// Copyright 2018 The go-aurora Authors
// This file is part of the go-aurora library.
//
// The go-aurora library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-aurora library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-aurora library. If not, see <http://www.gnu.org/licenses/>.

package vm

import (
	"math/big"
	"sync/atomic"
	"time"

	"errors"
	"github.com/Aurorachain/go-aoa/common"
	"github.com/Aurorachain/go-aoa/core/types"
	"github.com/Aurorachain/go-aoa/crypto"
	"github.com/Aurorachain/go-aoa/log"
	"github.com/Aurorachain/go-aoa/params"
)

// emptyCodeHash is used by create to ensure deployment is disallowed to already
// deployed contract addresses (relevant after the account abstraction).
var emptyCodeHash = crypto.Keccak256Hash(nil)

type (
	//the last but one arg is the asset ID. when assetid is nil then it represents our main Cash AOA.
	CanTransferFunc func(StateDB, common.Address, *common.Address, *big.Int) bool
	TransferFunc    func(StateDB, common.Address, common.Address, *common.Address, *big.Int)
	// GetHashFunc returns the nth block hash in the blockchain
	// and is used by the BLOCKHASH EVM op code.
	GetHashFunc func(uint64) common.Hash
	VoteFunc    func(StateDB, common.Address, *big.Int, []types.Vote, *map[common.Address]types.Candidate, int64) error
)

// run runs the given contract and takes care of running precompiles with a fallback to the byte code interpreter.
func run(evm *EVM, contract *Contract, input []byte) ([]byte, error) {
	if contract.CodeAddr != nil {
		precompiles := PrecompiledContracts
		if p := precompiles[*contract.CodeAddr]; p != nil {
			return RunPrecompiledContract(p, input, contract)
		}
	}
	return evm.interpreter.Run(contract, input)
}

// Context provides the EVM with auxiliary information. Once provided
// it shouldn't be modified.
type Context struct {
	// CanTransfer returns whether the account contains
	// sufficient aoa to transfer the value
	CanTransfer CanTransferFunc
	// Transfer transfers aoa from one account to the other
	Transfer TransferFunc
	// GetHash returns the hash corresponding to n
	GetHash GetHashFunc

	Vote VoteFunc

	// Message information
	Origin   common.Address // Provides information for ORIGIN
	GasPrice *big.Int       // Provides information for GASPRICE

	// Block information
	Coinbase     common.Address // Provides information for COINBASE
	GasLimit     uint64         // Provides information for GASLIMIT
	BlockNumber  *big.Int       // Provides information for NUMBER
	Time         *big.Int       // Provides information for TIME
	Difficulty   *big.Int       // Provides information for DIFFICULTY
	DelegateList *map[common.Address]types.Candidate
}

// EVM is the Aurora Virtual Machine base object and provides
// the necessary tools to run a contract on the given state with
// the provided context. It should be noted that any error
// generated through any of the calls should be considered a
// revert-state-and-consume-all-gas operation, no checks on
// specific errors should ever be performed. The interpreter makes
// sure that any errors generated are to be considered faulty code.
//
// The EVM should never be reused and is not thread safe.
type EVM struct {
	// Context provides auxiliary blockchain related information
	Context
	// StateDB gives access to the underlying state
	StateDB StateDB
	// Depth is the current call stack
	depth int

	// chainConfig contains information about the current chain
	chainConfig *params.ChainConfig
	// chain rules contains the chain rules for the current epoch
	chainRules params.Rules
	// virtual machine configuration options used to initialise the
	// evm.
	vmConfig Config
	// global (to this context) Aurora virtual machine
	// used throughout the execution of the tx.
	interpreter *Interpreter
	// abort is used to abort the EVM calling operations
	// NOTE: must be set atomically
	abort int32
	// callGasTemp holds the gas available for the current call. This is needed because the
	// available gas is calculated in gasCall* according to the 63/64 rule and later
	// applied in opCall*.
	callGasTemp uint64
	//WatchInnerTx is the switch of when to really do the watching.
	WatchInnerTx bool
	//InnerTxs temporary save the internal transactions of a contract call in memory.
	InnerTxs []*types.InnerTx
}

var maxElectDelegate int64

// NewEVM retutrns a new EVM . The returned EVM is not thread safe and should
// only ever be used *once*.
func NewEVM(ctx Context, statedb StateDB, chainConfig *params.ChainConfig, vmConfig Config) *EVM {
	maxElectDelegate = chainConfig.MaxElectDelegate.Int64()
	evm := &EVM{
		Context:     ctx,
		StateDB:     statedb,
		vmConfig:    vmConfig,
		chainConfig: chainConfig,
		chainRules:  chainConfig.Rules(ctx.BlockNumber),
	}

	evm.interpreter = NewInterpreter(evm, vmConfig)
	return evm
}

// Cancel cancels any running EVM operation. This may be called concurrently and
// it's safe to be called multiple times.
func (evm *EVM) Cancel() {
	atomic.StoreInt32(&evm.abort, 1)
}

// Call executes the contract associated with the addr with the given input as
// parameters. It also handles any necessary value transfer required and takes
// the necessary steps to create accounts and reverses the state in case of an
// execution error or failed value transfer.
func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas uint64, action uint64, value *big.Int, args ...interface{}) (ret []byte, leftOverGas uint64, err error) {
	if evm.vmConfig.NoRecursion && evm.depth > 0 {
		return nil, gas, nil
	}
	var voteList []types.Vote
	var asset *common.Address
	for _, a := range args {
		switch a.(type) {
		case []types.Vote:
			voteList = a.([]types.Vote)
		case *common.Address:
			asset = a.(*common.Address)
		default:
			return nil, gas, errors.New("wrong parameter")
		}
	}

	// Fail if we're trying to execute above the call depth limit
	if evm.depth > int(params.CallCreateDepth) {
		return nil, gas, ErrDepth
	}
	// Fail if we're trying to transfer more than the available balance
	registerCost := new(big.Int)
	registerCost.SetString(params.TxGasAgentCreation, 10)


	checkValue := value
	if action == types.ActionSubVote {
		checkValue = big.NewInt(1).Mul(big.NewInt(-1), value)
	}

	if !evm.Context.CanTransfer(evm.StateDB, caller.Address(), asset, checkValue) ||
		(action == types.ActionRegister && !evm.Context.CanTransfer(evm.StateDB, caller.Address(), nil, registerCost)) {
		return nil, gas, ErrInsufficientBalance
	}

	var (
		to       = AccountRef(addr)
		snapshot = evm.StateDB.Snapshot()
	)
	if !evm.StateDB.Exist(addr) {
		precompiles := PrecompiledContracts
		if precompiles[addr] == nil && value.Sign() == 0 {
			if evm.vmConfig.Debug && evm.depth == 0 {
				evm.vmConfig.Tracer.CaptureStart(caller.Address(), addr, false, input, gas, value)
				evm.vmConfig.Tracer.CaptureEnd(ret, 0, 0, nil)
			}
			return nil, gas, nil
		}
		evm.StateDB.CreateAccount(addr)
	}
	if action == types.ActionAddVote || action == types.ActionSubVote {
		if len(voteList) == 0 {
			return nil, gas, errors.New("empty vote list")
		}
		err := evm.Vote(evm.StateDB, caller.Address(), value, voteList, evm.DelegateList, maxElectDelegate)
		if err != nil {
			log.Warn("HereVote", "err", err)
			evm.StateDB.RevertToSnapshot(snapshot, evm.chainConfig.IsEpiphron(evm.BlockNumber))
			return nil, gas, err
		}
	} else if action == types.ActionRegister {
		if _, ok := (*evm.DelegateList)[caller.Address()]; ok {
			return nil, gas, errors.New("Address " + caller.Address().Hex() + " have already register delegate")
		}
	} else {
		evm.Transfer(evm.StateDB, caller.Address(), to.Address(), asset, value)
	}

	// Initialise a new contract and set the code that is to be used by the EVM.
	// The contract is a scoped environment for this execution context only.
	contract := NewContract(caller, to, asset, value, gas)
	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))

	start := time.Now()

	// Capture the tracer start/end events in debug mode
	if evm.vmConfig.Debug && evm.depth == 0 {
		evm.vmConfig.Tracer.CaptureStart(caller.Address(), addr, false, input, gas, value)

		defer func() { // Lazy evaluation of the parameters
			evm.vmConfig.Tracer.CaptureEnd(ret, gas-contract.Gas, time.Since(start), err)
		}()
	}
	ret, err = run(evm, contract, input)

	// When an error was returned by the EVM or when setting the creation code
	// above we revert to the snapshot and consume any gas remaining. Additionally
	// when we're in homestead this also counts for code storage gas errors.
	if err != nil {
		evm.StateDB.RevertToSnapshot(snapshot, evm.chainConfig.IsEpiphron(evm.BlockNumber))
		if err != errExecutionReverted {
			contract.UseGas(contract.Gas)
		}
	}
	return ret, contract.Gas, err
}

// CallCode executes the contract associated with the addr with the given input
// as parameters. It also handles any necessary value transfer required and takes
// the necessary steps to create accounts and reverses the state in case of an
// execution error or failed value transfer.
//
// CallCode differs from Call in the sense that it executes the given address'
// code with the caller as context.
func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int) (ret []byte, leftOverGas uint64, err error) {
	if evm.vmConfig.NoRecursion && evm.depth > 0 {
		return nil, gas, nil
	}

	// Fail if we're trying to execute above the call depth limit
	if evm.depth > int(params.CallCreateDepth) {
		return nil, gas, ErrDepth
	}
	// Fail if we're trying to transfer more than the available balance
	if !evm.CanTransfer(evm.StateDB, caller.Address(), nil, value) {
		return nil, gas, ErrInsufficientBalance
	}

	var (
		snapshot = evm.StateDB.Snapshot()
		to       = AccountRef(caller.Address())
	)
	// initialise a new contract and set the code that is to be used by the
	// E The contract is a scoped evmironment for this execution context
	// only.
	contract := NewContract(caller, to, nil, value, gas)
	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))

	ret, err = run(evm, contract, input)
	if err != nil {
		evm.StateDB.RevertToSnapshot(snapshot, evm.chainConfig.IsEpiphron(evm.BlockNumber))
		if err != errExecutionReverted {
			contract.UseGas(contract.Gas)
		}
	}
	return ret, contract.Gas, err
}

// DelegateCall executes the contract associated with the addr with the given input
// as parameters. It reverses the state in case of an execution error.
//
// DelegateCall differs from CallCode in the sense that it executes the given address'
// code with the caller as context and the caller is set to the caller of the caller.
func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []byte, gas uint64) (ret []byte, leftOverGas uint64, err error) {
	if evm.vmConfig.NoRecursion && evm.depth > 0 {
		return nil, gas, nil
	}
	// Fail if we're trying to execute above the call depth limit
	if evm.depth > int(params.CallCreateDepth) {
		return nil, gas, ErrDepth
	}

	var (
		snapshot = evm.StateDB.Snapshot()
		to       = AccountRef(caller.Address())
	)

	// Initialise a new contract and make initialise the delegate values
	contract := NewContract(caller, to, nil, nil, gas).AsDelegate()
	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))

	ret, err = run(evm, contract, input)
	if err != nil {
		evm.StateDB.RevertToSnapshot(snapshot, evm.chainConfig.IsEpiphron(evm.BlockNumber))
		if err != errExecutionReverted {
			contract.UseGas(contract.Gas)
		}
	}
	return ret, contract.Gas, err
}

// StaticCall executes the contract associated with the addr with the given input
// as parameters while disallowing any modifications to the state during the call.
// Opcodes that attempt to perform such modifications will result in exceptions
// instead of performing the modifications.
func (evm *EVM) StaticCall(caller ContractRef, addr common.Address, input []byte, gas uint64) (ret []byte, leftOverGas uint64, err error) {
	if evm.vmConfig.NoRecursion && evm.depth > 0 {
		return nil, gas, nil
	}
	// Fail if we're trying to execute above the call depth limit
	if evm.depth > int(params.CallCreateDepth) {
		return nil, gas, ErrDepth
	}
	// Make sure the readonly is only set if we aren't in readonly yet
	// this makes also sure that the readonly flag isn't removed for
	// child calls.
	if !evm.interpreter.readOnly {
		evm.interpreter.readOnly = true
		defer func() { evm.interpreter.readOnly = false }()
	}

	var (
		to       = AccountRef(addr)
		snapshot = evm.StateDB.Snapshot()
	)
	// Initialise a new contract and set the code that is to be used by the
	// EVM. The contract is a scoped environment for this execution context
	// only.
	contract := NewContract(caller, to, nil, new(big.Int), gas)
	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))

	// When an error was returned by the EVM or when setting the creation code
	// above we revert to the snapshot and consume any gas remaining. Additionally
	// when we're in Homestead this also counts for code storage gas errors.
	ret, err = run(evm, contract, input)
	if err != nil {
		evm.StateDB.RevertToSnapshot(snapshot, evm.chainConfig.IsEpiphron(evm.BlockNumber))
		if err != errExecutionReverted {
			contract.UseGas(contract.Gas)
		}
	}
	return ret, contract.Gas, err
}

// Create creates a new contract using code as deployment code.
func (evm *EVM) Create(caller ContractRef, code []byte, gas uint64, asset *common.Address, value *big.Int, abi string) (ret []byte, contractAddr common.Address, leftOverGas uint64, err error) {

	// Depth check execution. Fail if we're trying to execute above the
	// limit.
	if evm.depth > int(params.CallCreateDepth) {
		return nil, common.Address{}, gas, ErrDepth
	}
	if !evm.CanTransfer(evm.StateDB, caller.Address(), asset, value) {
		return nil, common.Address{}, gas, ErrInsufficientBalance
	}
	// Ensure there's no existing contract already at the designated address
	nonce := evm.StateDB.GetNonce(caller.Address())
	evm.StateDB.SetNonce(caller.Address(), nonce+1)

	contractAddr = crypto.CreateAddress(caller.Address(), nonce)
	contractHash := evm.StateDB.GetCodeHash(contractAddr)
	if evm.StateDB.GetNonce(contractAddr) != 0 || (contractHash != (common.Hash{}) && contractHash != emptyCodeHash) {
		return nil, common.Address{}, 0, ErrContractAddressCollision
	}
	// Create a new account on the state
	snapshot := evm.StateDB.Snapshot()
	evm.StateDB.CreateAccount(contractAddr)
	//if evm.ChainConfig().IsEIP158(evm.BlockNumber) {
	//	evm.StateDB.SetNonce(contractAddr, 1)
	//}
	evm.Transfer(evm.StateDB, caller.Address(), contractAddr, asset, value)

	// initialise a new contract and set the code that is to be used by the
	// E The contract is a scoped evmironment for this execution context
	// only.
	contract := NewContract(caller, AccountRef(contractAddr), asset, value, gas)
	contract.SetCallCode(&contractAddr, crypto.Keccak256Hash(code), code)

	if evm.vmConfig.NoRecursion && evm.depth > 0 {
		return nil, contractAddr, gas, nil
	}

	if evm.vmConfig.Debug && evm.depth == 0 {
		evm.vmConfig.Tracer.CaptureStart(caller.Address(), contractAddr, true, code, gas, value)
	}
	start := time.Now()

	ret, err = run(evm, contract, nil)

	// check whether the max code size has been exceeded
	maxCodeSizeExceeded := len(ret) > params.MaxCodeSize
	// if the contract creation ran successfully and no errors were returned
	// calculate the gas required to store the code. If the code could not
	// be stored due to not enough gas set an error and let it be handled
	// by the error checking condition below.
	if err == nil && !maxCodeSizeExceeded {
		createDataGas := uint64(len(ret)) * params.CreateDataGas
		createDataGas += uint64(len(abi)) * params.TxABIGas
		if contract.UseGas(createDataGas) {
			evm.StateDB.SetCode(contractAddr, ret)
			evm.StateDB.SetAbi(contractAddr, abi)
		} else {
			err = ErrCodeStoreOutOfGas
		}
	}

	// When an error was returned by the EVM or when setting the creation code
	// above we revert to the snapshot and consume any gas remaining. Additionally
	// when we're in homestead this also counts for code storage gas errors.
	if maxCodeSizeExceeded || (err != nil && (err != ErrCodeStoreOutOfGas)) {
		evm.StateDB.RevertToSnapshot(snapshot, evm.chainConfig.IsEpiphron(evm.BlockNumber))
		if err != errExecutionReverted {
			contract.UseGas(contract.Gas)
		}
	}
	// Assign err if contract code size exceeds the max while the err is still empty.
	if maxCodeSizeExceeded && err == nil {
		err = errMaxCodeSizeExceeded
	}
	if evm.vmConfig.Debug && evm.depth == 0 {
		evm.vmConfig.Tracer.CaptureEnd(ret, gas-contract.Gas, time.Since(start), err)
	}
	return ret, contractAddr, contract.Gas, err
}

// ChainConfig returns the environment's chain configuration
func (evm *EVM) ChainConfig() *params.ChainConfig { return evm.chainConfig }

// Interpreter returns the EVM interpreter
func (evm *EVM) Interpreter() *Interpreter { return evm.interpreter }

func (evm *EVM) watchInnerTx(from common.Address, to common.Address, asset *common.Address, value *big.Int) {
	if evm.WatchInnerTx && evm.vmConfig.WatchInnerTx && big.NewInt(0).Cmp(value) < 0 {
		itx := types.InnerTx{From: from, To: to, AssetID: asset, Value: new(big.Int).Set(value)}
		evm.InnerTxs = append(evm.InnerTxs, &itx)
	}
}
