package keeper

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"math/big"
	"time"

	"github.com/ethereum/go-ethereum/eth/tracers"

	"github.com/palantir/stacktrace"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"

	sdk "github.com/cosmos/cosmos-sdk/types"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/common/hexutil"
	"github.com/ethereum/go-ethereum/core"
	ethtypes "github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/core/vm"
	ethparams "github.com/ethereum/go-ethereum/params"

	ethermint "github.com/tharsis/ethermint/types"
	"github.com/tharsis/ethermint/x/evm/types"
)

var _ types.QueryServer = Keeper{}

const (
	defaultTraceTimeout = 5 * time.Second
)

// Account implements the Query/Account gRPC method
func (k Keeper) Account(c context.Context, req *types.QueryAccountRequest) (*types.QueryAccountResponse, error) {
	if req == nil {
		return nil, status.Error(codes.InvalidArgument, "empty request")
	}

	if err := ethermint.ValidateAddress(req.Address); err != nil {
		return nil, status.Error(
			codes.InvalidArgument, err.Error(),
		)
	}

	addr := common.HexToAddress(req.Address)

	ctx := sdk.UnwrapSDKContext(c)
	k.WithContext(ctx)

	return &types.QueryAccountResponse{
		Balance:  k.GetBalance(addr).String(),
		CodeHash: k.GetCodeHash(addr).Hex(),
		Nonce:    k.GetNonce(addr),
	}, nil
}

func (k Keeper) CosmosAccount(c context.Context, req *types.QueryCosmosAccountRequest) (*types.QueryCosmosAccountResponse, error) {
	if req == nil {
		return nil, status.Error(codes.InvalidArgument, "empty request")
	}

	if err := ethermint.ValidateAddress(req.Address); err != nil {
		return nil, status.Error(
			codes.InvalidArgument, err.Error(),
		)
	}

	ctx := sdk.UnwrapSDKContext(c)
	k.WithContext(ctx)

	ethAddr := common.HexToAddress(req.Address)
	cosmosAddr := sdk.AccAddress(ethAddr.Bytes())

	account := k.accountKeeper.GetAccount(ctx, cosmosAddr)
	res := types.QueryCosmosAccountResponse{
		CosmosAddress: cosmosAddr.String(),
	}

	if account != nil {
		res.Sequence = account.GetSequence()
		res.AccountNumber = account.GetAccountNumber()
	}

	return &res, nil
}

func (k Keeper) ValidatorAccount(c context.Context, req *types.QueryValidatorAccountRequest) (*types.QueryValidatorAccountResponse, error) {
	if req == nil {
		return nil, status.Error(codes.InvalidArgument, "empty request")
	}

	consAddr, err := sdk.ConsAddressFromBech32(req.ConsAddress)
	if err != nil {
		return nil, status.Error(
			codes.InvalidArgument, err.Error(),
		)
	}

	ctx := sdk.UnwrapSDKContext(c)
	k.WithContext(ctx)

	validator, found := k.stakingKeeper.GetValidatorByConsAddr(ctx, consAddr)
	if !found {
		return nil, nil
	}

	accAddr := sdk.AccAddress(validator.GetOperator())

	res := types.QueryValidatorAccountResponse{
		AccountAddress: accAddr.String(),
	}

	account := k.accountKeeper.GetAccount(ctx, accAddr)
	if account != nil {
		res.Sequence = account.GetSequence()
		res.AccountNumber = account.GetAccountNumber()
	}

	return &res, nil
}

// Balance implements the Query/Balance gRPC method
func (k Keeper) Balance(c context.Context, req *types.QueryBalanceRequest) (*types.QueryBalanceResponse, error) {
	if req == nil {
		return nil, status.Error(codes.InvalidArgument, "empty request")
	}

	if err := ethermint.ValidateAddress(req.Address); err != nil {
		return nil, status.Error(
			codes.InvalidArgument,
			types.ErrZeroAddress.Error(),
		)
	}

	ctx := sdk.UnwrapSDKContext(c)
	k.WithContext(ctx)

	balanceInt := k.GetBalance(common.HexToAddress(req.Address))

	return &types.QueryBalanceResponse{
		Balance: balanceInt.String(),
	}, nil
}

// Storage implements the Query/Storage gRPC method
func (k Keeper) Storage(c context.Context, req *types.QueryStorageRequest) (*types.QueryStorageResponse, error) {
	if req == nil {
		return nil, status.Error(codes.InvalidArgument, "empty request")
	}

	if err := ethermint.ValidateAddress(req.Address); err != nil {
		return nil, status.Error(
			codes.InvalidArgument,
			types.ErrZeroAddress.Error(),
		)
	}

	ctx := sdk.UnwrapSDKContext(c)
	k.WithContext(ctx)

	address := common.HexToAddress(req.Address)
	key := common.HexToHash(req.Key)

	state := k.GetState(address, key)
	stateHex := state.Hex()

	return &types.QueryStorageResponse{
		Value: stateHex,
	}, nil
}

// Code implements the Query/Code gRPC method
func (k Keeper) Code(c context.Context, req *types.QueryCodeRequest) (*types.QueryCodeResponse, error) {
	if req == nil {
		return nil, status.Error(codes.InvalidArgument, "empty request")
	}

	if err := ethermint.ValidateAddress(req.Address); err != nil {
		return nil, status.Error(
			codes.InvalidArgument,
			types.ErrZeroAddress.Error(),
		)
	}

	ctx := sdk.UnwrapSDKContext(c)
	k.WithContext(ctx)

	address := common.HexToAddress(req.Address)
	code := k.GetCode(address)

	return &types.QueryCodeResponse{
		Code: code,
	}, nil
}

// Params implements the Query/Params gRPC method
func (k Keeper) Params(c context.Context, _ *types.QueryParamsRequest) (*types.QueryParamsResponse, error) {
	ctx := sdk.UnwrapSDKContext(c)
	params := k.GetParams(ctx)

	return &types.QueryParamsResponse{
		Params: params,
	}, nil
}

// EthCall implements eth_call rpc api.
func (k Keeper) EthCall(c context.Context, req *types.EthCallRequest) (*types.MsgEthereumTxResponse, error) {
	if req == nil {
		return nil, status.Error(codes.InvalidArgument, "empty request")
	}

	ctx := sdk.UnwrapSDKContext(c)
	k.WithContext(ctx)

	var args types.TransactionArgs
	err := json.Unmarshal(req.Args, &args)
	if err != nil {
		return nil, status.Error(codes.InvalidArgument, err.Error())
	}

	params := k.GetParams(ctx)
	ethCfg := params.ChainConfig.EthereumConfig(k.eip155ChainID)

	var baseFee *big.Int
	if types.IsLondon(ethCfg, ctx.BlockHeight()) {
		baseFee = k.feeMarketKeeper.GetBaseFee(ctx)
	}

	msg, err := args.ToMessage(req.GasCap, baseFee)
	if err != nil {
		return nil, status.Error(codes.InvalidArgument, err.Error())
	}

	res, err := k.ApplyMessage(msg, nil, false)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}

	return res, nil
}

// EstimateGas implements eth_estimateGas rpc api.
func (k Keeper) EstimateGas(c context.Context, req *types.EthCallRequest) (*types.EstimateGasResponse, error) {
	if req == nil {
		return nil, status.Error(codes.InvalidArgument, "empty request")
	}

	ctx := sdk.UnwrapSDKContext(c)
	k.WithContext(ctx)

	if req.GasCap < ethparams.TxGas {
		return nil, status.Error(codes.InvalidArgument, "gas cap cannot be lower than 21,000")
	}

	var args types.TransactionArgs
	err := json.Unmarshal(req.Args, &args)
	if err != nil {
		return nil, status.Error(codes.InvalidArgument, err.Error())
	}

	// Binary search the gas requirement, as it may be higher than the amount used
	var (
		lo  = ethparams.TxGas - 1
		hi  uint64
		cap uint64
	)

	// Determine the highest gas limit can be used during the estimation.
	if args.Gas != nil && uint64(*args.Gas) >= ethparams.TxGas {
		hi = uint64(*args.Gas)
	} else {
		// Query block gas limit
		params := ctx.ConsensusParams()
		if params != nil && params.Block != nil && params.Block.MaxGas > 0 {
			hi = uint64(params.Block.MaxGas)
		} else {
			hi = req.GasCap
		}
	}

	// TODO: Recap the highest gas limit with account's available balance.

	// Recap the highest gas allowance with specified gascap.
	if req.GasCap != 0 && hi > req.GasCap {
		hi = req.GasCap
	}
	cap = hi

	cfg, err := k.EVMConfig(ctx)
	if err != nil {
		return nil, status.Error(codes.Internal, "failed to load evm config")
	}
	var baseFee *big.Int
	if types.IsLondon(cfg.ChainConfig, ctx.BlockHeight()) {
		baseFee = k.feeMarketKeeper.GetBaseFee(ctx)
	}

	// Create a helper to check if a gas allowance results in an executable transaction
	executable := func(gas uint64) (vmerror bool, rsp *types.MsgEthereumTxResponse, err error) {
		args.Gas = (*hexutil.Uint64)(&gas)

		// Reset to the initial context
		k.WithContext(ctx)

		msg, err := args.ToMessage(req.GasCap, baseFee)
		if err != nil {
			return false, nil, err
		}

		rsp, err = k.ApplyMessageWithConfig(msg, nil, false, cfg)

		if err != nil {
			if errors.Is(stacktrace.RootCause(err), core.ErrIntrinsicGas) {
				return true, nil, nil // Special case, raise gas limit
			}
			return true, nil, err // Bail out
		}
		return len(rsp.VmError) > 0, rsp, nil
	}

	// Execute the binary search and hone in on an executable gas limit
	hi, err = types.BinSearch(lo, hi, executable)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}

	// Reject the transaction as invalid if it still fails at the highest allowance
	if hi == cap {
		failed, result, err := executable(hi)
		if err != nil {
			return nil, status.Error(codes.Internal, err.Error())
		}
		if failed {
			if result != nil && result.VmError != vm.ErrOutOfGas.Error() {
				if result.VmError == vm.ErrExecutionReverted.Error() {
					return nil, types.NewExecErrorWithReason(result.Ret)
				}
				return nil, status.Error(codes.Internal, result.VmError)
			}
			// Otherwise, the specified gas cap is too low
			return nil, status.Error(codes.Internal, fmt.Sprintf("gas required exceeds allowance (%d)", cap))
		}
	}
	return &types.EstimateGasResponse{Gas: hi}, nil
}

// TraceTx configures a new tracer according to the provided configuration, and
// executes the given message in the provided environment. The return value will
// be tracer dependent.
func (k Keeper) TraceTx(c context.Context, req *types.QueryTraceTxRequest) (*types.QueryTraceTxResponse, error) {
	if req == nil {
		return nil, status.Error(codes.InvalidArgument, "empty request")
	}

	if req.TraceConfig != nil && req.TraceConfig.Limit < 0 {
		return nil, status.Errorf(codes.InvalidArgument, "output limit cannot be negative, got %d", req.TraceConfig.Limit)
	}

	ctx := sdk.UnwrapSDKContext(c)
	k.WithContext(ctx)

	params := k.GetParams(ctx)
	ethCfg := params.ChainConfig.EthereumConfig(k.eip155ChainID)
	signer := ethtypes.MakeSigner(ethCfg, big.NewInt(ctx.BlockHeight()))
	tx := req.Msg.AsTransaction()
	baseFee := k.feeMarketKeeper.GetBaseFee(ctx)

	result, err := k.traceTx(ctx, signer, req.TxIndex, ethCfg, tx, baseFee, req.TraceConfig)
	if err != nil {
		return nil, err
	}

	resultData, err := json.Marshal(result)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}

	return &types.QueryTraceTxResponse{
		Data: resultData,
	}, nil
}

func (k *Keeper) traceTx(
	ctx sdk.Context,
	signer ethtypes.Signer,
	txIndex uint64,
	ethCfg *ethparams.ChainConfig,
	tx *ethtypes.Transaction,
	baseFee *big.Int,
	traceConfig *types.TraceConfig,
) (*interface{}, error) {
	// Assemble the structured logger or the JavaScript tracer
	var (
		tracer    vm.Tracer
		overrides *ethparams.ChainConfig
		err       error
	)

	msg, err := tx.AsMessage(signer, baseFee)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}

	txHash := tx.Hash()

	if traceConfig != nil && traceConfig.Overrides != nil {
		overrides = traceConfig.Overrides.EthereumConfig(ethCfg.ChainID)
	}

	switch {
	case traceConfig != nil && traceConfig.Tracer != "":
		timeout := defaultTraceTimeout
		// TODO: change timeout to time.duration
		// Used string to comply with go ethereum
		if traceConfig.Timeout != "" {
			timeout, err = time.ParseDuration(traceConfig.Timeout)
			if err != nil {
				return nil, status.Errorf(codes.InvalidArgument, "timeout value: %s", err.Error())
			}
		}

		tCtx := &tracers.Context{
			BlockHash: k.GetHashFn()(uint64(ctx.BlockHeight())),
			TxIndex:   int(txIndex),
			TxHash:    txHash,
		}

		// Construct the JavaScript tracer to execute with
		if tracer, err = tracers.New(traceConfig.Tracer, tCtx); err != nil {
			return nil, status.Error(codes.Internal, err.Error())
		}

		// Handle timeouts and RPC cancellations
		deadlineCtx, cancel := context.WithTimeout(ctx.Context(), timeout)
		defer cancel()

		go func() {
			<-deadlineCtx.Done()
			if errors.Is(deadlineCtx.Err(), context.DeadlineExceeded) {
				tracer.(*tracers.Tracer).Stop(errors.New("execution timeout"))
			}
		}()

	case traceConfig != nil:
		logConfig := vm.LogConfig{
			EnableMemory:     traceConfig.EnableMemory,
			DisableStorage:   traceConfig.DisableStorage,
			DisableStack:     traceConfig.DisableStack,
			EnableReturnData: traceConfig.EnableReturnData,
			Debug:            traceConfig.Debug,
			Limit:            int(traceConfig.Limit),
			Overrides:        overrides,
		}
		tracer = vm.NewStructLogger(&logConfig)
	default:
		tracer = types.NewTracer(types.TracerStruct, msg, ethCfg, ctx.BlockHeight(), true)
	}

	k.SetTxHashTransient(txHash)
	k.SetTxIndexTransient(txIndex)

	res, err := k.ApplyMessage(msg, tracer, false)
	if err != nil {
		return nil, status.Error(codes.Internal, err.Error())
	}

	var result interface{}

	// Depending on the tracer type, format and return the trace result data.
	switch tracer := tracer.(type) {
	case *vm.StructLogger:
		// TODO: Return proper returnValue
		result = types.ExecutionResult{
			Gas:         res.GasUsed,
			Failed:      res.Failed(),
			ReturnValue: "",
			StructLogs:  types.FormatLogs(tracer.StructLogs()),
		}
	case *tracers.Tracer:
		result, err = tracer.GetResult()
		if err != nil {
			return nil, status.Error(codes.Internal, err.Error())
		}

	default:
		return nil, status.Errorf(codes.InvalidArgument, "invalid tracer type %T", tracer)
	}

	return &result, nil
}