// Copyright 2019 The Prometheus 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 remote

import (
	"bytes"
	"github.com/prometheus/prometheus/util/testutil"
	"io"
	"testing"
)

type mockedFlusher struct {
	flushed int
}

func (f *mockedFlusher) Flush() {
	f.flushed++
}

func TestStreamReaderCanReadWriter(t *testing.T) {
	b := &bytes.Buffer{}
	f := &mockedFlusher{}
	w := NewChunkedWriter(b, f)
	r := NewChunkedReader(b)

	msgs := [][]byte{
		[]byte("test1"),
		[]byte("test2"),
		[]byte("test3"),
		[]byte("test4"),
		[]byte{}, // This is ignored by writer.
		[]byte("test5-after-empty"),
	}

	for _, msg := range msgs {
		n, err := w.Write(msg)
		testutil.Ok(t, err)
		testutil.Equals(t, len(msg), n)
	}

	i := 0
	for ; i < 4; i++ {
		msg, err := r.Next()
		testutil.Ok(t, err)
		testutil.Assert(t, i < len(msgs), "more messages then expected")
		testutil.Equals(t, msgs[i], msg)
	}

	// Empty byte slice is skipped.
	i++

	msg, err := r.Next()
	testutil.Ok(t, err)
	testutil.Assert(t, i < len(msgs), "more messages then expected")
	testutil.Equals(t, msgs[i], msg)

	_, err = r.Next()
	testutil.NotOk(t, err, "expected io.EOF")
	testutil.Equals(t, io.EOF, err)

	testutil.Equals(t, 5, f.flushed)
}