Correctly handle Facebook errors (#14)

* Sending back the error message of Facebook as an error for some function calls

* Adding error handling for other function calls

* Private function to parse Facebook's response

* Handling errors for ProfileByID function

message.go

@@ -36,7 +36,7 @@ type Delivery struct {
 	Seq int `json:"seq"`
 }
 
-// Delivery represents a the event fired when a message is read by the
+// Read represents a the event fired when a message is read by the
 // recipient.
 type Read struct {
 	// RawWatermark is the timestamp before which all messages have been read

messenger.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"io/ioutil"
 	"net/http"
 	"time"
 )
@@ -120,9 +121,28 @@ func (m *Messenger) ProfileByID(id int64) (Profile, error) {
 
 	client := &http.Client{}
 	resp, err := client.Do(req)
+	if err != nil {
+		return p, err
+	}
 	defer resp.Body.Close()
 
-	err = json.NewDecoder(resp.Body).Decode(&p)
+	content, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return p, err
+	}
+
+	err = json.Unmarshal(content, &p)
+	if err != nil {
+		return p, err
+	}
+
+	if p == *new(Profile) {
+		qr := QueryResponse{}
+		err = json.Unmarshal(content, &qr)
+		if qr.Error != nil {
+			err = fmt.Errorf("Facebook error : %s", qr.Error.Message)
+		}
+	}
 
 	return p, err
 }
@@ -152,9 +172,12 @@ func (m *Messenger) GreetingSetting(text string) error {
 	client := &http.Client{}
 
 	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
 	defer resp.Body.Close()
 
-	return err
+	return checkFacebookError(resp.Body)
 }
 
 // CallToActionsSetting sends settings for Get Started or Persist Menu
@@ -181,9 +204,12 @@ func (m *Messenger) CallToActionsSetting(state string, actions []CallToActionsIt
 	client := &http.Client{}
 
 	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
 	defer resp.Body.Close()
 
-	return err
+	return checkFacebookError(resp.Body)
 }
 
 // handle is the internal HTTP handler for the webhooks.

response.go

@@ -16,6 +16,33 @@ const (
 	SendMessageURL = "https://graph.facebook.com/v2.6/me/messages"
 )
 
+// QueryResponse is the response sent back by Facebook when setting up things
+// like greetings or call-to-actions
+type QueryResponse struct {
+	Error  *QueryError `json:"error,omitempty"`
+	Result string      `json:"result,omitempty"`
+}
+
+// QueryError is representing an error sent back by Facebook
+type QueryError struct {
+	Message   string `json:"message"`
+	Type      string `json:"type"`
+	Code      int    `json:"code"`
+	FBTraceID string `json:"fbtrace_id"`
+}
+
+func checkFacebookError(r io.Reader) error {
+	var err error
+
+	qr := QueryResponse{}
+	err = json.NewDecoder(r).Decode(&qr)
+	if qr.Error != nil {
+		err = fmt.Errorf("Facebook error : %s", qr.Error.Message)
+	}
+
+	return err
+}
+
 // Response is used for responding to events with messages.
 type Response struct {
 	token string
@@ -136,9 +163,12 @@ func (r *Response) ButtonTemplate(text string, buttons *[]StructuredMessageButto
 	client := &http.Client{}
 
 	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
 	defer resp.Body.Close()
 
-	return err
+	return checkFacebookError(resp.Body)
 }
 
 // GenericTemplate is a message which allows for structural elements to be sent
@@ -173,9 +203,12 @@ func (r *Response) GenericTemplate(elements *[]StructuredMessageElement) error {
 	client := &http.Client{}
 
 	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
 	defer resp.Body.Close()
 
-	return err
+	return checkFacebookError(resp.Body)
 }
 
 // SenderAction sends a info about sender action
@@ -201,9 +234,12 @@ func (r *Response) SenderAction(action string) error {
 	client := &http.Client{}
 
 	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
 	defer resp.Body.Close()
 
-	return err
+	return checkFacebookError(resp.Body)
 }
 
 // SendMessage is the information sent in an API request to Facebook.