Add argv parser class

bin/bin/stow

@@ -11,36 +11,98 @@ function line(string $line): void
     echo $line . PHP_EOL;
 }
 
-$cwd = getcwd();
-$action = 'stow';
-$backup = $force = false;
-array_shift($argv); // we don't care about the script name
+class argParsed
+{
+    public function __construct(
+        private array $parsed = [],
+    ) {}
 
-if (count($argv) === 0) {
-    line("Usage: stow [-u] [-b] [-f] <stow-directory>");
+    public function initOptions(array $options, mixed $default = false): self
+    {
+        foreach (array_keys($options) as $name) {
+            $this->set($name, $default);
+        }
+
+        return $this;
+    }
+
+    public function get(string $key, mixed $default = null): mixed
+    {
+        return $this->parsed[$key] ?? $default;
+    }
+
+    public function set(string $key, mixed $value): self
+    {
+        $this->parsed[$key] = $value;
+        return $this;
+    }
+}
+
+readonly class argvParser
+{
+    /**
+     * @param array<string, string> $options
+     * @param array<string, string> $arguments
+     */
+    public function __construct(
+        private array $options = [],
+        private array $arguments = [],
+    ) {}
+
+    public function getOptionsHelp(): string
+    {
+        $line = '';
+        foreach ($this->options as $option => $description) {
+            $line .= sprintf('[-%s (%s)] ', $option, $description);
+        }
+        foreach ($this->arguments as $argument => $description) {
+            $line .= sprintf('<%s (%s)> ', $argument, $description);
+        }
+        return $line;
+    }
+
+    public function parseArgv(array $argv): argParsed|false
+    {
+        array_shift($argv); // shift the script name
+        if (count($argv) < count($this->arguments)) {
+            return false;
+        }
+
+        $parsed = (new argParsed())->initOptions($this->options);
+        while (str_starts_with($argv[0], '-')) {
+            $option = substr($argv[0], 1);
+            if ($this->options[$option]) {
+                $parsed->set($option, true);
+            }
+            array_shift($argv);
+        }
+        if (count($argv) !== count($this->arguments)) {
+            return false;
+        }
+        foreach ($this->arguments as $arg => $description) {
+            $parsed->set($arg, array_shift($argv));
+        }
+
+        return $parsed;
+    }
+}
+
+$argvParser = new ArgvParser(
+    ['u' => 'Unstow files', 'b' => 'Backup existing files', 'f' => 'Force overwrite'],
+    ['stow-directory' => 'The directory to stow']
+);
+$parsed = $argvParser->parseArgv($argv);
+if ($parsed === false) {
+    line('Usage: ' . __FILE__ . ' ' . $argvParser->getOptionsHelp());
     exit(1);
 }
 
-while (str_starts_with($argv[0], '-')) {
-    $option = substr($argv[0], 1);
-    switch ($option) {
-        case 'u':
-            $action = 'unstow';
-            break;
-        case 'b':
-            $backup = true;
-            break;
-        case 'f':
-            $force = true;
-            break;
-        default:
-            line("Unknown option: $option");
-            exit(1);
-    }
-    array_shift($argv);
-}
+$cwd = getcwd();
+$action = $parsed->get('u') ? 'unstow' : 'stow';
+$backup = $parsed->get('b');
+$force = $parsed->get('f');
 
-$stowName = $argv[0];
+$stowName = $parsed->get('stow-directory');
 $stowPath = path($cwd, $stowName);
 $targetPath = dirname($stowPath, 2);
 
@@ -125,4 +187,6 @@ readonly class stow
 }
 
 $stow = new stow($action, $backup, $force);
-$stow->run($stowPath, $targetPath);
+$stow->run($stowPath, $targetPath);
+
+exit(0);