// Copyright (c) 2020 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.

package gcs

// ErrorKind identifies a kind of error.  It has full support for errors.Is and
// errors.As, so the caller can directly check against an error kind when
// determining the reason for an error.
type ErrorKind string

// These constants are used to identify a specific RuleError.
const (
	// ErrNTooBig signifies that the filter can't handle N items.
	ErrNTooBig = ErrorKind("ErrNTooBig")

	// ErrPTooBig signifies that the filter can't handle `1/2**P`
	// collision probability.
	ErrPTooBig = ErrorKind("ErrPTooBig")

	// ErrBTooBig signifies that the provided Golomb coding bin size is larger
	// than the maximum allowed value.
	ErrBTooBig = ErrorKind("ErrBTooBig")

	// ErrMisserialized signifies a filter was misserialized and is missing the
	// N and/or P parameters of a serialized filter.
	ErrMisserialized = ErrorKind("ErrMisserialized")
)

// Error satisfies the error interface and prints human-readable errors.
func (e ErrorKind) Error() string {
	return string(e)
}

// Error identifies an error related to gcs filters. It has full support for
// errors.Is and errors.As, so the caller can ascertain the specific reason
// for the error by checking the underlying error.
type Error struct {
	Err         error
	Description string
}

// Error satisfies the error interface and prints human-readable errors.
func (e Error) Error() string {
	return e.Description
}

// Unwrap returns the underlying wrapped error.
func (e Error) Unwrap() error {
	return e.Err
}

// makeError creates an Error given a set of arguments.
func makeError(kind ErrorKind, desc string) Error {
	return Error{Err: kind, Description: desc}
}