func (self *XEth) AtStateNum(num int64) *XEth {
	var st *state.StateDB
	switch num {
	case -2:
		st = self.backend.Miner().PendingState().Copy()
	default:
		if block := self.getBlockByHeight(num); block != nil {
			st = state.New(block.Root(), self.backend.StateDb())
		} else {
			st = state.New(self.backend.ChainManager().GetBlockByNumber(0).Root(), self.backend.StateDb())
		}
	}

	return self.WithState(st)
}

// GenerateChain creates a chain of n blocks. The first block's
// parent will be the provided parent. db is used to store
// intermediate states and should contain the parent's state trie.
//
// The generator function is called with a new block generator for
// every block. Any transactions and uncles added to the generator
// become part of the block. If gen is nil, the blocks will be empty
// and their coinbase will be the zero address.
//
// Blocks created by GenerateChain do not contain valid proof of work
// values. Inserting them into BlockChain requires use of FakePow or
// a similar non-validating proof of work implementation.
func GenerateChain(parent *types.Block, db ethdb.Database, n int, gen func(int, *BlockGen)) ([]*types.Block, []types.Receipts) {
	statedb, err := state.New(parent.Root(), db)
	if err != nil {
		panic(err)
	}
	blocks, receipts := make(types.Blocks, n), make([]types.Receipts, n)
	genblock := func(i int, h *types.Header) (*types.Block, types.Receipts) {
		b := &BlockGen{parent: parent, i: i, chain: blocks, header: h, statedb: statedb}
		if gen != nil {
			gen(i, b)
		}
		AccumulateRewards(statedb, h, b.uncles)
		root, err := statedb.Commit()
		if err != nil {
			panic(fmt.Sprintf("state write error: %v", err))
		}
		h.Root = root
		return types.NewBlock(h, b.txs, b.uncles, b.receipts), b.receipts
	}
	for i := 0; i < n; i++ {
		header := makeHeader(parent, statedb)
		block, receipt := genblock(i, header)
		blocks[i] = block
		receipts[i] = receipt
		parent = block
	}
	return blocks, receipts
}

// Equivalent of the tx-pool state; updated by CheckTx and replaced on commit
// For now, we just return the last block state
func (app *EthereumApplication) ManagedState() *state.ManagedState {
	st, err := state.New(app.StateRoot(), app.ethereum.ChainDb())
	if err != nil {
		return nil // (?!)
	}
	return state.ManageState(st)
}

// GenesisBlock creates a genesis block with the given nonce.
func GenesisBlock(nonce uint64, db common.Database) *types.Block {
	var accounts map[string]struct {
		Balance string
		Code    string
	}
	err := json.Unmarshal(GenesisAccounts, &accounts)
	if err != nil {
		fmt.Println("unable to decode genesis json data:", err)
		os.Exit(1)
	}
	statedb := state.New(common.Hash{}, db)
	for addr, account := range accounts {
		codedAddr := common.Hex2Bytes(addr)
		accountState := statedb.CreateAccount(common.BytesToAddress(codedAddr))
		accountState.SetBalance(common.Big(account.Balance))
		accountState.SetCode(common.FromHex(account.Code))
		statedb.UpdateStateObject(accountState)
	}
	statedb.Sync()

	block := types.NewBlock(&types.Header{
		Difficulty: params.GenesisDifficulty,
		GasLimit:   params.GenesisGasLimit,
		Nonce:      types.EncodeNonce(nonce),
		Root:       statedb.Root(),
	}, nil, nil, nil)
	block.Td = params.GenesisDifficulty
	return block
}

// Execute executes the code using the input as call data during the execution.
// It returns the EVM's return value, the new state and an error if it failed.
//
// Executes sets up a in memory, temporarily, environment for the execution of
// the given code. It enabled the JIT by default and make sure that it's restored
// to it's original state afterwards.
func Execute(code, input []byte, cfg *Config) ([]byte, *state.StateDB, error) {
	if cfg == nil {
		cfg = new(Config)
	}
	setDefaults(cfg)

	if cfg.State == nil {
		db, _ := ethdb.NewMemDatabase()
		cfg.State, _ = state.New(common.Hash{}, db)
	}
	var (
		vmenv    = NewEnv(cfg, cfg.State)
		sender   = cfg.State.CreateAccount(cfg.Origin)
		receiver = cfg.State.CreateAccount(common.StringToAddress("contract"))
	)
	// set the receiver's (the executing contract) code for execution.
	receiver.SetCode(code)

	// Call the code with the given configuration.
	ret, err := vmenv.Call(
		sender,
		receiver.Address(),
		input,
		cfg.GasLimit,
		cfg.GasPrice,
		cfg.Value,
	)

	return ret, cfg.State, err
}

func TestTransactionChainFork(t *testing.T) {
	pool, key := setupTxPool()
	addr := crypto.PubkeyToAddress(key.PublicKey)
	resetState := func() {
		db, _ := ethdb.NewMemDatabase()
		statedb, _ := state.New(common.Hash{}, db)
		pool.currentState = func() (*state.StateDB, error) { return statedb, nil }
		currentState, _ := pool.currentState()
		currentState.AddBalance(addr, big.NewInt(100000000000000))
		pool.resetState()
	}
	resetState()

	tx := transaction(0, big.NewInt(100000), key)
	if err := pool.add(tx); err != nil {
		t.Error("didn't expect error", err)
	}
	pool.RemoveTransactions([]*types.Transaction{tx})

	// reset the pool's internal state
	resetState()
	if err := pool.add(tx); err != nil {
		t.Error("didn't expect error", err)
	}
}

func (self *XEth) LatestState() *XEth {
	st, err := state.New(self.StateRoot(), self.backend.ChainDb())
	if err != nil {
		return nil
	}
	return self.WithState(st)
}

// testBlockChainImport tries to process a chain of blocks, writing them into
// the database if successful.
func testBlockChainImport(chain types.Blocks, blockchain *BlockChain) error {
	for _, block := range chain {
		// Try and process the block
		err := blockchain.Validator().ValidateBlock(block)
		if err != nil {
			if IsKnownBlockErr(err) {
				continue
			}
			return err
		}
		statedb, err := state.New(blockchain.GetBlock(block.ParentHash()).Root(), blockchain.chainDb)
		if err != nil {
			return err
		}
		receipts, _, usedGas, err := blockchain.Processor().Process(block, statedb)
		if err != nil {
			reportBlock(block, err)
			return err
		}
		err = blockchain.Validator().ValidateState(block, blockchain.GetBlock(block.ParentHash()), statedb, receipts, usedGas)
		if err != nil {
			reportBlock(block, err)
			return err
		}
		blockchain.mu.Lock()
		WriteTd(blockchain.chainDb, block.Hash(), new(big.Int).Add(block.Difficulty(), blockchain.GetTd(block.ParentHash())))
		WriteBlock(blockchain.chainDb, block)
		statedb.Commit()
		blockchain.mu.Unlock()
	}
	return nil
}

func (js *jsre) dumpBlock(call otto.FunctionCall) otto.Value {
	var block *types.Block
	if len(call.ArgumentList) > 0 {
		if call.Argument(0).IsNumber() {
			num, _ := call.Argument(0).ToInteger()
			block = js.ethereum.ChainManager().GetBlockByNumber(uint64(num))
		} else if call.Argument(0).IsString() {
			hash, _ := call.Argument(0).ToString()
			block = js.ethereum.ChainManager().GetBlock(common.HexToHash(hash))
		} else {
			fmt.Println("invalid argument for dump. Either hex string or number")
		}

	} else {
		block = js.ethereum.ChainManager().CurrentBlock()
	}
	if block == nil {
		fmt.Println("block not found")
		return otto.UndefinedValue()
	}

	statedb := state.New(block.Root(), js.ethereum.StateDb())
	dump := statedb.RawDump()
	return js.re.ToVal(dump)

}

// makeCurrent creates a new environment for the current cycle.
func (self *worker) makeCurrent(parent *types.Block, header *types.Header) {
	state := state.New(parent.Root(), self.eth.ChainDb())
	work := &Work{
		state:     state,
		ancestors: set.New(),
		family:    set.New(),
		uncles:    set.New(),
		header:    header,
		coinbase:  state.GetOrNewStateObject(self.coinbase),
		createdAt: time.Now(),
	}

	// when 08 is processed ancestors contain 07 (quick block)
	for _, ancestor := range self.chain.GetBlocksFromHash(parent.Hash(), 7) {
		for _, uncle := range ancestor.Uncles() {
			work.family.Add(uncle.Hash())
		}
		work.family.Add(ancestor.Hash())
		work.ancestors.Add(ancestor.Hash())
	}
	accounts, _ := self.eth.AccountManager().Accounts()

	// Keep track of transactions which return errors so they can be removed
	work.remove = set.New()
	work.tcount = 0
	work.ignoredTransactors = set.New()
	work.lowGasTransactors = set.New()
	work.ownedAccounts = accountAddressesSet(accounts)
	if self.current != nil {
		work.localMinedBlocks = self.current.localMinedBlocks
	}
	self.current = work
}

func (self *Gui) DumpState(hash, path string) {
	var stateDump []byte

	if len(hash) == 0 {
		stateDump = self.eth.ChainManager().State().Dump()
	} else {
		var block *types.Block
		if hash[0] == '#' {
			i, _ := strconv.Atoi(hash[1:])
			block = self.eth.ChainManager().GetBlockByNumber(uint64(i))
		} else {
			block = self.eth.ChainManager().GetBlock(common.HexToHash(hash))
		}

		if block == nil {
			guilogger.Infof("block err: not found %s\n", hash)
			return
		}

		stateDump = state.New(block.Root(), self.eth.StateDb()).Dump()
	}

	file, err := os.OpenFile(path[7:], os.O_CREATE|os.O_RDWR, os.ModePerm)
	if err != nil {
		guilogger.Infoln("dump err: ", err)
		return
	}
	defer file.Close()

	guilogger.Infof("dumped state (%s) to %s\n", hash, path)

	file.Write(stateDump)
}

// subscribes to new head block events and
// waits until blockchain height is greater n at any time
// given the current head, waits for the next chain event
// sets the state to the current head
// loop is async and quit by closing the channel
// used in tests and JS console debug module to control advancing private chain manually
// Note: this is not threadsafe, only called in JS single process and tests
func (self *XEth) UpdateState() (wait chan *big.Int) {
	wait = make(chan *big.Int)
	go func() {
		sub := self.backend.EventMux().Subscribe(core.ChainHeadEvent{})
		var m, n *big.Int
		var ok bool
	out:
		for {
			select {
			case event := <-sub.Chan():
				ev, ok := event.(core.ChainHeadEvent)
				if ok {
					m = ev.Block.Number()
					if n != nil && n.Cmp(m) < 0 {
						wait <- n
						n = nil
					}
					statedb := state.New(ev.Block.Root(), self.backend.StateDb())
					self.state = NewState(self, statedb)
				}
			case n, ok = <-wait:
				if !ok {
					break out
				}
			}
		}
		sub.Unsubscribe()
	}()
	return
}

func TestTransactionDoubleNonce(t *testing.T) {
	pool, key := setupTxPool()
	addr := crypto.PubkeyToAddress(key.PublicKey)
	resetState := func() {
		db, _ := ethdb.NewMemDatabase()
		statedb := state.New(common.Hash{}, db)
		pool.currentState = func() *state.StateDB { return statedb }
		pool.currentState().AddBalance(addr, big.NewInt(100000000000000))
		pool.resetState()
	}
	resetState()

	tx := transaction(0, big.NewInt(100000), key)
	tx2 := transaction(0, big.NewInt(1000000), key)
	if err := pool.add(tx); err != nil {
		t.Error("didn't expect error", err)
	}
	if err := pool.add(tx2); err != nil {
		t.Error("didn't expect error", err)
	}

	pool.checkQueue()
	if len(pool.pending) != 2 {
		t.Error("expected 2 pending txs. Got", len(pool.pending))
	}
}

// Process block will attempt to process the given block's transactions and applies them
// on top of the block's parent state (given it exists) and will return wether it was
// successful or not.
func (sm *BlockProcessor) Process(block *types.Block) (logs vm.Logs, receipts types.Receipts, err error) {
	// Processing a blocks may never happen simultaneously
	sm.mutex.Lock()
	defer sm.mutex.Unlock()

	if sm.bc.HasBlock(block.Hash()) {
		if _, err := state.New(block.Root(), sm.chainDb); err == nil {
			return nil, nil, &KnownBlockError{block.Number(), block.Hash()}
		}
	}
	if parent := sm.bc.GetBlock(block.ParentHash()); parent != nil {
		if _, err := state.New(parent.Root(), sm.chainDb); err == nil {
			return sm.processWithParent(block, parent)
		}
	}
	return nil, nil, ParentError(block.ParentHash())
}

func setupTxPool() (*TxPool, *ecdsa.PrivateKey) {
	db, _ := ethdb.NewMemDatabase()
	statedb := state.New(common.Hash{}, db)

	var m event.TypeMux
	key, _ := crypto.GenerateKey()
	return NewTxPool(&m, func() *state.StateDB { return statedb }, func() *big.Int { return big.NewInt(1000000) }), key
}

// StorageAt returns the data stores in the state for the given address and location.
func (be *registryAPIBackend) StorageAt(addr string, storageAddr string) string {
	block := be.bc.CurrentBlock()
	state, err := state.New(block.Root(), be.chainDb)
	if err != nil {
		return ""
	}
	return state.GetState(common.HexToAddress(addr), common.HexToHash(storageAddr)).Hex()
}

// WriteBlock writes the block to the chain (or pending queue)
func (self *ChainManager) WriteBlock(block *types.Block, queued bool) (status writeStatus, err error) {
	self.wg.Add(1)
	defer self.wg.Done()

	cblock := self.currentBlock
	// Compare the TD of the last known block in the canonical chain to make sure it's greater.
	// At this point it's possible that a different chain (fork) becomes the new canonical chain.
	if block.Td.Cmp(self.Td()) > 0 {
		// chain fork
		if block.ParentHash() != cblock.Hash() {
			// during split we merge two different chains and create the new canonical chain
			err := self.merge(cblock, block)
			if err != nil {
				return nonStatTy, err
			}

			status = splitStatTy
		}

		self.mu.Lock()
		self.setTotalDifficulty(block.Td)
		self.insert(block)
		self.mu.Unlock()

		self.setTransState(state.New(block.Root(), self.stateDb))
		self.txState.SetState(state.New(block.Root(), self.stateDb))

		status = canonStatTy
	} else {
		status = sideStatTy
	}

	if queued {
		// Write block to database. Eventually we'll have to improve on this and throw away blocks that are
		// not in the canonical chain.
		self.mu.Lock()
		self.enqueueForWrite(block)
		self.mu.Unlock()
	} else {
		self.write(block)
	}
	// Delete from future blocks
	self.futureBlocks.Remove(block.Hash())

	return
}

func setupTxPool() (*TxPool, *ecdsa.PrivateKey) {
	db, _ := ethdb.NewMemDatabase()
	statedb, _ := state.New(common.Hash{}, db)

	var m event.TypeMux
	key, _ := crypto.GenerateKey()
	newPool := NewTxPool(testChainConfig(), &m, func() (*state.StateDB, error) { return statedb, nil }, func() *big.Int { return big.NewInt(1000000) })
	newPool.resetState()
	return newPool, key
}

// HasBlockAndState checks if a block and associated state trie is fully present
// in the database or not, caching it if present.
func (bc *BlockChain) HasBlockAndState(hash common.Hash) bool {
	// Check first that the block itself is known
	block := bc.GetBlock(hash)
	if block == nil {
		return false
	}
	// Ensure the associated state is also present
	_, err := state.New(block.Root(), bc.chainDb)
	return err == nil
}

// WriteBlock writes the block to the chain (or pending queue)
func (self *ChainManager) WriteBlock(block *types.Block, queued bool) (status writeStatus, err error) {
	self.wg.Add(1)
	defer self.wg.Done()

	cblock := self.currentBlock
	// Compare the TD of the last known block in the canonical chain to make sure it's greater.
	// At this point it's possible that a different chain (fork) becomes the new canonical chain.
	if block.Td.Cmp(self.Td()) > 0 {
		// chain fork
		if block.ParentHash() != cblock.Hash() {
			// during split we merge two different chains and create the new canonical chain
			err := self.merge(cblock, block)
			if err != nil {
				return NonStatTy, err
			}

			status = SplitStatTy
		}

		self.mu.Lock()
		self.setTotalDifficulty(block.Td)
		self.insert(block)
		self.mu.Unlock()

		self.setTransState(state.New(block.Root(), self.stateDb))
		self.txState.SetState(state.New(block.Root(), self.stateDb))

		status = CanonStatTy
	} else {
		status = SideStatTy
	}

	err = WriteBlock(self.blockDb, block)
	if err != nil {
		glog.Fatalln("db err:", err)
	}
	// Delete from future blocks
	self.futureBlocks.Remove(block.Hash())

	return
}