price watcher

internal/price/price.go

@@ -0,0 +1,104 @@
+package price
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+	"github.com/tidwall/gjson"
+)
+
+type PriceWatcher struct {
+	client         *http.Client
+	UpdateInterval time.Duration
+	Currencies     []string
+	Exchanges      map[string]func(string) (float64, error)
+	Price          map[string]float64
+}
+
+func NewPriceWatcher() *PriceWatcher {
+	pricewatcher := &PriceWatcher{
+		client: &http.Client{
+			Timeout: time.Second * time.Duration(5),
+		},
+		Currencies:     []string{"USD", "EUR"},
+		Price:          make(map[string]float64, 0),
+		Exchanges:      make(map[string]func(string) (float64, error), 0),
+		UpdateInterval: time.Second * time.Duration(30),
+	}
+	pricewatcher.Exchanges["coinbase"] = pricewatcher.GetCoinbasePrice
+	pricewatcher.Exchanges["bitfinex"] = pricewatcher.GetBitfinexPrice
+	log.Infof("[PriceWatcher] Watcher started")
+	return pricewatcher
+}
+
+func (p *PriceWatcher) Start() {
+	go p.Watch()
+}
+
+func (p *PriceWatcher) Watch() error {
+	for {
+		time.Sleep(p.UpdateInterval)
+		for _, currency := range p.Currencies {
+			avg_price := 0.0
+			n_responses := 0
+			for exchange, getPrice := range p.Exchanges {
+				fprice, err := getPrice(currency)
+				if err != nil {
+					log.Error(err)
+					// if one exchanges is down, use the next
+					continue
+				}
+				n_responses++
+				avg_price += fprice
+				log.Debugf("[PriceWatcher] %s %s price: %f", exchange, currency, fprice)
+			}
+			p.Price[currency] = avg_price / float64(n_responses)
+			log.Debugf("[PriceWatcher] Average %s price: %f", currency, p.Price[currency])
+		}
+	}
+}
+
+func (p *PriceWatcher) GetCoinbasePrice(currency string) (float64, error) {
+	coinbaseEndpoint, err := url.Parse(fmt.Sprintf("https://api.coinbase.com/v2/prices/spot?currency=%s", currency))
+	response, err := p.client.Get(coinbaseEndpoint.String())
+	if err, ok := err.(net.Error); ok && err.Timeout() {
+		return 0, err
+	}
+	bodyBytes, err := ioutil.ReadAll(response.Body)
+	if err != nil {
+		log.Fatal(err)
+	}
+	price := gjson.Get(string(bodyBytes), "data.amount")
+	fprice, err := strconv.ParseFloat(strings.TrimSpace(price.String()), 64)
+	if err != nil {
+		log.Fatal(err)
+	}
+	return fprice, nil
+}
+
+func (p *PriceWatcher) GetBitfinexPrice(currency string) (float64, error) {
+	var bitfinexCurrencyToPair = map[string]string{"USD": "btcusd", "EUR": "btceur"}
+	pair := bitfinexCurrencyToPair[currency]
+	bitfinexEndpoint, err := url.Parse(fmt.Sprintf("https://api.bitfinex.com/v1/pubticker/%s", pair))
+	response, err := p.client.Get(bitfinexEndpoint.String())
+	if err, ok := err.(net.Error); ok && err.Timeout() {
+		return 0, err
+	}
+	bodyBytes, err := ioutil.ReadAll(response.Body)
+	if err != nil {
+		log.Fatal(err)
+	}
+	price := gjson.Get(string(bodyBytes), "last_price")
+	fprice, err := strconv.ParseFloat(strings.TrimSpace(price.String()), 64)
+	if err != nil {
+		log.Fatal(err)
+	}
+	return fprice, nil
+}

main.go

@@ -1,11 +1,13 @@
 package main
 
 import (
+	"runtime/debug"
+
 	"github.com/LightningTipBot/LightningTipBot/internal/lnbits/webhook"
 	"github.com/LightningTipBot/LightningTipBot/internal/lnurl"
+	"github.com/LightningTipBot/LightningTipBot/internal/price"
 	"github.com/LightningTipBot/LightningTipBot/internal/telegram"
 	log "github.com/sirupsen/logrus"
-	"runtime/debug"
 )
 
 // setLogger will initialize the log format
@@ -24,6 +26,7 @@ func main() {
 	bot := telegram.NewBot()
 	webhook.NewServer(&bot)
 	lnurl.NewServer(&bot)
+	price.NewPriceWatcher().Start()
 	bot.Start()
 }