Implement a GraphQL interface

For now this simply wraps the machinebox/graphql library but it should
allow us to replace that module whenever we need to.

commercetools/client.go

@@ -101,9 +101,14 @@ func (qi QueryInput) toParams() (values url.Values) {
 
 // New creates a new client based on the provided Config.
 func New(cfg *Config) *Client {
+	apiURL, err := cleanURL(getConfigValue(cfg.URL, "CTP_API_URL"))
+	if err != nil {
+		return nil
+	}
+
 	client := &Client{
 		projectKey: getConfigValue(cfg.ProjectKey, "CTP_PROJECT_KEY"),
-		url:        getConfigValue(cfg.URL, "CTP_API_URL"),
+		url:        apiURL,
 		httpClient: cfg.HTTPClient,
 		userAgent:  GetUserAgent(cfg),
 	}
@@ -221,6 +226,15 @@ func (c *Client) doRequest(method string, endpoint string, params url.Values, da
 	}
 }
 
+func cleanURL(baseURL string) (string, error) {
+	u, err := url.Parse(baseURL)
+	if err != nil {
+		return baseURL, err
+	}
+	u.Path = ""
+	return u.String(), nil
+}
+
 func serializeInput(input interface{}) (io.Reader, error) {
 	m, err := json.MarshalIndent(input, "", "\t")
 	if err != nil {

commercetools/client_graphql.go

@@ -0,0 +1,57 @@
+package commercetools
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/machinebox/graphql"
+)
+
+type GraphQLQuery struct {
+	client  *graphql.Client
+	request *graphql.Request
+}
+
+// NewGraphQLQuery creates a new GraphQLQuery object which can be used to
+// execute a GraphQL query
+func (client *Client) NewGraphQLQuery(query string) *GraphQLQuery {
+	endpoint := fmt.Sprintf("%s/%s/graphql", client.url, client.projectKey)
+
+	gqlClient := graphql.NewClient(
+		endpoint,
+		graphql.WithHTTPClient(client.httpClient),
+	)
+
+	queryObject := GraphQLQuery{
+		client:  gqlClient,
+		request: graphql.NewRequest(query),
+	}
+
+	return &queryObject
+}
+
+func (client *Client) NewGraphQLQueryMerchantCenter(query string) *GraphQLQuery {
+	endpoint := fmt.Sprintf("%s/%s/graphql", client.url, client.projectKey)
+
+	gqlClient := graphql.NewClient(
+		endpoint,
+		graphql.WithHTTPClient(client.httpClient),
+	)
+
+	queryObject := GraphQLQuery{
+		client:  gqlClient,
+		request: graphql.NewRequest(query),
+	}
+
+	return &queryObject
+}
+
+// Bind variables to the GraphQL query
+func (gql *GraphQLQuery) Bind(key string, value interface{}) {
+	gql.request.Var(key, value)
+}
+
+// Execute the GraphQL query
+func (gql *GraphQLQuery) Execute(respData interface{}) error {
+	return gql.client.Run(context.TODO(), gql.request, &respData)
+}

go.mod

@@ -5,6 +5,7 @@ go 1.14
 require (
 	github.com/dave/jennifer v1.4.0
 	github.com/iancoleman/strcase v0.0.0-20191112232945-16388991a334
+	github.com/machinebox/graphql v0.2.2
 	github.com/mitchellh/mapstructure v1.3.2
 	github.com/pkg/errors v0.9.1
 	github.com/stretchr/testify v1.6.1

go.sum

@@ -6,6 +6,8 @@ github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/iancoleman/strcase v0.0.0-20191112232945-16388991a334 h1:VHgatEHNcBFEB7inlalqfNqw65aNkM1lGX2yt3NmbS8=
 github.com/iancoleman/strcase v0.0.0-20191112232945-16388991a334/go.mod h1:SK73tn/9oHe+/Y0h39VT4UCxmurVJkR5NA7kMEAOgSE=
+github.com/machinebox/graphql v0.2.2 h1:dWKpJligYKhYKO5A2gvNhkJdQMNZeChZYyBbrZkBZfo=
+github.com/machinebox/graphql v0.2.2/go.mod h1:F+kbVMHuwrQ5tYgU9JXlnskM8nOaFxCAEolaQybkjWA=
 github.com/mitchellh/mapstructure v1.3.2 h1:mRS76wmkOn3KkKAyXDu42V+6ebnXWIztFSYGN7GeoRg=
 github.com/mitchellh/mapstructure v1.3.2/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RRV2QTWOzhPopBRo=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=