From 762385ded80d8c59a62ce96b4348762baea0ab4c Mon Sep 17 00:00:00 2001
From: Guy Sartorelli <guy.sartorelli@silverstripe.com>
Date: Tue, 13 Aug 2024 15:50:52 +1200
Subject: [PATCH] FIX Correct trailing slash for locale in another domain

---
 src/Extension/FluentSiteTreeExtension.php     |  5 ++++-
 .../Extension/FluentSiteTreeExtensionTest.php | 19 ++++++++++++++++---
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/Extension/FluentSiteTreeExtension.php b/src/Extension/FluentSiteTreeExtension.php
index 0eedf5dc..3f09f2f0 100644
--- a/src/Extension/FluentSiteTreeExtension.php
+++ b/src/Extension/FluentSiteTreeExtension.php
@@ -153,7 +153,10 @@ public function updateLink(&$link, &$action, &$relativeLink)
             return;
         }
 
-        // Prefix with domain
+        // Prefix with domain, making sure trailing slash is normalised correctly.
+        if ($link === '/' || $link === '') {
+            $link = Controller::config()->get('add_trailing_slash') ? '/' : '';
+        }
         $link = Controller::join_links($domain->Link(), $link);
     }
 
diff --git a/tests/php/Extension/FluentSiteTreeExtensionTest.php b/tests/php/Extension/FluentSiteTreeExtensionTest.php
index aa0e1d97..b166f31f 100644
--- a/tests/php/Extension/FluentSiteTreeExtensionTest.php
+++ b/tests/php/Extension/FluentSiteTreeExtensionTest.php
@@ -75,8 +75,8 @@ public function testGetLocaleInformation()
             $this->assertEquals('English (New Zealand)', $result->getTitle());
             $this->assertEquals('English', $result->getLanguageNative());
             $this->assertEquals('en', $result->getLanguage());
-            $this->assertEquals(Controller::normaliseTrailingSlash('/newzealand/a-page/'), $result->getLink());
-            $this->assertEquals(Controller::normaliseTrailingSlash('http://mocked/newzealand/a-page/'), $result->getAbsoluteLink());
+            $this->assertEquals($this->normaliseTrailingSlash('/newzealand/a-page/'), $result->getLink());
+            $this->assertEquals($this->normaliseTrailingSlash('http://mocked/newzealand/a-page/'), $result->getAbsoluteLink());
             $this->assertEquals('link', $result->getLinkingMode());
             $this->assertEquals('newzealand', $result->getURLSegment());
         });
@@ -180,7 +180,7 @@ function (FluentState $newState) use ($domain, $locale, $prefixDisabled, $pageNa
 
                 /** @var Page|FluentSiteTreeExtension $page */
                 $page = $this->objFromFixture(Page::class, $pageName);
-                $this->assertEquals(Controller::normaliseTrailingSlash($url), $page->Link());
+                $this->assertEquals($this->normaliseTrailingSlash($url), $page->Link());
             }
         );
     }
@@ -562,4 +562,17 @@ public function localeFallbackProvider(): array
             ],
         ];
     }
+
+    /**
+     * Normalises a test URL's trailing slash, but ignores complexities
+     * such as whether the domain host in the UR matches Director::host()
+     */
+    private function normaliseTrailingSlash(string $testURL): string
+    {
+        if ($testURL === '/' || $testURL === '') {
+            return '/';
+        }
+        $slash = Controller::config()->get('add_trailing_slash') ? '/' : '';
+        return (rtrim($testURL, '/')) . $slash;
+    }
 }