// Copyright 2020 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package snap

import (
	"crypto/rand"
	"fmt"
	"testing"

	"github.com/ethereum/go-ethereum/crypto"
	"golang.org/x/crypto/sha3"
)

func TestHashing(t *testing.T) {
	var bytecodes = make([][]byte, 10)
	for i := 0; i < len(bytecodes); i++ {
		buf := make([]byte, 100)
		rand.Read(buf)
		bytecodes[i] = buf
	}
	var want, got string
	var old = func() {
		hasher := sha3.NewLegacyKeccak256()
		for i := 0; i < len(bytecodes); i++ {
			hasher.Reset()
			hasher.Write(bytecodes[i])
			hash := hasher.Sum(nil)
			got = fmt.Sprintf("%v\n%v", got, hash)
		}
	}
	var new = func() {
		hasher := sha3.NewLegacyKeccak256().(crypto.KeccakState)
		var hash = make([]byte, 32)
		for i := 0; i < len(bytecodes); i++ {
			hasher.Reset()
			hasher.Write(bytecodes[i])
			hasher.Read(hash)
			want = fmt.Sprintf("%v\n%v", want, hash)
		}
	}
	old()
	new()
	if want != got {
		t.Errorf("want\n%v\ngot\n%v\n", want, got)
	}
}

func BenchmarkHashing(b *testing.B) {
	var bytecodes = make([][]byte, 10000)
	for i := 0; i < len(bytecodes); i++ {
		buf := make([]byte, 100)
		rand.Read(buf)
		bytecodes[i] = buf
	}
	var old = func() {
		hasher := sha3.NewLegacyKeccak256()
		for i := 0; i < len(bytecodes); i++ {
			hasher.Reset()
			hasher.Write(bytecodes[i])
			hasher.Sum(nil)
		}
	}
	var new = func() {
		hasher := sha3.NewLegacyKeccak256().(crypto.KeccakState)
		var hash = make([]byte, 32)
		for i := 0; i < len(bytecodes); i++ {
			hasher.Reset()
			hasher.Write(bytecodes[i])
			hasher.Read(hash)
		}
	}
	b.Run("old", func(b *testing.B) {
		b.ReportAllocs()
		for i := 0; i < b.N; i++ {
			old()
		}
	})
	b.Run("new", func(b *testing.B) {
		b.ReportAllocs()
		for i := 0; i < b.N; i++ {
			new()
		}
	})
}