feat: admin editable email templates

addresses #869eg7ptr

src/Config/EmailTextCatalog.php

@@ -0,0 +1,75 @@
+<?php
+
+namespace App\Config;
+
+use Symfony\Component\Yaml\Yaml;
+
+/**
+ * Reads the delivered wording of the admin-editable mails from config/email_texts.yaml.
+ *
+ * That wording is the fallback used whenever no email_text row exists for a key, so the
+ * mails keep working on a fresh database and "reset to default" needs nothing but deleting
+ * the row.
+ *
+ * The file is parsed lazily and memoised: a request that sends no mail and opens no admin
+ * screen never touches it, and one that does reads it once. Nothing here is validated at
+ * compile time, so a missing entry surfaces as an error the first time the catalogue is
+ * built - EmailTextCatalogTest builds all of them.
+ */
+class EmailTextCatalog
+{
+    /**
+     * @var array<string, EmailTextDefinition>|null
+     */
+    private ?array $definitions = null;
+
+    public function __construct(
+        private readonly string $emailTextsFile,
+    ) {
+    }
+
+    /**
+     * @return array<string, EmailTextDefinition> keyed by EmailTextKey value
+     */
+    public function all(): array
+    {
+        return $this->definitions ??= $this->build();
+    }
+
+    public function get(EmailTextKey $key): EmailTextDefinition
+    {
+        return $this->all()[$key->value];
+    }
+
+    /**
+     * @return array<string, EmailTextDefinition>
+     */
+    private function build(): array
+    {
+        $config = Yaml::parseFile($this->emailTextsFile);
+        $descriptions = $config['placeholders'];
+
+        $definitions = [];
+
+        foreach (EmailTextKey::cases() as $key) {
+            $text = $config['texts'][$key->value];
+
+            $placeholders = [];
+
+            foreach ($text['placeholders'] as $name) {
+                $placeholders[$name] = $descriptions[$name];
+            }
+
+            $definitions[$key->value] = new EmailTextDefinition(
+                $key,
+                $text['label'],
+                $placeholders,
+                $text['subject'],
+                $text['headline'],
+                $text['body'],
+            );
+        }
+
+        return $definitions;
+    }
+}