package main

import (
	"fmt"
	"net"
	"net/http"
	"strings"
)

// check if net.ParseIP returns nil!!
func getIP(r *http.Request) net.IP {
	addr := r.URL.Query().Get("myip")
	if len(addr) > 0 {
		return net.ParseIP(addr)
	}

	addr = r.Header.Get(http.CanonicalHeaderKey("X-Forwarded-For"))
	if len(addr) > 0 {
		end := strings.Index(addr, ", ")
		if end == -1 {
			end = len(addr)
		}
		return net.ParseIP(addr[:end])
	}

	addr = r.Header.Get(http.CanonicalHeaderKey("X-Real-IP"))
	if len(addr) > 0 {
		return net.ParseIP(addr)
	}

	addr, _, err := net.SplitHostPort(r.RemoteAddr)
	if err != nil {
		panic(err)
	}
	return net.ParseIP(addr)
}

func handleRequest(w http.ResponseWriter, r *http.Request, data userData) {
	msg := "good"
	defer func() {
		w.Write([]byte(msg))
	}()

	hostname := r.URL.Query().Get("hostname")
	if len(hostname) <= 0 || hostname != data.hostname {
		msg = "nohost"
		return
	}

	ipaddr := getIP(r)
	if ipaddr == nil {
		//TODO:
		msg = "error"
		return
	}
	msg = "Hostname: " + hostname + " , IP: " + ipaddr.String()

	updated, err := updateNameserver(data, ipaddr)
	if err != nil {
		msg = "dnserr"
		fmt.Println(err)
		return
	}
	if !updated {
		msg = "nochg"
		return
	}
}