clients/horizon: Extend client with Offer details support

clients/horizonclient/client.go

@@ -9,6 +9,7 @@ import (
 	"io"
 	"net/http"
 	"net/url"
+	"strconv"
 	"strings"
 	"time"
 
@@ -345,6 +346,23 @@ func (c *Client) Offers(request OfferRequest) (offers hProtocol.OffersPage, err
 	return
 }
 
+// OfferDetails returns information for a single offer.
+// See https://www.stellar.org/developers/horizon/reference/endpoints/offer-details.html
+func (c *Client) OfferDetails(offerID string) (offer hProtocol.Offer, err error) {
+	if len(offerID) == 0 {
+		err = errors.New("no offer ID provided")
+		return
+	}
+
+	if _, err = strconv.ParseInt(offerID, 10, 64); err != nil {
+		err = errors.New("invalid offer ID provided")
+		return
+	}
+
+	err = c.sendRequest(OfferRequest{OfferID: offerID}, &offer)
+	return
+}
+
 // Operations returns stellar operations (https://www.stellar.org/developers/horizon/reference/resources/operation.html)
 // It can be used to return operations for an account, a ledger, a transaction and all operations on the network.
 func (c *Client) Operations(request OperationRequest) (ops operations.OperationsPage, err error) {

clients/horizonclient/examples_test.go

@@ -263,7 +263,6 @@ func ExampleClient_NextOffersPage() {
 		fmt.Println(nextPage)
 	}
 }
-
 func ExampleClient_NextOperationsPage() {
 	client := horizonclient.DefaultPublicNetClient
 	// all operations
@@ -410,6 +409,17 @@ func ExampleClient_NextTransactionsPage() {
 	}
 }
 
+func ExampleClient_OfferDetails() {
+	client := horizonclient.DefaultPublicNetClient
+	offer, err := client.OfferDetails("2")
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+
+	fmt.Print(offer)
+}
+
 func ExampleClient_Offers() {
 	client := horizonclient.DefaultPublicNetClient
 	offerRequest := horizonclient.OfferRequest{

clients/horizonclient/main.go

@@ -151,6 +151,7 @@ type ClientInterface interface {
 	Metrics() (hProtocol.Metrics, error)
 	FeeStats() (hProtocol.FeeStats, error)
 	Offers(request OfferRequest) (hProtocol.OffersPage, error)
+	OfferDetails(offerID string) (offer hProtocol.Offer, err error)
 	Operations(request OperationRequest) (operations.OperationsPage, error)
 	OperationDetail(id string) (operations.Operation, error)
 	SubmitTransactionXDR(transactionXdr string) (hProtocol.TransactionSuccess, error)
@@ -275,9 +276,9 @@ type feeStatsRequest struct {
 }
 
 // OfferRequest struct contains data for getting offers made by an account from a horizon server.
-// "ForAccount" is required.
 // The query parameters (Order, Cursor and Limit) are optional. All or none can be set.
 type OfferRequest struct {
+	OfferID    string
 	ForAccount string
 	Selling    string
 	Seller     string

clients/horizonclient/main_test.go

@@ -566,6 +566,40 @@ func TestOfferRequest(t *testing.T) {
 		assert.Len(t, offers.Embedded.Records, 1)
 	}
 }
+func TestOfferDetailsRequest(t *testing.T) {
+	hmock := httptest.NewClient()
+	client := &Client{
+		HorizonURL: "https://localhost/",
+		HTTP:       hmock,
+	}
+
+	// account offers
+	hmock.On(
+		"GET",
+		"https://localhost/offers/5635",
+	).ReturnString(200, offerResponse)
+
+	record, err := client.OfferDetails("5635")
+	if assert.NoError(t, err) {
+		assert.IsType(t, record, hProtocol.Offer{})
+		assert.Equal(t, record.ID, int64(5635))
+		assert.Equal(t, record.Seller, "GD6UOZ3FGFI5L2X6F52YPJ6ICSW375BNBZIQC4PCLSEOO6SMX7CUS5MB")
+		assert.Equal(t, record.PT, "5635")
+		assert.Equal(t, record.Selling.Type, "native")
+		assert.Equal(t, record.Buying.Code, "AstroDollar")
+		assert.Equal(t, record.Buying.Issuer, "GDA2EHKPDEWZTAL6B66FO77HMOZL3RHZTIJO7KJJK5RQYSDUXEYMPJYY")
+		assert.Equal(t, record.Amount, "100.0000000")
+		assert.Equal(t, record.LastModifiedLedger, int32(356183))
+	}
+
+	_, err = client.OfferDetails("S6ES")
+	assert.Error(t, err)
+	assert.EqualError(t, err, "invalid offer ID provided")
+
+	_, err = client.OfferDetails("")
+	assert.Error(t, err)
+	assert.EqualError(t, err, "no offer ID provided")
+}
 
 func TestOperationsRequest(t *testing.T) {
 	hmock := httptest.NewClient()
@@ -1474,6 +1508,38 @@ var offersResponse = `{
   }
 }`
 
+var offerResponse = `
+{
+  "_links": {
+    "self": {
+      "href": "https://horizon-testnet.stellar.org/offers/5635"
+    },
+    "offer_maker": {
+      "href": "https://horizon-testnet.stellar.org/accounts/GD6UOZ3FGFI5L2X6F52YPJ6ICSW375BNBZIQC4PCLSEOO6SMX7CUS5MB"
+    }
+  },
+  "id": "5635",
+  "paging_token": "5635",
+  "seller": "GD6UOZ3FGFI5L2X6F52YPJ6ICSW375BNBZIQC4PCLSEOO6SMX7CUS5MB",
+  "selling": {
+    "asset_type": "native"
+  },
+  "buying": {
+    "asset_type": "credit_alphanum12",
+    "asset_code": "AstroDollar",
+    "asset_issuer": "GDA2EHKPDEWZTAL6B66FO77HMOZL3RHZTIJO7KJJK5RQYSDUXEYMPJYY"
+  },
+  "amount": "100.0000000",
+  "price_r": {
+    "n": 10,
+    "d": 1
+  },
+  "price": "10.0000000",
+  "last_modified_ledger": 356183,
+  "last_modified_time": "2020-02-20T20:44:55Z"
+}
+`
+
 var multipleOpsResponse = `{
   "_links": {
     "self": {

clients/horizonclient/mocks.go

@@ -75,6 +75,12 @@ func (m *MockClient) Offers(request OfferRequest) (hProtocol.OffersPage, error)
 	return a.Get(0).(hProtocol.OffersPage), a.Error(1)
 }
 
+// OfferDetail is a mocking method
+func (m *MockClient) OfferDetails(offerID string) (hProtocol.Offer, error) {
+	a := m.Called(offerID)
+	return a.Get(0).(hProtocol.Offer), a.Error(1)
+}
+
 // Operations is a mocking method
 func (m *MockClient) Operations(request OperationRequest) (operations.OperationsPage, error) {
 	a := m.Called(request)

clients/horizonclient/offer_request.go

@@ -12,29 +12,33 @@ import (
 
 // BuildURL creates the endpoint to be queried based on the data in the OfferRequest struct.
 func (or OfferRequest) BuildURL() (endpoint string, err error) {
-	// backwards compatibility  support
-	if len(or.ForAccount) > 0 {
-		endpoint = fmt.Sprintf("accounts/%s/offers", or.ForAccount)
-		queryParams := addQueryParams(cursor(or.Cursor), limit(or.Limit), or.Order)
-		if queryParams != "" {
-			endpoint = fmt.Sprintf("%s?%s", endpoint, queryParams)
-		}
+	if len(or.OfferID) > 0 {
+		endpoint = fmt.Sprintf("offers/%s", or.OfferID)
 	} else {
-		query := url.Values{}
-		if len(or.Seller) > 0 {
-			query.Add("seller", or.Seller)
-		}
-		if len(or.Selling) > 0 {
-			query.Add("selling", or.Selling)
-		}
-		if len(or.Buying) > 0 {
-			query.Add("buying", or.Buying)
-		}
+		// backwards compatibility  support
+		if len(or.ForAccount) > 0 {
+			endpoint = fmt.Sprintf("accounts/%s/offers", or.ForAccount)
+			queryParams := addQueryParams(cursor(or.Cursor), limit(or.Limit), or.Order)
+			if queryParams != "" {
+				endpoint = fmt.Sprintf("%s?%s", endpoint, queryParams)
+			}
+		} else {
+			query := url.Values{}
+			if len(or.Seller) > 0 {
+				query.Add("seller", or.Seller)
+			}
+			if len(or.Selling) > 0 {
+				query.Add("selling", or.Selling)
+			}
+			if len(or.Buying) > 0 {
+				query.Add("buying", or.Buying)
+			}
 
-		endpoint = fmt.Sprintf("offers?%s", query.Encode())
-		pageParams := addQueryParams(cursor(or.Cursor), limit(or.Limit), or.Order)
-		if pageParams != "" {
-			endpoint = fmt.Sprintf("%s&%s", endpoint, pageParams)
+			endpoint = fmt.Sprintf("offers?%s", query.Encode())
+			pageParams := addQueryParams(cursor(or.Cursor), limit(or.Limit), or.Order)
+			if pageParams != "" {
+				endpoint = fmt.Sprintf("%s&%s", endpoint, pageParams)
+			}
 		}
 	}
 

clients/horizonclient/offer_request_test.go

@@ -25,6 +25,12 @@ func TestOfferRequestBuildUrl(t *testing.T) {
 	// It should return valid offers endpoint and no errors
 	require.NoError(t, err)
 	assert.Equal(t, "accounts/GCLWGQPMKXQSPF776IU33AH4PZNOOWNAWGGKVTBQMIC5IMKUNP3E6NVU/offers?cursor=now&order=desc", endpoint)
+
+	er = OfferRequest{OfferID: "12345"}
+	endpoint, err = er.BuildURL()
+
+	require.NoError(t, err)
+	assert.Equal(t, "offers/12345", endpoint)
 }
 
 func TestNextOffersPage(t *testing.T) {