[CORE][I18n] Add I18n::_m_list, which formats an array of elements into a list. Limited to 5 elements, as that should be enough (tm) and ICU doesn't support this natively

src/Core/I18n/I18n.php

@@ -39,6 +39,7 @@ declare(strict_types = 1);
 namespace App\Core\I18n;
 
 use App\Util\Common;
+use App\Util\Exception\BugFoundException;
 use App\Util\Exception\ServerException;
 use App\Util\Formatting;
 use InvalidArgumentException;
@@ -302,7 +303,7 @@ abstract class I18n
  *
  *    _m(string $msg)                                      -- simple message
  *    _m(string $ctx, string $msg)                         -- message with context
- *    _m(string|string[] $msg, array $params)              -- message
+ *    _m(string|string[] $msg, array $params)              -- parameterized message
  *    _m(string $ctx, string|string[] $msg, array $params) -- combination of the previous two
  *
  * @throws ServerException
@@ -346,3 +347,42 @@ function _m(...$args): string
         // @codeCoverageIgnoreEnd
     }
 }
+
+/**
+ * Convert an array into a localized list
+ *
+ * This is needed because not add languages use the form of
+ * `item <sep> item <sep> item <last-sep> item` (probably)
+ *
+ * Note that this simply generates the ICU format, doesn't magically
+ * perform the translation if no translation is available
+ *
+ * @example en: ['foo', 'bar', 'quux'] => "foo, bar and quux"
+ * @example pt: ['foo', 'bar', 'quux'] => "foo, bar e quux"
+ * @example ch: ['foo', 'bar', 'quux'] => "foo, bar, quux"
+ */
+function _m_list(array $elements): string
+{
+    if (\count($elements) > 5) {
+        // Could be generated dinamically for english, but we can't handle all languages
+        throw new BugFoundException('Currently only lists of 5 elements supported, as ICU does not support this natively');
+    }
+
+    $icu = I18n::formatICU(
+        [
+            0 => '',
+            1 => '%1$s',
+            2 => '%1$s and %2$s',
+            3 => '%1$s, %2$s and %3$s',
+            4 => '%1$s, %2$s, %3$s and %4$s',
+            5 => '%1$s, %2$s, %3$s, %4$s and %5$s',
+            6 => 'NULL',
+        ],
+        // this uses a string count so the generated is a select, as it's not really a pluralization thing
+        ['count' => (string) \count($elements)],
+    );
+
+    $format = I18n::$translator->trans($icu, ['count' => \count($elements)], I18n::_mdomain(''), Common::currentLanguage()->getLocale());
+
+    return sprintf($format, ...$elements);
+}