package mq

import (
	"context"
	"errors"
	"sync/atomic"
)

var consumerSequence atomic.Uint64

type MessageHandler func(context.Context, string, []byte) error

type permanentError struct{ err error }

func (e permanentError) Error() string { return e.err.Error() }
func (e permanentError) Unwrap() error { return e.err }

// Permanent marks an inbound handler failure that must not be requeued.
func Permanent(err error) error {
	if err == nil {
		return nil
	}
	return permanentError{err: err}
}

func IsPermanent(err error) bool {
	var target permanentError
	return errors.As(err, &target)
}