publicerror.go

package httperror

import (
	"bytes"
	"errors"
	"fmt"
	"net/http"
	"strconv"
)

// Public is an interface that requires a PublicMessage() string method.
// [httperror.PublicMessage] will extract the public error message from errors
// that implements this interface.
type Public = interface {
	PublicMessage() string
}

// PublicMessage extracts the public message from errors that have a
// `PUblicMessage() string` method.
func PublicMessage(err error) string {
	var publicError Public

	if err == nil {
		return ""
	}

	if errors.As(err, &publicError) {
		return publicError.PublicMessage()
	}

	return ""
}

// NewPublic returns a new public error with the given status code and public
// error message generated using the format string and arguments. The
// resulting error value implements the the [httperror.Public] interface.
func NewPublic(status int, message string) error {
	return publicError{message, httpError{status}}
}

// PublicErrorf returns a new public error with the given status code and
// public error message. The resulting value implements the the
// [httperror.Public] interface.

func PublicErrorf(status int, format string, args ...interface{}) error {
	return publicError{fmt.Sprintf(format, args...), httpError{status}}
}

type publicError struct {
	message string
	httpError
}

// Error returns the text corresponding to this HTTP error status code.
func (e publicError) Error() string {
	var b bytes.Buffer

	b.WriteString(strconv.Itoa(e.status))
	b.WriteString(" ")
	b.WriteString(http.StatusText(e.status))

	if e.message != "" {
		b.WriteString(": ")
		b.WriteString(e.message)
	}
	return b.String()
}

func (e publicError) PublicMessage() string {
	return e.message
}