// Copyright 2021 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.

package security

import (
	"crypto/sha256"
	"crypto/sha512"
	"hash"

	"github.com/xdg/scram"
)

var (
	// SHA256 func
	SHA256 scram.HashGeneratorFcn = func() hash.Hash { return sha256.New() }
	// SHA512 func
	SHA512 scram.HashGeneratorFcn = func() hash.Hash { return sha512.New() }
)

// XDGSCRAMClient xdg scram client
type XDGSCRAMClient struct {
	*scram.Client
	*scram.ClientConversation
	scram.HashGeneratorFcn
}

// Begin xdg scram client Begin
func (x *XDGSCRAMClient) Begin(userName, password, authzID string) (err error) {
	x.Client, err = x.HashGeneratorFcn.NewClient(userName, password, authzID)
	if err != nil {
		return err
	}
	x.ClientConversation = x.Client.NewConversation()
	return nil
}

// Step xdg scram client Step
func (x *XDGSCRAMClient) Step(challenge string) (response string, err error) {
	response, err = x.ClientConversation.Step(challenge)
	return
}

// Done xdg scram client Done
func (x *XDGSCRAMClient) Done() bool {
	return x.ClientConversation.Done()
}