source: frontend/node_modules/webpack/bin/webpack.js

#!/usr/bin/env node

"use strict";

/**
 * @param {string} command process to run
 * @param {string[]} args command line arguments
 * @returns {Promise<void>} promise
 */
const runCommand = (command, args) => {
        const cp = require("child_process");

        return new Promise((resolve, reject) => {
                const executedCommand = cp.spawn(command, args, {
                        stdio: "inherit",
                        shell: true
                });

                executedCommand.on("error", (error) => {
                        reject(error);
                });

                executedCommand.on("exit", (code) => {
                        if (code === 0) {
                                resolve();
                        } else {
                                reject();
                        }
                });
        });
};

/**
 * @param {string} packageName name of the package
 * @returns {boolean} is the package installed?
 */
const isInstalled = (packageName) => {
        if (process.versions.pnp) {
                return true;
        }

        const path = require("path");
        const fs = require("graceful-fs");

        let dir = __dirname;

        do {
                try {
                        if (
                                fs.statSync(path.join(dir, "node_modules", packageName)).isDirectory()
                        ) {
                                return true;
                        }
                } catch (_error) {
                        // Nothing
                }
        } while (dir !== (dir = path.dirname(dir)));

        // https://github.com/nodejs/node/blob/v18.9.1/lib/internal/modules/cjs/loader.js#L1274
        const { globalPaths } =
                /** @type {typeof import("module") & { globalPaths: string[] }} */
                (require("module"));

        for (const internalPath of globalPaths) {
                try {
                        if (fs.statSync(path.join(internalPath, packageName)).isDirectory()) {
                                return true;
                        }
                } catch (_error) {
                        // Nothing
                }
        }

        return false;
};

/**
 * @param {CliOption} cli options
 * @returns {void}
 */
const runCli = (cli) => {
        const path = require("path");

        const pkgPath = require.resolve(`${cli.package}/package.json`);

        /** @type {Record<string, EXPECTED_ANY> & { type: string, bin: Record<string, string> }} */
        const pkg = require(pkgPath);

        if (pkg.type === "module" || /\.mjs/i.test(pkg.bin[cli.binName])) {
                import(path.resolve(path.dirname(pkgPath), pkg.bin[cli.binName])).catch(
                        (err) => {
                                console.error(err);
                                process.exitCode = 1;
                        }
                );
        } else {
                require(path.resolve(path.dirname(pkgPath), pkg.bin[cli.binName]));
        }
};

/**
 * @typedef {object} CliOption
 * @property {string} name display name
 * @property {string} package npm package name
 * @property {string} binName name of the executable file
 * @property {boolean} installed currently installed?
 * @property {string} url homepage
 */

/** @type {CliOption} */
const cli = {
        name: "webpack-cli",
        package: "webpack-cli",
        binName: "webpack-cli",
        installed: isInstalled("webpack-cli"),
        url: "https://github.com/webpack/webpack-cli"
};

if (!cli.installed) {
        const path = require("path");
        const fs = require("graceful-fs");
        const readLine = require("readline");

        const notify = `CLI for webpack must be installed.\n  ${cli.name} (${cli.url})\n`;

        console.error(notify);

        /** @type {string | undefined} */
        let packageManager;

        if (fs.existsSync(path.resolve(process.cwd(), "yarn.lock"))) {
                packageManager = "yarn";
        } else if (fs.existsSync(path.resolve(process.cwd(), "pnpm-lock.yaml"))) {
                packageManager = "pnpm";
        } else {
                packageManager = "npm";
        }

        const installOptions = [packageManager === "yarn" ? "add" : "install", "-D"];

        console.error(
                `We will use "${packageManager}" to install the CLI via "${packageManager} ${installOptions.join(
                        " "
                )} ${cli.package}".`
        );

        const question = "Do you want to install 'webpack-cli' (yes/no): ";

        const questionInterface = readLine.createInterface({
                input: process.stdin,
                output: process.stderr
        });

        // In certain scenarios (e.g. when STDIN is not in terminal mode), the callback function will not be
        // executed. Setting the exit code here to ensure the script exits correctly in those cases. The callback
        // function is responsible for clearing the exit code if the user wishes to install webpack-cli.
        process.exitCode = 1;
        questionInterface.question(question, (answer) => {
                questionInterface.close();

                const normalizedAnswer = answer.toLowerCase().startsWith("y");

                if (!normalizedAnswer) {
                        console.error(
                                "You need to install 'webpack-cli' to use webpack via CLI.\n" +
                                        "You can also install the CLI manually."
                        );

                        return;
                }
                process.exitCode = 0;

                console.log(
                        `Installing '${
                                cli.package
                        }' (running '${packageManager} ${installOptions.join(" ")} ${
                                cli.package
                        }')...`
                );

                runCommand(
                        /** @type {string} */
                        (packageManager),
                        [...installOptions, cli.package]
                )
                        .then(() => {
                                runCli(cli);
                        })
                        .catch((err) => {
                                console.error(err);
                                process.exitCode = 1;
                        });
        });
} else {
        runCli(cli);
}