Naive solution to get a list of all included CSS Modules

collect-styles-path.js

const { resolve, dirname } = require('path');

const matchExtensions = /\.css$/i;

module.exports = function({ types: t }) {
    return {
        visitor: {
            // import styles from './style.css';
            ImportDefaultSpecifier(path) {
                const { value } = path.parentPath.node.source;

                if (matchExtensions.test(value)) {
                    const { name } = path.node.local;
                    const { parentPath } = path;
                    path.remove();
                    parentPath.replaceWith(t.variableDeclaration('const', [
                        t.variableDeclarator(
                            t.identifier(name),
                            t.callExpression(t.identifier('require'), [t.stringLiteral(value)])
                        )
                    ]));
                }
            },

            // const styles = require('./styles.css');
            CallExpression(path, { file }) {
                const { callee: { name: calleeName }, arguments: args } = path.node;

                if (calleeName !== 'require' || !args.length || !t.isStringLiteral(args[0])) {
                    return;
                }

                const [{ value: stylesheetPath }] = args;

                if (matchExtensions.test(stylesheetPath)) {
                    let csspath = resolve('node_modules/' + stylesheetPath);

                    if (stylesheetPath[0] === '.') {
                        const requiringFile = file.opts.filename;
                        csspath = resolve(dirname(requiringFile), stylesheetPath);
                    }

                    const tokens = require(csspath) || {};

                    if (!t.isExpressionStatement(path.parent)) {
                        path.replaceWithSourceString(`
                        (function(){
                            global.includedCssModules = global.includedCssModules || [];

                            if (global.includedCssModules.indexOf('${csspath}') === -1) {
                                global.includedCssModules.push('${csspath}');
                            }

                            return ${JSON.stringify(tokens)};
                        })()
                        `);
                    } else {
                        csspath.remove();
                    }
                }
            }
        }
    };
};