package cdns

import (
	"errors"
	"fmt"
	"log"
	"strings"

	"github.com/miekg/dns"
)

func localQuery(mychan chan DNSreply, qname string, qtype uint16) {
	if debug {
		fmt.Printf("DEBUG: start of DNS request \"%s\" / %d\n", qname, qtype)
	}
	var result DNSreply
	var trials uint
	result.qname = qname
	result.qtype = qtype
	result.r = nil
	result.err = errors.New("no name server to answer the question")
	localm := new(dns.Msg)
	localm.Id = dns.Id()
	localm.RecursionDesired = true
	localm.Question = make([]dns.Question, 1)
	localm.SetEdns0(bufsize, false) // Even if no EDNS requested, see #9 May be we should retry without it if timeout?
	localc := new(dns.Client)
	localc.ReadTimeout = timeout
	localm.Question[0] = dns.Question{Name: qname, Qtype: qtype, Qclass: dns.ClassINET}
Tests:
	for trials = 0; trials < uint(maxTrials); trials++ {
		for serverIndex := range conf.Servers {
			server := conf.Servers[serverIndex]
			result.nameserver = server
			// Brackets around the server address are necessary for IPv6 name servers
			// Brackets required for IPv6; do not use net.JoinHostPort (see check-soa commit 3e4edb1)
			r, rtt, err := localc.Exchange(localm, "["+server+"]:"+conf.Port)
			if r == nil {
				result.r = nil
				result.err = err
				log.Println(err.Error())
				if strings.Contains(err.Error(), "timeout") {
					// Try another resolver
					continue
				}
				// We give in
				break Tests
			}
			result.rtt = rtt
			if r.Rcode == dns.RcodeSuccess {
				// TODO: NODATA (NOERROR/ANSWER=0) are silently ignored (e.g. name exists but no IP address)
				// TODO: for rcodes like SERVFAIL, trying another resolver could make sense
				result.r = r
				result.err = nil
				break Tests
			}
			// All the other codes are errors
			result.r = r
			result.err = errors.New(dns.RcodeToString[r.Rcode])
			break Tests
		}
	}
	if debug {
		fmt.Printf("DEBUG: end of DNS request \"%s\" / %d\n", qname, qtype)
	}
	mychan <- result
}