more tinkering.

internal/formattools/compactidlist.go

@@ -0,0 +1,51 @@
+package formattools
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+func CompactIDList(ids []string) []string {
+	sort.Strings(ids)
+
+	currentGroup := ""
+	currentIDs := make([]string, 0, len(ids))
+	groups := make([]string, 0, 2)
+	for _, id := range ids {
+		if id == "" {
+			continue
+		}
+
+		split := strings.SplitN(id, ":", 3)
+		if len(split) < 3 {
+			continue
+		}
+
+		group := id[:len(split[0])+len(split[1])+1]
+
+		if group != currentGroup {
+			if len(currentIDs) > 0 {
+				if len(currentIDs) == 1 {
+					groups = append(groups, fmt.Sprintf("%s:%s", currentGroup, currentIDs[0]))
+				} else {
+					groups = append(groups, fmt.Sprintf("%s:{%s}", currentGroup, strings.Join(currentIDs, ",")))
+				}
+				currentIDs = currentIDs[:0]
+			}
+			currentGroup = group
+		}
+
+		currentIDs = append(currentIDs, split[2])
+	}
+
+	if len(currentIDs) > 0 {
+		if len(currentIDs) == 1 {
+			groups = append(groups, fmt.Sprintf("%s:%s", currentGroup, currentIDs[0]))
+		} else {
+			groups = append(groups, fmt.Sprintf("%s:{%s}", currentGroup, strings.Join(currentIDs, ",")))
+		}
+	}
+
+	return groups
+}