(for|return)([^\w])/g, to: '["$1"]$2' },
        /**
         * Replaces reserved words as object literal property names
         * See: https://eslint.style/rules/quote-props#quote-props
         * For example { for: 0 } -> { "for": 0 }
         */
        { from: /(for|return):/g, to: '"$1":' },
        /**
         * Some Regexp uses "/" character in character sets but must be escaped in QtScript syntax (don't know why)
         */
        { from: /\[\^\\s\(\/\]/g, to: "[^\\s(\\/]" },
        { from: /\[\\w\.\/\]/g, to: "[\\w.\\/]" },
        { from: /\[a-z_\+-\/\]/g, to: "[a-z_+-\\/]" },
      ],
    }),
  ],
  optimization: {
    minimize: false,
  },
};

export default config;