package consensus

import (
	"testing"
	"time"

	"github.com/nspcc-dev/dbft/block"
	"github.com/nspcc-dev/dbft/payload"
	"github.com/nspcc-dev/neo-go/pkg/config"
	"github.com/nspcc-dev/neo-go/pkg/config/netmode"
	"github.com/nspcc-dev/neo-go/pkg/core"
	"github.com/nspcc-dev/neo-go/pkg/core/storage"
	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
	"github.com/nspcc-dev/neo-go/pkg/internal/testchain"
	"github.com/nspcc-dev/neo-go/pkg/io"
	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
	"github.com/nspcc-dev/neo-go/pkg/util"
	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
	"github.com/stretchr/testify/require"
	"go.uber.org/zap/zaptest"
)

func TestNewService(t *testing.T) {
	srv := newTestService(t)
	tx := transaction.New(netmode.UnitTestNet, []byte{byte(opcode.PUSH1)}, 0)
	tx.ValidUntilBlock = 1
	addSender(t, tx)
	signTx(t, srv.Chain.FeePerByte(), tx)
	require.NoError(t, srv.Chain.PoolTx(tx))

	var txx []block.Transaction
	require.NotPanics(t, func() { txx = srv.getVerifiedTx() })
	require.Len(t, txx, 1)
	require.Equal(t, tx, txx[0])
	srv.Chain.Close()
}

func TestService_GetVerified(t *testing.T) {
	srv := newTestService(t)
	srv.dbft.Start()
	var txs []*transaction.Transaction
	for i := 0; i < 4; i++ {
		tx := transaction.New(netmode.UnitTestNet, []byte{byte(opcode.PUSH1)}, 0)
		tx.Nonce = 123 + uint32(i)
		tx.ValidUntilBlock = 1
		txs = append(txs, tx)
	}
	addSender(t, txs...)
	signTx(t, srv.Chain.FeePerByte(), txs...)
	require.NoError(t, srv.Chain.PoolTx(txs[3]))

	hashes := []util.Uint256{txs[0].Hash(), txs[1].Hash(), txs[2].Hash()}

	// Everyone sends a message.
	for i := 0; i < 4; i++ {
		p := new(Payload)
		p.message = &message{}
		// One PrepareRequest and three ChangeViews.
		if i == 1 {
			p.SetType(payload.PrepareRequestType)
			p.SetPayload(&prepareRequest{transactionHashes: hashes})
		} else {
			p.SetType(payload.ChangeViewType)
			p.SetPayload(&changeView{newViewNumber: 1, timestamp: uint32(time.Now().Unix())})
		}
		p.SetHeight(1)
		p.SetValidatorIndex(uint16(i))

		priv, _ := getTestValidator(i)
		require.NoError(t, p.Sign(priv))

		// Skip srv.OnPayload, because the service is not really started.
		srv.dbft.OnReceive(p)
	}
	require.Equal(t, uint8(1), srv.dbft.ViewNumber)
	require.Equal(t, hashes, srv.lastProposal)

	t.Run("new transactions will be proposed in case of failure", func(t *testing.T) {
		txx := srv.getVerifiedTx()
		require.Equal(t, 1, len(txx), "there is only 1 tx in mempool")
		require.Equal(t, txs[3], txx[0])
	})

	t.Run("more than half of the last proposal will be reused", func(t *testing.T) {
		for _, tx := range txs[:2] {
			require.NoError(t, srv.Chain.PoolTx(tx))
		}

		txx := srv.getVerifiedTx()
		require.Contains(t, txx, txs[0])
		require.Contains(t, txx, txs[1])
		require.NotContains(t, txx, txs[2])
	})
	srv.Chain.Close()
}

func TestService_ValidatePayload(t *testing.T) {
	srv := newTestService(t)
	priv, _ := getTestValidator(1)
	p := new(Payload)
	p.message = &message{}

	p.SetPayload(&prepareRequest{})

	t.Run("invalid validator index", func(t *testing.T) {
		p.SetValidatorIndex(11)
		require.NoError(t, p.Sign(priv))

		var ok bool
		require.NotPanics(t, func() { ok = srv.validatePayload(p) })
		require.False(t, ok)
	})

	t.Run("wrong validator index", func(t *testing.T) {
		p.SetValidatorIndex(2)
		require.NoError(t, p.Sign(priv))
		require.False(t, srv.validatePayload(p))
	})

	t.Run("normal case", func(t *testing.T) {
		p.SetValidatorIndex(1)
		require.NoError(t, p.Sign(priv))
		require.True(t, srv.validatePayload(p))
	})
	srv.Chain.Close()
}

func TestService_getTx(t *testing.T) {
	srv := newTestService(t)

	t.Run("transaction in mempool", func(t *testing.T) {
		tx := transaction.New(netmode.UnitTestNet, []byte{byte(opcode.PUSH1)}, 0)
		tx.Nonce = 1234
		tx.ValidUntilBlock = 1
		addSender(t, tx)
		signTx(t, srv.Chain.FeePerByte(), tx)
		h := tx.Hash()

		require.Equal(t, nil, srv.getTx(h))

		require.NoError(t, srv.Chain.PoolTx(tx))

		got := srv.getTx(h)
		require.NotNil(t, got)
		require.Equal(t, h, got.Hash())
	})

	t.Run("transaction in local cache", func(t *testing.T) {
		tx := transaction.New(netmode.UnitTestNet, []byte{byte(opcode.PUSH1)}, 0)
		tx.Nonce = 4321
		tx.ValidUntilBlock = 1
		h := tx.Hash()

		require.Equal(t, nil, srv.getTx(h))

		srv.txx.Add(tx)

		got := srv.getTx(h)
		require.NotNil(t, got)
		require.Equal(t, h, got.Hash())
	})
	srv.Chain.Close()
}

func TestService_OnPayload(t *testing.T) {
	srv := newTestService(t)
	// This test directly reads things from srv.messages that normally
	// is read by internal goroutine started with Start(). So let's
	// pretend we really did start already.
	srv.started.Store(true)

	priv, _ := getTestValidator(1)
	p := new(Payload)
	p.message = &message{}
	p.SetValidatorIndex(1)
	p.SetPayload(&prepareRequest{})

	// payload is not signed
	srv.OnPayload(p)
	shouldNotReceive(t, srv.messages)
	require.Nil(t, srv.GetPayload(p.Hash()))

	require.NoError(t, p.Sign(priv))
	srv.OnPayload(p)
	shouldReceive(t, srv.messages)
	require.Equal(t, p, srv.GetPayload(p.Hash()))

	// payload has already been received
	srv.OnPayload(p)
	shouldNotReceive(t, srv.messages)
	srv.Chain.Close()
}

func shouldReceive(t *testing.T, ch chan Payload) {
	select {
	case <-ch:
	default:
		require.Fail(t, "missing expected message")
	}
}

func shouldNotReceive(t *testing.T, ch chan Payload) {
	select {
	case <-ch:
		require.Fail(t, "unexpected message receive")
	default:
	}
}

func newTestService(t *testing.T) *service {
	srv, err := NewService(Config{
		Logger:    zaptest.NewLogger(t),
		Broadcast: func(*Payload) {},
		Chain:     newTestChain(t),
		RequestTx: func(...util.Uint256) {},
		Wallet: &config.Wallet{
			Path:     "./testdata/wallet1.json",
			Password: "one",
		},
	})
	require.NoError(t, err)

	return srv.(*service)
}

func getTestValidator(i int) (*privateKey, *publicKey) {
	key := testchain.PrivateKeyByID(i)
	return &privateKey{PrivateKey: key}, &publicKey{PublicKey: key.PublicKey()}
}

func newTestChain(t *testing.T) *core.Blockchain {
	unitTestNetCfg, err := config.Load("../../config", netmode.UnitTestNet)
	require.NoError(t, err)

	chain, err := core.NewBlockchain(storage.NewMemoryStore(), unitTestNetCfg.ProtocolConfiguration, zaptest.NewLogger(t))
	require.NoError(t, err)

	go chain.Run()

	return chain
}

var neoOwner = testchain.MultisigScriptHash()

func addSender(t *testing.T, txs ...*transaction.Transaction) {
	for _, tx := range txs {
		tx.Sender = neoOwner
	}
}

func signTx(t *testing.T, feePerByte int64, txs ...*transaction.Transaction) {
	validators := make([]*keys.PublicKey, 4)
	privNetKeys := make([]*keys.PrivateKey, 4)
	for i := 0; i < 4; i++ {
		privNetKeys[i] = testchain.PrivateKey(i)
		validators[i] = privNetKeys[i].PublicKey()
	}
	rawScript, err := smartcontract.CreateMultiSigRedeemScript(3, validators)
	require.NoError(t, err)
	for _, tx := range txs {
		size := io.GetVarSize(tx)
		netFee, sizeDelta := core.CalculateNetworkFee(rawScript)
		tx.NetworkFee += +netFee
		size += sizeDelta
		tx.NetworkFee += int64(size) * feePerByte
		data := tx.GetSignedPart()

		buf := io.NewBufBinWriter()
		for _, key := range privNetKeys {
			signature := key.Sign(data)
			emit.Bytes(buf.BinWriter, signature)
		}

		tx.Scripts = []transaction.Witness{{
			InvocationScript:   buf.Bytes(),
			VerificationScript: rawScript,
		}}
	}
}