feat(cli): implement help, display version

src/cli.ts

@@ -1,13 +1,21 @@
 #!/usr/bin/env node
+import chalk from 'chalk';
 import * as commandLineArgs from 'command-line-args';
 
+/**
+ * Supported output style. Mirrors `style_option_strings[]` in sassc
+ * (https://github.com/sass/sassc/blob/6a64d0569205bfcf0794a473f97affcb60b22fcc/sassc.c#L184-L189)
+ */
 enum StyleOption {
   SASS_STYLE_COMPRESSED = 'compressed',
   SASS_STYLE_COMPACT = 'compact',
   SASS_STYLE_EXPANDED = 'expanded',
   SASS_STYLE_NESTED = 'nested'
 }
 
+/**
+ * Definitions of available command line args.
+ */
 const optionDefinitions = [
   { name: 'stdin', alias: 's', description: 'Read input from standard input instead of an input file.' },
   {
@@ -22,18 +30,43 @@ const optionDefinitions = [
   { name: 'omit-map-comment', alias: 'M', description: 'Omits the source map url comment.' },
   { name: 'precision', alias: 'p', description: 'Set the precision for numbers.' },
   { name: 'sass', alias: 'a', description: 'Treat input as indented syntax.' },
-  { name: 'version', alias: 'v', description: 'Display compiled versions.' },
+  { name: 'version', alias: 'v', description: 'Display compiled versions.', type: Boolean },
   { name: 'help', alias: 'h', description: 'Display this help message.', type: Boolean }
 ];
 
+/**
+ * Get usage definition for library version.
+ *
+ */
+const buildDisplayVersion = async () => {
+  const { loadModule } = await import('./loadModule');
+  const sassFactory = await loadModule();
+  const { libsassAsm, libsass, sassLang, sass2scss } = await sassFactory.getVersion();
+
+  return {
+    header: chalk.reset('Version'),
+    content: [
+      { name: 'libsass-asm', summary: libsassAsm },
+      { name: 'libsass', summary: libsass },
+      { name: 'sass', summary: sassLang },
+      { name: 'sass2scss', summary: sass2scss }
+    ]
+  };
+};
+
 (async () => {
   const options = commandLineArgs(optionDefinitions, { camelCase: true });
 
-  if (options.help || Object.keys(options).length === 0) {
-    const commandLineUsage = await import('command-line-usage');
-    const usage = commandLineUsage([{ header: 'Options', optionList: optionDefinitions }]);
+  const displayHelp = options.help || Object.keys(options).length === 0;
+  const displayVersion = options.version;
+
+  if (displayHelp || displayVersion) {
+    const cmdUsage = await import('command-line-usage');
+    const usageDefinition = displayHelp
+      ? { header: chalk.reset('Options'), optionList: optionDefinitions }
+      : await buildDisplayVersion();
+    const usage = cmdUsage([usageDefinition]);
     console.log(usage);
-  } else if (options.version) {
     return;
   }
 })();