// Copyright (c) 2021 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.

package stdscript

// ErrorKind identifies a kind of error.
type ErrorKind string

// These constants are used to identify a specific ErrorKind.
const (
	// ErrUnsupportedScriptVersion indicates that a given script version is not
	// supported.
	ErrUnsupportedScriptVersion = ErrorKind("ErrUnsupportedScriptVersion")

	// ErrNegativeRequiredSigs is returned from MultiSigScript when the
	// specified number of required signatures is negative.
	ErrNegativeRequiredSigs = ErrorKind("ErrNegativeRequiredSigs")

	// ErrTooManyRequiredSigs is returned from MultiSigScript when the
	// specified number of required signatures is larger than the number of
	// provided public keys.
	ErrTooManyRequiredSigs = ErrorKind("ErrTooManyRequiredSigs")

	// ErrPubKeyType is returned when a script contains invalid public keys.
	ErrPubKeyType = ErrorKind("ErrPubKeyType")

	// ErrTooMuchNullData is returned when attempting to generate a
	// provably-pruneable script with data that exceeds the maximum allowed
	// length.
	ErrTooMuchNullData = ErrorKind("ErrTooMuchNullData")
)

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

// Error identifies an script-related error.
//
// 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}
}