micro/errors/errors.go

// Package errors provides a way to return detailed information
// for an RPC request error. The error is normally JSON encoded.
package errors

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"strconv"
	"strings"

	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
)

var (
	// ErrBadRequest returns then requests contains invalid data
	ErrBadRequest = &Error{Code: 400}
	// ErrUnauthorized returns then user have unauthorized call
	ErrUnauthorized = &Error{Code: 401}
	// ErrForbidden returns then user have not access the resource
	ErrForbidden = &Error{Code: 403}
	// ErrNotFound returns then user specify invalid endpoint
	ErrNotFound = &Error{Code: 404}
	// ErrMethodNotAllowed returns then user try to get invalid method
	ErrMethodNotAllowed = &Error{Code: 405}
	// ErrTimeout returns then timeout exceeded
	ErrTimeout = &Error{Code: 408}
	// ErrConflict returns then request create duplicate resource
	ErrConflict = &Error{Code: 409}
	// ErrInternalServerError returns then server cant process request because of internal error
	ErrInternalServerError = &Error{Code: 500}
	// ErNotImplemented returns then server does not have desired endpoint method
	ErNotImplemented = &Error{Code: 501}
	// ErrBadGateway returns then server cant process request
	ErrBadGateway = &Error{Code: 502}
	// ErrServiceUnavailable returns then service unavailable
	ErrServiceUnavailable = &Error{Code: 503}
	// ErrGatewayTimeout returns then server have long time to process request
	ErrGatewayTimeout = &Error{Code: 504}
)

const ProblemContentType = "application/problem+json"

type Problem struct {
	Type     string `json:"type,omitempty"`
	Title    string `json:"title,omitempty"`
	Detail   string `json:"detail,omitempty"`
	Instance string `json:"instance,omitempty"`
	Errors   []struct {
		Title  string `json:"title,omitempty"`
		Detail string `json:"detail,omitempty"`
	} `json:"errors,omitempty"`
	Status int `json:"status,omitempty"`
}

// Error type
type Error struct {
	// ID holds error id or service, usually someting like my_service or id
	ID string
	// Detail holds some useful details about error
	Detail string
	// Status usually holds text of http status
	Status string
	// Code holds error code
	Code int32
}

// Error satisfies error interface
func (e *Error) Error() string {
	b, _ := json.Marshal(e)
	return string(b)
}

/*
// Generator struct holds id of error
type Generator struct {
	id string
}

// Generator can emit new error with static id
func NewGenerator(id string) *Generator {
	return &Generator{id: id}
}

func (g *Generator) BadRequest(format string, args ...interface{}) error {
	return BadRequest(g.id, format, args...)
}
*/

// New generates a custom error
func New(id, detail string, code int32) error {
	return &Error{
		ID:     id,
		Code:   code,
		Detail: detail,
		Status: http.StatusText(int(code)),
	}
}

// Parse tries to parse a JSON string into an error. If that
// fails, it will set the given string as the error detail.
func Parse(err string) *Error {
	e := &Error{}
	nerr := json.Unmarshal([]byte(err), e)
	if nerr != nil {
		e.Detail = err
	}
	return e
}

// BadRequest generates a 400 error.
func BadRequest(id, format string, args ...interface{}) error {
	return &Error{
		ID:     id,
		Code:   400,
		Detail: fmt.Sprintf(format, args...),
		Status: http.StatusText(400),
	}
}

// Unauthorized generates a 401 error.
func Unauthorized(id, format string, args ...interface{}) error {
	return &Error{
		ID:     id,
		Code:   401,
		Detail: fmt.Sprintf(format, args...),
		Status: http.StatusText(401),
	}
}

// Forbidden generates a 403 error.
func Forbidden(id, format string, args ...interface{}) error {
	return &Error{
		ID:     id,
		Code:   403,
		Detail: fmt.Sprintf(format, args...),
		Status: http.StatusText(403),
	}
}

// NotFound generates a 404 error.
func NotFound(id, format string, args ...interface{}) error {
	return &Error{
		ID:     id,
		Code:   404,
		Detail: fmt.Sprintf(format, args...),
		Status: http.StatusText(404),
	}
}

// MethodNotAllowed generates a 405 error.
func MethodNotAllowed(id, format string, args ...interface{}) error {
	return &Error{
		ID:     id,
		Code:   405,
		Detail: fmt.Sprintf(format, args...),
		Status: http.StatusText(405),
	}
}

// Timeout generates a 408 error.
func Timeout(id, format string, args ...interface{}) error {
	return &Error{
		ID:     id,
		Code:   408,
		Detail: fmt.Sprintf(format, args...),
		Status: http.StatusText(408),
	}
}

// Conflict generates a 409 error.
func Conflict(id, format string, args ...interface{}) error {
	return &Error{
		ID:     id,
		Code:   409,
		Detail: fmt.Sprintf(format, args...),
		Status: http.StatusText(409),
	}
}

// InternalServerError generates a 500 error.
func InternalServerError(id, format string, args ...interface{}) error {
	return &Error{
		ID:     id,
		Code:   500,
		Detail: fmt.Sprintf(format, args...),
		Status: http.StatusText(500),
	}
}

// NotImplemented generates a 501 error
func NotImplemented(id, format string, args ...interface{}) error {
	return &Error{
		ID:     id,
		Code:   501,
		Detail: fmt.Sprintf(format, args...),
		Status: http.StatusText(501),
	}
}

// BadGateway generates a 502 error
func BadGateway(id, format string, args ...interface{}) error {
	return &Error{
		ID:     id,
		Code:   502,
		Detail: fmt.Sprintf(format, args...),
		Status: http.StatusText(502),
	}
}

// ServiceUnavailable generates a 503 error
func ServiceUnavailable(id, format string, args ...interface{}) error {
	return &Error{
		ID:     id,
		Code:   503,
		Detail: fmt.Sprintf(format, args...),
		Status: http.StatusText(503),
	}
}

// GatewayTimeout generates a 504 error
func GatewayTimeout(id, format string, args ...interface{}) error {
	return &Error{
		ID:     id,
		Code:   504,
		Detail: fmt.Sprintf(format, args...),
		Status: http.StatusText(504),
	}
}

// Equal tries to compare errors
func Equal(err1 error, err2 error) bool {
	verr1, ok1 := err1.(*Error)
	verr2, ok2 := err2.(*Error)

	if ok1 != ok2 {
		return false
	}

	if !ok1 {
		return err1 == err2
	}

	if verr1.Code != verr2.Code {
		return false
	}

	return true
}

// CodeIn return true if err has specified code
func CodeIn(err interface{}, codes ...int32) bool {
	var code int32
	switch verr := err.(type) {
	case *Error:
		code = verr.Code
	case int32:
		code = verr
	default:
		return false
	}

	for _, check := range codes {
		if code == check {
			return true
		}
	}

	return false
}

// FromError try to convert go error to *Error
func FromError(err error) *Error {
	if err == nil {
		return nil
	}

	if verr, ok := err.(*Error); ok && verr != nil {
		return verr
	}

	return Parse(err.Error())
}

// MarshalJSON returns error data
func (e *Error) MarshalJSON() ([]byte, error) {
	return e.Marshal()
}

// UnmarshalJSON set error data
func (e *Error) UnmarshalJSON(data []byte) error {
	return e.Unmarshal(data)
}

// ProtoMessage noop func
func (e *Error) ProtoMessage() {}

// Reset resets error
func (e *Error) Reset() {
	*e = Error{}
}

// String returns error as string
func (e *Error) String() string {
	return fmt.Sprintf(`{"id":"%s","detail":"%s","status":"%s","code":%d}`, addslashes(e.ID), addslashes(e.Detail), addslashes(e.Status), e.Code)
}

// Marshal returns error data
func (e *Error) Marshal() ([]byte, error) {
	return []byte(e.String()), nil
}

// Unmarshal set error data
func (e *Error) Unmarshal(data []byte) error {
	str := string(data)
	if len(data) < 41 {
		return fmt.Errorf("invalid data")
	}
	parts := strings.FieldsFunc(str[1:len(str)-1], func(r rune) bool {
		return r == ','
	})
	for _, part := range parts {
		nparts := strings.FieldsFunc(part, func(r rune) bool {
			return r == ':'
		})
		for idx := 0; idx < len(nparts)/2; idx += 2 {
			val := strings.Trim(nparts[idx+1], `"`)
			if len(val) == 0 {
				continue
			}
			switch {
			case nparts[idx] == `"id"`:
				e.ID = val
			case nparts[idx] == `"detail"`:
				e.Detail = val
			case nparts[idx] == `"status"`:
				e.Status = val
			case nparts[idx] == `"code"`:
				c, err := strconv.ParseInt(val, 10, 32)
				if err != nil {
					return err
				}
				e.Code = int32(c)
			}
			idx++
		}
	}
	return nil
}

func addslashes(str string) string {
	var buf bytes.Buffer
	for _, char := range str {
		switch char {
		case '\'', '"', '\\':
			buf.WriteRune('\\')
		}
		buf.WriteRune(char)
	}
	return buf.String()
}

type retryableError struct {
	err error
}

// Retryable returns error that can be retried later
func Retryable(err error) error {
	return &retryableError{err: err}
}

type IsRetryableFunc func(error) bool

var (
	RetrayableOracleErrors = []IsRetryableFunc{
		func(err error) bool {
			errmsg := err.Error()
			switch {
			case strings.Contains(errmsg, `ORA-`):
				return true
			case strings.Contains(errmsg, `can not assign`):
				return true
			case strings.Contains(errmsg, `can't assign`):
				return true
			}
			return false
		},
	}
	RetrayablePostgresErrors = []IsRetryableFunc{
		func(err error) bool {
			errmsg := err.Error()
			switch {
			case strings.Contains(errmsg, `number of field descriptions must equal number of`):
				return true
			case strings.Contains(errmsg, `not a pointer`):
				return true
			case strings.Contains(errmsg, `values, but dst struct has only`):
				return true
			case strings.Contains(errmsg, `struct doesn't have corresponding row field`):
				return true
			case strings.Contains(errmsg, `cannot find field`):
				return true
			case strings.Contains(errmsg, `cannot scan`) || strings.Contains(errmsg, `cannot convert`):
				return true
			case strings.Contains(errmsg, `failed to connect to`):
				return true
			}
			return false
		},
	}
	RetryableMicroErrors = []IsRetryableFunc{
		func(err error) bool {
			switch verr := err.(type) {
			case *Error:
				switch verr.Code {
				case 401, 403, 408, 500, 501, 502, 503, 504:
					return true
				default:
					return false
				}
			case *retryableError:
				return true
			}
			return false
		},
	}
	RetryableGoErrors = []IsRetryableFunc{
		func(err error) bool {
			switch verr := err.(type) {
			case interface{ SafeToRetry() bool }:
				return verr.SafeToRetry()
			case interface{ Timeout() bool }:
				return verr.Timeout()
			}
			switch {
			case errors.Is(err, io.EOF), errors.Is(err, io.ErrUnexpectedEOF):
				return true
			case errors.Is(err, context.DeadlineExceeded):
				return true
			case errors.Is(err, io.ErrClosedPipe), errors.Is(err, io.ErrShortBuffer), errors.Is(err, io.ErrShortWrite):
				return true
			}
			return false
		},
	}
	RetryableGrpcErrors = []IsRetryableFunc{
		func(err error) bool {
			st, ok := status.FromError(err)
			if !ok {
				return false
			}
			switch st.Code() {
			case codes.Unavailable, codes.ResourceExhausted:
				return true
			case codes.DeadlineExceeded:
				return true
			case codes.Internal:
				switch {
				case strings.Contains(st.Message(), `transport: received the unexpected content-type "text/html; charset=UTF-8"`):
					return true
				case strings.Contains(st.Message(), io.ErrUnexpectedEOF.Error()):
					return true
				case strings.Contains(st.Message(), `stream terminated by RST_STREAM with error code: INTERNAL_ERROR`):
					return true
				}
			}
			return false
		},
	}
)

// Unwrap provides error wrapping
func (e *retryableError) Unwrap() error {
	return e.err
}

// Error returns the error string
func (e *retryableError) Error() string {
	if e.err == nil {
		return ""
	}
	return e.err.Error()
}

// IsRetryable checks error for ability to retry later
func IsRetryable(err error, fns ...IsRetryableFunc) bool {
	for _, fn := range fns {
		if ok := fn(err); ok {
			return true
		}
	}
	return false
}