package aave

import (
	"context"
	"math/big"
	"time"

	"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"
)

const (
	SECONDSPERYEAR = 31536000
)

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
}

type ReserveData struct {
	LiquidityIndex              decimal.Decimal
	VariableBorrowIndex         decimal.Decimal
	CurrentLiquidityRate        decimal.Decimal
	CurrentVariableBorrowRate   decimal.Decimal
	CurrentStableBorrowRate     decimal.Decimal
	LastUpdateTimestamp         time.Time
	ATokenAddress               common.Address
	StableDebtTokenAddress      common.Address
	VariableDebtTokenAddress    common.Address
	InterestRateStrategyAddress common.Address
	Id                          uint8
}

func (lp *LendingPool) ReserveData(asset evm.Token) (ReserveData, error) {
	rd, err := lp.contract.GetReserveData(&bind.CallOpts{}, asset.Address())
	if err != nil {
		return ReserveData{}, errors.Wrap(err, "calling contract")
	}
	res := ReserveData{
		LiquidityIndex:              decimal.NewFromBigInt(rd.LiquidityIndex, -27),
		VariableBorrowIndex:         decimal.NewFromBigInt(rd.VariableBorrowIndex, -27),
		CurrentLiquidityRate:        decimal.NewFromBigInt(rd.CurrentLiquidityRate, -27),
		CurrentVariableBorrowRate:   decimal.NewFromBigInt(rd.CurrentVariableBorrowRate, -27),
		CurrentStableBorrowRate:     decimal.NewFromBigInt(rd.CurrentStableBorrowRate, -27),
		LastUpdateTimestamp:         time.Unix(rd.LastUpdateTimestamp.Int64(), 0),
		ATokenAddress:               rd.ATokenAddress,
		StableDebtTokenAddress:      rd.StableDebtTokenAddress,
		VariableDebtTokenAddress:    rd.VariableDebtTokenAddress,
		InterestRateStrategyAddress: rd.InterestRateStrategyAddress,
		Id:                          rd.Id,
	}
	return res, nil
}

func (lp *LendingPool) Borrow(ctx context.Context, asset evm.Token, amount decimal.Decimal, opts ...evm.ExecutionOption) (evm.Transaction, error) {
	return lp.client.Execute(ctx, func(ctx context.Context, opts *evm.TransactOpts) (*types.Transaction, error) {
		return lp.contract.Borrow(opts.TransactOpts, asset.Address(), asset.ValueToBigInt(amount), big.NewInt(2), 0, lp.client.PublicAddress())
	}, opts...)
}

func (lp *LendingPool) Repay(ctx context.Context, asset evm.Token, amount decimal.Decimal, opts ...evm.ExecutionOption) (evm.Transaction, error) {
	balance, err := asset.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", asset.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.Address(), asset.ValueToBigInt(amount), big.NewInt(2), lp.client.PublicAddress())
	}, opts...)
}