feat: add Help to CLI (#45)

* feat: add Help to CLI

* rename args after rebase

Author: bartveneman

src/cli/arguments.ts

@@ -64,7 +64,6 @@ export function validate_arguments(args: ReturnType<typeof parse_arguments>): Cl
 export function parse_arguments(args: string[]) {
 	let { values } = parseArgs({
 		args,
-		allowPositionals: true,
 		options: {
 			'coverage-dir': {
 				type: 'string',

src/cli/cli.ts

@@ -5,8 +5,13 @@ import { program } from './program.js'
 import { read } from './file-reader.js'
 import { print as pretty } from './reporters/pretty.js'
 import { print as tap } from './reporters/tap.js'
+import { help } from './help.js'
 
 async function cli(cli_args: string[]) {
+	if (!cli_args || cli_args.length === 0 || cli_args.includes('--help') || cli_args.includes('-h')) {
+		return console.log(help())
+	}
+
 	let params = validate_arguments(parse_arguments(cli_args))
 	let coverage_data = await read(params['coverage-dir'])
 	let report = program(

src/cli/help.ts

@@ -0,0 +1,37 @@
+import { styleText } from 'node:util'
+
+export function help() {
+	return `
+${styleText(['bold'], 'USAGE')}
+  $ css-coverage --coverage-dir=<dir> --min-coverage=<number> [options]
+
+${styleText('bold', 'OPTIONS')}
+Required:
+  --coverage-dir        Where your Coverage JSON files are
+  --min-coverage        Minimum overall CSS coverage [0-1]
+
+Optional:
+  --min-file-coverage   Minimal coverage per file [0-1]
+
+  --show-uncovered      Which files to show when not meeting 
+                        the --min-file-line-coverage threshold
+                        • violations [default] ${styleText('dim', 'show under-threshold files')}
+                        • all ${styleText('dim', 'show partially covered files')}
+                        • none ${styleText('dim', 'do not show files')}
+
+  --reporter            How to show the results 
+                        • pretty [default]
+                        • tap
+                        • json
+
+${styleText('bold', 'EXAMPLES')}
+  ${styleText('dim', '# analyze all .json files in ./coverage; require 80% overall coverage')}
+  $ css-coverage --coverage-dir=./coverage --min-coverage=0.8
+
+  ${styleText('dim', '# Require 50% coverage per file')}
+  $ css-coverage --coverage-dir=./coverage --min-coverage=0.8 --min-file-coverage=0.5
+
+  ${styleText('dim', 'Report JSON')}
+  $ css-coverage --coverage-dir=./coverage --min-coverage=0.8 --reporter=json
+  `.trim()
+}