From 986e8585614cecb78d7374a1b5b558d3da0bd680 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Joachim=20L=C3=B8vgaard?= <joachim@loevgaard.dk>
Date: Tue, 26 Jul 2022 15:44:15 +0200
Subject: [PATCH] Handle scenarios where two unique tags are added and we have
 to decide which one to keep

---
 src/TagBag.php       | 55 +++++++++++++++++++++++++++++++++++++++-----
 tests/TagBagTest.php | 15 ++++++++++++
 2 files changed, 64 insertions(+), 6 deletions(-)

diff --git a/src/TagBag.php b/src/TagBag.php
index 01ebb91..b54fc71 100644
--- a/src/TagBag.php
+++ b/src/TagBag.php
@@ -53,8 +53,8 @@ public function add(TagInterface $tag): void
         try {
             $renderedValue = $this->renderer->render($tag);
             $fingerprint = $tag->getFingerprint() ?? $this->fingerprintGenerator->generate($tag, $renderedValue);
-            $existingTag = $this->findTagByFingerprint($fingerprint);
-            if (null !== $existingTag && ($existingTag->unique || $tag->isUnique())) {
+
+            if (!$this->handleExistingTag($tag, $fingerprint)) {
                 return;
             }
 
@@ -89,6 +89,46 @@ public function renderSection(string $section): string
         return $value;
     }
 
+    /**
+     * Returns true if the tag should be added
+     */
+    private function handleExistingTag(TagInterface $tag, string $fingerprint): bool
+    {
+        $search = $this->findTagByFingerprint($fingerprint);
+
+        // if no existing tag exists we should add the tag
+        if (null === $search) {
+            return true;
+        }
+
+        [$section, $idx, $existingTag] = $search;
+
+        // if both tags are unique
+        if ($existingTag->unique && $tag->isUnique()) {
+            // ... we check the priority and if the priority of the new tag is higher than the existing tag
+            if ($existingTag->priority >= $tag->getPriority()) {
+                return false;
+            }
+
+            // ... we will remove the old tag and add the new tag
+            unset($this->tags[$section][$idx]);
+
+            return true;
+        }
+
+        // if the old tag is unique, but the new tag isn't, we will not add the new tag
+        if ($existingTag->unique) {
+            return false;
+        }
+
+        // if the old tag is not unique, but the new tag is, we will remove the old tag and add the new tag
+        if ($tag->isUnique()) {
+            unset($this->tags[$section][$idx]);
+        }
+
+        return true;
+    }
+
     /**
      * @param list<RenderedTag> $tags
      */
@@ -183,12 +223,15 @@ private function dispatch(object $event): void
         $this->eventDispatcher->dispatch($event);
     }
 
-    private function findTagByFingerprint(string $fingerprint): ?RenderedTag
+    /**
+     * @return array{0: string, 1: int, 2: RenderedTag}|null
+     */
+    private function findTagByFingerprint(string $fingerprint): ?array
     {
-        foreach ($this->tags as $section) {
-            foreach ($section as $tag) {
+        foreach ($this->tags as $section => $sectionTags) {
+            foreach ($sectionTags as $idx => $tag) {
                 if ($tag->fingerprint === $fingerprint) {
-                    return $tag;
+                    return [$section, $idx, $tag];
                 }
             }
         }
diff --git a/tests/TagBagTest.php b/tests/TagBagTest.php
index 4a83c04..ff5383c 100644
--- a/tests/TagBagTest.php
+++ b/tests/TagBagTest.php
@@ -215,6 +215,21 @@ public function it_does_not_ignore_fingerprint_when_one_of_the_tags_is_unique():
         self::assertSame('content', $tagBag->renderAll());
     }
 
+    /**
+     * @test
+     */
+    public function it_replaces_unique_tag_with_new_one_with_higher_priority(): void
+    {
+        $tag1 = $this->getTag('tag1')->unique()->withPriority(10)->withFingerprint('tag');
+        $tag2 = $this->getTag('tag2')->unique()->withPriority(20)->withFingerprint('tag');
+
+        $tagBag = $this->getTagBag();
+        $tagBag->add($tag1);
+        $tagBag->add($tag2);
+
+        self::assertSame('tag2', $tagBag->renderAll());
+    }
+
     private function getTag(
         string $content = 'content',
         string $section = null,