package keeper

import (
	"math/big"

	errorsmod "cosmossdk.io/errors"
	sdkmath "cosmossdk.io/math"
	sdk "github.com/cosmos/cosmos-sdk/types"

	"github.com/0glabs/0g-chain/x/evmutil/types"
)

// MintConversionPairCoin mints the given amount of a ConversionPair denom and
// sends it to the provided address.
func (k Keeper) MintConversionPairCoin(
	ctx sdk.Context,
	pair types.ConversionPair,
	amount *big.Int,
	recipient sdk.AccAddress,
) (sdk.Coin, error) {
	coin := sdk.NewCoin(pair.Denom, sdkmath.NewIntFromBigInt(amount))
	coins := sdk.NewCoins(coin)

	if err := k.bankKeeper.MintCoins(ctx, types.ModuleName, coins); err != nil {
		return sdk.Coin{}, err
	}

	if err := k.bankKeeper.SendCoinsFromModuleToAccount(ctx, types.ModuleName, recipient, coins); err != nil {
		return sdk.Coin{}, err
	}

	return coin, nil
}

// BurnConversionPairCoin transfers the provided amount to the module account
// then burns it.
func (k Keeper) BurnConversionPairCoin(
	ctx sdk.Context,
	pair types.ConversionPair,
	coin sdk.Coin,
	account sdk.AccAddress,
) error {
	coins := sdk.NewCoins(coin)

	if err := k.bankKeeper.SendCoinsFromAccountToModule(ctx, account, types.ModuleName, coins); err != nil {
		return err
	}

	if err := k.bankKeeper.BurnCoins(ctx, types.ModuleName, coins); err != nil {
		return err
	}

	return nil
}

// ConvertCoinToERC20 converts an sdk.Coin from the originating account to an
// ERC20 to the receiver account.
func (k Keeper) ConvertCoinToERC20(
	ctx sdk.Context,
	initiatorAccount sdk.AccAddress,
	receiverAccount types.InternalEVMAddress,
	coin sdk.Coin,
) error {
	pair, err := k.GetEnabledConversionPairFromDenom(ctx, coin.Denom)
	if err != nil {
		// Coin not in enabled conversion pair list
		return err
	}

	if err := k.BurnConversionPairCoin(ctx, pair, coin, initiatorAccount); err != nil {
		return err
	}

	if err := k.UnlockERC20Tokens(ctx, pair, coin.Amount.BigInt(), receiverAccount); err != nil {
		return err
	}

	ctx.EventManager().EmitEvent(sdk.NewEvent(
		types.EventTypeConvertCoinToERC20,
		sdk.NewAttribute(types.AttributeKeyInitiator, initiatorAccount.String()),
		sdk.NewAttribute(types.AttributeKeyReceiver, receiverAccount.String()),
		sdk.NewAttribute(types.AttributeKeyERC20Address, pair.GetAddress().String()),
		sdk.NewAttribute(types.AttributeKeyAmount, coin.String()),
	))

	return nil
}

// ConvertERC20ToCoin converts an ERC20 coin from the originating account to an
// sdk.Coin to the receiver account.
func (k Keeper) ConvertERC20ToCoin(
	ctx sdk.Context,
	initiator types.InternalEVMAddress,
	receiver sdk.AccAddress,
	contractAddr types.InternalEVMAddress,
	amount sdkmath.Int,
) error {
	// Check that the contract is enabled to convert to coin
	pair, err := k.GetEnabledConversionPairFromERC20Address(ctx, contractAddr)
	if err != nil {
		// contract not in enabled conversion pair list
		return err
	}

	// lock erc20 tokens
	if err := k.LockERC20Tokens(ctx, pair, amount.BigInt(), initiator); err != nil {
		return err
	}

	// mint conversion pair coin
	coin, err := k.MintConversionPairCoin(ctx, pair, amount.BigInt(), receiver)
	if err != nil {
		return err
	}

	ctx.EventManager().EmitEvent(sdk.NewEvent(
		types.EventTypeConvertERC20ToCoin,
		sdk.NewAttribute(types.AttributeKeyERC20Address, contractAddr.String()),
		sdk.NewAttribute(types.AttributeKeyInitiator, initiator.String()),
		sdk.NewAttribute(types.AttributeKeyReceiver, receiver.String()),
		sdk.NewAttribute(types.AttributeKeyAmount, coin.String()),
	))

	return nil
}

// UnlockERC20Tokens transfers the given amount of a conversion pair ERC20 token
// to the provided account.
func (k Keeper) UnlockERC20Tokens(
	ctx sdk.Context,
	pair types.ConversionPair,
	amount *big.Int,
	receiver types.InternalEVMAddress,
) error {
	contractAddr := pair.GetAddress()
	startBal, err := k.QueryERC20BalanceOf(ctx, contractAddr, receiver)
	if err != nil {
		return errorsmod.Wrapf(types.ErrEVMCall, "failed to retrieve balance %s", err.Error())
	}
	res, err := k.CallEVM(
		ctx,
		types.ERC20MintableBurnableContract.ABI, // abi
		types.ModuleEVMAddress,                  // from addr
		pair.GetAddress(),                       // contract addr
		"transfer",                              // method
		// Transfer ERC20 args
		receiver.Address,
		amount,
	)
	if err != nil {
		return err
	}

	// validate end bal
	endBal, err := k.QueryERC20BalanceOf(ctx, contractAddr, receiver)
	if err != nil {
		return errorsmod.Wrapf(types.ErrEVMCall, "failed to retrieve balance %s", err.Error())
	}
	expectedEndBal := big.NewInt(0).Add(startBal, amount)
	if expectedEndBal.Cmp(endBal) != 0 {
		return errorsmod.Wrapf(
			types.ErrBalanceInvariance,
			"invalid token balance - expected: %v, actual: %v",
			expectedEndBal, endBal,
		)
	}

	// Check for unexpected `Approval` event in logs
	if err := k.monitorApprovalEvent(res); err != nil {
		return err
	}

	return err
}

// LockERC20Tokens transfers the given amount of a conversion pair ERC20 token
// from the initiator account to the module account.
func (k Keeper) LockERC20Tokens(
	ctx sdk.Context,
	pair types.ConversionPair,
	amount *big.Int,
	initiator types.InternalEVMAddress,
) error {
	contractAddr := pair.GetAddress()
	initiatorStartBal, err := k.QueryERC20BalanceOf(ctx, contractAddr, initiator)
	if err != nil {
		return errorsmod.Wrapf(types.ErrEVMCall, "failed to retrieve balance: %s", err.Error())
	}

	res, err := k.CallEVM(
		ctx,
		types.ERC20MintableBurnableContract.ABI, // abi
		initiator.Address,                       // from addr
		contractAddr,                            // contract addr
		"transfer",                              // method
		// Transfer ERC20 args
		types.ModuleEVMAddress,
		amount,
	)
	if err != nil {
		return err
	}

	// validate end bal
	initiatorEndBal, err := k.QueryERC20BalanceOf(ctx, contractAddr, initiator)
	if err != nil {
		return errorsmod.Wrapf(types.ErrEVMCall, "failed to retrieve balance %s", err.Error())
	}
	expectedEndBal := big.NewInt(0).Sub(initiatorStartBal, amount)
	if expectedEndBal.Cmp(initiatorEndBal) != 0 {
		return errorsmod.Wrapf(
			types.ErrBalanceInvariance,
			"invalid token balance - expected: %v, actual: %v",
			expectedEndBal, initiatorEndBal,
		)
	}

	// Check for unexpected `Approval` event in logs
	if err := k.monitorApprovalEvent(res); err != nil {
		return err
	}

	return err
}