package tests

import (
	"context"
	"crypto/ecdsa"
	"fmt"
	"math/big"
	"testing"

	"github.com/ledgerwatch/turbo-geth/accounts/abi/bind"
	"github.com/ledgerwatch/turbo-geth/accounts/abi/bind/backends"
	"github.com/ledgerwatch/turbo-geth/common"
	"github.com/ledgerwatch/turbo-geth/consensus/ethash"
	"github.com/ledgerwatch/turbo-geth/core"
	"github.com/ledgerwatch/turbo-geth/core/types"
	"github.com/ledgerwatch/turbo-geth/core/vm"
	"github.com/ledgerwatch/turbo-geth/crypto"
	"github.com/ledgerwatch/turbo-geth/ethdb"
	"github.com/ledgerwatch/turbo-geth/params"
	"github.com/ledgerwatch/turbo-geth/tests/contracts"
)

func TestInsertIncorrectStateRootDifferentAccounts(t *testing.T) {
	data := getGenesis()
	from := data.addresses[0]
	fromKey := data.keys[0]
	to := common.Address{1}

	blockchain, blocks, receipts, err := genBlocks(data.genesisSpec, map[int]tx{
		0: {
			getBlockTx(from, to, big.NewInt(1000)),
			fromKey,
		},
		1: {
			getBlockTx(from, to, big.NewInt(2000)),
			fromKey,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	// BLOCK 1
	incorrectHeader := blocks[0].Header()
	incorrectHeader.Root = blocks[1].Header().Root

	if blocks[0].Header().Root == incorrectHeader.Root {
		t.Fatal("roots are the same")
	}

	incorrectBlock := types.NewBlock(incorrectHeader, blocks[0].Transactions(), blocks[0].Uncles(), receipts[0])
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{incorrectBlock}); err == nil {
		t.Fatal("should fail")
	}

	// insert a correct block
	blockchain, blocks, _, err = genBlocks(data.genesisSpec, map[int]tx{
		0: {
			getBlockTx(data.addresses[1], to, big.NewInt(5000)),
			data.keys[1],
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	if _, err = blockchain.InsertChain(context.Background(), blocks); err != nil {
		t.Fatal(err)
	}

	st, _, _ := blockchain.State()
	if !st.Exist(to) {
		t.Error("expected account to exist")
	}

	if balance := st.GetBalance(from); balance.Cmp(big.NewInt(1000000000)) != 0 {
		t.Fatalf("got %v, expected %v", balance, big.NewInt(1000000000))
	}
	if balance := st.GetBalance(data.addresses[1]); balance.Cmp(big.NewInt(999995000)) != 0 {
		t.Fatalf("got %v, expected %v", balance, big.NewInt(5000))
	}
	if balance := st.GetBalance(to); balance.Cmp(big.NewInt(5000)) != 0 {
		t.Fatalf("got %v, expected %v", balance, big.NewInt(5000))
	}
}

func TestInsertIncorrectStateRootSameAccount(t *testing.T) {
	data := getGenesis()
	from := data.addresses[0]
	fromKey := data.keys[0]
	to := common.Address{1}

	blockchain, blocks, receipts, err := genBlocks(data.genesisSpec, map[int]tx{
		0: {
			getBlockTx(from, to, big.NewInt(1000)),
			fromKey,
		},
		1: {
			getBlockTx(from, to, big.NewInt(2000)),
			fromKey,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	// BLOCK 1
	incorrectHeader := blocks[0].Header()
	incorrectHeader.Root = blocks[1].Header().Root

	if blocks[0].Header().Root == incorrectHeader.Root {
		t.Fatal("roots are the same")
	}

	incorrectBlock := types.NewBlock(incorrectHeader, blocks[0].Transactions(), blocks[0].Uncles(), receipts[0])
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{incorrectBlock}); err == nil {
		t.Fatal("should fail")
	}

	// insert a correct block
	blockchain, blocks, _, err = genBlocks(data.genesisSpec, map[int]tx{
		0: {
			getBlockTx(from, to, big.NewInt(5000)),
			fromKey,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	if _, err = blockchain.InsertChain(context.Background(), blocks); err != nil {
		t.Fatal(err)
	}

	st, _, _ := blockchain.State()
	if !st.Exist(to) {
		t.Error("expected account to exist")
	}

	if balance := st.GetBalance(from); balance.Cmp(big.NewInt(999995000)) != 0 {
		t.Fatalf("got %v, expected %v", balance, big.NewInt(999995000))
	}
	if balance := st.GetBalance(to); balance.Cmp(big.NewInt(5000)) != 0 {
		t.Fatalf("got %v, expected %v", balance, big.NewInt(5000))
	}
}

func TestInsertIncorrectStateRootSameAccountSameAmount(t *testing.T) {
	data := getGenesis()
	from := data.addresses[0]
	fromKey := data.keys[0]
	to := common.Address{1}

	blockchain, blocks, receipts, err := genBlocks(data.genesisSpec, map[int]tx{
		0: {
			getBlockTx(from, to, big.NewInt(1000)),
			fromKey,
		},
		1: {
			getBlockTx(from, to, big.NewInt(2000)),
			fromKey,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	// BLOCK 1
	incorrectHeader := blocks[0].Header()
	incorrectHeader.Root = blocks[1].Header().Root

	incorrectBlock := types.NewBlock(incorrectHeader, blocks[0].Transactions(), blocks[0].Uncles(), receipts[0])

	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{incorrectBlock}); err == nil {
		t.Fatal("should fail")
	}

	// insert a correct block
	blockchain, blocks, _, err = genBlocks(data.genesisSpec, map[int]tx{
		0: {
			getBlockTx(from, to, big.NewInt(1000)),
			fromKey,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	if _, err = blockchain.InsertChain(context.Background(), blocks); err != nil {
		t.Fatal(err)
	}

	st, _, _ := blockchain.State()
	if !st.Exist(to) {
		t.Error("expected account to exist")
	}

	if balance := st.GetBalance(from); balance.Cmp(big.NewInt(999999000)) != 0 {
		t.Fatalf("got %v, expected %v", balance, big.NewInt(999999000))
	}
	if balance := st.GetBalance(to); balance.Cmp(big.NewInt(1000)) != 0 {
		t.Fatalf("got %v, expected %v", balance, big.NewInt(1000))
	}
}

func TestInsertIncorrectStateRootAllFundsRoot(t *testing.T) {
	data := getGenesis(big.NewInt(3000))
	from := data.addresses[0]
	fromKey := data.keys[0]
	to := common.Address{1}

	blockchain, blocks, receipts, err := genBlocks(data.genesisSpec, map[int]tx{
		0: {
			getBlockTx(from, to, big.NewInt(1000)),
			fromKey,
		},
		1: {
			getBlockTx(from, to, big.NewInt(2000)),
			fromKey,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	// BLOCK 1
	incorrectHeader := blocks[0].Header()
	incorrectHeader.Root = blocks[1].Header().Root

	incorrectBlock := types.NewBlock(incorrectHeader, blocks[0].Transactions(), blocks[0].Uncles(), receipts[0])

	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{incorrectBlock}); err == nil {
		t.Fatal("should fail")
	}

	// insert a correct block
	blockchain, blocks, _, err = genBlocks(data.genesisSpec, map[int]tx{
		0: {
			getBlockTx(from, to, big.NewInt(1000)),
			fromKey,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	if _, err = blockchain.InsertChain(context.Background(), blocks); err != nil {
		t.Fatal(err)
	}

	st, _, _ := blockchain.State()
	if !st.Exist(to) {
		t.Error("expected account to exist")
	}

	if balance := st.GetBalance(from); balance.Cmp(big.NewInt(2000)) != 0 {
		t.Fatalf("got %v, expected %v", balance, big.NewInt(2000))
	}
	if balance := st.GetBalance(to); balance.Cmp(big.NewInt(1000)) != 0 {
		t.Fatalf("got %v, expected %v", balance, big.NewInt(1000))
	}
}

func TestInsertIncorrectStateRootAllFunds(t *testing.T) {
	data := getGenesis(big.NewInt(3000))
	from := data.addresses[0]
	fromKey := data.keys[0]
	to := common.Address{1}

	blockchain, blocks, receipts, err := genBlocks(data.genesisSpec, map[int]tx{
		0: {
			getBlockTx(from, to, big.NewInt(3000)),
			fromKey,
		},
		1: {
			getBlockTx(data.addresses[1], to, big.NewInt(2000)),
			data.keys[1],
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	// BLOCK 1
	incorrectHeader := blocks[0].Header()
	incorrectHeader.Root = blocks[1].Header().Root
	incorrectBlock := types.NewBlock(incorrectHeader, blocks[0].Transactions(), blocks[0].Uncles(), receipts[0])

	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{incorrectBlock}); err == nil {
		t.Fatal("should fail")
	}

	// insert a correct block
	blockchain, blocks, _, err = genBlocks(data.genesisSpec, map[int]tx{
		0: {
			getBlockTx(from, to, big.NewInt(1000)),
			fromKey,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	if _, err = blockchain.InsertChain(context.Background(), blocks); err != nil {
		t.Fatal(err)
	}

	st, _, _ := blockchain.State()
	if !st.Exist(to) {
		t.Error("expected account to exist")
	}

	if balance := st.GetBalance(from); balance.Cmp(big.NewInt(2000)) != 0 {
		t.Fatalf("got %v, expected %v", balance, big.NewInt(2000))
	}
	if balance := st.GetBalance(to); balance.Cmp(big.NewInt(1000)) != 0 {
		t.Fatalf("got %v, expected %v", balance, big.NewInt(1000))
	}
}

func TestAccountDeployIncorrectRoot(t *testing.T) {
	data := getGenesis()
	from := data.addresses[0]
	fromKey := data.keys[0]
	to := common.Address{1}

	var contractAddress common.Address
	eipContract := new(contracts.Eip2027)

	blockchain, blocks, receipts, err := genBlocks(data.genesisSpec, map[int]tx{
		0: {
			getBlockTx(from, to, big.NewInt(10)),
			fromKey,
		},
		1: {
			getBlockDeployEip2027Tx(data.transactOpts[0], &contractAddress, eipContract),
			fromKey,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	// BLOCK 1
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{blocks[0]}); err != nil {
		t.Fatal(err)
	}

	st, _, _ := blockchain.State()
	if !st.Exist(from) {
		t.Error("expected account to exist")
	}

	if st.Exist(contractAddress) {
		t.Error("expected contractAddress to not exist at the block 0", contractAddress.Hash().String())
	}

	incorrectHeader := blocks[1].Header()
	incorrectHeader.Root = blocks[0].Header().Root
	incorrectBlock := types.NewBlock(incorrectHeader, blocks[1].Transactions(), blocks[1].Uncles(), receipts[1])

	// BLOCK 2 - INCORRECT
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{incorrectBlock}); err == nil {
		t.Fatal("should fail")
	}

	st, _, _ = blockchain.State()
	if !st.Exist(from) {
		t.Error("expected account to exist")
	}

	if st.Exist(contractAddress) {
		t.Error("expected contractAddress to not exist at the block 1", contractAddress.Hash().String())
	}

	// BLOCK 2 - CORRECT
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{blocks[1]}); err != nil {
		t.Fatal(err)
	}

	st, _, _ = blockchain.State()
	if !st.Exist(from) {
		t.Error("expected account to exist")
	}

	if !st.Exist(contractAddress) {
		t.Error("expected contractAddress to not exist at the block 1", contractAddress.Hash().String())
	}
}

func TestAccountCreateIncorrectRoot(t *testing.T) {
	data := getGenesis()
	from := data.addresses[0]
	fromKey := data.keys[0]
	to := common.Address{1}

	var contractAddress common.Address
	eipContract := new(contracts.Eip2027)

	blockchain, blocks, receipts, err := genBlocks(data.genesisSpec, map[int]tx{
		0: {
			getBlockTx(from, to, big.NewInt(10)),
			fromKey,
		},
		1: {
			getBlockDeployEip2027Tx(data.transactOpts[0], &contractAddress, eipContract),
			fromKey,
		},
		2: {
			getBlockEip2027Tx(data.transactOpts[0], eipContract.Create, big.NewInt(2)),
			fromKey,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	// BLOCK 1
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{blocks[0]}); err != nil {
		t.Fatal(err)
	}

	st, _, _ := blockchain.State()
	if !st.Exist(from) {
		t.Error("expected account to exist")
	}

	if st.Exist(contractAddress) {
		t.Error("expected contractAddress to not exist at the block 0", contractAddress.Hash().String())
	}

	// BLOCK 2
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{blocks[1]}); err != nil {
		t.Fatal(err)
	}

	st, _, _ = blockchain.State()
	if !st.Exist(from) {
		t.Error("expected account to exist")
	}

	if !st.Exist(contractAddress) {
		t.Error("expected contractAddress to exist at the block 2", contractAddress.Hash().String())
	}

	// BLOCK 3 - INCORRECT
	incorrectHeader := blocks[2].Header()
	incorrectHeader.Root = blocks[1].Header().Root
	incorrectBlock := types.NewBlock(incorrectHeader, blocks[2].Transactions(), blocks[2].Uncles(), receipts[2])

	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{incorrectBlock}); err == nil {
		t.Fatal("should fail")
	}

	// BLOCK 3
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{blocks[2]}); err != nil {
		t.Fatal(err)
	}
}

func TestAccountUpdateIncorrectRoot(t *testing.T) {
	data := getGenesis()
	from := data.addresses[0]
	fromKey := data.keys[0]
	to := common.Address{1}

	var contractAddress common.Address
	eipContract := new(contracts.Eip2027)

	blockchain, blocks, receipts, err := genBlocks(data.genesisSpec, map[int]tx{
		0: {
			getBlockTx(from, to, big.NewInt(10)),
			fromKey,
		},
		1: {
			getBlockDeployEip2027Tx(data.transactOpts[0], &contractAddress, eipContract),
			fromKey,
		},
		2: {
			getBlockEip2027Tx(data.transactOpts[0], eipContract.Create, big.NewInt(2)),
			fromKey,
		},
		3: {
			getBlockEip2027Tx(data.transactOpts[0], eipContract.Update, big.NewInt(0)),
			fromKey,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	// BLOCK 1
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{blocks[0]}); err != nil {
		t.Fatal(err)
	}

	st, _, _ := blockchain.State()
	if !st.Exist(from) {
		t.Error("expected account to exist")
	}

	if st.Exist(contractAddress) {
		t.Error("expected contractAddress to not exist at the block 0", contractAddress.Hash().String())
	}

	// BLOCK 2
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{blocks[1]}); err != nil {
		t.Fatal(err)
	}

	st, _, _ = blockchain.State()
	if !st.Exist(from) {
		t.Error("expected account to exist")
	}

	if !st.Exist(contractAddress) {
		t.Error("expected contractAddress to exist at the block 2", contractAddress.Hash().String())
	}

	// BLOCK 3
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{blocks[2]}); err != nil {
		t.Fatal(err)
	}

	// BLOCK 4 - INCORRECT
	incorrectHeader := blocks[3].Header()
	incorrectHeader.Root = blocks[1].Header().Root
	incorrectBlock := types.NewBlock(incorrectHeader, blocks[3].Transactions(), blocks[3].Uncles(), receipts[3])

	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{incorrectBlock}); err == nil {
		t.Fatal("should fail")
	}

	// BLOCK 4
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{blocks[3]}); err != nil {
		t.Fatal(err)
	}
}

func TestAccountDeleteIncorrectRoot(t *testing.T) {
	data := getGenesis()
	from := data.addresses[0]
	fromKey := data.keys[0]
	to := common.Address{1}

	var contractAddress common.Address
	eipContract := new(contracts.Eip2027)

	blockchain, blocks, receipts, err := genBlocks(data.genesisSpec, map[int]tx{
		0: {
			getBlockTx(from, to, big.NewInt(10)),
			fromKey,
		},
		1: {
			getBlockDeployEip2027Tx(data.transactOpts[0], &contractAddress, eipContract),
			fromKey,
		},
		2: {
			getBlockEip2027Tx(data.transactOpts[0], eipContract.Create, big.NewInt(2)),
			fromKey,
		},
		3: {
			getBlockEip2027Tx(data.transactOpts[0], eipContract.Remove),
			fromKey,
		},
	})
	if err != nil {
		t.Fatal(err)
	}

	// BLOCK 1
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{blocks[0]}); err != nil {
		t.Fatal(err)
	}

	st, _, _ := blockchain.State()
	if !st.Exist(from) {
		t.Error("expected account to exist")
	}

	if st.Exist(contractAddress) {
		t.Error("expected contractAddress to not exist at the block 0", contractAddress.Hash().String())
	}

	// BLOCK 2
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{blocks[1]}); err != nil {
		t.Fatal(err)
	}

	st, _, _ = blockchain.State()
	if !st.Exist(from) {
		t.Error("expected account to exist")
	}

	if !st.Exist(contractAddress) {
		t.Error("expected contractAddress to exist at the block 1", contractAddress.Hash().String())
	}

	// BLOCK 3
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{blocks[2]}); err != nil {
		t.Fatal(err)
	}

	// BLOCK 4 - INCORRECT
	incorrectHeader := blocks[3].Header()
	incorrectHeader.Root = blocks[1].Header().Root
	incorrectBlock := types.NewBlock(incorrectHeader, blocks[3].Transactions(), blocks[3].Uncles(), receipts[3])

	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{incorrectBlock}); err == nil {
		t.Fatal("should fail")
	}

	// BLOCK 4
	if _, err = blockchain.InsertChain(context.Background(), types.Blocks{blocks[3]}); err != nil {
		t.Fatal(err)
	}
}

type initialData struct {
	keys         []*ecdsa.PrivateKey
	addresses    []common.Address
	transactOpts []*bind.TransactOpts
	genesisSpec  *core.Genesis
}

func getGenesis(funds ...*big.Int) initialData {
	accountFunds := big.NewInt(1000000000)
	if len(funds) > 0 {
		accountFunds = funds[0]
	}

	keys := make([]*ecdsa.PrivateKey, 3)
	keys[0], _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
	keys[1], _ = crypto.HexToECDSA("49a7b37aa6f6645917e7b807e9d1c00d4fa71f18343b0d4122a4d2df64dd6fee")
	keys[2], _ = crypto.HexToECDSA("8a1f9a8f95be41cd7ccb6168179afb4504aefe388d1e14474d32c45c72ce7b7a")

	addresses := make([]common.Address, 0, len(keys))
	transactOpts := make([]*bind.TransactOpts, 0, len(keys))
	allocs := core.GenesisAlloc{}
	for _, key := range keys {
		addr := crypto.PubkeyToAddress(key.PublicKey)
		addresses = append(addresses, addr)
		transactOpts = append(transactOpts, bind.NewKeyedTransactor(key))

		allocs[addr] = core.GenesisAccount{Balance: accountFunds}
	}

	return initialData{
		keys:         keys,
		addresses:    addresses,
		transactOpts: transactOpts,
		genesisSpec: &core.Genesis{
			Config: &params.ChainConfig{
				ChainID:             big.NewInt(1),
				HomesteadBlock:      new(big.Int),
				EIP150Block:         new(big.Int),
				EIP155Block:         new(big.Int),
				EIP158Block:         big.NewInt(1),
				ByzantiumBlock:      big.NewInt(1),
				ConstantinopleBlock: big.NewInt(1),
			},
			Alloc: allocs,
		},
	}
}

type tx struct {
	txFn blockTx
	key  *ecdsa.PrivateKey
}

func genBlocks(gspec *core.Genesis, txs map[int]tx) (*core.BlockChain, []*types.Block, []types.Receipts, error) {
	engine := ethash.NewFaker()
	db := ethdb.NewMemDatabase()
	genesis := gspec.MustCommit(db)
	genesisDb := db.MemCopy()

	blockchain, err := core.NewBlockChain(db, nil, gspec.Config, engine, vm.Config{}, nil)
	if err != nil {
		return nil, nil, nil, err
	}
	blockchain.EnableReceipts(true)

	contractBackend := backends.NewSimulatedBackendWithConfig(gspec.Alloc, gspec.Config, gspec.GasLimit)
	ctx := blockchain.WithContext(context.Background(), big.NewInt(genesis.Number().Int64()+1))

	var blockNumber int
	blocks, receipts := core.GenerateChain(ctx, gspec.Config, genesis, engine, genesisDb, len(txs), func(i int, block *core.BlockGen) {
		var tx *types.Transaction
		var isContractCall bool
		blockNumber = i
		signer := types.HomesteadSigner{}
		ctx = gspec.Config.WithEIPsFlags(ctx, block.Number())

		if txToSend, ok := txs[i]; ok {
			tx, isContractCall = txToSend.txFn(block, contractBackend)
			tx, err = types.SignTx(tx, signer, txToSend.key)
			if err != nil {
				return
			}
		}

		if tx != nil {
			if !isContractCall {
				err = contractBackend.SendTransaction(ctx, tx)
				if err != nil {
					return
				}
			}

			block.AddTx(tx)
		}

		contractBackend.Commit()
	})

	if err != nil {
		err = fmt.Errorf("block %d, error %v", blockNumber, err)
	}

	return blockchain, blocks, receipts, err
}

type blockTx func(_ *core.BlockGen, backend bind.ContractBackend) (*types.Transaction, bool)

func getBlockTx(from common.Address, to common.Address, amount *big.Int) blockTx {
	return func(block *core.BlockGen, _ bind.ContractBackend) (*types.Transaction, bool) {
		return types.NewTransaction(block.TxNonce(from), to, amount, 21000, new(big.Int), nil), false
	}
}

func getBlockDeployEip2027Tx(transactOpts *bind.TransactOpts, contractAddress *common.Address, eipContract *contracts.Eip2027) blockTx {
	return func(_ *core.BlockGen, backend bind.ContractBackend) (*types.Transaction, bool) {
		contractAddressRes, tx, eipContractRes, err := contracts.DeployEip2027(transactOpts, backend)
		if err != nil {
			panic(err)
		}

		*contractAddress = contractAddressRes
		*eipContract = *eipContractRes

		return tx, true
	}
}

func getBlockEip2027Tx(transactOpts *bind.TransactOpts, contractCall interface{}, newBalance ...*big.Int) blockTx {
	return func(_ *core.BlockGen, backend bind.ContractBackend) (*types.Transaction, bool) {
		var (
			tx  *types.Transaction
			err error
		)

		switch fn := contractCall.(type) {
		case func(opts *bind.TransactOpts) (*types.Transaction, error):
			tx, err = fn(transactOpts)
		case func(opts *bind.TransactOpts, newBalance *big.Int) (*types.Transaction, error):
			if len(newBalance) != 1 {
				panic("*big.Int type new balance is expected")
			}
			tx, err = fn(transactOpts, newBalance[0])
		default:
			panic("non expected function type")
		}

		if err != nil {
			panic(err)
		}

		return tx, true
	}
}