// Copyright 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"
	"fmt"
	"strconv"
	"testing"

	"github.com/stretchr/testify/require"

	"github.com/prometheus/prometheus/model/labels"
	"github.com/prometheus/prometheus/storage"
	"github.com/prometheus/prometheus/tsdb/index"
)

// Make entries ~50B in size, to emulate real-world high cardinality.
const (
	postingsBenchSuffix = "aaaaaaaaaabbbbbbbbbbccccccccccdddddddddd"
)

func BenchmarkQuerier(b *testing.B) {
	opts := DefaultHeadOptions()
	opts.ChunkRange = 1000
	opts.ChunkDirRoot = b.TempDir()
	h, err := NewHead(nil, nil, nil, nil, opts, nil)
	require.NoError(b, err)
	defer func() {
		require.NoError(b, h.Close())
	}()

	app := h.Appender(context.Background())
	addSeries := func(l labels.Labels) {
		app.Append(0, l, 0, 0)
	}

	for n := range 10 {
		addSeries(labels.FromStrings("a", strconv.Itoa(n)+postingsBenchSuffix))
		for i := range 100000 {
			addSeries(labels.FromStrings("i", strconv.Itoa(i)+postingsBenchSuffix, "n", strconv.Itoa(n)+postingsBenchSuffix, "j", "foo"))
			// Have some series that won't be matched, to properly test inverted matches.
			addSeries(labels.FromStrings("i", strconv.Itoa(i)+postingsBenchSuffix, "n", strconv.Itoa(n)+postingsBenchSuffix, "j", "bar"))
			addSeries(labels.FromStrings("i", strconv.Itoa(i)+postingsBenchSuffix, "n", "0_"+strconv.Itoa(n)+postingsBenchSuffix, "j", "bar"))
			addSeries(labels.FromStrings("i", strconv.Itoa(i)+postingsBenchSuffix, "n", "1_"+strconv.Itoa(n)+postingsBenchSuffix, "j", "bar"))
			addSeries(labels.FromStrings("i", strconv.Itoa(i)+postingsBenchSuffix, "n", "2_"+strconv.Itoa(n)+postingsBenchSuffix, "j", "foo"))
		}
		require.NoError(b, app.Commit())
		app = h.Appender(context.Background())
	}
	require.NoError(b, app.Commit())

	b.Run("Head", func(b *testing.B) {
		ir, err := h.Index()
		require.NoError(b, err)
		defer func() {
			require.NoError(b, ir.Close())
		}()

		b.Run("PostingsForMatchers", func(b *testing.B) {
			benchmarkPostingsForMatchers(b, ir)
		})
		b.Run("labelValuesWithMatchers", func(b *testing.B) {
			benchmarkLabelValuesWithMatchers(b, ir)
		})
	})

	b.Run("Block", func(b *testing.B) {
		blockdir := createBlockFromHead(b, b.TempDir(), h)
		block, err := OpenBlock(nil, blockdir, nil, nil)
		require.NoError(b, err)
		defer func() {
			require.NoError(b, block.Close())
		}()

		ir, err := block.Index()
		require.NoError(b, err)
		defer func() {
			require.NoError(b, ir.Close())
		}()

		b.Run("PostingsForMatchers", func(b *testing.B) {
			benchmarkPostingsForMatchers(b, ir)
		})
		b.Run("labelValuesWithMatchers", func(b *testing.B) {
			benchmarkLabelValuesWithMatchers(b, ir)
		})
	})
}

func benchmarkPostingsForMatchers(b *testing.B, ir IndexReader) {
	ctx := context.Background()

	a1 := labels.MustNewMatcher(labels.MatchEqual, "a", "1"+postingsBenchSuffix)
	n1 := labels.MustNewMatcher(labels.MatchEqual, "n", "1"+postingsBenchSuffix)
	n0_1 := labels.MustNewMatcher(labels.MatchEqual, "n", "0_1"+postingsBenchSuffix)
	nX := labels.MustNewMatcher(labels.MatchEqual, "n", "X"+postingsBenchSuffix)

	jFoo := labels.MustNewMatcher(labels.MatchEqual, "j", "foo")
	jNotFoo := labels.MustNewMatcher(labels.MatchNotEqual, "j", "foo")

	iStar := labels.MustNewMatcher(labels.MatchRegexp, "i", ".*")
	i1Star := labels.MustNewMatcher(labels.MatchRegexp, "i", "1.*")
	iStar1 := labels.MustNewMatcher(labels.MatchRegexp, "i", ".*1")
	iStar1Star := labels.MustNewMatcher(labels.MatchRegexp, "i", ".*1.*")
	iPlus := labels.MustNewMatcher(labels.MatchRegexp, "i", ".+")
	i1Plus := labels.MustNewMatcher(labels.MatchRegexp, "i", "1.+")
	iEmptyRe := labels.MustNewMatcher(labels.MatchRegexp, "i", "")
	iNotEmpty := labels.MustNewMatcher(labels.MatchNotEqual, "i", "")
	iNot2 := labels.MustNewMatcher(labels.MatchNotEqual, "i", "2"+postingsBenchSuffix)
	iNot2Star := labels.MustNewMatcher(labels.MatchNotRegexp, "i", "2.*")
	iNotStar2Star := labels.MustNewMatcher(labels.MatchNotRegexp, "i", ".*2.*")
	jFooBar := labels.MustNewMatcher(labels.MatchRegexp, "j", "foo|bar")
	jXXXYYY := labels.MustNewMatcher(labels.MatchRegexp, "j", "XXX|YYY")
	jXplus := labels.MustNewMatcher(labels.MatchRegexp, "j", "X.+")
	iCharSet := labels.MustNewMatcher(labels.MatchRegexp, "i", "1[0-9]")
	iAlternate := labels.MustNewMatcher(labels.MatchRegexp, "i", "(1|2|3|4|5|6|20|55)")
	iNotAlternate := labels.MustNewMatcher(labels.MatchNotRegexp, "i", "(1|2|3|4|5|6|20|55)")
	iXYZ := labels.MustNewMatcher(labels.MatchRegexp, "i", "X|Y|Z")
	iNotXYZ := labels.MustNewMatcher(labels.MatchNotRegexp, "i", "X|Y|Z")
	cases := []struct {
		name     string
		matchers []*labels.Matcher
	}{
		{`n="1"`, []*labels.Matcher{n1}},
		{`n="X"`, []*labels.Matcher{nX}},
		{`n="1",j="foo"`, []*labels.Matcher{n1, jFoo}},
		{`n="X",j="foo"`, []*labels.Matcher{nX, jFoo}},
		{`j="foo",n="1"`, []*labels.Matcher{jFoo, n1}},
		{`n="1",j!="foo"`, []*labels.Matcher{n1, jNotFoo}},
		{`n="1",i!="2"`, []*labels.Matcher{n1, iNot2}},
		{`n="0_1",j="foo,a="1"`, []*labels.Matcher{n0_1, jFoo, a1}},
		{`n="X",j!="foo"`, []*labels.Matcher{nX, jNotFoo}},
		{`i=~"1[0-9]",j=~"foo|bar"`, []*labels.Matcher{iCharSet, jFooBar}},
		{`j=~"foo|bar"`, []*labels.Matcher{jFooBar}},
		{`j=~"XXX|YYY"`, []*labels.Matcher{jXXXYYY}},
		{`j=~"X.+"`, []*labels.Matcher{jXplus}},
		{`i=~"(1|2|3|4|5|6|20|55)"`, []*labels.Matcher{iAlternate}},
		{`i!~"(1|2|3|4|5|6|20|55)"`, []*labels.Matcher{iNotAlternate}},
		{`i=~"X|Y|Z"`, []*labels.Matcher{iXYZ}},
		{`i!~"X|Y|Z"`, []*labels.Matcher{iNotXYZ}},
		{`i=~".*"`, []*labels.Matcher{iStar}},
		{`i=~"1.*"`, []*labels.Matcher{i1Star}},
		{`i=~".*1"`, []*labels.Matcher{iStar1}},
		{`i=~".+"`, []*labels.Matcher{iPlus}},
		{`i=~".+",j=~"X.+"`, []*labels.Matcher{iPlus, jXplus}},
		{`i=~""`, []*labels.Matcher{iEmptyRe}},
		{`i!=""`, []*labels.Matcher{iNotEmpty}},
		{`n="1",i=~".*",j="foo"`, []*labels.Matcher{n1, iStar, jFoo}},
		{`n="X",i=~".*",j="foo"`, []*labels.Matcher{nX, iStar, jFoo}},
		{`n="1",i=~".*",i!="2",j="foo"`, []*labels.Matcher{n1, iStar, iNot2, jFoo}},
		{`n="1",i!=""`, []*labels.Matcher{n1, iNotEmpty}},
		{`n="1",i!="",j="foo"`, []*labels.Matcher{n1, iNotEmpty, jFoo}},
		{`n="1",i!="",j=~"X.+"`, []*labels.Matcher{n1, iNotEmpty, jXplus}},
		{`n="1",i!="",j=~"XXX|YYY"`, []*labels.Matcher{n1, iNotEmpty, jXXXYYY}},
		{`n="1",i=~"X|Y|Z",j="foo"`, []*labels.Matcher{n1, iXYZ, jFoo}},
		{`n="1",i!~"X|Y|Z",j="foo"`, []*labels.Matcher{n1, iNotXYZ, jFoo}},
		{`n="1",i=~".+",j="foo"`, []*labels.Matcher{n1, iPlus, jFoo}},
		{`n="1",i=~"1.+",j="foo"`, []*labels.Matcher{n1, i1Plus, jFoo}},
		{`n="1",i=~".*1.*",j="foo"`, []*labels.Matcher{n1, iStar1Star, jFoo}},
		{`n="1",i=~".+",i!="2",j="foo"`, []*labels.Matcher{n1, iPlus, iNot2, jFoo}},
		{`n="1",i=~".+",i!~"2.*",j="foo"`, []*labels.Matcher{n1, iPlus, iNot2Star, jFoo}},
		{`n="1",i=~".+",i!~".*2.*",j="foo"`, []*labels.Matcher{n1, iPlus, iNotStar2Star, jFoo}},
		{`n="X",i=~".+",i!~".*2.*",j="foo"`, []*labels.Matcher{nX, iPlus, iNotStar2Star, jFoo}},
	}

	for _, c := range cases {
		b.Run(c.name, func(b *testing.B) {
			b.ReportAllocs()
			b.ResetTimer()
			for b.Loop() {
				p, err := PostingsForMatchers(ctx, ir, c.matchers...)
				require.NoError(b, err)
				// Iterate over the postings
				for p.Next() {
					// Do nothing
				}
			}
		})
	}
}

func benchmarkLabelValuesWithMatchers(b *testing.B, ir IndexReader) {
	i1 := labels.MustNewMatcher(labels.MatchEqual, "i", "1")
	i1Plus := labels.MustNewMatcher(labels.MatchRegexp, "i", "1.+")
	i1PostingsBenchSuffix := labels.MustNewMatcher(labels.MatchEqual, "i", "1"+postingsBenchSuffix)
	iSuffix := labels.MustNewMatcher(labels.MatchRegexp, "i", ".+ddd")
	iStar := labels.MustNewMatcher(labels.MatchRegexp, "i", ".*")
	jNotFoo := labels.MustNewMatcher(labels.MatchNotEqual, "j", "foo")
	jXXXYYY := labels.MustNewMatcher(labels.MatchRegexp, "j", "XXX|YYY")
	jXplus := labels.MustNewMatcher(labels.MatchRegexp, "j", "X.+")
	n1 := labels.MustNewMatcher(labels.MatchEqual, "n", "1"+postingsBenchSuffix)
	nX := labels.MustNewMatcher(labels.MatchNotEqual, "n", "X"+postingsBenchSuffix)
	nPlus := labels.MustNewMatcher(labels.MatchRegexp, "n", ".+")

	ctx := context.Background()

	cases := []struct {
		name      string
		labelName string
		matchers  []*labels.Matcher
	}{
		// i is never "1", this isn't matching anything.
		{`i with i="1"`, "i", []*labels.Matcher{i1}},
		// i has 100k values.
		{`i with n="1"`, "i", []*labels.Matcher{n1}},
		{`i with n=".+"`, "i", []*labels.Matcher{nPlus}},
		{`i with n="1",j!="foo"`, "i", []*labels.Matcher{n1, jNotFoo}},
		{`i with n="1",j=~"X.+"`, "i", []*labels.Matcher{n1, jXplus}},
		{`i with n="1",j=~"XXX|YYY"`, "i", []*labels.Matcher{n1, jXXXYYY}},
		{`i with n="X",j!="foo"`, "i", []*labels.Matcher{nX, jNotFoo}},
		{`i with n="1",i=~".*",j!="foo"`, "i", []*labels.Matcher{n1, iStar, jNotFoo}},
		// matchers on i itself
		{`i with i="1aaa...ddd"`, "i", []*labels.Matcher{i1PostingsBenchSuffix}},
		{`i with i=~"1.+"`, "i", []*labels.Matcher{i1Plus}},
		{`i with i=~"1.+",i=~".+ddd"`, "i", []*labels.Matcher{i1Plus, iSuffix}},
		// n has 10 values.
		{`n with j!="foo"`, "n", []*labels.Matcher{jNotFoo}},
		{`n with i="1"`, "n", []*labels.Matcher{i1}},
		{`n with i=~"1.+"`, "n", []*labels.Matcher{i1Plus}},
		// there's no label "none"
		{`none with i=~"1"`, "none", []*labels.Matcher{i1Plus}},
	}

	for _, c := range cases {
		b.Run(c.name, func(b *testing.B) {
			for b.Loop() {
				_, err := labelValuesWithMatchers(ctx, ir, c.labelName, nil, c.matchers...)
				require.NoError(b, err)
			}
		})
	}
}

func BenchmarkMergedStringIter(b *testing.B) {
	numSymbols := 100000
	s := make([]string, numSymbols)
	for i := range numSymbols {
		s[i] = fmt.Sprintf("symbol%v", i)
	}

	for b.Loop() {
		it := NewMergedStringIter(index.NewStringListIter(s), index.NewStringListIter(s))
		for range 100 {
			it = NewMergedStringIter(it, index.NewStringListIter(s))
		}

		for it.Next() {
			require.NotNil(b, it.At())
			require.NoError(b, it.Err())
		}
	}

	b.ReportAllocs()
}

func createHeadForBenchmarkSelect(b *testing.B, numSeries int, addSeries func(app storage.Appender, i int)) (*Head, *DB) {
	dir := b.TempDir()
	opts := DefaultOptions()
	opts.OutOfOrderCapMax = 255
	opts.OutOfOrderTimeWindow = 1000
	db, err := Open(dir, nil, nil, opts, nil)
	require.NoError(b, err)
	b.Cleanup(func() {
		require.NoError(b, db.Close())
	})
	h := db.Head()

	app := h.Appender(context.Background())
	for i := range numSeries {
		addSeries(app, i)
		if i%1000 == 999 { // Commit every so often, so the appender doesn't get too big.
			require.NoError(b, app.Commit())
			app = h.Appender(context.Background())
		}
	}
	require.NoError(b, app.Commit())
	return h, db
}

func benchmarkSelect(b *testing.B, queryable storage.Queryable, numSeries int, sorted bool) {
	matcher := labels.MustNewMatcher(labels.MatchEqual, "foo", "bar")
	b.ResetTimer()
	for s := 1; s <= numSeries; s *= 10 {
		b.Run(fmt.Sprintf("%dof%d", s, numSeries), func(b *testing.B) {
			q, err := queryable.Querier(0, int64(s-1))
			require.NoError(b, err)

			b.ResetTimer()
			for b.Loop() {
				ss := q.Select(context.Background(), sorted, nil, matcher)
				for ss.Next() {
				}
				require.NoError(b, ss.Err())
			}
			q.Close()
		})
	}
}

func BenchmarkQuerierSelect(b *testing.B) {
	numSeries := 1000000
	h, db := createHeadForBenchmarkSelect(b, numSeries, func(app storage.Appender, i int) {
		_, err := app.Append(0, labels.FromStrings("foo", "bar", "i", fmt.Sprintf("%d%s", i, postingsBenchSuffix)), int64(i), 0)
		if err != nil {
			b.Fatal(err)
		}
	})

	b.Run("Head", func(b *testing.B) {
		benchmarkSelect(b, db, numSeries, false)
	})
	b.Run("SortedHead", func(b *testing.B) {
		benchmarkSelect(b, db, numSeries, true)
	})

	b.Run("Block", func(b *testing.B) {
		tmpdir := b.TempDir()

		blockdir := createBlockFromHead(b, tmpdir, h)
		block, err := OpenBlock(nil, blockdir, nil, nil)
		require.NoError(b, err)
		defer func() {
			require.NoError(b, block.Close())
		}()

		benchmarkSelect(b, (*queryableBlock)(block), numSeries, false)
	})
}

// Type wrapper to let a Block be a Queryable in benchmarkSelect().
type queryableBlock Block

func (pb *queryableBlock) Querier(mint, maxt int64) (storage.Querier, error) {
	return NewBlockQuerier((*Block)(pb), mint, maxt)
}

func BenchmarkQuerierSelectWithOutOfOrder(b *testing.B) {
	numSeries := 1000000
	_, db := createHeadForBenchmarkSelect(b, numSeries, func(app storage.Appender, i int) {
		l := labels.FromStrings("foo", "bar", "i", fmt.Sprintf("%d%s", i, postingsBenchSuffix))
		ref, err := app.Append(0, l, int64(i+1), 0)
		if err != nil {
			b.Fatal(err)
		}
		_, err = app.Append(ref, l, int64(i), 1) // Out of order sample
		if err != nil {
			b.Fatal(err)
		}
	})

	b.Run("Head", func(b *testing.B) {
		benchmarkSelect(b, db, numSeries, false)
	})
}
