Server/internal/formattools/compactidlist.go

package formattools

import (
	"fmt"
	"sort"
	"strings"
)

func CompactMatch(ids []string) string {
	if len(ids) == 1 {
		return ids[0]
	}

	shortestPrefix := ids[0]
	for _, curr := range ids[1:] {
		minLength := len(shortestPrefix)
		if len(curr) < minLength {
			minLength = len(curr)
		}

		if len(shortestPrefix) > minLength {
			shortestPrefix = shortestPrefix[:minLength]
		}

		for i := 0; i < minLength; i++ {
			if curr[i] != shortestPrefix[i] {
				shortestPrefix = curr[:i]
				break
			}
		}
	}

	sb := strings.Builder{}
	sb.WriteString(shortestPrefix)
	sb.WriteByte('{')
	for i, curr := range ids {
		if i != 0 {
			sb.WriteByte(',')
		}

		sb.WriteString(curr[len(shortestPrefix):])
	}
	sb.WriteByte('}')

	return sb.String()
}

func CompactIDList(ids []string) []string {
	ids = append(ids[:0:0], ids...)
	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
}