pancakeswapnft/floor.go

package pancakeswapnft

import (
	"context"
	"sync"
	"time"

	"github.com/machinebox/graphql"
	"github.com/pkg/errors"
	"github.com/rs/zerolog/log"
)

type FloorService struct {
	Done chan struct{}

	collection  string
	graphClient *graphql.Client

	floors        map[time.Time]float64
	lock          *sync.RWMutex
	cacheDuration time.Duration
}

func NewFloorService(ctx context.Context, collection string, graphClient *graphql.Client, cacheDuration time.Duration) *FloorService {
	s := &FloorService{
		Done:          make(chan struct{}),
		collection:    collection,
		graphClient:   graphClient,
		floors:        make(map[time.Time]float64),
		lock:          &sync.RWMutex{},
		cacheDuration: cacheDuration,
	}
	s.start(ctx)
	return s
}

func (s *FloorService) start(ctx context.Context) {
	t := time.NewTicker(1 * time.Minute)
	err := s.watchfloor(ctx)
	if err != nil {
		log.Error().Err(err).Msg("watching floor")
	}
	go func() {
		defer close(s.Done)
		for {
			select {
			case <-ctx.Done():
				return
			case <-t.C:
				err := s.watchfloor(ctx)
				if err != nil {
					log.Error().Err(err).Msg("watching floor")
				}
			}
		}
	}()
}

func (s *FloorService) watchfloor(ctx context.Context) error {
	req := graphql.NewRequest(`
		query ($first: Int, $skip: Int!, $where: NFT_filter, $orderBy: NFT_orderBy, $orderDirection: OrderDirection) {
			nfts(where: $where, first: $first, orderBy: $orderBy, orderDirection: $orderDirection, skip: $skip) {
				currentAskPrice
			}
		}`)
	req.Var("first", 1)
	req.Var("orderBy", "currentAskPrice")
	req.Var("orderDirection", "asc")
	req.Var("skip", 0)

	req.Var("where", struct {
		Collection string `json:"collection"`
		IsTradable bool   `json:"isTradable"`
	}{
		Collection: s.collection,
		IsTradable: true,
	})

	var respData struct {
		Nfts []Nft `json:"nfts"`
	}
	if err := s.graphClient.Run(ctx, req, &respData); err != nil {
		return errors.Wrap(err, "querying graphql")
	}

	if len(respData.Nfts) <= 0 {
		return errors.Errorf("no tradable nft found")
	}
	floor := respData.Nfts[0].CurrentAskPrice

	s.lock.Lock()
	newfloors := make(map[time.Time]float64)
	for t, f := range s.floors {
		if t.After(time.Now().Add(-s.cacheDuration)) {
			newfloors[t] = f
		}

	}
	newfloors[time.Now()] = floor
	s.floors = newfloors
	s.lock.Unlock()
	return nil
}

func (s *FloorService) GetFloor() float64 {
	s.lock.RLock()
	defer s.lock.RUnlock()

	var tot float64
	for _, f := range s.floors {
		tot += f
	}
	res := tot / float64(len(s.floors))
	if res < 0.001 {
		res = 3
	}
	return res
}