package birdfmt

import (
	"net/netip"
	"sort"
	"strings"
)

// RenderStaticIPv4Protocol renders a BIRD 2 `protocol static` block for IPv4 prefixes.
// Prefixes are sorted for stable output (golden tests, reproducible rev).
func RenderStaticIPv4Protocol(protocolName string, prefixes []netip.Prefix) string {
	if protocolName == "" {
		protocolName = "evobgp_static_v4"
	}
	uniq := make(map[string]netip.Prefix)
	for _, p := range prefixes {
		if !p.Addr().Is4() {
			continue
		}
		uniq[p.String()] = p.Masked()
	}
	keys := make([]string, 0, len(uniq))
	for k := range uniq {
		keys = append(keys, k)
	}
	sort.Strings(keys)

	var b strings.Builder
	b.WriteString("protocol static ")
	b.WriteString(protocolName)
	b.WriteString(" {\n    ipv4;\n")
	for _, k := range keys {
		b.WriteString("    route ")
		b.WriteString(k)
		b.WriteString(" unreachable;\n")
	}
	b.WriteString("}\n")
	return b.String()
}