// Copyright 2020 Google LLC
//
// 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
//
//     https://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

package wire

import (
	"bytes"
	"testing"
	"time"

	"cloud.google.com/go/internal/testutil"
	"cloud.google.com/go/pubsublite/internal/test"
	"github.com/google/go-cmp/cmp"
	"golang.org/x/xerrors"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
	"google.golang.org/protobuf/proto"

	pb "google.golang.org/genproto/googleapis/cloud/pubsublite/v1"
)

// testPublishResultReceiver provides convenience methods for receiving and
// validating Publish results.
type testPublishResultReceiver struct {
	done   chan struct{}
	msg    string
	t      *testing.T
	got    *MessageMetadata
	gotErr error
}

func newTestPublishResultReceiver(t *testing.T, msg *pb.PubSubMessage) *testPublishResultReceiver {
	return &testPublishResultReceiver{
		t:    t,
		msg:  string(msg.Data),
		done: make(chan struct{}),
	}
}

func (r *testPublishResultReceiver) set(mm *MessageMetadata, err error) {
	r.got = mm
	r.gotErr = err
	close(r.done)
}

func (r *testPublishResultReceiver) wait() bool {
	select {
	case <-time.After(serviceTestWaitTimeout):
		r.t.Errorf("Publish(%q) result not available within %v", r.msg, serviceTestWaitTimeout)
		return false
	case <-r.done:
		return true
	}
}

func (r *testPublishResultReceiver) ValidateResult(wantPartition int, wantOffset int64) {
	if !r.wait() {
		return
	}
	if r.gotErr != nil {
		r.t.Errorf("Publish(%q) error: (%v), want: partition=%d,offset=%d", r.msg, r.gotErr, wantPartition, wantOffset)
	} else if r.got.Partition != wantPartition || r.got.Offset != wantOffset {
		r.t.Errorf("Publish(%q) got: partition=%d,offset=%d, want: partition=%d,offset=%d", r.msg, r.got.Partition, r.got.Offset, wantPartition, wantOffset)
	}
}

func (r *testPublishResultReceiver) ValidateError(wantErr error) {
	if !r.wait() {
		return
	}
	if !test.ErrorEqual(r.gotErr, wantErr) {
		r.t.Errorf("Publish(%q) error: (%v), want: (%v)", r.msg, r.gotErr, wantErr)
	}
}

func (r *testPublishResultReceiver) ValidateErrorCode(wantCode codes.Code) {
	if !r.wait() {
		return
	}
	if !test.ErrorHasCode(r.gotErr, wantCode) {
		r.t.Errorf("Publish(%q) error: (%v), want code: %v", r.msg, r.gotErr, wantCode)
	}
}

func (r *testPublishResultReceiver) ValidateErrorMsg(wantStr string) {
	if !r.wait() {
		return
	}
	if !test.ErrorHasMsg(r.gotErr, wantStr) {
		r.t.Errorf("Publish(%q) error: (%v), want msg: %q", r.msg, r.gotErr, wantStr)
	}
}

// testPublishBatchReceiver receives message batches from the Bundler.
type testPublishBatchReceiver struct {
	t        *testing.T
	batchesC chan *publishBatch
}

func newTestPublishBatchReceiver(t *testing.T) *testPublishBatchReceiver {
	return &testPublishBatchReceiver{
		t:        t,
		batchesC: make(chan *publishBatch, 3),
	}
}

func (br *testPublishBatchReceiver) onNewBatch(batch *publishBatch) {
	br.batchesC <- batch
}

func (br *testPublishBatchReceiver) ValidateBatches(want []*publishBatch) {
	var got []*publishBatch
	for count := 0; count < len(want); count++ {
		select {
		case <-time.After(serviceTestWaitTimeout):
			br.t.Errorf("Publish batches count: got %d, want %d", count, len(want))
		case batch := <-br.batchesC:
			got = append(got, batch)
		}
	}

	if diff := testutil.Diff(got, want, cmp.AllowUnexported(publishBatch{}, messageHolder{})); diff != "" {
		br.t.Errorf("Batches got: -, want: +\n%s", diff)
	}
}

func makeMsgHolder(msg *pb.PubSubMessage, receiver ...*testPublishResultReceiver) *messageHolder {
	h := &messageHolder{
		msg:  msg,
		size: proto.Size(msg),
	}
	if len(receiver) > 0 {
		h.onResult = receiver[0].set
	}
	return h
}

func makePublishBatch(msgs ...*messageHolder) *publishBatch {
	batch := new(publishBatch)
	for _, msg := range msgs {
		batch.msgHolders = append(batch.msgHolders, msg)
		batch.totalSize += msg.size
	}
	return batch
}

func TestPublishBatcherAddMessage(t *testing.T) {
	const initAvailableBytes = MaxPublishRequestBytes
	settings := DefaultPublishSettings
	settings.BufferedByteLimit = initAvailableBytes

	receiver := newTestPublishBatchReceiver(t)
	batcher := newPublishMessageBatcher(&settings, 0, receiver.onNewBatch)

	if got, want := batcher.availableBufferBytes, initAvailableBytes; got != want {
		t.Errorf("availableBufferBytes: got %d, want %d", got, want)
	}

	t.Run("small messages", func(t *testing.T) {
		msg1 := &pb.PubSubMessage{Data: []byte("foo")}
		msgSize1 := proto.Size(msg1)
		if err := batcher.AddMessage(msg1, nil); err != nil {
			t.Errorf("AddMessage(%v) got err: %v", msg1, err)
		}
		if got, want := batcher.availableBufferBytes, initAvailableBytes-msgSize1; got != want {
			t.Errorf("availableBufferBytes: got %d, want %d", got, want)
		}

		msg2 := &pb.PubSubMessage{Data: []byte("hello world")}
		msgSize2 := proto.Size(msg2)
		if err := batcher.AddMessage(msg2, nil); err != nil {
			t.Errorf("AddMessage(%v) got err: %v", msg2, err)
		}
		if got, want := batcher.availableBufferBytes, initAvailableBytes-msgSize1-msgSize2; got != want {
			t.Errorf("availableBufferBytes: got %d, want %d", got, want)
		}
	})

	t.Run("oversized message", func(t *testing.T) {
		msg := &pb.PubSubMessage{Data: bytes.Repeat([]byte{'0'}, MaxPublishRequestBytes)}
		if gotErr := batcher.AddMessage(msg, nil); !xerrors.Is(gotErr, ErrOversizedMessage) {
			t.Errorf("AddMessage(%v) got err: %v, want err: %q", msg, gotErr, ErrOversizedMessage)
		}
	})

	t.Run("buffer overflow", func(t *testing.T) {
		msg := &pb.PubSubMessage{Data: bytes.Repeat([]byte{'1'}, batcher.availableBufferBytes)}
		if gotErr, wantErr := batcher.AddMessage(msg, nil), ErrOverflow; !test.ErrorEqual(gotErr, wantErr) {
			t.Errorf("AddMessage(%v) got err: %v, want err: %v", msg, gotErr, wantErr)
		}
	})
}

func TestPublishBatcherBundlerCountThreshold(t *testing.T) {
	settings := DefaultPublishSettings
	settings.DelayThreshold = time.Minute // Batching delay disabled
	settings.CountThreshold = 2

	// Batch 1
	msg1 := &pb.PubSubMessage{Data: []byte{'1'}}
	msg2 := &pb.PubSubMessage{Data: []byte{'2'}}
	wantBatch1 := makePublishBatch(makeMsgHolder(msg1), makeMsgHolder(msg2))

	// Batch 2
	msg3 := &pb.PubSubMessage{Data: []byte{'3'}}
	msg4 := &pb.PubSubMessage{Data: []byte{'4'}}
	wantBatch2 := makePublishBatch(makeMsgHolder(msg3), makeMsgHolder(msg4))

	// Batch 3
	msg5 := &pb.PubSubMessage{Data: []byte{'5'}}
	wantBatch3 := makePublishBatch(makeMsgHolder(msg5))

	receiver := newTestPublishBatchReceiver(t)
	batcher := newPublishMessageBatcher(&settings, 0, receiver.onNewBatch)

	msgs := []*pb.PubSubMessage{msg1, msg2, msg3, msg4, msg5}
	for _, msg := range msgs {
		if err := batcher.AddMessage(msg, nil); err != nil {
			t.Errorf("AddMessage(%v) got err: %v", msg, err)
		}
	}
	batcher.Flush()

	receiver.ValidateBatches([]*publishBatch{wantBatch1, wantBatch2, wantBatch3})
}

func TestPublishBatcherBundlerBatchingDelay(t *testing.T) {
	settings := DefaultPublishSettings
	settings.DelayThreshold = 5 * time.Millisecond

	// Batch 1
	msg1 := &pb.PubSubMessage{Data: []byte{'1'}}
	wantBatch1 := makePublishBatch(makeMsgHolder(msg1))

	// Batch 2
	msg2 := &pb.PubSubMessage{Data: []byte{'2'}}
	wantBatch2 := makePublishBatch(makeMsgHolder(msg2))

	receiver := newTestPublishBatchReceiver(t)
	batcher := newPublishMessageBatcher(&settings, 0, receiver.onNewBatch)

	if err := batcher.AddMessage(msg1, nil); err != nil {
		t.Errorf("AddMessage(%v) got err: %v", msg1, err)
	}
	// Wait much longer than DelayThreshold to prevent test flakiness, as the
	// Bundler may place the messages in the same batch.
	time.Sleep(settings.DelayThreshold * 5)
	if err := batcher.AddMessage(msg2, nil); err != nil {
		t.Errorf("AddMessage(%v) got err: %v", msg2, err)
	}
	batcher.Flush()

	receiver.ValidateBatches([]*publishBatch{wantBatch1, wantBatch2})
}

func TestPublishBatcherBundlerOnPermanentError(t *testing.T) {
	receiver := newTestPublishBatchReceiver(t)
	batcher := newPublishMessageBatcher(&DefaultPublishSettings, 0, receiver.onNewBatch)

	msg1 := &pb.PubSubMessage{Data: []byte{'1'}}
	msg2 := &pb.PubSubMessage{Data: []byte{'2'}}
	pubResult1 := newTestPublishResultReceiver(t, msg1)
	pubResult2 := newTestPublishResultReceiver(t, msg2)
	batcher.AddBatch(makePublishBatch(makeMsgHolder(msg1, pubResult1), makeMsgHolder(msg2, pubResult2)))

	wantErr := status.Error(codes.FailedPrecondition, "failed")
	batcher.OnPermanentError(wantErr)
	pubResult1.ValidateError(wantErr)
	pubResult2.ValidateError(wantErr)
}

func TestPublishBatcherBundlerOnPublishResponse(t *testing.T) {
	const partition = 2
	receiver := newTestPublishBatchReceiver(t)
	batcher := newPublishMessageBatcher(&DefaultPublishSettings, partition, receiver.onNewBatch)

	t.Run("empty in-flight batches", func(t *testing.T) {
		if gotErr, wantErr := batcher.OnPublishResponse(0), errPublishQueueEmpty; !test.ErrorEqual(gotErr, wantErr) {
			t.Errorf("OnPublishResponse() got err: %v, want err: %v", gotErr, wantErr)
		}
	})

	t.Run("set publish results", func(t *testing.T) {
		// Batch 1
		msg1 := &pb.PubSubMessage{Data: []byte{'1'}}
		msg2 := &pb.PubSubMessage{Data: []byte{'2'}}

		// Batch 2
		msg3 := &pb.PubSubMessage{Data: []byte{'3'}}
		pubResult1 := newTestPublishResultReceiver(t, msg1)
		pubResult2 := newTestPublishResultReceiver(t, msg2)
		pubResult3 := newTestPublishResultReceiver(t, msg3)

		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg1, pubResult1), makeMsgHolder(msg2, pubResult2)))
		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg3, pubResult3)))
		if err := batcher.OnPublishResponse(70); err != nil {
			t.Errorf("OnPublishResponse() got err: %v", err)
		}
		if err := batcher.OnPublishResponse(80); err != nil {
			t.Errorf("OnPublishResponse() got err: %v", err)
		}

		pubResult1.ValidateResult(partition, 70)
		pubResult2.ValidateResult(partition, 71)
		pubResult3.ValidateResult(partition, 80)
	})

	t.Run("inconsistent offset", func(t *testing.T) {
		msg := &pb.PubSubMessage{Data: []byte{'4'}}
		pubResult := newTestPublishResultReceiver(t, msg)
		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg, pubResult)))

		if gotErr, wantMsg := batcher.OnPublishResponse(80), "inconsistent start offset = 80"; !test.ErrorHasMsg(gotErr, wantMsg) {
			t.Errorf("OnPublishResponse() got err: %v, want err msg: %q", gotErr, wantMsg)
		}
	})
}

func TestPublishBatcherRebatching(t *testing.T) {
	const partition = 2
	receiver := newTestPublishBatchReceiver(t)

	t.Run("single batch", func(t *testing.T) {
		msg1 := &pb.PubSubMessage{Data: []byte{'1'}}

		batcher := newPublishMessageBatcher(&DefaultPublishSettings, partition, receiver.onNewBatch)
		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg1)))

		got := batcher.InFlightBatches()
		want := []*publishBatch{
			makePublishBatch(makeMsgHolder(msg1)),
		}
		if diff := testutil.Diff(got, want, cmp.AllowUnexported(publishBatch{}, messageHolder{})); diff != "" {
			t.Errorf("Batches got: -, want: +\n%s", diff)
		}
	})

	t.Run("merge into single batch", func(t *testing.T) {
		msg1 := &pb.PubSubMessage{Data: bytes.Repeat([]byte{1}, 100)}
		msg2 := &pb.PubSubMessage{Data: bytes.Repeat([]byte{2}, 200)}
		msg3 := &pb.PubSubMessage{Data: bytes.Repeat([]byte{3}, 300)}
		msg4 := &pb.PubSubMessage{Data: bytes.Repeat([]byte{4}, 400)}

		batcher := newPublishMessageBatcher(&DefaultPublishSettings, partition, receiver.onNewBatch)
		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg1)))
		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg2), makeMsgHolder(msg3)))
		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg4)))

		got := batcher.InFlightBatches()
		want := []*publishBatch{
			makePublishBatch(makeMsgHolder(msg1), makeMsgHolder(msg2), makeMsgHolder(msg3), makeMsgHolder(msg4)),
		}
		if diff := testutil.Diff(got, want, cmp.AllowUnexported(publishBatch{}, messageHolder{})); diff != "" {
			t.Errorf("Batches got: -, want: +\n%s", diff)
		}
	})

	t.Run("no rebatching", func(t *testing.T) {
		msg1 := &pb.PubSubMessage{Data: bytes.Repeat([]byte{1}, MaxPublishRequestBytes-10)}
		msg2 := &pb.PubSubMessage{Data: bytes.Repeat([]byte{2}, MaxPublishRequestBytes/2)}
		msg3 := &pb.PubSubMessage{Data: bytes.Repeat([]byte{3}, MaxPublishRequestBytes/2)}

		batcher := newPublishMessageBatcher(&DefaultPublishSettings, partition, receiver.onNewBatch)
		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg1)))
		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg2)))
		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg3)))

		got := batcher.InFlightBatches()
		want := []*publishBatch{
			makePublishBatch(makeMsgHolder(msg1)),
			makePublishBatch(makeMsgHolder(msg2)),
			makePublishBatch(makeMsgHolder(msg3)),
		}
		if diff := testutil.Diff(got, want, cmp.AllowUnexported(publishBatch{}, messageHolder{})); diff != "" {
			t.Errorf("Batches got: -, want: +\n%s", diff)
		}
	})

	t.Run("mixed rebatching", func(t *testing.T) {
		// Should be merged into a single batch.
		msg1 := &pb.PubSubMessage{Data: bytes.Repeat([]byte{1}, MaxPublishRequestBytes/2)}
		msg2 := &pb.PubSubMessage{Data: bytes.Repeat([]byte{2}, 200)}
		msg3 := &pb.PubSubMessage{Data: bytes.Repeat([]byte{3}, 300)}
		// Not merged due to byte limit.
		msg4 := &pb.PubSubMessage{Data: bytes.Repeat([]byte{4}, MaxPublishRequestBytes-500)}
		msg5 := &pb.PubSubMessage{Data: bytes.Repeat([]byte{5}, 500)}

		batcher := newPublishMessageBatcher(&DefaultPublishSettings, partition, receiver.onNewBatch)
		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg1)))
		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg2)))
		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg3)))
		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg4)))
		batcher.AddBatch(makePublishBatch(makeMsgHolder(msg5)))

		got := batcher.InFlightBatches()
		want := []*publishBatch{
			makePublishBatch(makeMsgHolder(msg1), makeMsgHolder(msg2), makeMsgHolder(msg3)),
			makePublishBatch(makeMsgHolder(msg4)),
			makePublishBatch(makeMsgHolder(msg5)),
		}
		if diff := testutil.Diff(got, want, cmp.AllowUnexported(publishBatch{}, messageHolder{})); diff != "" {
			t.Errorf("Batches got: -, want: +\n%s", diff)
		}
	})

	t.Run("max count", func(t *testing.T) {
		var msgs []*pb.PubSubMessage
		var batch1 []*messageHolder
		var batch2 []*messageHolder
		batcher := newPublishMessageBatcher(&DefaultPublishSettings, partition, receiver.onNewBatch)
		for i := 0; i <= MaxPublishRequestCount; i++ {
			msg := &pb.PubSubMessage{Data: []byte{'0'}}
			msgs = append(msgs, msg)

			msgHolder := makeMsgHolder(msg)
			if i < MaxPublishRequestCount {
				batch1 = append(batch1, msgHolder)
			} else {
				batch2 = append(batch2, msgHolder)
			}
			batcher.AddBatch(makePublishBatch(msgHolder))
		}

		got := batcher.InFlightBatches()
		want := []*publishBatch{
			makePublishBatch(batch1...),
			makePublishBatch(batch2...),
		}
		if diff := testutil.Diff(got, want, cmp.AllowUnexported(publishBatch{}, messageHolder{})); diff != "" {
			t.Errorf("Batches got: -, want: +\n%s", diff)
		}
	})
}