/*
 *
 * Copyright 2020 gRPC authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package rls

import (
	"context"
	"errors"
	"fmt"
	"testing"
	"time"

	"github.com/golang/protobuf/proto"
	"github.com/google/go-cmp/cmp"
	"google.golang.org/grpc"
	rlspb "google.golang.org/grpc/balancer/rls/internal/proto/grpc_lookup_v1"
	"google.golang.org/grpc/balancer/rls/internal/testutils/fakeserver"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/internal/testutils"
	"google.golang.org/grpc/status"
)

const (
	defaultDialTarget = "dummy"
	defaultRPCTimeout = 5 * time.Second
)

func setup(t *testing.T) (*fakeserver.Server, *grpc.ClientConn, func()) {
	t.Helper()

	server, sCleanup, err := fakeserver.Start(nil)
	if err != nil {
		t.Fatalf("Failed to start fake RLS server: %v", err)
	}

	cc, cCleanup, err := server.ClientConn()
	if err != nil {
		sCleanup()
		t.Fatalf("Failed to get a ClientConn to the RLS server: %v", err)
	}

	return server, cc, func() {
		sCleanup()
		cCleanup()
	}
}

// TestLookupFailure verifies the case where the RLS server returns an error.
func (s) TestLookupFailure(t *testing.T) {
	server, cc, cleanup := setup(t)
	defer cleanup()

	// We setup the fake server to return an error.
	server.ResponseChan <- fakeserver.Response{Err: errors.New("rls failure")}

	rlsClient := newRLSClient(cc, defaultDialTarget, defaultRPCTimeout)

	errCh := testutils.NewChannel()
	rlsClient.lookup("", nil, func(targets []string, headerData string, err error) {
		if err == nil {
			errCh.Send(errors.New("rlsClient.lookup() succeeded, should have failed"))
			return
		}
		if len(targets) != 0 || headerData != "" {
			errCh.Send(fmt.Errorf("rlsClient.lookup() = (%v, %s), want (nil, \"\")", targets, headerData))
			return
		}
		errCh.Send(nil)
	})

	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
	defer cancel()
	if e, err := errCh.Receive(ctx); err != nil || e != nil {
		t.Fatalf("lookup error: %v, error receiving from channel: %v", e, err)
	}
}

// TestLookupDeadlineExceeded tests the case where the RPC deadline associated
// with the lookup expires.
func (s) TestLookupDeadlineExceeded(t *testing.T) {
	_, cc, cleanup := setup(t)
	defer cleanup()

	// Give the Lookup RPC a small deadline, but don't setup the fake server to
	// return anything. So the Lookup call will block and eventually expire.
	rlsClient := newRLSClient(cc, defaultDialTarget, 100*time.Millisecond)

	errCh := testutils.NewChannel()
	rlsClient.lookup("", nil, func(_ []string, _ string, err error) {
		if st, ok := status.FromError(err); !ok || st.Code() != codes.DeadlineExceeded {
			errCh.Send(fmt.Errorf("rlsClient.lookup() returned error: %v, want %v", err, codes.DeadlineExceeded))
			return
		}
		errCh.Send(nil)
	})

	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
	defer cancel()
	if e, err := errCh.Receive(ctx); err != nil || e != nil {
		t.Fatalf("lookup error: %v, error receiving from channel: %v", e, err)
	}
}

// TestLookupSuccess verifies the successful Lookup API case.
func (s) TestLookupSuccess(t *testing.T) {
	server, cc, cleanup := setup(t)
	defer cleanup()

	const (
		rlsReqPath     = "/service/method"
		wantHeaderData = "headerData"
	)

	rlsReqKeyMap := map[string]string{
		"k1": "v1",
		"k2": "v2",
	}
	wantLookupRequest := &rlspb.RouteLookupRequest{
		Server:     defaultDialTarget,
		Path:       rlsReqPath,
		TargetType: "grpc",
		KeyMap:     rlsReqKeyMap,
	}
	wantRespTargets := []string{"us_east_1.firestore.googleapis.com"}

	rlsClient := newRLSClient(cc, defaultDialTarget, defaultRPCTimeout)

	errCh := testutils.NewChannel()
	rlsClient.lookup(rlsReqPath, rlsReqKeyMap, func(targets []string, hd string, err error) {
		if err != nil {
			errCh.Send(fmt.Errorf("rlsClient.Lookup() failed: %v", err))
			return
		}
		if !cmp.Equal(targets, wantRespTargets) || hd != wantHeaderData {
			errCh.Send(fmt.Errorf("rlsClient.lookup() = (%v, %s), want (%v, %s)", targets, hd, wantRespTargets, wantHeaderData))
			return
		}
		errCh.Send(nil)
	})

	// Make sure that the fake server received the expected RouteLookupRequest
	// proto.
	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
	defer cancel()
	req, err := server.RequestChan.Receive(ctx)
	if err != nil {
		t.Fatalf("Timed out wile waiting for a RouteLookupRequest")
	}
	gotLookupRequest := req.(*rlspb.RouteLookupRequest)
	if diff := cmp.Diff(wantLookupRequest, gotLookupRequest, cmp.Comparer(proto.Equal)); diff != "" {
		t.Fatalf("RouteLookupRequest diff (-want, +got):\n%s", diff)
	}

	// We setup the fake server to return this response when it receives a
	// request.
	server.ResponseChan <- fakeserver.Response{
		Resp: &rlspb.RouteLookupResponse{
			Targets:    wantRespTargets,
			HeaderData: wantHeaderData,
		},
	}

	if e, err := errCh.Receive(ctx); err != nil || e != nil {
		t.Fatalf("lookup error: %v, error receiving from channel: %v", e, err)
	}
}