mirror of
https://github.com/lightninglabs/faraday.git
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dffb00929f
Add Currency field to the price struct so that Price can be used to represent any currency.
101 lines
2.6 KiB
Go
101 lines
2.6 KiB
Go
package fiat
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import (
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"context"
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"encoding/json"
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"fmt"
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"io/ioutil"
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"net/http"
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"time"
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"github.com/shopspring/decimal"
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)
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const (
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// coinDeskHistoryAPI is the endpoint we hit for historical price data.
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coinDeskHistoryAPI = "https://api.coindesk.com/v1/bpi/historical/close.json"
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// coinDeskTimeFormat is the date format used by coindesk.
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coinDeskTimeFormat = "2006-01-02"
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// coinDeskDefaultCurrency is the default currency that the price data
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// returned by the Coin Desk API is quoted in.
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coinDeskDefaultCurrency = "USD"
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)
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// coinDeskAPI implements the fiatBackend interface.
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type coinDeskAPI struct{}
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type coinDeskResponse struct {
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Data map[string]float64 `json:"bpi"`
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}
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// queryCoinDesk constructs and sends a request to coindesk to query historical
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// price information.
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func queryCoinDesk(start, end time.Time) ([]byte, error) {
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queryURL := fmt.Sprintf("%v?start=%v&end=%v",
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coinDeskHistoryAPI, start.Format(coinDeskTimeFormat),
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end.Format(coinDeskTimeFormat))
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log.Debugf("coindesk url: %v", queryURL)
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// Query the http endpoint with the url provided
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// #nosec G107
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response, err := http.Get(queryURL)
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if err != nil {
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return nil, err
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}
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defer response.Body.Close()
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return ioutil.ReadAll(response.Body)
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}
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// parseCoinDeskData parses http response data from coindesk into Price
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// structs.
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func parseCoinDeskData(data []byte) ([]*Price, error) {
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var priceEntries coinDeskResponse
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if err := json.Unmarshal(data, &priceEntries); err != nil {
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return nil, err
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}
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var usdRecords = make([]*Price, 0, len(priceEntries.Data))
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for date, price := range priceEntries.Data {
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timestamp, err := time.Parse(coinDeskTimeFormat, date)
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if err != nil {
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return nil, err
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}
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usdRecords = append(usdRecords, &Price{
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Timestamp: timestamp,
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Price: decimal.NewFromFloat(price),
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Currency: coinDeskDefaultCurrency,
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})
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}
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return usdRecords, nil
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}
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// rawPriceData retrieves price information from coindesks's api for the given
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// time range.
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func (c *coinDeskAPI) rawPriceData(ctx context.Context, start,
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end time.Time) ([]*Price, error) {
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query := func() ([]byte, error) {
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return queryCoinDesk(start, end)
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}
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// CoinDesk uses a granularity of 1 day and does not include the current
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// day's price information. So subtract 1 period from the start date so
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// that at least one day's price data is always included.
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start = start.Add(time.Hour * -24)
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// Query the api for this page of data. We allow retries at this
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// stage in case the api experiences a temporary limit.
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records, err := retryQuery(ctx, query, parseCoinDeskData)
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if err != nil {
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return nil, err
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}
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return records, nil
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}
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