implement forced-login for the case of experience 'force'

fulcrm_shoppingcart.module

@@ -342,8 +342,39 @@ function fulcrm_shoppingcart_buy_eventbookingtype_form_submit( $form, &$form_sta
     $form_state[ 'fulcrm_shoppingcart' ][ 'shoppingcart' ] = $cart;
 }
 
+function fulcrm_shoppingcart_buy_eventbookingtype_login_form_submit( $form, &$form_state ) {
+    user_login_submit( $form, $form_state );
+    $form_state[ 'redirect' ] = fulcrm_shoppingcart_buy_url( $form_state[ 'fulcrm_shoppingcart_redirect_buy_product_id' ] );
+}
+
 function fulcrm_shoppingcart_buy_eventbookingtype_form( $form, &$form_state, $person, $eventbookingtype, $product ) {
     $form = array();
+
+    $person_id = NULL;
+    if ( array_key_exists( 'id', $person ) )
+        $person_id = $person[ 'id' ];
+
+    if ( is_null( $person_id ) ) {
+        switch ( variable_get( 'fulcrm_shoppingcart_experience', 'force' ) ) {
+        case 'guest':
+            break;
+        case 'user':
+            break;
+        case 'force':
+            if ( user_is_anonymous() ) {
+                drupal_set_message( t('You need to be logged in to continue shopping.'), 'error' );
+                $form = user_login( $form, $form_state );
+                $form_state[ 'fulcrm_shoppingcart_redirect_buy_product_id' ] = $product[ 'id' ];
+                $form['#submit'][] = 'fulcrm_shoppingcart_buy_eventbookingtype_login_form_submit';
+                return $form;
+            } else {
+                drupal_set_message( t('Sorry! There was a problem looking up your record, and this means we cannot complete this order.'), 'error' );
+                return $form;
+            }
+            break;
+        }
+    }
+
     $event_id = $eventbookingtype[ 'event' ][ 'id' ];
 
     $capacity = null;