feat: Better support for multiple themes

This change adds support for two CLI options to the build-tokens
command.

The first, --all-themes makes the build-tokens command process all
themes in the source directory as opposed to specifying all the names
via --theme.

Secondly, --base-theme allows you to have multiple themes derived from
the same common base. If specified, you can have a derived theme that
still loads tokens from the light theme. For example, you can have a
site theme called 'theme-one' and set the base theme to light so it will
reuse the core light theme tokens and layer on changes from 'theme-one'.

lib/build-tokens.js

@@ -1,3 +1,4 @@
+const fs = require('fs');
 const path = require('path');
 const minimist = require('minimist');
 const { StyleDictionary, colorTransform, createCustomCSSVariables } = require('../tokens/style-dictionary');
@@ -9,13 +10,17 @@ const { createIndexCssFile } = require('../tokens/utils');
  * @param {string[]} commandArgs - Command line arguments for building tokens.
  * @param {string} [commandArgs.build-dir='./build/'] - The directory where the build output will be placed.
  * @param {string} [commandArgs.source] - The source directory containing JSON token files.
+ * @param {string} [commandArgs.base-theme] - The base theme to use from Paragon if named differently than the theme.
  * @param {boolean} [commandArgs.source-tokens-only=false] - Indicates whether to include only source tokens.
  * @param {string|string[]} [commandArgs.themes=['light']] - The themes (variants) for which to build tokens.
+ * @param {boolean} [commandArgs.all-themes] - Indicated whether to process all themes.
  */
 async function buildTokensCommand(commandArgs) {
   const defaultParams = {
-    themes: ['light'],
+    themes: 'light',
+    'base-theme': null,
     'build-dir': './build/',
+    'all-themes': false,
   };
 
   const alias = {
@@ -28,7 +33,20 @@ async function buildTokensCommand(commandArgs) {
     source: tokensSource,
     'source-tokens-only': hasSourceTokensOnly,
     themes,
-  } = minimist(commandArgs, { alias, default: defaultParams, boolean: 'source-tokens-only' });
+    'base-theme': baseTheme,
+    'all-themes': allThemes,
+  } = minimist(commandArgs, { alias, default: defaultParams, boolean: ['source-tokens-only', 'all-themes'] });
+
+  let themesToProcess = null;
+
+  if (allThemes) {
+    themesToProcess = fs
+      .readdirSync(`${tokensSource}/themes/`, { withFileTypes: true })
+      .filter(entry => entry.isDirectory())
+      .map(entry => entry.name);
+  } else {
+    themesToProcess = themes.split(' ');
+  }
 
   const coreConfig = {
     include: [path.resolve(__dirname, '../tokens/src/core/**/*.json')],
@@ -65,9 +83,9 @@ async function buildTokensCommand(commandArgs) {
     },
   };
 
-  const getStyleDictionaryConfig = (themeVariant) => ({
+  const getStyleDictionaryConfig = (themeVariant, baseThemeVariant) => ({
     ...coreConfig,
-    include: [...coreConfig.include, path.resolve(__dirname, `../tokens/src/themes/${themeVariant}/**/*.json`)],
+    include: [...coreConfig.include, path.resolve(__dirname, `../tokens/src/themes/${baseThemeVariant}/**/*.json`)],
     source: tokensSource ? [`${tokensSource}/themes/${themeVariant}/**/*.json`] : [],
     transform: {
       'color/sass-color-functions': {
@@ -109,8 +127,8 @@ async function buildTokensCommand(commandArgs) {
   StyleDictionary.extend(coreConfig).buildAllPlatforms();
   createIndexCssFile({ buildDir, isTheme: false });
 
-  themes.forEach((themeVariant) => {
-    const config = getStyleDictionaryConfig(themeVariant);
+  themesToProcess.forEach((themeVariant) => {
+    const config = getStyleDictionaryConfig(themeVariant, baseTheme || themeVariant);
     StyleDictionary.extend(config).buildAllPlatforms();
     createIndexCssFile({ buildDir, isTheme: true, themeVariant });
   });