package aave

import (
	"context"
	"math/big"

	"git.lehouerou.net/laurent/evm"
	"git.lehouerou.net/laurent/evm/aave/contracts"
	"github.com/ethereum/go-ethereum/accounts/abi/bind"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/pkg/errors"
	"github.com/shopspring/decimal"
)

type LendingPool struct {
	client   evm.Client
	contract *contracts.LendingPool
}

func NewLendingPool(client evm.Client, address common.Address) (*LendingPool, error) {
	contract, err := contracts.NewLendingPool(address, client)
	if err != nil {
		return nil, errors.Wrap(err, "init contract")
	}

	return &LendingPool{
		client:   client,
		contract: contract,
	}, nil
}

type UserAccountData struct {
	TotalCollateralETH          decimal.Decimal
	TotalDebtETH                decimal.Decimal
	AvailableBorrowsETH         decimal.Decimal
	CurrentLiquidationThreshold decimal.Decimal
	CurrentLtv                  decimal.Decimal
	MaxLtv                      decimal.Decimal
	HealthFactor                decimal.Decimal
}

func (uad UserAccountData) BorrowAmountToLtv(ltv decimal.Decimal) decimal.Decimal {
	return uad.TotalCollateralETH.Mul(ltv).Div(decimal.NewFromInt(100)).Sub(uad.TotalDebtETH)
}

func (lp *LendingPool) UserAccountDataForAddress(address common.Address) (UserAccountData, error) {
	uad, err := lp.contract.GetUserAccountData(&bind.CallOpts{}, address)
	if err != nil {
		return UserAccountData{}, errors.Wrap(err, "calling contract")
	}
	res := UserAccountData{
		TotalCollateralETH:          decimal.NewFromBigInt(uad.TotalCollateralETH, -8),
		TotalDebtETH:                decimal.NewFromBigInt(uad.TotalDebtETH, -8),
		AvailableBorrowsETH:         decimal.NewFromBigInt(uad.AvailableBorrowsETH, -8),
		CurrentLiquidationThreshold: decimal.NewFromBigInt(uad.CurrentLiquidationThreshold, -2),
		MaxLtv:                      decimal.NewFromBigInt(uad.Ltv, -2),
		HealthFactor:                decimal.NewFromBigInt(uad.HealthFactor, -18),
	}
	res.CurrentLtv = res.TotalDebtETH.Div(res.TotalCollateralETH).Mul(decimal.NewFromInt(100))
	return res, nil
}

func (lp *LendingPool) Borrow(ctx context.Context, asset common.Address, amount decimal.Decimal) (evm.Transaction, error) {
	token, err := lp.client.TokenService().TokenByAddress(asset)
	if err != nil {
		return nil, errors.Wrap(err, "getting token")
	}
	return lp.client.Execute(ctx, func(ctx context.Context, opts *evm.TransactOpts) (*types.Transaction, error) {
		return lp.contract.Borrow(opts.TransactOpts, asset, token.ValueToBigInt(amount), big.NewInt(2), 0, lp.client.PublicAddress())
	})
}

func (lp *LendingPool) Repay(ctx context.Context, asset common.Address, amount decimal.Decimal) (evm.Transaction, error) {
	token, err := lp.client.TokenService().TokenByAddress(asset)
	if err != nil {
		return nil, errors.Wrap(err, "getting token")
	}
	balance, err := token.Balance()
	if err != nil {
		return nil, errors.Wrap(err, "getting token balance")
	}
	if balance.LessThan(amount) {
		return nil, errors.Wrapf(err, "balance of %s insufficient. need %s have %s", token.Symbol(), amount, balance)
	}
	return lp.client.Execute(ctx, func(ctx context.Context, opts *evm.TransactOpts) (*types.Transaction, error) {
		return lp.contract.Repay(opts.TransactOpts, asset, token.ValueToBigInt(amount), big.NewInt(2), lp.client.PublicAddress())
	})
}