Add WIP intersphinx reference resolver

Author: wouterj

packages/guides/src/ReferenceResolvers/IntersphinxReferenceResolver.php

@@ -0,0 +1,60 @@
+<?php
+
+declare(strict_types=1);
+
+namespace phpDocumentor\Guides\ReferenceResolvers;
+
+use phpDocumentor\Guides\Intersphinx\InventoryRepository;
+use phpDocumentor\Guides\Nodes\Inline\CrossReferenceNode;
+use phpDocumentor\Guides\Nodes\Inline\DocReferenceNode;
+use phpDocumentor\Guides\Nodes\Inline\LinkInlineNode;
+use phpDocumentor\Guides\RenderContext;
+
+use function explode;
+use function str_contains;
+
+class IntersphinxReferenceResolver implements ReferenceResolver
+{
+    public final const PRIORITY = 50;
+
+    public function __construct(private InventoryRepository $inventoryRepository)
+    {
+    }
+
+    public function resolve(LinkInlineNode $node, RenderContext $renderContext): bool
+    {
+        if (!$node instanceof CrossReferenceNode || !str_contains($node->getTargetReference(), ':')) {
+            return false;
+        }
+
+        [$domain, $target] = explode(':', $node->getTargetReference(), 2);
+        if (!$this->inventoryRepository->hasInventory($domain)) {
+            return false;
+        }
+
+        $inventory = $this->inventoryRepository->getInventory($domain);
+        $group = $node instanceof DocReferenceNode ? 'std:doc' : 'std:label';
+        if (!$inventory->hasInventoryGroup($group)) {
+            return false;
+        }
+
+        $inventoryGroup = $inventory->getInventory($group);
+        if (!$inventoryGroup->hasLink($target)) {
+            return false;
+        }
+
+        $link = $inventory->getLink($group, $target);
+
+        $node->setUrl($inventory->getBaseUrl() . $link->getPath());
+        if ($node->getValue() === '') {
+            $node->setValue($link->getTitle());
+        }
+
+        return false;
+    }
+
+    public static function getPriority(): int
+    {
+        return self::PRIORITY;
+    }
+}