1 files changed, 59 insertions, 0 deletions
diff --git a/Psso/Challenge.php b/Psso/Challenge.php
new file mode 100644
index 0000000..72100ce
--- /dev/null
+++ b/Psso/Challenge.php
@@ -0,0 +1,59 @@
+<?php
+namespace Psso;
+
+abstract class Challenge {
+    public protected(set) Context $context;
+    protected array $inputs = [];
+    public protected(set) string $serial;
+    
+    protected function __construct(Context $context) {
+        $this->context = $context;
+        $this->serial = base64_encode(random_bytes(9));
+    }
+    
+    public static function create(Context $context): ?static {
+        return new static($context);
+    }
+    
+    public abstract function getInputs(): array;
+    
+    public abstract function validate(
+        AuthProvider $provider, array $inputData
+    ): ChallengeResult;
+
+    public function addAsHtml(\SimpleXMLElement $parent): void {
+        $form = $parent->addChild('form');
+        $form->addAttribute('method', 'post');
+        foreach ($this->getInputs() as $input) {
+            $input->addAsHtml($form);
+            $this->inputs[$input->serial] = $input;
+        }
+        $serial = $form->addChild('input');
+        $serial->addAttribute('type', 'hidden');
+        $serial->addAttribute('name', 'challenge');
+        $serial->addAttribute('value', $this->serial);
+        $submit = $form->addChild('button', L('challenge.continue'));
+    }
+
+    public function findInput(string $serial): ?Input {
+        return $this->inputs[$serial] ?? null;
+    }
+
+    protected static function requireInterface(
+        AuthProvider $provider, string $interface
+    ): void {
+        if (!($provider instanceof $interface)) {
+            throw new \InvalidArgumentException(
+                "Provider must implement $interface"
+            );
+        };
+    }
+
+    protected static function requireKnownUser(Context $context): void {
+        if (!isset($context->user)) {
+            throw new \RuntimeException(
+                'Unknown user, but known user required for ' . static::class
+            );
+        }
+    }
+}