package netxlite

import (
	"context"
	"crypto/tls"
	"errors"
	"testing"

	"github.com/miekg/dns"
	"github.com/ooni/probe-cli/v3/internal/atomicx"
	"github.com/ooni/probe-cli/v3/internal/model"
	"github.com/ooni/probe-cli/v3/internal/model/mocks"
)

func TestParallelResolver(t *testing.T) {
	t.Run("transport okay", func(t *testing.T) {
		txp := NewDNSOverTLS((&tls.Dialer{}).DialContext, "8.8.8.8:853")
		r := NewUnwrappedParallelResolver(txp)
		rtx := r.Transport()
		if rtx.Network() != "dot" || rtx.Address() != "8.8.8.8:853" {
			t.Fatal("not the transport we expected")
		}
		if r.Network() != rtx.Network() {
			t.Fatal("invalid network seen from the resolver")
		}
		if r.Address() != rtx.Address() {
			t.Fatal("invalid address seen from the resolver")
		}
	})

	t.Run("LookupHost", func(t *testing.T) {
		t.Run("Encode error", func(t *testing.T) {
			mocked := errors.New("mocked error")
			txp := NewDNSOverTLS((&tls.Dialer{}).DialContext, "8.8.8.8:853")
			r := ParallelResolver{
				Encoder: &mocks.DNSEncoder{
					MockEncode: func(domain string, qtype uint16, padding bool) ([]byte, uint16, error) {
						return nil, 0, mocked
					},
				},
				Txp: txp,
			}
			addrs, err := r.LookupHost(context.Background(), "www.gogle.com")
			if !errors.Is(err, mocked) {
				t.Fatal("not the error we expected")
			}
			if addrs != nil {
				t.Fatal("expected nil address here")
			}
		})

		t.Run("RoundTrip error", func(t *testing.T) {
			mocked := errors.New("mocked error")
			txp := &mocks.DNSTransport{
				MockRoundTrip: func(ctx context.Context, query []byte) (reply []byte, err error) {
					return nil, mocked
				},
				MockRequiresPadding: func() bool {
					return true
				},
			}
			r := NewUnwrappedParallelResolver(txp)
			addrs, err := r.LookupHost(context.Background(), "www.gogle.com")
			if !errors.Is(err, mocked) {
				t.Fatal("not the error we expected")
			}
			if addrs != nil {
				t.Fatal("expected nil address here")
			}
		})

		t.Run("empty reply", func(t *testing.T) {
			txp := &mocks.DNSTransport{
				MockRoundTrip: func(ctx context.Context, query []byte) (reply []byte, err error) {
					return dnsGenLookupHostReplySuccess(query), nil
				},
				MockRequiresPadding: func() bool {
					return true
				},
			}
			r := NewUnwrappedParallelResolver(txp)
			addrs, err := r.LookupHost(context.Background(), "www.gogle.com")
			if !errors.Is(err, ErrOODNSNoAnswer) {
				t.Fatal("not the error we expected", err)
			}
			if addrs != nil {
				t.Fatal("expected nil address here")
			}
		})

		t.Run("with A reply", func(t *testing.T) {
			txp := &mocks.DNSTransport{
				MockRoundTrip: func(ctx context.Context, query []byte) (reply []byte, err error) {
					return dnsGenLookupHostReplySuccess(query, "8.8.8.8"), nil
				},
				MockRequiresPadding: func() bool {
					return true
				},
			}
			r := NewUnwrappedParallelResolver(txp)
			addrs, err := r.LookupHost(context.Background(), "www.gogle.com")
			if err != nil {
				t.Fatal(err)
			}
			if len(addrs) != 1 || addrs[0] != "8.8.8.8" {
				t.Fatal("not the result we expected", addrs)
			}
		})

		t.Run("with AAAA reply", func(t *testing.T) {
			txp := &mocks.DNSTransport{
				MockRoundTrip: func(ctx context.Context, query []byte) (reply []byte, err error) {
					return dnsGenLookupHostReplySuccess(query, "::1"), nil
				},
				MockRequiresPadding: func() bool {
					return true
				},
			}
			r := NewUnwrappedParallelResolver(txp)
			addrs, err := r.LookupHost(context.Background(), "www.gogle.com")
			if err != nil {
				t.Fatal(err)
			}
			if len(addrs) != 1 || addrs[0] != "::1" {
				t.Fatal("not the result we expected", addrs)
			}
		})

		t.Run("A failure takes precedence over AAAA failure", func(t *testing.T) {
			afailure := errors.New("a failure")
			aaaafailure := errors.New("aaaa failure")
			txp := &mocks.DNSTransport{
				MockRoundTrip: func(ctx context.Context, query []byte) (reply []byte, err error) {
					msg := &dns.Msg{}
					if err := msg.Unpack(query); err != nil {
						return nil, err
					}
					if len(msg.Question) != 1 {
						return nil, errors.New("expected just one question")
					}
					q := msg.Question[0]
					if q.Qtype == dns.TypeA {
						return nil, afailure
					}
					if q.Qtype == dns.TypeAAAA {
						return nil, aaaafailure
					}
					return nil, errors.New("expected A or AAAA query")
				},
				MockRequiresPadding: func() bool {
					return true
				},
			}
			r := NewUnwrappedParallelResolver(txp)
			addrs, err := r.LookupHost(context.Background(), "www.gogle.com")
			if !errors.Is(err, afailure) {
				t.Fatal("unexpected error", err)
			}
			if len(addrs) != 0 {
				t.Fatal("not the result we expected")
			}
		})
	})

	t.Run("CloseIdleConnections", func(t *testing.T) {
		var called bool
		r := &ParallelResolver{
			Txp: &mocks.DNSTransport{
				MockCloseIdleConnections: func() {
					called = true
				},
			},
		}
		r.CloseIdleConnections()
		if !called {
			t.Fatal("not called")
		}
	})

	t.Run("LookupHTTPS", func(t *testing.T) {
		t.Run("for encoding error", func(t *testing.T) {
			expected := errors.New("mocked error")
			r := &ParallelResolver{
				Encoder: &mocks.DNSEncoder{
					MockEncode: func(domain string, qtype uint16, padding bool) ([]byte, uint16, error) {
						return nil, 0, expected
					},
				},
				Decoder:     nil,
				NumTimeouts: &atomicx.Int64{},
				Txp: &mocks.DNSTransport{
					MockRequiresPadding: func() bool {
						return false
					},
				},
			}
			ctx := context.Background()
			https, err := r.LookupHTTPS(ctx, "example.com")
			if !errors.Is(err, expected) {
				t.Fatal("unexpected err", err)
			}
			if https != nil {
				t.Fatal("unexpected result")
			}
		})

		t.Run("for round-trip error", func(t *testing.T) {
			expected := errors.New("mocked error")
			r := &ParallelResolver{
				Encoder: &mocks.DNSEncoder{
					MockEncode: func(domain string, qtype uint16, padding bool) ([]byte, uint16, error) {
						return make([]byte, 64), 0, nil
					},
				},
				Decoder:     nil,
				NumTimeouts: &atomicx.Int64{},
				Txp: &mocks.DNSTransport{
					MockRoundTrip: func(ctx context.Context, query []byte) (reply []byte, err error) {
						return nil, expected
					},
					MockRequiresPadding: func() bool {
						return false
					},
				},
			}
			ctx := context.Background()
			https, err := r.LookupHTTPS(ctx, "example.com")
			if !errors.Is(err, expected) {
				t.Fatal("unexpected err", err)
			}
			if https != nil {
				t.Fatal("unexpected result")
			}
		})

		t.Run("for decode error", func(t *testing.T) {
			expected := errors.New("mocked error")
			r := &ParallelResolver{
				Encoder: &mocks.DNSEncoder{
					MockEncode: func(domain string, qtype uint16, padding bool) ([]byte, uint16, error) {
						return make([]byte, 64), 0, nil
					},
				},
				Decoder: &mocks.DNSDecoder{
					MockDecodeHTTPS: func(reply []byte, queryID uint16) (*model.HTTPSSvc, error) {
						return nil, expected
					},
				},
				NumTimeouts: &atomicx.Int64{},
				Txp: &mocks.DNSTransport{
					MockRoundTrip: func(ctx context.Context, query []byte) (reply []byte, err error) {
						return make([]byte, 128), nil
					},
					MockRequiresPadding: func() bool {
						return false
					},
				},
			}
			ctx := context.Background()
			https, err := r.LookupHTTPS(ctx, "example.com")
			if !errors.Is(err, expected) {
				t.Fatal("unexpected err", err)
			}
			if https != nil {
				t.Fatal("unexpected result")
			}
		})
	})
}