new /x/client sub-package

x/client/error.go

@@ -0,0 +1,84 @@
+package client
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+	"strings"
+)
+
+// APIError errors that may return from the Client.
+type APIError struct {
+	Response *http.Response
+	Body     json.RawMessage // may be any []byte, response body is closed at this point.
+}
+
+// Error implements the standard error type.
+func (e APIError) Error() string {
+	var b strings.Builder
+	if e.Response != nil {
+		b.WriteString(e.Response.Request.URL.String())
+		b.WriteByte(':')
+		b.WriteByte(' ')
+
+		b.WriteString(http.StatusText(e.Response.StatusCode))
+		b.WriteByte(' ')
+		b.WriteByte('(')
+		b.WriteString(e.Response.Status)
+		b.WriteByte(')')
+
+		if len(e.Body) > 0 {
+			b.WriteByte(':')
+			b.WriteByte(' ')
+			b.Write(e.Body)
+		}
+	}
+
+	return b.String()
+}
+
+// ExtractError returns the response wrapped inside an APIError.
+func ExtractError(resp *http.Response) APIError {
+	body, _ := ioutil.ReadAll(resp.Body)
+
+	return APIError{
+		Response: resp,
+		Body:     body,
+	}
+}
+
+// GetError reports whether the given "err" is an APIError.
+func GetError(err error) (APIError, bool) {
+	if err == nil {
+		return APIError{}, false
+	}
+
+	apiErr, ok := err.(APIError)
+	if !ok {
+		return APIError{}, false
+	}
+
+	return apiErr, true
+}
+
+// DecodeError binds a json error to the "destPtr".
+func DecodeError(err error, destPtr interface{}) error {
+	apiErr, ok := GetError(err)
+	if !ok {
+		return err
+	}
+
+	return json.Unmarshal(apiErr.Body, destPtr)
+}
+
+// GetErrorCode reads an error, which should be a type of APIError,
+// and returns its status code.
+// If the given "err" is nil or is not an APIError it returns 200, acting as we have no error.
+func GetErrorCode(err error) int {
+	apiErr, ok := GetError(err)
+	if !ok {
+		return http.StatusOK
+	}
+
+	return apiErr.Response.StatusCode
+}