package dasigners

import (
	"fmt"
	"strings"

	precopmiles_common "github.com/0glabs/0g-chain/precompiles/common"
	dasignerskeeper "github.com/0glabs/0g-chain/x/dasigners/v1/keeper"
	"github.com/ethereum/go-ethereum/accounts/abi"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core/vm"
	"github.com/evmos/ethermint/x/evm/statedb"
)

const (
	PrecompileAddress        = "0x0000000000000000000000000000000000001000"
	RequiredGasBasic  uint64 = 100

	DASignersFunctionEpochNumber       = "epochNumber"
	DASignersFunctionGetSigner         = "getSigner"
	DASignersFunctionGetSigners        = "getSigners"
	DASignersFunctionUpdateSocket      = "updateSocket"
	DASignersFunctionRegisterNextEpoch = "registerNextEpoch"
	DASignersFunctionRegisterSigner    = "registerSigner"
	DASignersFunctionGetAggPkG1        = "getAggPkG1"
)

var _ vm.PrecompiledContract = &DASignersPrecompile{}

type DASignersPrecompile struct {
	abi             abi.ABI
	dasignersKeeper dasignerskeeper.Keeper
}

func NewDASignersPrecompile(dasignersKeeper dasignerskeeper.Keeper) (*DASignersPrecompile, error) {
	abi, err := abi.JSON(strings.NewReader(DASignersABI))
	if err != nil {
		return nil, err
	}
	return &DASignersPrecompile{
		abi:             abi,
		dasignersKeeper: dasignersKeeper,
	}, nil
}

// Address implements vm.PrecompiledContract.
func (d *DASignersPrecompile) Address() common.Address {
	return common.HexToAddress(PrecompileAddress)
}

// RequiredGas implements vm.PrecompiledContract.
func (d *DASignersPrecompile) RequiredGas(input []byte) uint64 {
	return RequiredGasBasic
}

// Run implements vm.PrecompiledContract.
func (d *DASignersPrecompile) Run(evm *vm.EVM, contract *vm.Contract, readonly bool) ([]byte, error) {
	// parse input
	if len(contract.Input) < 4 {
		return nil, vm.ErrExecutionReverted
	}
	method, err := d.abi.MethodById(contract.Input[:4])
	if err != nil {
		return nil, vm.ErrExecutionReverted
	}
	args, err := method.Inputs.Unpack(contract.Input[4:])
	if err != nil {
		return nil, err
	}
	// get state db and context
	stateDB, ok := evm.StateDB.(*statedb.StateDB)
	if !ok {
		return nil, fmt.Errorf(precopmiles_common.ErrGetStateDB)
	}
	ctx := stateDB.GetContext()
	initialGas := ctx.GasMeter().GasConsumed()

	var bz []byte
	switch method.Name {
	// queries
	case DASignersFunctionEpochNumber:
		bz, err = d.EpochNumber(ctx, evm, method, args)
	case DASignersFunctionGetSigner:
		bz, err = d.GetSigner(ctx, evm, method, args)
	case DASignersFunctionGetSigners:
		bz, err = d.GetSigners(ctx, evm, method, args)
	case DASignersFunctionGetAggPkG1:
		bz, err = d.GetAggPkG1(ctx, evm, method, args)
	// txs
	case DASignersFunctionRegisterSigner:
		bz, err = d.RegisterSigner(ctx, evm, stateDB, method, args)
	case DASignersFunctionRegisterNextEpoch:
		bz, err = d.RegisterNextEpoch(ctx, evm, stateDB, method, args)
	case DASignersFunctionUpdateSocket:
		bz, err = d.UpdateSocket(ctx, evm, stateDB, method, args)
	}

	if err != nil {
		return nil, err
	}

	cost := ctx.GasMeter().GasConsumed() - initialGas

	if !contract.UseGas(cost) {
		return nil, vm.ErrOutOfGas
	}
	return bz, nil
}