// 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 (
	"fmt"
	"io/ioutil"
	"os"
	"strconv"
	"testing"

	"github.com/prometheus/prometheus/pkg/labels"
	"github.com/prometheus/prometheus/util/testutil"
)

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

func BenchmarkPostingsForMatchers(b *testing.B) {
	h, err := NewHead(nil, nil, nil, 1000)
	testutil.Ok(b, err)
	defer func() {
		testutil.Ok(b, h.Close())
	}()

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

	for n := 0; n < 10; n++ {
		for i := 0; i < 100000; i++ {
			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"))
		}
	}
	testutil.Ok(b, app.Commit())

	ir, err := h.Index()
	testutil.Ok(b, err)
	b.Run("Head", func(b *testing.B) {
		benchmarkPostingsForMatchers(b, ir)
	})

	tmpdir, err := ioutil.TempDir("", "test_benchpostingsformatchers")
	testutil.Ok(b, err)
	defer func() {
		testutil.Ok(b, os.RemoveAll(tmpdir))
	}()

	blockdir := createBlockFromHead(b, tmpdir, h)
	block, err := OpenBlock(nil, blockdir, nil)
	testutil.Ok(b, err)
	defer func() {
		testutil.Ok(b, block.Close())
	}()
	ir, err = block.Index()
	testutil.Ok(b, err)
	defer ir.Close()
	b.Run("Block", func(b *testing.B) {
		benchmarkPostingsForMatchers(b, ir)
	})
}

func benchmarkPostingsForMatchers(b *testing.B, ir IndexReader) {
	n1 := labels.MustNewMatcher(labels.MatchEqual, "n", "1"+postingsBenchSuffix)

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

	iStar := labels.MustNewMatcher(labels.MatchRegexp, "i", "^.*$")
	iPlus := labels.MustNewMatcher(labels.MatchRegexp, "i", "^.+$")
	i1Plus := labels.MustNewMatcher(labels.MatchRegexp, "i", "^1.+$")
	iEmptyRe := labels.MustNewMatcher(labels.MatchRegexp, "i", "^$")
	iNotEmpty := labels.MustNewMatcher(labels.MatchNotEqual, "i", "")
	iNot2 := labels.MustNewMatcher(labels.MatchNotEqual, "n", "2"+postingsBenchSuffix)
	iNot2Star := labels.MustNewMatcher(labels.MatchNotRegexp, "i", "^2.*$")

	cases := []struct {
		name     string
		matchers []*labels.Matcher
	}{
		{`n="1"`, []*labels.Matcher{n1}},
		{`n="1",j="foo"`, []*labels.Matcher{n1, jFoo}},
		{`j="foo",n="1"`, []*labels.Matcher{jFoo, n1}},
		{`n="1",j!="foo"`, []*labels.Matcher{n1, jNotFoo}},
		{`i=~".*"`, []*labels.Matcher{iStar}},
		{`i=~".+"`, []*labels.Matcher{iPlus}},
		{`i=~""`, []*labels.Matcher{iEmptyRe}},
		{`i!=""`, []*labels.Matcher{iNotEmpty}},
		{`n="1",i=~".*",j="foo"`, []*labels.Matcher{n1, 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="foo"`, []*labels.Matcher{n1, iPlus, jFoo}},
		{`n="1",i=~"1.+",j="foo"`, []*labels.Matcher{n1, i1Plus, 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}},
	}

	for _, c := range cases {
		b.Run(c.name, func(b *testing.B) {
			for i := 0; i < b.N; i++ {
				_, err := PostingsForMatchers(ir, c.matchers...)
				testutil.Ok(b, err)
			}
		})
	}
}

func BenchmarkQuerierSelect(b *testing.B) {
	h, err := NewHead(nil, nil, nil, 1000)
	testutil.Ok(b, err)
	defer h.Close()
	app := h.Appender()
	numSeries := 1000000
	for i := 0; i < numSeries; i++ {
		app.Add(labels.FromStrings("foo", "bar", "i", fmt.Sprintf("%d%s", i, postingsBenchSuffix)), int64(i), 0)
	}
	testutil.Ok(b, app.Commit())

	emptyHead, err := NewHead(nil, nil, nil, 1000)
	testutil.Ok(b, err)
	defer emptyHead.Close()

	bench := func(b *testing.B, br BlockReader, multiBlock bool) {
		matcher := labels.MustNewMatcher(labels.MatchEqual, "foo", "bar")
		for s := 1; s <= numSeries; s *= 10 {
			b.Run(fmt.Sprintf("%dof%d", s, numSeries), func(b *testing.B) {
				bq, err := NewBlockQuerier(br, 0, int64(s-1))
				testutil.Ok(b, err)
				blocks := []Querier{bq}

				if multiBlock {
					// Passing more than one block to the querier will trigger
					// sorting of the returned series.
					bq, err := NewBlockQuerier(emptyHead, 0, int64(s-1))
					testutil.Ok(b, err)
					blocks = append(blocks, bq)
				}
				q := &querier{blocks: blocks}

				b.ResetTimer()
				for i := 0; i < b.N; i++ {
					ss, err := q.Select(matcher)
					testutil.Ok(b, err)
					for ss.Next() {
					}
					testutil.Ok(b, ss.Err())
				}
				q.Close()
			})
		}
	}

	b.Run("Head", func(b *testing.B) {
		bench(b, h, false)
	})
	b.Run("SortedHead", func(b *testing.B) {
		bench(b, h, true)
	})

	tmpdir, err := ioutil.TempDir("", "test_benchquerierselect")
	testutil.Ok(b, err)
	defer func() {
		testutil.Ok(b, os.RemoveAll(tmpdir))
	}()

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

	b.Run("Block", func(b *testing.B) {
		bench(b, block, false)
	})
}