package crypto_test

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

	"github.com/google/go-cmp/cmp"

	"v2ray.com/core/common"
	"v2ray.com/core/common/buf"
	. "v2ray.com/core/common/crypto"
	"v2ray.com/core/common/protocol"
)

func TestAuthenticationReaderWriter(t *testing.T) {
	key := make([]byte, 16)
	rand.Read(key)
	block, err := aes.NewCipher(key)
	common.Must(err)

	aead, err := cipher.NewGCM(block)
	common.Must(err)

	const payloadSize = 1024 * 80
	rawPayload := make([]byte, payloadSize)
	rand.Read(rawPayload)

	payload := buf.MergeBytes(nil, rawPayload)

	cache := bytes.NewBuffer(nil)
	iv := make([]byte, 12)
	rand.Read(iv)

	writer := NewAuthenticationWriter(&AEADAuthenticator{
		AEAD:                    aead,
		NonceGenerator:          GenerateStaticBytes(iv),
		AdditionalDataGenerator: GenerateEmptyBytes(),
	}, PlainChunkSizeParser{}, cache, protocol.TransferTypeStream, nil)

	common.Must(writer.WriteMultiBuffer(payload))
	if cache.Len() <= 1024*80 {
		t.Error("cache len: ", cache.Len())
	}
	common.Must(writer.WriteMultiBuffer(buf.MultiBuffer{}))

	reader := NewAuthenticationReader(&AEADAuthenticator{
		AEAD:                    aead,
		NonceGenerator:          GenerateStaticBytes(iv),
		AdditionalDataGenerator: GenerateEmptyBytes(),
	}, PlainChunkSizeParser{}, cache, protocol.TransferTypeStream, nil)

	var mb buf.MultiBuffer

	for mb.Len() < payloadSize {
		mb2, err := reader.ReadMultiBuffer()
		common.Must(err)

		mb, _ = buf.MergeMulti(mb, mb2)
	}

	if mb.Len() != payloadSize {
		t.Error("mb len: ", mb.Len())
	}

	mbContent := make([]byte, payloadSize)
	buf.SplitBytes(mb, mbContent)
	if r := cmp.Diff(mbContent, rawPayload); r != "" {
		t.Error(r)
	}

	_, err = reader.ReadMultiBuffer()
	if err != io.EOF {
		t.Error("error: ", err)
	}
}

func TestAuthenticationReaderWriterPacket(t *testing.T) {
	key := make([]byte, 16)
	common.Must2(rand.Read(key))
	block, err := aes.NewCipher(key)
	common.Must(err)

	aead, err := cipher.NewGCM(block)
	common.Must(err)

	cache := buf.New()
	iv := make([]byte, 12)
	rand.Read(iv)

	writer := NewAuthenticationWriter(&AEADAuthenticator{
		AEAD:                    aead,
		NonceGenerator:          GenerateStaticBytes(iv),
		AdditionalDataGenerator: GenerateEmptyBytes(),
	}, PlainChunkSizeParser{}, cache, protocol.TransferTypePacket, nil)

	var payload buf.MultiBuffer
	pb1 := buf.New()
	pb1.Write([]byte("abcd"))
	payload = append(payload, pb1)

	pb2 := buf.New()
	pb2.Write([]byte("efgh"))
	payload = append(payload, pb2)

	common.Must(writer.WriteMultiBuffer(payload))
	if cache.Len() == 0 {
		t.Error("cache len: ", cache.Len())
	}

	common.Must(writer.WriteMultiBuffer(buf.MultiBuffer{}))

	reader := NewAuthenticationReader(&AEADAuthenticator{
		AEAD:                    aead,
		NonceGenerator:          GenerateStaticBytes(iv),
		AdditionalDataGenerator: GenerateEmptyBytes(),
	}, PlainChunkSizeParser{}, cache, protocol.TransferTypePacket, nil)

	mb, err := reader.ReadMultiBuffer()
	common.Must(err)

	mb, b1 := buf.SplitFirst(mb)
	if b1.String() != "abcd" {
		t.Error("b1: ", b1.String())
	}

	mb, b2 := buf.SplitFirst(mb)
	if b2.String() != "efgh" {
		t.Error("b2: ", b2.String())
	}

	if !mb.IsEmpty() {
		t.Error("not empty")
	}

	_, err = reader.ReadMultiBuffer()
	if err != io.EOF {
		t.Error("error: ", err)
	}
}