package main

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

// generateBindConf produces a BIND domains.conf from all zone entries.
// Zones are sorted alphabetically. Each zone block uses 8-space indentation.
// DNSSEC zones get dnssec-policy and inline-signing directives on the file line.
// Zones in catalogs with also-notify configured get an also-notify directive.
func generateBindConf(entries []ZoneEntry, cfg *Config) string {
	sorted := make([]ZoneEntry, len(entries))
	copy(sorted, entries)
	sort.Slice(sorted, func(i, j int) bool {
		return sorted[i].Zone < sorted[j].Zone
	})

	var b strings.Builder
	b.WriteString("# THIS FILE IS GENERATED BY catz (go install go.askask.com/catz@latest)\n")
	b.WriteString("#=============================================\n")
	b.WriteString("#\n")

	for _, entry := range sorted {
		if entry.ZoneFile == "" {
			continue // catalog-only zone, no BIND config needed
		}

		// Strip trailing dot for BIND zone name
		zoneName := strings.TrimSuffix(entry.Zone, ".")

		fmt.Fprintf(&b, "zone \"%s\" {\n", zoneName)
		b.WriteString("        type master;\n")

		fileLine := fmt.Sprintf("        file  \"%s\";", entry.ZoneFile)
		if entry.DNSSEC {
			fileLine += " dnssec-policy standard; inline-signing yes;"
		}
		b.WriteString(fileLine + "\n")

		// Collect also-notify IPs from all catalogs this zone belongs to
		ips := alsoNotifyIPs(entry.Catalogs, cfg)
		if len(ips) > 0 {
			b.WriteString("        also-notify {")
			for _, ip := range ips {
				fmt.Fprintf(&b, " %s;", ip)
			}
			b.WriteString(" };\n")
		}

		b.WriteString("};\n")
	}

	return b.String()
}

// alsoNotifyIPs returns the deduplicated, sorted list of also-notify IPs
// for a zone based on its catalog memberships.
func alsoNotifyIPs(catalogs []string, cfg *Config) []string {
	if len(cfg.BindConf.AlsoNotify) == 0 {
		return nil
	}

	seen := make(map[string]bool)
	var ips []string
	for _, catName := range catalogs {
		for _, ip := range cfg.BindConf.AlsoNotify[catName] {
			if !seen[ip] {
				seen[ip] = true
				ips = append(ips, ip)
			}
		}
	}
	sort.Strings(ips)
	return ips
}

// writeBindConf writes the BIND config to path.
// Zones without a ZoneFile are skipped (catalog-only zones).
func writeBindConf(path string, entries []ZoneEntry, cfg *Config) error {
	content := generateBindConf(entries, cfg)
	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
		return fmt.Errorf("writing bind config %s: %w", path, err)
	}
	return nil
}