package support

import (
	"context"
	"fmt"
	"sync"
	"time"

	"github.com/c9s/bbgo/pkg/service"
	"github.com/sirupsen/logrus"

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

const ID = "support"

const stateKey = "state-v1"

var log = logrus.WithField("strategy", ID)

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

type State struct {
	Position *bbgo.Position `json:"position,omitempty"`
}

type Target struct {
	ProfitPercentage      float64                         `json:"profitPercentage"`
	QuantityPercentage    float64                         `json:"quantityPercentage"`
	MarginOrderSideEffect types.MarginOrderSideEffectType `json:"marginOrderSideEffect"`
}

type Strategy struct {
	*bbgo.Notifiability `json:"-"`
	*bbgo.Persistence
	*bbgo.Graceful

	Symbol              string         `json:"symbol"`
	Interval            types.Interval `json:"interval"`
	Market              types.Market   `json:"-"`
	MovingAverageWindow int            `json:"movingAverageWindow"`

	LongTermMovingAverageInterval types.Interval `json:"longTermMovingAverage"`
	LongTermMovingAverageWindow   int `json:"longTermMovingAverageWindow"`

	Quantity              fixedpoint.Value                `json:"quantity"`
	MinVolume             fixedpoint.Value                `json:"minVolume"`
	Sensitivity           fixedpoint.Value                `json:"sensitivity"`
	TakerBuyRatio         fixedpoint.Value                `json:"takerBuyRatio"`
	MarginOrderSideEffect types.MarginOrderSideEffectType `json:"marginOrderSideEffect"`
	Targets               []Target                        `json:"targets"`

	ResistanceSensitivity   fixedpoint.Value `json:"resistanceSensitivity"`
	ResistanceMinVolume     fixedpoint.Value `json:"resistanceMinVolume"`
	ResistanceTakerBuyRatio fixedpoint.Value `json:"resistanceTakerBuyRatio"`


	MinBaseAssetBalance  fixedpoint.Value `json:"minBaseAssetBalance"`
	// Max BaseAsset balance to buy
	MaxBaseAssetBalance  fixedpoint.Value `json:"maxBaseAssetBalance"`
	MinQuoteAssetBalance fixedpoint.Value `json:"minQuoteAssetBalance"`

	ScaleQuantity *bbgo.PriceVolumeScale `json:"scaleQuantity"`

	orderStore *bbgo.OrderStore
	tradeStore *bbgo.TradeStore
	tradeC     chan types.Trade
	state      *State
}

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

func (s *Strategy) Validate() error {
	if s.Quantity == 0 && s.ScaleQuantity == nil {
		return fmt.Errorf("quantity or scaleQuantity can not be zero")
	}

	if s.MinVolume == 0 && s.Sensitivity == 0 {
		return fmt.Errorf("either minVolume nor sensitivity can not be zero")
	}

	return nil
}

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

func (s *Strategy) handleTradeUpdate(trade types.Trade) {
	s.tradeC <- trade
}

func (s *Strategy) tradeCollector(ctx context.Context) {
	for {
		select {
		case <-ctx.Done():
			return

		case trade := <-s.tradeC:
			s.tradeStore.Add(trade)

		}
	}
}

func (s *Strategy) SaveState() error {
	if err := s.Persistence.Save(s.state, ID, s.Symbol, stateKey); err != nil {
		return err
	} else {
		log.Infof("state is saved => %+v", s.state)
	}
	return nil
}

func (s *Strategy) LoadState() error {
	var state State

	// load position
	if err := s.Persistence.Load(&state, ID, s.Symbol, stateKey); err != nil {
		if err != service.ErrPersistenceNotExists {
			return err
		}

		s.state = &State{}
	} else {
		s.state = &state
		log.Infof("state is restored: %+v", s.state)
	}

	return nil
}

func (s *Strategy) submitOrders(ctx context.Context, orderExecutor bbgo.OrderExecutor, orderForms ...types.SubmitOrder) error {
	for _, o := range orderForms {
		s.Notifiability.Notify(o)
	}

	createdOrders, err := orderExecutor.SubmitOrders(ctx, orderForms...)
	if err != nil {
		return err
	}

	s.orderStore.Add(createdOrders...)
	return nil
}

func (s *Strategy) calculateQuantity(session *bbgo.ExchangeSession, side types.SideType, closePrice fixedpoint.Value, volume float64) (fixedpoint.Value, error) {
	var quantity fixedpoint.Value
	if s.Quantity > 0 {
		quantity = s.Quantity
	} else if s.ScaleQuantity != nil {
		qf, err := s.ScaleQuantity.Scale(closePrice.Float64(), volume)
		if err != nil {
			return 0, err
		}
		quantity = fixedpoint.NewFromFloat(qf)
	}


	baseBalance, _ := session.Account.Balance(s.Market.BaseCurrency)
	if side == types.SideTypeSell {
		// quantity = bbgo.AdjustQuantityByMaxAmount(quantity, closePrice, quota)
		if s.MinBaseAssetBalance > 0 && (baseBalance.Total() - quantity) < s.MinBaseAssetBalance {
			quota := baseBalance.Available - s.MinBaseAssetBalance
			quantity = bbgo.AdjustQuantityByMaxAmount(quantity, closePrice, quota)
		}

	} else if side == types.SideTypeBuy {
		if s.MaxBaseAssetBalance > 0 && baseBalance.Total()+quantity > s.MaxBaseAssetBalance {
			quota := s.MaxBaseAssetBalance - baseBalance.Total()
			quantity = bbgo.AdjustQuantityByMaxAmount(quantity, closePrice, quota)
		}

		quoteBalance, ok := session.Account.Balance(s.Market.QuoteCurrency)
		if !ok {
			return 0, fmt.Errorf("quote balance %s not found", s.Market.QuoteCurrency)
		}

		// for spot, we need to modify the quantity according to the quote balance
		if !session.Margin {
			// add 0.3% for price slippage
			notional := closePrice.Mul(quantity).MulFloat64(1.003)

			if s.MinQuoteAssetBalance > 0 && quoteBalance.Available-notional < s.MinQuoteAssetBalance {
				log.Warnf("modifying quantity %f according to the min quote asset balance %f %s",
					quantity.Float64(),
					quoteBalance.Available.Float64(),
					s.Market.QuoteCurrency)
				quota := quoteBalance.Available - s.MinQuoteAssetBalance
				quantity = bbgo.AdjustQuantityByMinAmount(quantity, closePrice, quota)
			} else if notional > quoteBalance.Available {
				log.Warnf("modifying quantity %f according to the quote asset balance %f %s",
					quantity.Float64(),
					quoteBalance.Available.Float64(),
					s.Market.QuoteCurrency)
				quantity = bbgo.AdjustQuantityByMaxAmount(quantity, closePrice, quoteBalance.Available)
			}
		}
	}

	return quantity, nil
}

func (s *Strategy) Run(ctx context.Context, orderExecutor bbgo.OrderExecutor, session *bbgo.ExchangeSession) error {
	// buffer 100 trades in the channel
	s.tradeC = make(chan types.Trade, 100)
	s.tradeStore = bbgo.NewTradeStore(s.Symbol)

	// set default values
	if s.Interval == "" {
		s.Interval = types.Interval5m
	}

	if s.MovingAverageWindow == 0 {
		s.MovingAverageWindow = 99
	}

	if s.Sensitivity > 0 {
		volRange, err := s.ScaleQuantity.ByVolumeRule.Range()
		if err != nil {
			return err
		}

		s.MinVolume = fixedpoint.NewFromFloat(volRange[0]) + fixedpoint.NewFromFloat(volRange[1]-volRange[0]).Mul(fixedpoint.NewFromFloat(1.0)-s.Sensitivity)
		log.Infof("adjusted minimal support volume to %f according to sensitivity %f", s.MinVolume.Float64(), s.Sensitivity.Float64())
	}

	if s.ResistanceTakerBuyRatio == 0 {
		s.ResistanceTakerBuyRatio = fixedpoint.NewFromFloat(0.5)
	}

	if s.ResistanceSensitivity > 0 {
		volRange, err := s.ScaleQuantity.ByVolumeRule.Range()
		if err != nil {
			return err
		}

		s.ResistanceMinVolume = fixedpoint.NewFromFloat(volRange[0]) + fixedpoint.NewFromFloat(volRange[1]-volRange[0]).Mul(fixedpoint.NewFromFloat(1.0)-s.ResistanceSensitivity)
		log.Infof("adjusted minimal resistance volume to %f according to sensitivity %f", s.ResistanceMinVolume.Float64(), s.ResistanceSensitivity.Float64())
	}

	market, ok := session.Market(s.Symbol)
	if !ok {
		return fmt.Errorf("market %s is not defined", s.Symbol)
	}
	s.Market = market

	standardIndicatorSet, ok := session.StandardIndicatorSet(s.Symbol)
	if !ok {
		return fmt.Errorf("standardIndicatorSet is nil, symbol %s", s.Symbol)
	}

	s.orderStore = bbgo.NewOrderStore(s.Symbol)
	s.orderStore.BindStream(session.UserDataStream)

	var iw = types.IntervalWindow{Interval: s.Interval, Window: s.MovingAverageWindow}
	var ema = standardIndicatorSet.EWMA(iw)

	if err := s.LoadState(); err != nil {
		return err
	} else {
		s.Notify("%s state is restored => %+v", s.Symbol, s.state)
	}

	// init state
	if s.state.Position == nil {
		s.state.Position = &bbgo.Position{
			Symbol:        s.Symbol,
			BaseCurrency:  market.BaseCurrency,
			QuoteCurrency: market.QuoteCurrency,
		}
	}

	go s.tradeCollector(ctx)

	session.UserDataStream.OnTradeUpdate(s.handleTradeUpdate)
	session.MarketDataStream.OnKLineClosed(func(kline types.KLine) {
		// skip k-lines from other symbols
		if kline.Symbol != s.Symbol {
			return
		}

		closePriceF := kline.GetClose()
		closePrice := fixedpoint.NewFromFloat(closePriceF)

		// if it's above the EMA, it's resistance
		if closePriceF > ema.Last() {
			// check resistance volume
			if kline.Volume < s.ResistanceMinVolume.Float64() {
				return
			}

			takerBuyBaseVolumeThreshold := kline.Volume * s.ResistanceTakerBuyRatio.Float64()
			if kline.TakerBuyBaseAssetVolume < takerBuyBaseVolumeThreshold {
				s.Notify("%s: resistance detected, taker buy base volume %f < threshold %f (volume %f) at price %f",
					s.Symbol,
					kline.TakerBuyBaseAssetVolume,
					takerBuyBaseVolumeThreshold,
					kline.Volume,
					closePriceF,
				)

				quantity, err := s.calculateQuantity(session, types.SideTypeSell, closePrice, kline.Volume)
				if err != nil {
					log.WithError(err).Errorf("quantity calculation error")
					return
				}

				orderForm := types.SubmitOrder{
					Symbol:   s.Symbol,
					Market:   market,
					Side:     types.SideTypeSell,
					Type:     types.OrderTypeMarket,
					Quantity: quantity.Float64(),
				}

				if err := s.submitOrders(ctx, orderExecutor, orderForm); err != nil {
					log.WithError(err).Error("submit sell order error")
					return
				}

				return
			}

			return
		}

		// check support
		if kline.Volume < s.MinVolume.Float64() {
			return
		}

		if s.TakerBuyRatio > 0 {
			takerBuyBaseVolumeThreshold := kline.Volume * s.TakerBuyRatio.Float64()
			if kline.TakerBuyBaseAssetVolume < takerBuyBaseVolumeThreshold {
				s.Notify("%s: taker buy base volume %f is less than threshold %f (volume %f volume ratio %f)",
					s.Symbol,
					kline.TakerBuyBaseAssetVolume,
					takerBuyBaseVolumeThreshold,
					kline.Volume,
					s.TakerBuyRatio.Float64(),
				)
				return
			}
		}

		s.Notify("Found %s support: the close price %f is under EMA %f and volume %f > minimum volume %f",
			s.Symbol,
			closePrice.Float64(),
			ema.Last(),
			kline.Volume,
			s.MinVolume.Float64(),
			kline)

		quantity, err := s.calculateQuantity(session, types.SideTypeBuy, closePrice, kline.Volume)
		if err != nil {
			log.WithError(err).Errorf("%s quantity calculation error", s.Symbol)
			return
		}

		orderForm := types.SubmitOrder{
			Symbol:           s.Symbol,
			Market:           market,
			Side:             types.SideTypeBuy,
			Type:             types.OrderTypeMarket,
			Quantity:         quantity.Float64(),
			MarginSideEffect: s.MarginOrderSideEffect,
		}

		s.Notify("Submitting %s market order buy with quantity %f according to the base volume %f, taker buy base volume %f",
			s.Symbol,
			quantity.Float64(),
			kline.Volume,
			kline.TakerBuyBaseAssetVolume,
			orderForm)

		if err := s.submitOrders(ctx, orderExecutor, orderForm); err != nil {
			log.WithError(err).Error("submit order error")
			return
		}

		time.Sleep(500 * time.Millisecond)

		trades := s.tradeStore.GetAndClear()
		for _, trade := range trades {
			if s.orderStore.Exists(trade.OrderID) {
				s.Notify(trade)
				s.state.Position.AddTrade(trade)
			}
		}
		s.Notify(s.state.Position)

		// submit target orders
		var targetOrders []types.SubmitOrder
		for _, target := range s.Targets {
			targetPrice := closePrice.Float64() * (1.0 + target.ProfitPercentage)
			targetQuantity := quantity.Float64() * target.QuantityPercentage
			targetQuoteQuantity := targetPrice * targetQuantity

			if targetQuoteQuantity <= market.MinNotional {
				continue
			}

			if targetQuantity <= market.MinQuantity {
				continue
			}

			targetOrders = append(targetOrders, types.SubmitOrder{
				Symbol:   kline.Symbol,
				Market:   market,
				Type:     types.OrderTypeLimit,
				Side:     types.SideTypeSell,
				Price:    targetPrice,
				Quantity: targetQuantity,

				MarginSideEffect: target.MarginOrderSideEffect,
				TimeInForce:      "GTC",
			})
		}

		if err := s.submitOrders(ctx, orderExecutor, targetOrders...); err != nil {
			log.WithError(err).Error("submit profit target order error")
			return
		}
	})

	s.Graceful.OnShutdown(func(ctx context.Context, wg *sync.WaitGroup) {
		defer wg.Done()

		if err := s.SaveState(); err != nil {
			log.WithError(err).Errorf("can not save state: %+v", s.state)
		} else {
			s.Notify("%s position is saved", s.Symbol, s.state.Position)
		}
	})

	return nil
}