package schedule

import (
	"context"
	"fmt"

	"github.com/c9s/bbgo/pkg/fixedpoint"
	"github.com/pkg/errors"
	log "github.com/sirupsen/logrus"

	"github.com/c9s/bbgo/pkg/bbgo"
	"github.com/c9s/bbgo/pkg/types"
)

const ID = "schedule"

func init() {
	bbgo.RegisterStrategy(ID, &Strategy{})
}

// Float64Indicator is the indicators (SMA and EWMA) that we want to use are returning float64 data.
type Float64Indicator interface {
	Last() float64
}

type MovingAverageSettings struct {
	Type     string         `json:"type"`
	Interval types.Interval `json:"interval"`
	Window   int            `json:"window"`

	Side     *types.SideType   `json:"side"`
	Quantity *fixedpoint.Value `json:"quantity"`
	Amount   *fixedpoint.Value `json:"amount"`
}

func (settings MovingAverageSettings) IntervalWindow() types.IntervalWindow {
	var window = 99
	if settings.Window > 0 {
		window = settings.Window
	}

	return types.IntervalWindow{
		Interval: settings.Interval,
		Window:   window,
	}
}

func (settings *MovingAverageSettings) Indicator(indicatorSet *bbgo.StandardIndicatorSet) (inc Float64Indicator, err error) {
	var iw = settings.IntervalWindow()

	switch settings.Type {
	case "SMA":
		inc = indicatorSet.SMA(iw)

	case "EWMA", "EMA":
		inc = indicatorSet.EWMA(iw)

	default:
		return nil, fmt.Errorf("unsupported moving average type: %s", settings.Type)
	}

	return inc, nil
}

type Strategy struct {
	Market types.Market

	Notifiability *bbgo.Notifiability

	// StandardIndicatorSet contains the standard indicators of a market (symbol)
	// This field will be injected automatically since we defined the Symbol field.
	*bbgo.StandardIndicatorSet

	// Interval is the period that you want to submit order
	Interval types.Interval `json:"interval"`

	// Symbol is the symbol of the market
	Symbol string `json:"symbol"`

	// Side is the order side type, which can be buy or sell
	Side types.SideType `json:"side"`

	// Quantity is the quantity of the submit order
	Quantity fixedpoint.Value `json:"quantity,omitempty"`

	Amount fixedpoint.Value `json:"amount,omitempty"`

	BelowMovingAverage *MovingAverageSettings `json:"belowMovingAverage,omitempty"`

	AboveMovingAverage *MovingAverageSettings `json:"aboveMovingAverage,omitempty"`
}

func (s *Strategy) ID() string {
	return ID
}

func (s *Strategy) Subscribe(session *bbgo.ExchangeSession) {
	session.Subscribe(types.KLineChannel, s.Symbol, types.SubscribeOptions{Interval: s.Interval.String()})
}

func (s *Strategy) Validate() error {
	if s.Quantity == 0 && s.Amount == 0 {
		return errors.New("either quantity or amount can not be empty")
	}

	return nil
}

func (s *Strategy) Run(ctx context.Context, orderExecutor bbgo.OrderExecutor, session *bbgo.ExchangeSession) error {
	if s.StandardIndicatorSet == nil {
		return errors.New("StandardIndicatorSet can not be nil, injection failed?")
	}

	var belowMA Float64Indicator
	var aboveMA Float64Indicator
	var err error
	if s.BelowMovingAverage != nil {
		belowMA, err = s.BelowMovingAverage.Indicator(s.StandardIndicatorSet)
		if err != nil {
			return err
		}
	}

	if s.AboveMovingAverage != nil {
		aboveMA, err = s.AboveMovingAverage.Indicator(s.StandardIndicatorSet)
		if err != nil {
			return err
		}
	}

	session.Stream.OnKLineClosed(func(kline types.KLine) {
		if kline.Symbol != s.Symbol {
			return
		}

		closePrice := fixedpoint.NewFromFloat(kline.Close)
		quantity := s.Quantity
		amount := s.Amount

		side := s.Side

		if s.BelowMovingAverage != nil || s.AboveMovingAverage != nil {

			match := false
			// if any of the conditions satisfies then we execute order
			if belowMA != nil && closePrice.Float64() < belowMA.Last() {
				match = true
				if s.BelowMovingAverage != nil {
					if s.BelowMovingAverage.Side != nil {
						side = *s.BelowMovingAverage.Side
					}

					// override the default quantity or amount
					if s.BelowMovingAverage.Quantity != nil {
						quantity = *s.BelowMovingAverage.Quantity
					} else if s.BelowMovingAverage.Amount != nil {
						amount = *s.BelowMovingAverage.Amount
					}

				}
			} else if aboveMA != nil && closePrice.Float64() > aboveMA.Last() {
				match = true
				if s.AboveMovingAverage != nil {
					if s.AboveMovingAverage.Side != nil {
						side = *s.AboveMovingAverage.Side
					}

					// override the default quantity or amount
					if s.AboveMovingAverage.Quantity != nil {
						quantity = *s.AboveMovingAverage.Quantity
					} else if s.AboveMovingAverage.Amount != nil {
						amount = *s.AboveMovingAverage.Amount
					}
				}
			}

			if !match {
				s.Notifiability.Notify("skip, the closed price is below or above moving average")
				return
			}
		}

		// convert amount to quantity if amount is given
		if amount > 0 {
			quantity = amount.Div(closePrice)
		}

		// calculate quote quantity for balance checking
		quoteQuantity := quantity.Mul(closePrice)

		// execute orders
		switch side {
		case types.SideTypeBuy:
			quoteBalance, ok := session.Account.Balance(s.Market.QuoteCurrency)
			if !ok {
				return
			}
			if quoteBalance.Available < quoteQuantity {
				s.Notifiability.Notify("Quote balance %s is not enough: %f < %f", s.Market.QuoteCurrency, quoteBalance.Available.Float64(), quoteQuantity.Float64())
				return
			}

		case types.SideTypeSell:
			baseBalance, ok := session.Account.Balance(s.Market.BaseCurrency)
			if !ok {
				return
			}
			if baseBalance.Available < quantity {
				s.Notifiability.Notify("Base balance %s is not enough: %f < %f", s.Market.QuoteCurrency, baseBalance.Available.Float64(), quantity.Float64())
				return
			}

		}

		s.Notifiability.Notify("Submitting scheduled order %s quantity %f", s.Symbol, quantity.Floor())
		_, err := orderExecutor.SubmitOrders(ctx, types.SubmitOrder{
			Symbol:   s.Symbol,
			Side:     side,
			Type:     types.OrderTypeMarket,
			Quantity: quantity.Float64(),
		})

		if err != nil {
			log.WithError(err).Error("submit order error")
		}
	})

	return nil
}