#1: Fix Mojang's API HTTPClient default configuration, make mojang.ResponseError interface not applicable to any type, add handling of some possible network errors

api/mojang/mojang.go

@@ -5,9 +5,12 @@ import (
 	"encoding/json"
 	"io/ioutil"
 	"net/http"
+	"time"
 )
 
-var HttpClient = &http.Client{}
+var HttpClient = &http.Client{
+	Timeout: 3 * time.Second,
+}
 
 type SignedTexturesResponse struct {
 	Id    string     `json:"id"`
@@ -32,10 +35,7 @@ type ProfileInfo struct {
 // See https://wiki.vg/Mojang_API#Playernames_-.3E_UUIDs
 func UsernamesToUuids(usernames []string) ([]*ProfileInfo, error) {
 	requestBody, _ := json.Marshal(usernames)
-	request, err := http.NewRequest("POST", "https://api.mojang.com/profiles/minecraft", bytes.NewBuffer(requestBody))
-	if err != nil {
-		panic(err)
-	}
+	request, _ := http.NewRequest("POST", "https://api.mojang.com/profiles/minecraft", bytes.NewBuffer(requestBody))
 
 	request.Header.Set("Content-Type", "application/json")
 
@@ -65,10 +65,7 @@ func UuidToTextures(uuid string, signed bool) (*SignedTexturesResponse, error) {
 		url += "?unsigned=false"
 	}
 
-	request, err := http.NewRequest("GET", url, nil)
-	if err != nil {
-		panic(err)
-	}
+	request, _ := http.NewRequest("GET", url, nil)
 
 	response, err := HttpClient.Do(request)
 	if err != nil {
@@ -92,15 +89,30 @@ func validateResponse(response *http.Response) error {
 	switch {
 	case response.StatusCode == 204:
 		return &EmptyResponse{}
+	case response.StatusCode == 400:
+		type errorResponse struct {
+			Error   string `json:"error"`
+			Message string `json:"errorMessage"`
+		}
+
+		var decodedError *errorResponse
+		body, _ := ioutil.ReadAll(response.Body)
+		_ = json.Unmarshal(body, &decodedError)
+
+		return &BadRequestError{ErrorType: decodedError.Error, Message: decodedError.Message}
 	case response.StatusCode == 429:
 		return &TooManyRequestsError{}
 	case response.StatusCode >= 500:
-		return &ServerError{response.StatusCode}
+		return &ServerError{Status: response.StatusCode}
 	}
 
 	return nil
 }
 
+type ResponseError interface {
+	IsMojangError() bool
+}
+
 // Mojang API doesn't return a 404 Not Found error for non-existent data identifiers
 // Instead, they return 204 with an empty body
 type EmptyResponse struct {
@@ -110,19 +122,48 @@ func (*EmptyResponse) Error() string {
 	return "Empty Response"
 }
 
+func (*EmptyResponse) IsMojangError() bool {
+	return true
+}
+
+// When passed request params are invalid, Mojang returns 400 Bad Request error
+type BadRequestError struct {
+	ResponseError
+	ErrorType string
+	Message   string
+}
+
+func (e *BadRequestError) Error() string {
+	return e.Message
+}
+
+func (*BadRequestError) IsMojangError() bool {
+	return true
+}
+
 // When you exceed the set limit of requests, this error will be returned
 type TooManyRequestsError struct {
+	ResponseError
 }
 
 func (*TooManyRequestsError) Error() string {
 	return "Too Many Requests"
 }
 
+func (*TooManyRequestsError) IsMojangError() bool {
+	return true
+}
+
 // ServerError happens when Mojang's API returns any response with 50* status
 type ServerError struct {
+	ResponseError
 	Status int
 }
 
 func (e *ServerError) Error() string {
 	return "Server error"
 }
+
+func (*ServerError) IsMojangError() bool {
+	return true
+}