Introduce configurable sorting

main.go

@@ -49,7 +49,8 @@ func showQueue() {
 		fmt.Printf("Could not fetch queue entries: %s\n", err.Error())
 		os.Exit(1)
 	}
-	queue.Sort()
+	sortConfig := parser.NewSortConfig().By("Status", "ASC").By("Sender", "ASC").By("Recipients", "DESC")
+	queue.Sort(sortConfig)
 	if settings["usePager"] == "true" {
 		pagerReader, pagerWriter := io.Pipe()
 		pagerDone := make(chan bool)

parser/parser.go

@@ -54,14 +54,32 @@ func (m QEntry) DetailedString() string {
 	return fmt.Sprintf("Id: %s\nDate: %s\nStatus: %s\nReason: %s\nSize: %d\nSender: %s\nRecipients: %s", m.Id, m.Date.Format(SortableDateFormat), m.Status, reasonStr, m.Size, m.Sender, strings.Join(m.Recipients, ", "))
 }
 
-func (queue MailQ) Sort() {
-	var sortByAttributes []string = []string{"Status", "Recipients", "Sender", "Date"}
-	if len(sortByAttributes) == 0 {
+type qEntrySortConfig struct {
+	attributes []qEntryAttributeSortConfig
+}
+
+type qEntryAttributeSortConfig struct {
+	attribute string
+	order     string
+}
+
+func NewSortConfig() qEntrySortConfig {
+	return qEntrySortConfig{}
+}
+
+func (c qEntrySortConfig) By(field string, order string) qEntrySortConfig {
+	newAttributeConfig := qEntryAttributeSortConfig{attribute: field, order: order}
+	c.attributes = append(c.attributes, newAttributeConfig)
+	return c
+}
+
+func (queue MailQ) Sort(config qEntrySortConfig) {
+	if len(config.attributes) == 0 {
 		return
 	}
 	sort.Slice(queue.Entries, func(a int, b int) bool {
-		for _, sortBy := range sortByAttributes {
-			switch sortBy {
+		for _, sortBy := range config.attributes {
+			switch sortBy.attribute {
 			case "Id":
 				if queue.Entries[a].Id != queue.Entries[b].Id {
 					return queue.Entries[a].Id < queue.Entries[b].Id