package main

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"fmt"
	"io"
	"testing"

	"github.com/alecthomas/units"
)

func newCipher(keySize int64) cipher.AEAD {
	key := make([]byte, keySize)
	io.ReadFull(rand.Reader, key)

	block, err := aes.NewCipher(key)
	if err != nil {
		panic(err)
	}

	aead, err := cipher.NewGCM(block)
	if err != nil {
		panic(err)
	}

	return aead
}

func benchmarkSeal(b *testing.B, chunkSize units.Base2Bytes, aead cipher.AEAD) {
	plaintext := make([]byte, chunkSize)
	nonce := make([]byte, 12)

	b.SetBytes(int64(chunkSize))
	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		aead.Seal(nil, nonce, plaintext, nil)
	}
}

func benchmarkOpen(b *testing.B, chunkSize units.Base2Bytes, aead cipher.AEAD) {
	nonce := make([]byte, 12)
	ciphertext := aead.Seal(nil, nonce, make([]byte, chunkSize), nil)

	b.SetBytes(int64(chunkSize))
	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		aead.Open(nil, nonce, ciphertext, nil)
	}
}

func BenchmarkGCM(b *testing.B) {
	for _, keySize := range []int64{16, 32} {
		for _, chunkSize := range []units.Base2Bytes{units.KiB, units.MiB, units.GiB} {
			aead := newCipher(keySize)

			seal := fmt.Sprintf("AES-%d-GCM-Seal-%s", int64(keySize)*8, chunkSize.String())
			open := fmt.Sprintf("AES-%d-GCM-Open-%s", int64(keySize)*8, chunkSize.String())

			b.Run(seal, func(b *testing.B) { benchmarkSeal(b, chunkSize, aead) })
			b.Run(open, func(b *testing.B) { benchmarkOpen(b, chunkSize, aead) })
		}
	}
}