Create a cached talk counter

Create a cached version of the talk counter service that returns a
cached result of the talk count for that day.

This uses the Decorator design pattern to decorate the existing
`TalkCounter` service and works as they both implement the same
`TalkCounterInterface`.

web/modules/custom/talks/opdavies_talks.module

@@ -10,6 +10,7 @@ declare(strict_types=1);
 use Drupal\Core\Entity\EntityTypeInterface;
 use Drupal\Core\Render\BubbleableMetadata;
 use Drupal\opdavies_talks\Service\TalkCounter;
+use Drupal\opdavies_talks\Service\TalkCounterInterface;
 use Drupal\opdavies_talks\Service\TalkDateUpdater;
 
 /**
@@ -57,8 +58,8 @@ function opdavies_talks_tokens(string $type, array $tokens, array $data, array $
   $replacements = [];
 
   if ($type == 'opdavies_talks') {
-    /** @var TalkCounter $talkCounter */
+    /** @var TalkCounterInterface $talkCounter */
-    $talkCounter = Drupal::service(TalkCounter::class);
+    $talkCounter = Drupal::service(TalkCounterInterface::class);
 
     foreach ($tokens as $name => $original) {
       switch ($name) {

web/modules/custom/talks/opdavies_talks.services.yml

@@ -1,10 +1,21 @@
 services:
+  Drupal\Core\Cache\CacheBackendInterface:
+    alias: cache.default
+    private: true
+
   Drupal\opdavies_talks\Repository\TalkRepository:
     autowire: true
 
+  Drupal\opdavies_talks\Service\CachedTalkCounter:
+    autowire: true
+
   Drupal\opdavies_talks\Service\TalkCounter:
     autowire: true
 
+  Drupal\opdavies_talks\Service\TalkCounterInterface:
+    autowire: true
+    class: Drupal\opdavies_talks\Service\CachedTalkCounter
+
   Drupal\opdavies_talks\Service\TalkDateUpdater:
     autowire: true
 

web/modules/custom/talks/src/Service/CachedTalkCounter.php

@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\opdavies_talks\Service;
+
+use Drupal\Core\Cache\CacheBackendInterface;
+
+final class CachedTalkCounter {
+
+  public function __construct(
+    private TalkCounter $talkCounter,
+    private CacheBackendInterface $cache,
+  ) {}
+
+  public function getCount(): int {
+    if ($cacheData = $this->cache->get(cid: 'talk_count')) {
+      return $cacheData->data;
+    }
+
+    $count = $this->talkCounter->getCount();
+
+    $this->cache->set(
+      cid: 'talk_count',
+      data: $count,
+      expire: strtotime('tomorrow'),
+    );
+
+    return $count;
+  }
+
+}

web/modules/custom/talks/src/Service/TalkCounter.php

@@ -10,11 +10,7 @@ use Drupal\paragraphs\ParagraphInterface;
 
 final class TalkCounter {
 
-  private TalkRepository $talkRepository;
+  public function __construct(private TalkRepository $talkRepository) {}
-
-  public function __construct(TalkRepository $talkRepository) {
-    $this->talkRepository = $talkRepository;
-  }
 
   public function getCount(): int {
     $today = Carbon::today()->format('Y-m-d H:i:s');

web/modules/custom/talks/src/Service/TalkCounterInterface.php

@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\opdavies_talks\Service;
+
+interface TalkCounterInterface {
+
+  public function getCount(): int;
+
+}