index.js

/*
 * Copyright OpenSearch Contributors
 * SPDX-License-Identifier: Apache-2.0
 */

const { join, dirname } = require('path');
const {
  compileWithVariablesSync,
} = require('../../lib/compile-scss-with-variables');

const idKey = '!!variables-from-scss!!';
const keyLength = idKey.length;

const forbiddenKeyNames = [
  ...Object.getOwnPropertyNames(Object.prototype),
  'prototype',
];

module.exports = (babel) => ({
  visitor: {
    ImportDeclaration(path, state) {
      if (path.node.source.value.startsWith(idKey)) {
        const deconstructedAssignments = [];
        const usedVariableNames = [];
        const assignments = [];
        for (const specifier of path.node.specifiers) {
          if (specifier.type === 'ImportDefaultSpecifier') {
            assignments.push(specifier.local.name);
          } else if (specifier.type === 'ImportSpecifier') {
            usedVariableNames.push(specifier.imported.name);
            deconstructedAssignments.push(
              specifier.imported.name === specifier.local.name
                ? specifier.local.name
                : `${specifier.imported.name}: ${specifier.local.name}`
            );
          }
        }

        const importTarget = join(
          dirname(state.file.opts.filename),
          path.node.source.value.substring(keyLength)
        );
        const { variables } = compileWithVariablesSync(importTarget);

        // If no default specifier is used, reduce the variables to only those needed
        const importedVariables =
          assignments.length === 0
            ? usedVariableNames.reduce((acc, name) => {
                if (!forbiddenKeyNames.includes(name))
                  acc[name] = variables[name];
                return acc;
              }, {})
            : variables;

        if (deconstructedAssignments.length > 0)
          assignments.push(`{ ${deconstructedAssignments.join(', ')} }`);
        path.replaceWith(
          babel.template.statement.ast(
            `const ${assignments.join(', ')} = ${JSON.stringify(
              importedVariables
            )};`
          )
        );
      }
    },
  },
});