package app

import (
	"os"
	"sort"
	"strings"
)

func readWildcardObservedHostsContent() string {
	data, err := os.ReadFile(lastIPsMapDyn)
	if err != nil {
		return ""
	}
	seen := make(map[string]struct{})
	out := make([]string, 0, 256)
	for _, ln := range strings.Split(string(data), "\n") {
		ln = strings.TrimSpace(ln)
		if ln == "" || strings.HasPrefix(ln, "#") {
			continue
		}
		fields := strings.Fields(ln)
		if len(fields) < 2 {
			continue
		}
		host := strings.TrimSpace(fields[1])
		if host == "" || strings.HasPrefix(host, "[") {
			continue
		}
		if _, ok := seen[host]; ok {
			continue
		}
		seen[host] = struct{}{}
		out = append(out, host)
	}
	sort.Strings(out)
	if len(out) == 0 {
		return ""
	}
	return strings.Join(out, "\n") + "\n"
}