package resolver

import (
	"strconv"
	"syscall"
	"testing"

	"github.com/miekg/dns"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// TestClassifyResponse sets a nameserver's status from the results of
// its queries and the record types whose query failed, built here. One
// that answered some record types, even with no records, has not failed
// when its query for another type got no usable reply, whatever the
// reason, and is ok, not nodata: that type may have records. One whose
// every query got none has failed. Only one whose every type answered
// with no records is nodata.
func TestClassifyResponse(t *testing.T) {
	t.Parallel()

	tests := []struct {
		name        string
		results     queryState
		failedTypes []string
		wantStatus  string
		wantError   string
	}{
		{
			"every type answered with no records",
			queryState{answered: true},
			nil,
			StatusNoData, "",
		},
		{
			"some types answered with no records, another timed out",
			queryState{answered: true, gotTimeout: true},
			[]string{"A"},
			StatusOK, "",
		},
		{
			"some types answered with no records, another got SERVFAIL",
			queryState{
				answered: true, gotErrorReply: true, errorReply: "SERVFAIL",
			},
			[]string{"A"},
			StatusOK, "",
		},
		{
			"some types answered with no records, another was refused",
			queryState{answered: true, gotRefused: true},
			[]string{"A"},
			StatusOK, "",
		},
		{
			"some types answered with no records, another got a network error",
			queryState{answered: true, netErr: syscall.ECONNREFUSED},
			[]string{"A"},
			StatusOK, "",
		},
		{
			"some types answered with no records, another's reply was " +
				"truncated and its retry over TCP failed",
			queryState{answered: true, netErr: ErrTruncated},
			[]string{"TXT"},
			StatusOK, "",
		},
		{
			"some types answered with no records, another got a referral",
			queryState{answered: true, gotReferral: true},
			[]string{"A"},
			StatusOK, "",
		},
		{
			"every query timed out",
			queryState{gotTimeout: true},
			[]string{"A", "AAAA", "CNAME"},
			StatusTimeout, "all queries timed out",
		},
		{
			"every query got NOTIMP",
			queryState{gotErrorReply: true, errorReply: "NOTIMP"},
			[]string{"A", "AAAA", "CNAME"},
			StatusError, "server returned NOTIMP",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()

			resp := &NameserverResponse{
				Status:      StatusOK,
				FailedTypes: tt.failedTypes,
			}
			classifyResponse(resp, tt.results)

			assert.Equal(t, tt.wantStatus, resp.Status)
			assert.Equal(t, tt.wantError, resp.Error)
			assert.Equal(t, tt.failedTypes, resp.FailedTypes)
		})
	}
}

// TestReadReply checks which replies to a query about one record type,
// built here, are an answer: one with the code NOERROR or NXDOMAIN. A
// reply with any other code is not, and the type's query has failed; a
// nameserver whose only reply it is has failed, and Error gives the
// code, or its number when the code has no name.
func TestReadReply(t *testing.T) {
	t.Parallel()

	tests := []struct {
		rcode      int
		wantStatus string
		wantError  string
	}{
		{dns.RcodeSuccess, StatusNoData, ""},
		{dns.RcodeNameError, StatusNXDomain, ""},
		{dns.RcodeServerFailure, StatusError, "server returned SERVFAIL"},
		{dns.RcodeNotImplemented, StatusError, "server returned NOTIMP"},
		{dns.RcodeFormatError, StatusError, "server returned FORMERR"},
		{12, StatusError, "server returned 12"}, // unassigned, no name
	}

	for _, tt := range tests {
		t.Run(strconv.Itoa(tt.rcode), func(t *testing.T) {
			t.Parallel()

			msg := new(dns.Msg)
			msg.Authoritative = true
			msg.Rcode = tt.rcode

			resp := &NameserverResponse{Records: map[string][]string{}}

			var state queryState

			err := readReply(msg, resp, &state)
			classifyResponse(resp, state)

			if tt.wantStatus == StatusError {
				require.ErrorIs(t, err, ErrUnusableReply)
			} else {
				require.NoError(t, err)
			}

			assert.Equal(t, tt.wantStatus, resp.Status)
			assert.Equal(t, tt.wantError, resp.Error)
		})
	}
}