Fix issue processwire/processwire-issues#1082 as well as improve error handling when one places a fieldset closer before its opener

wire/modules/Fieldtype/FieldtypeFieldsetOpen.module

@@ -113,6 +113,60 @@ class FieldtypeFieldsetOpen extends Fieldtype {
 		return $field->type instanceof FieldtypeFieldsetOpen && !($field->type instanceof FieldtypeFieldsetClose);
 	}
 
+	/**
+	 * Check that Fieldgroup has matching open/close fieldsets and in correct order
+	 * 
+	 * @param Fieldgroup $fieldgroup
+	 * @return bool
+	 * @since 3.0.164
+	 * 
+	 */
+	public function checkFieldgroupFieldsets(Fieldgroup $fieldgroup) {
+		
+		list($openers, $closers, $isChanged) = array(array(), array(), false);
+
+		foreach($fieldgroup as $field) {
+			/** @var Fieldtype $fieldtype */
+			if(!$field->type instanceof FieldtypeFieldsetOpen) continue;
+			if($field->type instanceof FieldtypeFieldsetClose) {
+				if(!strpos($field->name, self::fieldsetCloseIdentifier)) continue;
+				$name = substr($field->name, 0, -1 * strlen(self::fieldsetCloseIdentifier));
+				$closers[$name] = $field;
+			} else if(!isset($closers[$field->name])) {
+				// ensure opener comes before closer, otherwise only closer remains
+				$openers[$field->name] = $field;
+			}
+		}
+
+		if(count($openers) === count($closers)) return true;
+
+		foreach($openers as $name => $opener) {
+			/** @var Field $opener */
+			if(isset($closers[$name])) continue;
+			$closer = $this->getFieldsetCloseField($opener);
+			if($closer) {
+				$fieldgroup->insertAfter($closer, $opener);
+			} else {
+				$fieldgroup->remove($opener);
+			}
+			$isChanged = true;
+		}
+		
+		foreach($closers as $name => $closer) {
+			/** @var Field $closer */
+			if(isset($openers[$name])) continue;
+			$opener = $this->getFieldsetOpenField($closer); 
+			if($opener) {
+				$fieldgroup->insertBefore($opener, $closer); 
+			} else {
+				$fieldgroup->remove($closer);
+			}
+			$isChanged = true;
+		}
+		
+		return $isChanged;
+	}
+
 	/**
 	 * Get the Field that closes/terminates the given Fieldset field
 	 * 
@@ -123,7 +177,7 @@ class FieldtypeFieldsetOpen extends Fieldtype {
 	 */
 	public function getFieldsetCloseField(Field $field, $createIfNotExists = false) {
 		
-		if(!$this->isFieldset($field)) return;
+		if(!$this->isFieldset($field)) return null;
 	
 		$name = $field->name . self::fieldsetCloseIdentifier;
 		$closer = $this->wire('fields')->get($name); 
@@ -155,6 +209,35 @@ class FieldtypeFieldsetOpen extends Fieldtype {
 		return $closer; 
 	}
 	
+	/**
+	 * Get the Field that opens the given FieldsetClose field
+	 *
+	 * @param Field $field
+	 * @return null|Field of type FieldtypeFieldsetOpen, if found
+	 * @since 3.0.164
+	 *
+	 */
+	public function getFieldsetOpenField(Field $field) {
+
+		if(!$field->type instanceof FieldtypeFieldsetClose) return null;
+		if(!strpos($field->name, self::fieldsetCloseIdentifier)) return null;
+
+		$name = substr($field->name, 0, -1 * strlen(self::fieldsetCloseIdentifier));
+		$opener = $this->wire()->fields->get($name);
+
+		if($opener) return $opener;
+
+		foreach($this->wire()->fields as $f) {
+			if(!$f->type instanceof FieldtypeFieldsetOpen) continue;
+			$closeFieldID = (int) $f->get('closeFieldID');
+			if($closeFieldID != $field->id) continue;
+			$opener = $f;
+			break;
+		}
+
+		return $opener;
+	}
+
 	/**
 	 * Hook executed when field is added via ProcessField
 	 * 

wire/modules/Process/ProcessTemplate/ProcessTemplate.module

@@ -2756,9 +2756,14 @@ class ProcessTemplate extends Process {
 				}
 			}
 		
+			if(count($badFieldsets)) {
 				foreach($badFieldsets as $field) {
 					$this->error(sprintf($this->_('Error with placement of fieldset/tab "%s" - please fix and save again'), $field->name));
 				}
+				/** @var FieldtypeFieldsetOpen $fieldset */
+				$fieldset = $this->wire()->fieldtypes->get('FieldtypeFieldsetOpen');
+				if($fieldset->checkFieldgroupFieldsets($this->template->fieldgroup)) $saveFieldgroup = true;
+			}
 		}
 
 		// check if any other fieldgroup should be imported
@@ -2921,6 +2926,7 @@ class ProcessTemplate extends Process {
 		$removeIds = $this->wire('input')->get('fields'); 
 		if(empty($removeIds)) $this->session->redirect('./');
 		$removeIds = explode(',', $removeIds); 
+		$removeFields = array();
 
 		$fieldgroup = $this->template->fieldgroup; 
 		$this->wire('processHeadline', sprintf($this->_('Remove Fields from Template: %s'), $this->template->name)); 
@@ -2942,6 +2948,17 @@ class ProcessTemplate extends Process {
 		
 		foreach($fieldgroup as $field) {
 			if(!in_array($field->id, $removeIds)) continue;
+			$removeFields[$field->id] = $field;
+			if($field->type instanceof FieldtypeFieldsetClose) {
+				$opener = $field->type->getFieldsetOpenField($field);
+				if($opener && $fieldgroup->hasField($opener) && !in_array($opener->id, $removeIds)) {
+					unset($removeFields[$field->id]); 
+					$removeFields[$opener->id] = $opener;
+				}
+			}
+		}
+
+		foreach($removeFields as $field) {
 			$checkboxes->addOption($field->id, sprintf($this->_('Remove field "%1$s" from template "%2$s"'), $field->name, $this->template->name)); 
 		}