From b7fb46ea3857059a673470ea19849d0c3f83ebad Mon Sep 17 00:00:00 2001
From: Vladimir Bryzgalov <vladimir.bryzgalov@gmail.com>
Date: Sat, 16 May 2026 22:33:39 +0500
Subject: [PATCH] feat(wpmc S5): LinkFilter scaffold + register 3 URL filters

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 includes/class-link-filter.php |  38 ++++++++
 tests/LinkFilterTest.php       | 162 +++++++++++++++++++++++++++++++++
 2 files changed, 200 insertions(+)
 create mode 100644 includes/class-link-filter.php
 create mode 100644 tests/LinkFilterTest.php

diff --git a/includes/class-link-filter.php b/includes/class-link-filter.php
new file mode 100644
index 0000000..d6a6872
--- /dev/null
+++ b/includes/class-link-filter.php
@@ -0,0 +1,38 @@
+<?php
+declare(strict_types=1);
+
+namespace WPMultiCity;
+
+final class LinkFilter
+{
+    public static function register(): void
+    {
+        \add_filter('home_url',       [self::class, 'filter_home_url'],       9999, 4);
+        \add_filter('post_link',      [self::class, 'filter_post_link'],      10,   3);
+        \add_filter('acf/load_value', [self::class, 'filter_acf_load_value'], 9999, 3);
+    }
+
+    public static function filter_home_url(string $url, string $path = '', $orig_scheme = null, $blog_id = null): string
+    {
+        return self::add_town_prefix($url);
+    }
+
+    public static function filter_post_link(string $permalink, $post = null, bool $leavename = false): string
+    {
+        return self::add_town_prefix($permalink);
+    }
+
+    public static function filter_acf_load_value($value, $post_id = null, $field = null)
+    {
+        if (!is_string($value)) {
+            return $value;
+        }
+        return self::add_town_prefix($value);
+    }
+
+    public static function add_town_prefix(string $url): string
+    {
+        // Implementation in Task 4.
+        return $url;
+    }
+}
diff --git a/tests/LinkFilterTest.php b/tests/LinkFilterTest.php
new file mode 100644
index 0000000..e330954
--- /dev/null
+++ b/tests/LinkFilterTest.php
@@ -0,0 +1,162 @@
+<?php
+declare(strict_types=1);
+
+namespace WPMultiCity\Tests;
+
+use WPMultiCity\LinkFilter;
+
+final class LinkFilterTest extends TestCase
+{
+    public function test_register_attaches_home_url_filter_at_9999(): void
+    {
+        LinkFilter::register();
+
+        self::assertSame(
+            9999,
+            has_filter('home_url', [LinkFilter::class, 'filter_home_url']),
+            'LinkFilter::register() must hook home_url at priority 9999'
+        );
+    }
+
+    public function test_register_attaches_post_link_filter_at_10(): void
+    {
+        LinkFilter::register();
+
+        self::assertSame(
+            10,
+            has_filter('post_link', [LinkFilter::class, 'filter_post_link']),
+            'LinkFilter::register() must hook post_link at priority 10'
+        );
+    }
+
+    public function test_register_attaches_acf_load_value_filter_at_9999(): void
+    {
+        LinkFilter::register();
+
+        self::assertSame(
+            9999,
+            has_filter('acf/load_value', [LinkFilter::class, 'filter_acf_load_value']),
+            'LinkFilter::register() must hook acf/load_value at priority 9999'
+        );
+    }
+
+    private function set_routing_context(string $town_slug = 'tyumen', string $main = 'spb', string $host = 'site.com'): void
+    {
+        $_SERVER['REQUEST_URI'] = '/' . $town_slug . '/';
+        $_SERVER['HTTP_HOST'] = $host;
+        \Brain\Monkey\Functions\when('get_terms')->justReturn([11 => $town_slug]);
+        \Brain\Monkey\Functions\when('get_field')->alias(function ($name) use ($main) {
+            if ($name === 'main_town_slug') return $main;
+            return false;  // page_no_rep empty, page_unic empty
+        });
+    }
+
+    public function test_add_town_prefix_no_change_when_current_town_equals_main(): void
+    {
+        $this->set_routing_context('spb', 'spb');
+
+        self::assertSame('/about/', LinkFilter::add_town_prefix('/about/'));
+    }
+
+    public function test_add_town_prefix_no_change_when_current_town_is_null(): void
+    {
+        $_SERVER['REQUEST_URI'] = '/random/';
+        $_SERVER['HTTP_HOST'] = 'site.com';
+        \Brain\Monkey\Functions\when('get_terms')->justReturn([10 => 'spb']);
+        \Brain\Monkey\Functions\when('get_field')->justReturn(false);
+
+        self::assertSame('/about/', LinkFilter::add_town_prefix('/about/'));
+    }
+
+    public function test_add_town_prefix_prepends_town_to_path_only_url(): void
+    {
+        $this->set_routing_context();
+
+        self::assertSame('/tyumen/about/', LinkFilter::add_town_prefix('/about/'));
+    }
+
+    public function test_add_town_prefix_skips_path_already_prefixed(): void
+    {
+        $this->set_routing_context();
+
+        self::assertSame('/tyumen/about/', LinkFilter::add_town_prefix('/tyumen/about/'));
+        self::assertSame('/tyumen', LinkFilter::add_town_prefix('/tyumen'));
+    }
+
+    public function test_add_town_prefix_full_url_same_host(): void
+    {
+        $this->set_routing_context();
+
+        self::assertSame(
+            'https://site.com/tyumen/about/',
+            LinkFilter::add_town_prefix('https://site.com/about/')
+        );
+        self::assertSame(
+            'https://site.com/tyumen/',
+            LinkFilter::add_town_prefix('https://site.com/')
+        );
+    }
+
+    public function test_add_town_prefix_full_url_already_prefixed_no_double_prefix(): void
+    {
+        $this->set_routing_context();
+
+        self::assertSame(
+            'https://site.com/tyumen/about/',
+            LinkFilter::add_town_prefix('https://site.com/tyumen/about/')
+        );
+    }
+
+    public function test_add_town_prefix_external_host_no_change(): void
+    {
+        $this->set_routing_context();
+
+        self::assertSame(
+            'https://external.com/foo/',
+            LinkFilter::add_town_prefix('https://external.com/foo/')
+        );
+    }
+
+    public function test_add_town_prefix_non_http_scheme_no_change(): void
+    {
+        $this->set_routing_context();
+
+        self::assertSame('mailto:x@y.com', LinkFilter::add_town_prefix('mailto:x@y.com'));
+        self::assertSame('tel:+79991234567', LinkFilter::add_town_prefix('tel:+79991234567'));
+    }
+
+    public function test_add_town_prefix_respects_page_no_rep_exclusions(): void
+    {
+        $_SERVER['REQUEST_URI'] = '/tyumen/';
+        $_SERVER['HTTP_HOST'] = 'site.com';
+        \Brain\Monkey\Functions\when('get_terms')->justReturn([11 => 'tyumen']);
+        \Brain\Monkey\Functions\when('get_field')->alias(function ($name) {
+            if ($name === 'main_town_slug') return 'spb';
+            if ($name === 'page_no_rep') return [['link' => '/privacy/']];
+            return false;
+        });
+
+        self::assertSame('/privacy/', LinkFilter::add_town_prefix('/privacy/'));
+    }
+
+    public function test_add_town_prefix_returns_unchanged_when_bypassed(): void
+    {
+        $this->set_routing_context();
+
+        $result = \WPMultiCity\Helpers::without_url_filters(function () {
+            return LinkFilter::add_town_prefix('/about/');
+        });
+
+        self::assertSame('/about/', $result);
+    }
+
+    public function test_filter_acf_load_value_returns_array_unchanged(): void
+    {
+        $this->set_routing_context();
+
+        self::assertSame(
+            ['a', 'b'],
+            LinkFilter::filter_acf_load_value(['a', 'b'])
+        );
+    }
+}