// Copyright 2018 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 (
	"io/ioutil"
	"os"
	"path/filepath"
	"testing"

	"github.com/prometheus/tsdb/fileutil"
	"github.com/prometheus/tsdb/labels"
	"github.com/prometheus/tsdb/testutil"
	"github.com/prometheus/tsdb/wal"
)

func TestLastCheckpoint(t *testing.T) {
	dir, err := ioutil.TempDir("", "test_checkpoint")
	testutil.Ok(t, err)
	defer os.RemoveAll(dir)

	_, _, err = LastCheckpoint(dir)
	testutil.Equals(t, ErrNotFound, err)

	testutil.Ok(t, os.MkdirAll(filepath.Join(dir, "checkpoint.0000"), 0777))
	s, k, err := LastCheckpoint(dir)
	testutil.Ok(t, err)
	testutil.Equals(t, filepath.Join(dir, "checkpoint.0000"), s)
	testutil.Equals(t, 0, k)

	testutil.Ok(t, os.MkdirAll(filepath.Join(dir, "checkpoint.xyz"), 0777))
	s, k, err = LastCheckpoint(dir)
	testutil.Ok(t, err)
	testutil.Equals(t, filepath.Join(dir, "checkpoint.0000"), s)
	testutil.Equals(t, 0, k)

	testutil.Ok(t, os.MkdirAll(filepath.Join(dir, "checkpoint.1"), 0777))
	s, k, err = LastCheckpoint(dir)
	testutil.Ok(t, err)
	testutil.Equals(t, filepath.Join(dir, "checkpoint.1"), s)
	testutil.Equals(t, 1, k)

	testutil.Ok(t, os.MkdirAll(filepath.Join(dir, "checkpoint.1000"), 0777))
	s, k, err = LastCheckpoint(dir)
	testutil.Ok(t, err)
	testutil.Equals(t, filepath.Join(dir, "checkpoint.1000"), s)
	testutil.Equals(t, 1000, k)
}

func TestDeleteCheckpoints(t *testing.T) {
	dir, err := ioutil.TempDir("", "test_checkpoint")
	testutil.Ok(t, err)
	defer os.RemoveAll(dir)

	testutil.Ok(t, DeleteCheckpoints(dir, 0))

	testutil.Ok(t, os.MkdirAll(filepath.Join(dir, "checkpoint.00"), 0777))
	testutil.Ok(t, os.MkdirAll(filepath.Join(dir, "checkpoint.01"), 0777))
	testutil.Ok(t, os.MkdirAll(filepath.Join(dir, "checkpoint.02"), 0777))
	testutil.Ok(t, os.MkdirAll(filepath.Join(dir, "checkpoint.03"), 0777))

	testutil.Ok(t, DeleteCheckpoints(dir, 2))

	files, err := fileutil.ReadDir(dir)
	testutil.Ok(t, err)
	testutil.Equals(t, []string{"checkpoint.02", "checkpoint.03"}, files)
}

func TestCheckpoint(t *testing.T) {
	dir, err := ioutil.TempDir("", "test_checkpoint")
	testutil.Ok(t, err)
	defer os.RemoveAll(dir)

	var enc RecordEncoder
	// Create a dummy segment to bump the initial number.
	seg, err := wal.CreateSegment(dir, 100)
	testutil.Ok(t, err)
	testutil.Ok(t, seg.Close())

	// Manually create checkpoint for 99 and earlier.
	w, err := wal.New(nil, nil, filepath.Join(dir, "checkpoint.0099"))
	testutil.Ok(t, err)

	// Add some data we expect to be around later.
	err = w.Log(enc.Series([]RefSeries{
		{Ref: 0, Labels: labels.FromStrings("a", "b", "c", "0")},
		{Ref: 1, Labels: labels.FromStrings("a", "b", "c", "1")},
	}, nil))
	testutil.Ok(t, err)
	testutil.Ok(t, w.Close())

	// Start a WAL and write records to it as usual.
	w, err = wal.NewSize(nil, nil, dir, 64*1024)
	testutil.Ok(t, err)

	var last int64
	for i := 0; ; i++ {
		_, n, err := w.Segments()
		testutil.Ok(t, err)
		if n >= 106 {
			break
		}
		// Write some series initially.
		if i == 0 {
			b := enc.Series([]RefSeries{
				{Ref: 2, Labels: labels.FromStrings("a", "b", "c", "2")},
				{Ref: 3, Labels: labels.FromStrings("a", "b", "c", "3")},
				{Ref: 4, Labels: labels.FromStrings("a", "b", "c", "4")},
				{Ref: 5, Labels: labels.FromStrings("a", "b", "c", "5")},
			}, nil)
			testutil.Ok(t, w.Log(b))
		}
		// Write samples until the WAL has enough segments.
		// Make them have drifting timestamps within a record to see that they
		// get filtered properly.
		b := enc.Samples([]RefSample{
			{Ref: 0, T: last, V: float64(i)},
			{Ref: 1, T: last + 10000, V: float64(i)},
			{Ref: 2, T: last + 20000, V: float64(i)},
			{Ref: 3, T: last + 30000, V: float64(i)},
		}, nil)
		testutil.Ok(t, w.Log(b))

		last += 100
	}
	testutil.Ok(t, w.Close())

	_, err = Checkpoint(w, 100, 106, func(x uint64) bool {
		return x%2 == 0
	}, last/2)
	testutil.Ok(t, err)
	testutil.Ok(t, w.Truncate(107))
	testutil.Ok(t, DeleteCheckpoints(w.Dir(), 106))

	// Only the new checkpoint should be left.
	files, err := fileutil.ReadDir(dir)
	testutil.Ok(t, err)
	testutil.Equals(t, 1, len(files))
	testutil.Equals(t, "checkpoint.000106", files[0])

	sr, err := wal.NewSegmentsReader(filepath.Join(dir, "checkpoint.000106"))
	testutil.Ok(t, err)
	defer sr.Close()

	var dec RecordDecoder
	var series []RefSeries
	r := wal.NewReader(sr)

	for r.Next() {
		rec := r.Record()

		switch dec.Type(rec) {
		case RecordSeries:
			series, err = dec.Series(rec, series)
			testutil.Ok(t, err)
		case RecordSamples:
			samples, err := dec.Samples(rec, nil)
			testutil.Ok(t, err)
			for _, s := range samples {
				testutil.Assert(t, s.T >= last/2, "sample with wrong timestamp")
			}
		}
	}
	testutil.Ok(t, r.Err())
	testutil.Equals(t, []RefSeries{
		{Ref: 0, Labels: labels.FromStrings("a", "b", "c", "0")},
		{Ref: 2, Labels: labels.FromStrings("a", "b", "c", "2")},
		{Ref: 4, Labels: labels.FromStrings("a", "b", "c", "4")},
	}, series)
}