// Copyright 2017 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 tsdb

import (
	"context"
	"encoding/binary"
	"errors"
	"io/ioutil"
	"math/rand"
	"os"
	"path/filepath"
	"testing"

	"github.com/go-kit/kit/log"
	"github.com/prometheus/tsdb/chunks"
	"github.com/prometheus/tsdb/testutil"
	"github.com/prometheus/tsdb/tsdbutil"
)

// In Prometheus 2.1.0 we had a bug where the meta.json version was falsely bumped
// to 2. We had a migration in place resetting it to 1 but we should move immediately to
// version 3 next time to avoid confusion and issues.
func TestBlockMetaMustNeverBeVersion2(t *testing.T) {
	dir, err := ioutil.TempDir("", "metaversion")
	testutil.Ok(t, err)
	defer func() {
		testutil.Ok(t, os.RemoveAll(dir))
	}()

	testutil.Ok(t, writeMetaFile(dir, &BlockMeta{}))

	meta, err := readMetaFile(dir)
	testutil.Ok(t, err)
	testutil.Assert(t, meta.Version != 2, "meta.json version must never be 2")
}

func TestSetCompactionFailed(t *testing.T) {
	tmpdir, err := ioutil.TempDir("", "test")
	testutil.Ok(t, err)
	defer func() {
		testutil.Ok(t, os.RemoveAll(tmpdir))
	}()

	blockDir := createBlock(t, tmpdir, genSeries(1, 1, 0, 0))
	b, err := OpenBlock(nil, blockDir, nil)
	testutil.Ok(t, err)
	testutil.Equals(t, false, b.meta.Compaction.Failed)
	testutil.Ok(t, b.setCompactionFailed())
	testutil.Equals(t, true, b.meta.Compaction.Failed)
	testutil.Ok(t, b.Close())

	b, err = OpenBlock(nil, blockDir, nil)
	testutil.Ok(t, err)
	testutil.Equals(t, true, b.meta.Compaction.Failed)
	testutil.Ok(t, b.Close())
}

func TestCreateBlock(t *testing.T) {
	tmpdir, err := ioutil.TempDir("", "test")
	testutil.Ok(t, err)
	defer func() {
		testutil.Ok(t, os.RemoveAll(tmpdir))
	}()
	b, err := OpenBlock(nil, createBlock(t, tmpdir, genSeries(1, 1, 0, 10)), nil)
	if err == nil {
		testutil.Ok(t, b.Close())
	}
	testutil.Ok(t, err)
}

func TestCorruptedChunk(t *testing.T) {
	for name, test := range map[string]struct {
		corrFunc func(f *os.File) // Func that applies the corruption.
		expErr   error
	}{
		"invalid header size": {
			func(f *os.File) {
				err := f.Truncate(1)
				testutil.Ok(t, err)
			},
			errors.New("invalid chunk header in segment 0: invalid size"),
		},
		"invalid magic number": {
			func(f *os.File) {
				magicChunksOffset := int64(0)
				_, err := f.Seek(magicChunksOffset, 0)
				testutil.Ok(t, err)

				// Set invalid magic number.
				b := make([]byte, chunks.MagicChunksSize)
				binary.BigEndian.PutUint32(b[:chunks.MagicChunksSize], 0x00000000)
				n, err := f.Write(b)
				testutil.Ok(t, err)
				testutil.Equals(t, chunks.MagicChunksSize, n)
			},
			errors.New("invalid magic number 0"),
		},
		"invalid chunk format version": {
			func(f *os.File) {
				chunksFormatVersionOffset := int64(4)
				_, err := f.Seek(chunksFormatVersionOffset, 0)
				testutil.Ok(t, err)

				// Set invalid chunk format version.
				b := make([]byte, chunks.ChunksFormatVersionSize)
				b[0] = 0
				n, err := f.Write(b)
				testutil.Ok(t, err)
				testutil.Equals(t, chunks.ChunksFormatVersionSize, n)
			},
			errors.New("invalid chunk format version 0"),
		},
	} {
		t.Run(name, func(t *testing.T) {
			tmpdir, err := ioutil.TempDir("", "test_open_block_chunk_corrupted")
			testutil.Ok(t, err)
			defer func() {
				testutil.Ok(t, os.RemoveAll(tmpdir))
			}()

			blockDir := createBlock(t, tmpdir, genSeries(1, 1, 0, 0))
			files, err := sequenceFiles(chunkDir(blockDir))
			testutil.Ok(t, err)
			testutil.Assert(t, len(files) > 0, "No chunk created.")

			f, err := os.OpenFile(files[0], os.O_RDWR, 0666)
			testutil.Ok(t, err)

			// Apply corruption function.
			test.corrFunc(f)
			testutil.Ok(t, f.Close())

			_, err = OpenBlock(nil, blockDir, nil)
			testutil.Equals(t, test.expErr.Error(), err.Error())
		})
	}
}

// createBlock creates a block with given set of series and returns its dir.
func createBlock(tb testing.TB, dir string, series []Series) string {
	head, err := NewHead(nil, nil, nil, 2*60*60*1000)
	testutil.Ok(tb, err)
	defer head.Close()

	app := head.Appender()
	for _, s := range series {
		ref := uint64(0)
		it := s.Iterator()
		for it.Next() {
			t, v := it.At()
			if ref != 0 {
				err := app.AddFast(ref, t, v)
				if err == nil {
					continue
				}
			}
			ref, err = app.Add(s.Labels(), t, v)
			testutil.Ok(tb, err)
		}
		testutil.Ok(tb, it.Err())
	}
	err = app.Commit()
	testutil.Ok(tb, err)

	compactor, err := NewLeveledCompactor(context.Background(), nil, log.NewNopLogger(), []int64{1000000}, nil)
	testutil.Ok(tb, err)

	testutil.Ok(tb, os.MkdirAll(dir, 0777))

	ulid, err := compactor.Write(dir, head, head.MinTime(), head.MaxTime(), nil)
	testutil.Ok(tb, err)
	return filepath.Join(dir, ulid.String())
}

// genSeries generates series with a given number of labels and values.
func genSeries(totalSeries, labelCount int, mint, maxt int64) []Series {
	if totalSeries == 0 || labelCount == 0 {
		return nil
	}

	series := make([]Series, totalSeries)
	for i := 0; i < totalSeries; i++ {
		lbls := make(map[string]string, labelCount)
		for len(lbls) < labelCount {
			lbls[randString()] = randString()
		}
		samples := make([]tsdbutil.Sample, 0, maxt-mint+1)
		for t := mint; t <= maxt; t++ {
			samples = append(samples, sample{t: t, v: rand.Float64()})
		}
		series[i] = newSeries(lbls, samples)
	}
	return series
}

// populateSeries generates series from given labels, mint and maxt.
func populateSeries(lbls []map[string]string, mint, maxt int64) []Series {
	if len(lbls) == 0 {
		return nil
	}

	series := make([]Series, 0, len(lbls))
	for _, lbl := range lbls {
		if len(lbl) == 0 {
			continue
		}
		samples := make([]tsdbutil.Sample, 0, maxt-mint+1)
		for t := mint; t <= maxt; t++ {
			samples = append(samples, sample{t: t, v: rand.Float64()})
		}
		series = append(series, newSeries(lbl, samples))
	}
	return series
}

const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
const (
	letterIdxBits = 6                    // 6 bits to represent a letter index
	letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
	letterIdxMax  = 63 / letterIdxBits   // # of letter indices fitting in 63 bits
)

// randString generates random string.
func randString() string {
	maxLength := int32(50)
	length := rand.Int31n(maxLength)
	b := make([]byte, length+1)
	// A rand.Int63() generates 63 random bits, enough for letterIdxMax characters!
	for i, cache, remain := length, rand.Int63(), letterIdxMax; i >= 0; {
		if remain == 0 {
			cache, remain = rand.Int63(), letterIdxMax
		}
		if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
			b[i] = letterBytes[idx]
			i--
		}
		cache >>= letterIdxBits
		remain--
	}

	return string(b)
}