✨ Add support for registering multiple field groups in a single Field…

… Composer (Fixes #182)

src/Field.php

@@ -2,8 +2,71 @@
 
 namespace Log1x\AcfComposer;
 
+use Exception;
+use StoutLogic\AcfBuilder\FieldsBuilder;
+
 abstract class Field extends Composer
 {
+    /**
+     * Register the field groups with Advanced Custom Fields.
+     */
+    protected function register(?callable $callback = null): void
+    {
+        if (empty($this->fields)) {
+            return;
+        }
+
+        if ($callback) {
+            $callback();
+        }
+
+        foreach ($this->fields as $fields) {
+            acf_add_local_field_group(
+                $this->build($fields)
+            );
+        }
+    }
+
+    /**
+     * Retrieve the field group fields.
+     */
+    public function getFields(bool $cache = true): array
+    {
+        if ($this->fields && $cache) {
+            return $this->fields;
+        }
+
+        if ($cache && $this->composer->hasCache($this)) {
+            return $this->composer->getCache($this);
+        }
+
+        $fields = $this->fields();
+
+        $fields = is_a($fields, FieldsBuilder::class)
+            ? [$fields]
+            : $fields;
+
+        if (! is_array($fields)) {
+            throw new Exception('Fields must be an array or an instance of Builder.');
+        }
+
+        $fields = ! empty($fields['fields']) ? [$fields] : $fields;
+
+        foreach ($fields as $key => $field) {
+            $fields[$key] = is_a($field, FieldsBuilder::class)
+                ? $field->build()
+                : $field;
+        }
+
+        if ($this->defaults->has('field_group')) {
+            foreach ($fields as $key => $field) {
+                $fields[$key] = array_merge($this->defaults->get('field_group'), $field);
+            }
+        }
+
+        return $fields;
+    }
+
     /**
      * Compose and register the defined field groups with ACF.
      *