Move packages to proejct/pkg to follow go project folder structure convention (#1190)

pkg/error/httperror.go

@@ -0,0 +1,136 @@
+/*
+Copyright 2016 The Fission Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package error
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"strings"
+)
+
+type (
+	// Errors returned by the Fission API.
+	Error struct {
+		Code    errorCode `json:"code"`
+		Message string    `json:"message"`
+	}
+
+	errorCode int
+)
+
+func (err Error) Error() string {
+	return fmt.Sprintf("%v - %v", err.Description(), err.Message)
+}
+
+func MakeError(code int, msg string) Error {
+	return Error{Code: errorCode(code), Message: msg}
+}
+
+func MakeErrorFromHTTP(resp *http.Response) error {
+	if resp.StatusCode == http.StatusOK {
+		return nil
+	}
+
+	var errCode int
+	switch resp.StatusCode {
+	case http.StatusBadRequest:
+		errCode = ErrorInvalidArgument
+	case http.StatusForbidden:
+		errCode = ErrorNotAuthorized
+	case http.StatusNotFound:
+		errCode = ErrorNotFound
+	case http.StatusConflict:
+		errCode = ErrorNameExists
+	default:
+		errCode = ErrorInternal
+	}
+
+	msg := resp.Status
+	defer resp.Body.Close()
+	body, err := ioutil.ReadAll(resp.Body)
+	if err == nil && len(body) > 0 {
+		msg = strings.TrimSpace(string(body))
+	}
+
+	return MakeError(errCode, msg)
+}
+
+func (err Error) HTTPStatus() int {
+	var code int
+	switch err.Code {
+	case ErrorInvalidArgument:
+		code = http.StatusBadRequest
+	case ErrorNotAuthorized:
+		code = http.StatusForbidden
+	case ErrorNotFound:
+		code = http.StatusNotFound
+	case ErrorNameExists:
+		code = http.StatusConflict
+	default:
+		code = http.StatusInternalServerError
+	}
+	return code
+}
+
+func GetHTTPError(err error) (int, string) {
+	var msg string
+	var code int
+	fe, ok := err.(Error)
+	if ok {
+		code = fe.HTTPStatus()
+		msg = fe.Message
+	} else {
+		code = http.StatusInternalServerError
+		msg = err.Error()
+	}
+	return code, msg
+}
+
+func (err Error) Description() string {
+	idx := int(err.Code)
+	if idx < 0 || idx > len(errorDescriptions)-1 {
+		return ""
+	}
+	return errorDescriptions[idx]
+}
+
+const (
+	ErrorInternal = iota
+
+	ErrorNotAuthorized
+	ErrorNotFound
+	ErrorNameExists
+	ErrorInvalidArgument
+	ErrorNoSpace
+	ErrorNotImplmented
+	ErrorChecksumFail
+	ErrorSizeLimitExceeded
+)
+
+// must match order and len of the above const
+var errorDescriptions = []string{
+	"Internal error",
+	"Not authorized",
+	"Resource not found",
+	"Resource exists",
+	"Invalid argument",
+	"No space",
+	"Not implemented",
+	"Checksum verification failed",
+	"Size limit exceeded",
+}