Implemented Spread endpoint and tests.

README.md

@@ -1,8 +1,6 @@
 # Go Kraken [![GoDoc](https://godoc.org/github.com/danmrichards/gokraken?status.svg)](https://godoc.org/github.com/danmrichards/gokraken) [![License](http://img.shields.io/badge/license-mit_bsd-blue.svg)](https://raw.githubusercontent.com/danmrichards/gokraken/master/LICENSE) [![Go Report Card](https://goreportcard.com/badge/github.com/danmrichards/gokraken)](https://goreportcard.com/report/github.com/danmrichards/gokraken) [![Build Status](https://travis-ci.org/danmrichards/gokraken.svg?branch=master)](https://travis-ci.org/danmrichards/gokraken)
 A Go API client for the [Kraken](https://www.kraken.com) cryptocurrency exchange
 
-> Note: This is stupidly early in development. Don't use it please...no really don't
-
 ## Usage
 ### Public API
 ```go
@@ -63,7 +61,7 @@ Coming soon
 - [x] Public API calls working
 - [x] Private API calls working
 - [x] Travis CI
-- [ ] Implement public market data endpoints
+- [x] Implement public market data endpoints
 - [ ] Implement private user data endpoints
 - [ ] Implement private user trading endpoints
 - [ ] Implement private user funding endpoints

depth.go

@@ -15,7 +15,7 @@ type DepthRequest struct {
 	Count int
 }
 
-// TradesResponse represents the response from the Kraken order book endpoint.
+// DepthResponse represents the response from the Kraken order book endpoint.
 type DepthResponse map[string]Depth
 
 // Depth is an order book response for a given asset pair.

market.go

@@ -391,3 +391,97 @@ func (m *Market) Trades(ctx context.Context, tradeReq *TradesRequest) (res *Trad
 
 	return
 }
+
+// Spread returns the spread data from Kraken.
+// https://www.kraken.com/en-gb/help/api#get-recent-spread-data
+func (m *Market) Spread(ctx context.Context, spreadReq *SpreadRequest) (res *SpreadResponse, err error) {
+	body := url.Values{
+		"pair": []string{spreadReq.Pair},
+	}
+
+	if spreadReq.Since != 0 {
+		body["since"] = []string{strconv.FormatInt(spreadReq.Since, 10)}
+	}
+
+	req, err := m.Client.Dial(ctx, http.MethodPost, SpreadResource, body)
+	if err != nil {
+		return
+	}
+
+	krakenResp, err := m.Client.Call(req)
+	if err != nil {
+		return
+	}
+
+	var tmp map[string]interface{}
+	err = krakenResp.ExtractResult(&tmp)
+	if err != nil {
+		return
+	}
+
+	lastFloat, ok := tmp["last"].(float64)
+	if !ok {
+		err = errors.New("could not extract last from ohlc response")
+		return
+	}
+
+	res = &SpreadResponse{
+		Last: int64(lastFloat),
+		Data: make([]SpreadData, 0),
+	}
+
+	spreadData, ok := tmp[spreadReq.Pair].([]interface{})
+	if !ok {
+		err = fmt.Errorf("could not extract spread data where pair=%s", spreadReq.Pair)
+		return
+	}
+
+	for key, spreadDatum := range spreadData {
+		spreadDatum, ok := spreadDatum.([]interface{})
+		if !ok {
+			err = fmt.Errorf("could not extract at spreadDatum=%d", key)
+			return
+		}
+
+		timestampFloat, ok := spreadDatum[0].(float64)
+		if !ok {
+			err = fmt.Errorf("could not extract timestamp at spreadDatum=%d", key)
+			return
+		}
+		timestamp := time.Unix(int64(timestampFloat), 0)
+
+		bidStr, ok := spreadDatum[1].(string)
+		if !ok {
+			err = fmt.Errorf("could not extract bid at spreadDatum=%d", key)
+			return
+		}
+
+		var bid float64
+		bid, err = strconv.ParseFloat(bidStr, 64)
+		if err != nil {
+			err = fmt.Errorf("could not parse bid to float at spreadDatum=%d", key)
+			return
+		}
+
+		askStr, ok := spreadDatum[2].(string)
+		if !ok {
+			err = fmt.Errorf("could not extract ask at spreadDatum=%d", key)
+			return
+		}
+
+		var ask float64
+		ask, err = strconv.ParseFloat(askStr, 64)
+		if err != nil {
+			err = fmt.Errorf("could not parse ask to float at spreadDatum=%d", key)
+			return
+		}
+
+		res.Data = append(res.Data, SpreadData{
+			Timestamp: timestamp,
+			Bid:       bid,
+			Ask:       ask,
+		})
+	}
+
+	return
+}

market_test.go

@@ -687,3 +687,50 @@ func TestMarket_Trades(t *testing.T) {
 		})
 	}
 }
+
+func TestMarket_Spread(t *testing.T) {
+	cases := []struct {
+		name             string
+		request          *SpreadRequest
+		mockResponse     []byte
+		expectedResponse *SpreadResponse
+	}{
+		{
+			name:         "valid request",
+			request:      &SpreadRequest{Pair: "BCHEUR"},
+			mockResponse: []byte(`{"error":[],"result":{"BCHEUR":[[1518904771,"1225.600000","1229.200000"]],"last":1518905570}}`),
+			expectedResponse: &SpreadResponse{
+				Data: []SpreadData{
+					{
+						Timestamp: time.Unix(1518904771, 0),
+						Bid:       1225.6,
+						Ask:       1229.2,
+					},
+				},
+				Last: 1518905570,
+			},
+		},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				w.Header().Set("Content-Type", "application/json")
+				w.WriteHeader(http.StatusOK)
+
+				w.Write(c.mockResponse)
+			}))
+
+			defer ts.Close()
+
+			k := New()
+			k.BaseURL = ts.URL
+
+			res, err := k.Market.Spread(context.Background(), &SpreadRequest{Pair: "BCHEUR"})
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			assert(c.expectedResponse, res, t)
+		})
+	}
+}

spread.go

@@ -0,0 +1,25 @@
+package gokraken
+
+import "time"
+
+// SpreadResource is the API resource for the Kraken API spread data.
+const SpreadResource = "Spread"
+
+// SpreadRequest represents a request to get spread data from Kraken.
+type SpreadRequest struct {
+	Pair  string
+	Since int64
+}
+
+// SpreadResponse represents the response from the Kraken spread data endpoint.
+type SpreadResponse struct {
+	Data []SpreadData
+	Last int64
+}
+
+// SpreadData is the spread of data for trades.
+type SpreadData struct {
+	Timestamp time.Time
+	Bid       float64
+	Ask       float64
+}