package stats

import (
	"net/netip"
	"regexp"
	"strings"
	"time"
)

// Event is one response named logged.
type Event struct {
	Time   time.Time
	Client netip.Addr
	View   string // "" without views
	Name   string // lowercase, without the final dot ("." for the root)
	Type   string // e.g. A, AAAA, PTR
	RCode  string // e.g. NOERROR, NXDOMAIN
}

// responseRe matches named's response log lines (BIND 9.20, print-time):
//
//	07-Oct-2026 19:46:22.195 client @0x7135... 10.10.0.37#51709 (nas.adbraun.lol): view internal: response: nas.adbraun.lol IN A NOERROR 1 0 1 +E(0)K (10.10.0.2)
//
// The "view NAME: " part is missing when no views are configured.
var responseRe = regexp.MustCompile(`^(\d{2}-[A-Za-z]{3}-\d{4} \d{2}:\d{2}:\d{2}\.\d{3}) client @0x[0-9a-fA-F]+ (\S+)#\d+ \(.*?\): (?:view (.+?): )?response: (\S+) (\S+) (\S+) ([A-Z0-9]+) `)

const logTimeLayout = "02-Jan-2006 15:04:05.000"

// ParseResponse parses a response log line. ok is false for other lines
// (named also logs to the channel when it starts and rotates files).
func ParseResponse(line string, loc *time.Location) (ev Event, ok bool) {
	m := responseRe.FindStringSubmatch(line)
	if m == nil {
		return ev, false
	}
	t, err := time.ParseInLocation(logTimeLayout, m[1], loc)
	if err != nil {
		return ev, false
	}
	client, err := netip.ParseAddr(m[2])
	if err != nil {
		return ev, false
	}
	return Event{
		Time:   t,
		Client: client.Unmap(),
		View:   m[3],
		Name:   normalizeName(m[4]),
		Type:   m[6],
		RCode:  m[7],
	}, true
}

func normalizeName(n string) string {
	n = strings.ToLower(n)
	if n == "." {
		return n
	}
	return strings.TrimSuffix(n, ".")
}