// Copyright 2019 The OpenZipkin 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 zipkintracer

import (
	"bytes"
	"fmt"
	"math/rand"
	"net/http"
	"testing"
	"time"

	opentracing "github.com/opentracing/opentracing-go"
)

// More benchmarks can be added when extra fields propagation
// and binary propagation is in place. See
// https://github.com/openzipkin-contrib/zipkin-go-opentracing/blob/6ca6cf7bc4eadcb2ba7570f899b6e6dc1044eebb/bench_test.go

var tags []string

func init() {
	rand.Seed(time.Now().UnixNano())
	tags = make([]string, 1000)
	for j := 0; j < len(tags); j++ {
		tags[j] = fmt.Sprintf("%d", rand.Uint64())
	}
}

func executeOps(sp opentracing.Span, numEvent, numTag, numItems int) {
	for j := 0; j < numEvent; j++ {
		sp.LogEvent("event")
	}
	for j := 0; j < numTag; j++ {
		sp.SetTag(tags[j], nil)
	}
	for j := 0; j < numItems; j++ {
		sp.SetBaggageItem(tags[j], tags[j])
	}
}

func benchmarkWithOps(b *testing.B, numEvent, numTag, numItems int) {
	var r CountingSender
	t := newTracer(&r)
	benchmarkWithOpsAndCB(b, func() opentracing.Span {
		return t.StartSpan("test")
	}, numEvent, numTag, numItems)
	if int(r) != b.N {
		b.Fatalf("missing traces: expected %d, got %d", b.N, r)
	}
}

func benchmarkWithOpsAndCB(b *testing.B, create func() opentracing.Span,
	numEvent, numTag, numItems int) {
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		sp := create()
		executeOps(sp, numEvent, numTag, numItems)
		sp.Finish()
	}
	b.StopTimer()
}

func BenchmarkSpan_Empty(b *testing.B) {
	benchmarkWithOps(b, 0, 0, 0)
}

func BenchmarkSpan_100Events(b *testing.B) {
	benchmarkWithOps(b, 100, 0, 0)
}

func BenchmarkSpan_1000Events(b *testing.B) {
	benchmarkWithOps(b, 1000, 0, 0)
}

func BenchmarkSpan_100Tags(b *testing.B) {
	benchmarkWithOps(b, 0, 100, 0)
}

func BenchmarkSpan_1000Tags(b *testing.B) {
	benchmarkWithOps(b, 0, 1000, 0)
}

func benchmarkInject(b *testing.B, format opentracing.BuiltinFormat, numItems int) {
	var r CountingSender
	tracer := newTracer(&r)
	sp := tracer.StartSpan("testing")
	executeOps(sp, 0, 0, numItems)
	var carrier interface{}
	switch format {
	case opentracing.TextMap, opentracing.HTTPHeaders:
		carrier = opentracing.HTTPHeadersCarrier(http.Header{})
	case opentracing.Binary:
		carrier = &bytes.Buffer{}
	default:
		b.Fatalf("unhandled format %d", format)
	}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		err := tracer.Inject(sp.Context(), format, carrier)
		if err != nil {
			b.Fatal(err)
		}
	}
}

func benchmarkExtract(b *testing.B, format opentracing.BuiltinFormat, numItems int) {
	var r CountingSender
	tracer := newTracer(&r)
	sp := tracer.StartSpan("testing")
	executeOps(sp, 0, 0, numItems)
	var carrier interface{}
	switch format {
	case opentracing.TextMap, opentracing.HTTPHeaders:
		carrier = opentracing.HTTPHeadersCarrier(http.Header{})
	case opentracing.Binary:
		carrier = &bytes.Buffer{}
	default:
		b.Fatalf("unhandled format %d", format)
	}
	if err := tracer.Inject(sp.Context(), format, carrier); err != nil {
		b.Fatal(err)
	}

	// We create a new bytes.Buffer every time for tracer.Extract() to keep
	// this benchmark realistic.
	var rawBinaryBytes []byte
	if format == opentracing.Binary {
		rawBinaryBytes = carrier.(*bytes.Buffer).Bytes()
	}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		if format == opentracing.Binary {
			carrier = bytes.NewBuffer(rawBinaryBytes)
		}
		_, err := tracer.Extract(format, carrier)
		if err != nil {
			b.Fatal(err)
		}
	}
}

func BenchmarkInject_TextMap_Empty(b *testing.B) {
	benchmarkInject(b, opentracing.TextMap, 0)
}

func BenchmarkInject_TextMap_100BaggageItems(b *testing.B) {
	benchmarkInject(b, opentracing.TextMap, 100)
}

func BenchmarkExtract_TextMap_Empty(b *testing.B) {
	benchmarkExtract(b, opentracing.TextMap, 0)
}

func BenchmarkExtract_TextMap_100BaggageItems(b *testing.B) {
	benchmarkExtract(b, opentracing.TextMap, 100)
}