forked from cpacia/BitcoinCash-Wallet
/
exchangerates.go
175 lines (159 loc) · 4.06 KB
/
exchangerates.go
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package exchangerates
import (
"encoding/json"
"errors"
"fmt"
"github.com/OpenBazaar/openbazaar-go/bitcoin/exchange"
"golang.org/x/net/proxy"
"net"
"net/http"
"strconv"
"sync"
"time"
)
type ExchangeRateProvider struct {
fetchUrl string
cache map[string]float64
client *http.Client
decoder ExchangeRateDecoder
bitcoinProvider *exchange.BitcoinPriceFetcher
}
type ExchangeRateDecoder interface {
decode(dat interface{}, cache map[string]float64, bp *exchange.BitcoinPriceFetcher) (err error)
}
type KrakenDecoder struct{}
type BitcoinCashPriceFetcher struct {
sync.Mutex
cache map[string]float64
providers []*ExchangeRateProvider
}
func NewBitcoinCashPriceFetcher(dialer proxy.Dialer) *BitcoinCashPriceFetcher {
bp := exchange.NewBitcoinPriceFetcher(dialer)
b := BitcoinCashPriceFetcher{
cache: make(map[string]float64),
}
dial := net.Dial
if dialer != nil {
dial = dialer.Dial
}
tbTransport := &http.Transport{Dial: dial}
client := &http.Client{Transport: tbTransport, Timeout: time.Minute}
b.providers = []*ExchangeRateProvider{
{"https://api.kraken.com/0/public/Ticker?pair=BCHXBT", b.cache, client, KrakenDecoder{}, bp},
}
go b.run()
return &b
}
func (b *BitcoinCashPriceFetcher) GetExchangeRate(currencyCode string) (float64, error) {
b.Lock()
defer b.Unlock()
price, ok := b.cache[currencyCode]
if !ok {
return 0, errors.New("Currency not tracked")
}
return price, nil
}
func (b *BitcoinCashPriceFetcher) GetLatestRate(currencyCode string) (float64, error) {
b.fetchCurrentRates()
b.Lock()
defer b.Unlock()
price, ok := b.cache[currencyCode]
if !ok {
return 0, errors.New("Currency not tracked")
}
return price, nil
}
func (b *BitcoinCashPriceFetcher) GetAllRates() (map[string]float64, error) {
b.Lock()
defer b.Unlock()
return b.cache, nil
}
func (b *BitcoinCashPriceFetcher) UnitsPerCoin() int {
return exchange.SatoshiPerBTC
}
func (b *BitcoinCashPriceFetcher) fetchCurrentRates() error {
b.Lock()
defer b.Unlock()
for _, provider := range b.providers {
err := provider.fetch()
if err == nil {
return nil
}
fmt.Println(err)
}
return errors.New("All exchange rate API queries failed")
}
func (b *BitcoinCashPriceFetcher) run() {
b.fetchCurrentRates()
ticker := time.NewTicker(time.Minute * 15)
for range ticker.C {
b.fetchCurrentRates()
}
}
func (provider *ExchangeRateProvider) fetch() (err error) {
if len(provider.fetchUrl) == 0 {
err = errors.New("Provider has no fetchUrl")
return err
}
resp, err := provider.client.Get(provider.fetchUrl)
if err != nil {
return err
}
decoder := json.NewDecoder(resp.Body)
var dataMap interface{}
err = decoder.Decode(&dataMap)
if err != nil {
return err
}
return provider.decoder.decode(dataMap, provider.cache, provider.bitcoinProvider)
}
func (b KrakenDecoder) decode(dat interface{}, cache map[string]float64, bp *exchange.BitcoinPriceFetcher) (err error) {
rates, err := bp.GetAllRates()
if err != nil {
return err
}
obj, ok := dat.(map[string]interface{})
if !ok {
return errors.New("KrackenDecoder type assertion failure")
}
result, ok := obj["result"]
if !ok {
return errors.New("KrakenDecoder: field `result` not found")
}
resultMap, ok := result.(map[string]interface{})
if !ok {
return errors.New("KrackenDecoder type assertion failure")
}
pair, ok := resultMap["BCHXBT"]
if !ok {
return errors.New("KrakenDecoder: field `BCHXBT` not found")
}
pairMap, ok := pair.(map[string]interface{})
if !ok {
return errors.New("KrackenDecoder type assertion failure")
}
c, ok := pairMap["c"]
if !ok {
return errors.New("KrakenDecoder: field `c` not found")
}
cList, ok := c.([]interface{})
if !ok {
return errors.New("KrackenDecoder type assertion failure")
}
rateStr, ok := cList[0].(string)
if !ok {
return errors.New("KrackenDecoder type assertion failure")
}
price, err := strconv.ParseFloat(rateStr, 64)
if err != nil {
return err
}
rate := price
if rate == 0 {
return errors.New("Bitcoin-BitcoinCash price data not available")
}
for k, v := range rates {
cache[k] = v * rate
}
return nil
}