// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum 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-ethereum 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-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package core

import (
	"errors"
	"fmt"
	"math/big"
	"time"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/consensus"
	"github.com/ethereum/go-ethereum/consensus/misc"
	"github.com/ethereum/go-ethereum/core/state"
	"github.com/ethereum/go-ethereum/core/systemcontracts"
	"github.com/ethereum/go-ethereum/core/tracing"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/core/vm"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/log"
	"github.com/ethereum/go-ethereum/params"
)

const largeTxGasLimit = 10000000 // 10M Gas, to measure the execution time of large tx

// StateProcessor is a basic Processor, which takes care of transitioning
// state from one point to another.
//
// StateProcessor implements Processor.
type StateProcessor struct {
	config *params.ChainConfig // Chain configuration options
	chain  *HeaderChain        // Canonical header chain
}

// NewStateProcessor initialises a new StateProcessor.
func NewStateProcessor(config *params.ChainConfig, chain *HeaderChain) *StateProcessor {
	return &StateProcessor{
		config: config,
		chain:  chain,
	}
}

// Process processes the state changes according to the Ethereum rules by running
// the transaction messages using the statedb and applying any rewards to both
// the processor (coinbase) and any included uncles.
//
// Process returns the receipts and logs accumulated during the process and
// returns the amount of gas that was used in the process. If any of the
// transactions failed to execute due to insufficient gas it will return an error.
func (p *StateProcessor) Process(block *types.Block, statedb *state.StateDB, cfg vm.Config) (*ProcessResult, error) {
	var (
		receipts    = make([]*types.Receipt, 0)
		usedGas     = new(uint64)
		header      = block.Header()
		blockHash   = block.Hash()
		blockNumber = block.Number()
		allLogs     []*types.Log
		gp          = new(GasPool).AddGas(block.GasLimit())
	)

	// Mutate the block and state according to any hard-fork specs
	if p.config.DAOForkSupport && p.config.DAOForkBlock != nil && p.config.DAOForkBlock.Cmp(block.Number()) == 0 {
		misc.ApplyDAOHardFork(statedb)
	}

	lastBlock := p.chain.GetHeaderByHash(block.ParentHash())
	if lastBlock == nil {
		return nil, errors.New("could not get parent block")
	}
	// Handle upgrade built-in system contract code
	systemcontracts.TryUpdateBuildInSystemContract(p.config, blockNumber, lastBlock.Time, block.Time(), statedb, true)

	var (
		context vm.BlockContext
		signer  = types.MakeSigner(p.config, header.Number, header.Time)
		txNum   = len(block.Transactions())
		err     error
	)

	// Apply pre-execution system calls.
	var tracingStateDB = vm.StateDB(statedb)
	if hooks := cfg.Tracer; hooks != nil {
		tracingStateDB = state.NewHookedState(statedb, hooks)
	}
	context = NewEVMBlockContext(header, p.chain, nil)
	evm := vm.NewEVM(context, tracingStateDB, p.config, cfg)

	if beaconRoot := block.BeaconRoot(); beaconRoot != nil {
		ProcessBeaconBlockRoot(*beaconRoot, evm)
	}
	if p.config.IsPrague(block.Number(), block.Time()) || p.config.IsVerkle(block.Number(), block.Time()) {
		ProcessParentBlockHash(block.ParentHash(), evm)
	}

	// Iterate over and process the individual transactions
	posa, isPoSA := p.chain.engine.(consensus.PoSA)
	commonTxs := make([]*types.Transaction, 0, txNum)

	// initialise bloom processors
	bloomProcessors := NewAsyncReceiptBloomGenerator(txNum)

	// usually do have two tx, one for validator set contract, another for system reward contract.
	systemTxs := make([]*types.Transaction, 0, 2)

	for i, tx := range block.Transactions() {
		if isPoSA {
			if isSystemTx, err := posa.IsSystemTransaction(tx, block.Header()); err != nil {
				bloomProcessors.Close()
				return nil, err
			} else if isSystemTx {
				systemTxs = append(systemTxs, tx)
				continue
			}
		}
		if p.config.IsCancun(block.Number(), block.Time()) {
			if len(systemTxs) > 0 {
				bloomProcessors.Close()
				// systemTxs should be always at the end of block.
				return nil, fmt.Errorf("normal tx %d [%v] after systemTx", i, tx.Hash().Hex())
			}
		}

		msg, err := TransactionToMessage(tx, signer, header.BaseFee)
		if err != nil {
			bloomProcessors.Close()
			return nil, fmt.Errorf("could not apply tx %d [%v]: %w", i, tx.Hash().Hex(), err)
		}
		statedb.SetTxContext(tx.Hash(), i)

		receipt, err := ApplyTransactionWithEVM(msg, gp, statedb, blockNumber, blockHash, context.Time, tx, usedGas, evm, bloomProcessors)
		if err != nil {
			bloomProcessors.Close()
			return nil, fmt.Errorf("could not apply tx %d [%v]: %w", i, tx.Hash().Hex(), err)
		}
		commonTxs = append(commonTxs, tx)
		receipts = append(receipts, receipt)
	}
	bloomProcessors.Close()

	// Read requests if Prague is enabled.
	var requests [][]byte
	if p.config.IsPrague(block.Number(), block.Time()) && p.chain.config.Parlia == nil {
		var allCommonLogs []*types.Log
		for _, receipt := range receipts {
			allCommonLogs = append(allCommonLogs, receipt.Logs...)
		}
		requests = [][]byte{}
		// EIP-6110
		if err := ParseDepositLogs(&requests, allCommonLogs, p.config); err != nil {
			return nil, err
		}
		// EIP-7002
		if err := ProcessWithdrawalQueue(&requests, evm); err != nil {
			return nil, err
		}
		// EIP-7251
		if err := ProcessConsolidationQueue(&requests, evm); err != nil {
			return nil, err
		}
	}

	// Finalize the block, applying any consensus engine specific extras (e.g. block rewards)
	err = p.chain.engine.Finalize(p.chain, header, tracingStateDB, &commonTxs, block.Uncles(), block.Withdrawals(), &receipts, &systemTxs, usedGas, cfg.Tracer)
	if err != nil {
		return nil, err
	}
	for _, receipt := range receipts {
		allLogs = append(allLogs, receipt.Logs...)
	}

	return &ProcessResult{
		Receipts: receipts,
		Requests: requests,
		Logs:     allLogs,
		GasUsed:  *usedGas,
	}, nil
}

// ApplyTransactionWithEVM attempts to apply a transaction to the given state database
// and uses the input parameters for its environment similar to ApplyTransaction. However,
// this method takes an already created EVM instance as input.
func ApplyTransactionWithEVM(msg *Message, gp *GasPool, statedb *state.StateDB, blockNumber *big.Int, blockHash common.Hash, blockTime uint64, tx *types.Transaction, usedGas *uint64, evm *vm.EVM, receiptProcessors ...ReceiptProcessor) (receipt *types.Receipt, err error) {
	// Add timing measurement
	var result *ExecutionResult
	if tx.Gas() > largeTxGasLimit {
		start := time.Now()
		defer func() {
			if result != nil && result.UsedGas > largeTxGasLimit {
				elapsed := time.Since(start)
				log.Info("LargeTX execution time", "block", blockNumber, "tx", tx.Hash(), "gasUsed", result.UsedGas, "elapsed", elapsed)
			}
		}()
	}

	if hooks := evm.Config.Tracer; hooks != nil {
		if hooks.OnTxStart != nil {
			hooks.OnTxStart(evm.GetVMContext(), tx, msg.From)
		}
		if hooks.OnTxEnd != nil {
			defer func() { hooks.OnTxEnd(receipt, err) }()
		}
	}
	// Apply the transaction to the current state (included in the env).
	result, err = ApplyMessage(evm, msg, gp)
	if err != nil {
		return nil, err
	}
	// Update the state with pending changes.
	var root []byte
	if evm.ChainConfig().IsByzantium(blockNumber) {
		evm.StateDB.Finalise(true)
	} else {
		root = statedb.IntermediateRoot(evm.ChainConfig().IsEIP158(blockNumber)).Bytes()
	}
	*usedGas += result.UsedGas

	// Merge the tx-local access event into the "block-local" one, in order to collect
	// all values, so that the witness can be built.
	if statedb.Database().TrieDB().IsVerkle() {
		statedb.AccessEvents().Merge(evm.AccessEvents)
	}

	return MakeReceipt(evm, result, statedb, blockNumber, blockHash, blockTime, tx, *usedGas, root, receiptProcessors...), nil
}

// MakeReceipt generates the receipt object for a transaction given its execution result.
func MakeReceipt(evm *vm.EVM, result *ExecutionResult, statedb *state.StateDB, blockNumber *big.Int, blockHash common.Hash, blockTime uint64, tx *types.Transaction, usedGas uint64, root []byte, receiptProcessors ...ReceiptProcessor) *types.Receipt {
	// Create a new receipt for the transaction, storing the intermediate root and gas used
	// by the tx.
	receipt := &types.Receipt{Type: tx.Type(), PostState: root, CumulativeGasUsed: usedGas}
	if result.Failed() {
		receipt.Status = types.ReceiptStatusFailed
	} else {
		receipt.Status = types.ReceiptStatusSuccessful
	}
	receipt.TxHash = tx.Hash()
	receipt.GasUsed = result.UsedGas

	if tx.Type() == types.BlobTxType {
		receipt.BlobGasUsed = uint64(len(tx.BlobHashes()) * params.BlobTxBlobGasPerBlob)
		receipt.BlobGasPrice = evm.Context.BlobBaseFee
	}

	// If the transaction created a contract, store the creation address in the receipt.
	if tx.To() == nil {
		receipt.ContractAddress = crypto.CreateAddress(evm.TxContext.Origin, tx.Nonce())
	}

	// Set the receipt logs and create the bloom filter.
	receipt.Logs = statedb.GetLogs(tx.Hash(), blockNumber.Uint64(), blockHash, blockTime)
	receipt.BlockHash = blockHash
	receipt.BlockNumber = blockNumber
	receipt.TransactionIndex = uint(statedb.TxIndex())
	for _, receiptProcessor := range receiptProcessors {
		receiptProcessor.Apply(receipt)
	}
	return receipt
}

// ApplyTransaction attempts to apply a transaction to the given state database
// and uses the input parameters for its environment. It returns the receipt
// for the transaction, gas used and an error if the transaction failed,
// indicating the block was invalid.
func ApplyTransaction(evm *vm.EVM, gp *GasPool, statedb *state.StateDB, header *types.Header, tx *types.Transaction, usedGas *uint64, receiptProcessors ...ReceiptProcessor) (*types.Receipt, error) {
	msg, err := TransactionToMessage(tx, types.MakeSigner(evm.ChainConfig(), header.Number, header.Time), header.BaseFee)
	if err != nil {
		return nil, err
	}
	// Create a new context to be used in the EVM environment
	return ApplyTransactionWithEVM(msg, gp, statedb, header.Number, header.Hash(), header.Time, tx, usedGas, evm, receiptProcessors...)
}

// ProcessBeaconBlockRoot applies the EIP-4788 system call to the beacon block root
// contract. This method is exported to be used in tests.
func ProcessBeaconBlockRoot(beaconRoot common.Hash, evm *vm.EVM) {
	// Return immediately if beaconRoot equals the zero hash when using the Parlia engine.
	if beaconRoot == (common.Hash{}) {
		if chainConfig := evm.ChainConfig(); chainConfig != nil && chainConfig.Parlia != nil {
			return
		}
	}
	if tracer := evm.Config.Tracer; tracer != nil {
		onSystemCallStart(tracer, evm.GetVMContext())
		if tracer.OnSystemCallEnd != nil {
			defer tracer.OnSystemCallEnd()
		}
	}
	msg := &Message{
		From:      params.SystemAddress,
		GasLimit:  30_000_000,
		GasPrice:  common.Big0,
		GasFeeCap: common.Big0,
		GasTipCap: common.Big0,
		To:        &params.BeaconRootsAddress,
		Data:      beaconRoot[:],
	}
	evm.SetTxContext(NewEVMTxContext(msg))
	evm.StateDB.AddAddressToAccessList(params.BeaconRootsAddress)
	_, _, _ = evm.Call(msg.From, *msg.To, msg.Data, 30_000_000, common.U2560)
	evm.StateDB.Finalise(true)
}

// ProcessParentBlockHash stores the parent block hash in the history storage contract
// as per EIP-2935/7709.
func ProcessParentBlockHash(prevHash common.Hash, evm *vm.EVM) {
	if tracer := evm.Config.Tracer; tracer != nil {
		onSystemCallStart(tracer, evm.GetVMContext())
		if tracer.OnSystemCallEnd != nil {
			defer tracer.OnSystemCallEnd()
		}
	}
	msg := &Message{
		From:      params.SystemAddress,
		GasLimit:  30_000_000,
		GasPrice:  common.Big0,
		GasFeeCap: common.Big0,
		GasTipCap: common.Big0,
		To:        &params.HistoryStorageAddress,
		Data:      prevHash.Bytes(),
	}
	evm.SetTxContext(NewEVMTxContext(msg))
	evm.StateDB.AddAddressToAccessList(params.HistoryStorageAddress)
	_, _, err := evm.Call(msg.From, *msg.To, msg.Data, 30_000_000, common.U2560)
	if err != nil {
		panic(err)
	}
	if evm.StateDB.AccessEvents() != nil {
		evm.StateDB.AccessEvents().Merge(evm.AccessEvents)
	}
	evm.StateDB.Finalise(true)
}

// ProcessWithdrawalQueue calls the EIP-7002 withdrawal queue contract.
// It returns the opaque request data returned by the contract.
func ProcessWithdrawalQueue(requests *[][]byte, evm *vm.EVM) error {
	return processRequestsSystemCall(requests, evm, 0x01, params.WithdrawalQueueAddress)
}

// ProcessConsolidationQueue calls the EIP-7251 consolidation queue contract.
// It returns the opaque request data returned by the contract.
func ProcessConsolidationQueue(requests *[][]byte, evm *vm.EVM) error {
	return processRequestsSystemCall(requests, evm, 0x02, params.ConsolidationQueueAddress)
}

func processRequestsSystemCall(requests *[][]byte, evm *vm.EVM, requestType byte, addr common.Address) error {
	if tracer := evm.Config.Tracer; tracer != nil {
		onSystemCallStart(tracer, evm.GetVMContext())
		if tracer.OnSystemCallEnd != nil {
			defer tracer.OnSystemCallEnd()
		}
	}
	msg := &Message{
		From:      params.SystemAddress,
		GasLimit:  30_000_000,
		GasPrice:  common.Big0,
		GasFeeCap: common.Big0,
		GasTipCap: common.Big0,
		To:        &addr,
	}
	evm.SetTxContext(NewEVMTxContext(msg))
	evm.StateDB.AddAddressToAccessList(addr)
	ret, _, err := evm.Call(msg.From, *msg.To, msg.Data, 30_000_000, common.U2560)
	evm.StateDB.Finalise(true)
	if err != nil {
		return fmt.Errorf("system call failed to execute: %v", err)
	}
	if len(ret) == 0 {
		return nil // skip empty output
	}
	// Append prefixed requestsData to the requests list.
	requestsData := make([]byte, len(ret)+1)
	requestsData[0] = requestType
	copy(requestsData[1:], ret)
	*requests = append(*requests, requestsData)
	return nil
}

var depositTopic = common.HexToHash("0x649bbc62d0e31342afea4e5cd82d4049e7e1ee912fc0889aa790803be39038c5")

// ParseDepositLogs extracts the EIP-6110 deposit values from logs emitted by
// BeaconDepositContract.
func ParseDepositLogs(requests *[][]byte, logs []*types.Log, config *params.ChainConfig) error {
	deposits := make([]byte, 1) // note: first byte is 0x00 (== deposit request type)
	for _, log := range logs {
		if log.Address == config.DepositContractAddress && len(log.Topics) > 0 && log.Topics[0] == depositTopic {
			request, err := types.DepositLogToRequest(log.Data)
			if err != nil {
				return fmt.Errorf("unable to parse deposit data: %v", err)
			}
			deposits = append(deposits, request...)
		}
	}
	if len(deposits) > 1 {
		*requests = append(*requests, deposits)
	}
	return nil
}

func onSystemCallStart(tracer *tracing.Hooks, ctx *tracing.VMContext) {
	if tracer.OnSystemCallStartV2 != nil {
		tracer.OnSystemCallStartV2(ctx)
	} else if tracer.OnSystemCallStart != nil {
		tracer.OnSystemCallStart()
	}
}
