More over engineering.

TBH at this point I think I need a DI container.

src/Configuration.php

@@ -60,9 +60,4 @@ class Configuration
     {
         return $this->stateFile;
     }
-
-    public function isOpen(): bool
-    {
-        return file_exists($this->stateFile);
-    }
 }

src/ReadableState.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace FooBar;
+
+interface ReadableState
+{
+    /**
+     * Check whether the FooBar is open
+     *
+     * @return bool true if the FooBar is open.
+     */
+    public function isOpen(): bool;
+}

src/State.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace FooBar;
+
+class State implements ReadableState
+{
+    private $config;
+
+    public function __construct(Configuration $config)
+    {
+        $this->config = $config;
+    }
+
+    /**
+     * Check whether the FooBar is open
+     *
+     * @return bool true if the FooBar is open.
+     */
+    public function isOpen(): bool
+    {
+        return file_exists($this->config->stateFile());
+    }
+
+    /**
+     * Toggle the current state of the FooBar.
+     *
+     * @return bool the new state of the FooBar.
+     */
+    public function toggle(): bool
+    {
+        if ($this->isOpen()) {
+            unlink($this->config->stateFile());
+            return false;
+        } else {
+            touch($this->config->stateFile());
+            return true;
+        }
+    }
+}