// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pkcs12

import (
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/asn1"
	"errors"
)

var (
	// see https://tools.ietf.org/html/rfc7292#appendix-D
	oidCertTypeX509Certificate = asn1.ObjectIdentifier([]int{1, 2, 840, 113549, 1, 9, 22, 1})
	oidPKCS8ShroudedKeyBag     = asn1.ObjectIdentifier([]int{1, 2, 840, 113549, 1, 12, 10, 1, 2})
	oidCertBag                 = asn1.ObjectIdentifier([]int{1, 2, 840, 113549, 1, 12, 10, 1, 3})
)

type certBag struct {
	Id   asn1.ObjectIdentifier
	Data []byte `asn1:"tag:0,explicit"`
}

func getAlgorithmParams(salt []byte, iterations int) (asn1.RawValue, error) {
	params := pbeParams{
		Salt:       salt,
		Iterations: iterations,
	}

	return convertToRawVal(params)
}

func encodePkcs8ShroudedKeyBag(privateKey interface{}, password []byte) (bytes []byte, err error) {
	privateKeyBytes, err := marshalPKCS8PrivateKey(privateKey)

	if err != nil {
		return nil, errors.New("pkcs12: error encoding PKCS#8 private key: " + err.Error())
	}

	salt, err := makeSalt(pbeSaltSizeBytes)
	if err != nil {
		return nil, errors.New("pkcs12: error creating PKCS#8 salt: " + err.Error())
	}

	pkData, err := pbEncrypt(privateKeyBytes, salt, password, pbeIterationCount)
	if err != nil {
		return nil, errors.New("pkcs12: error encoding PKCS#8 shrouded key bag when encrypting cert bag: " + err.Error())
	}

	params, err := getAlgorithmParams(salt, pbeIterationCount)
	if err != nil {
		return nil, errors.New("pkcs12: error encoding PKCS#8 shrouded key bag algorithm's parameters: " + err.Error())
	}

	pkinfo := encryptedPrivateKeyInfo{
		AlgorithmIdentifier: pkix.AlgorithmIdentifier{
			Algorithm:  oidPBEWithSHAAnd3KeyTripleDESCBC,
			Parameters: params,
		},
		EncryptedData: pkData,
	}

	bytes, err = asn1.Marshal(pkinfo)
	if err != nil {
		return nil, errors.New("pkcs12: error encoding PKCS#8 shrouded key bag: " + err.Error())
	}

	return bytes, err
}

func decodePkcs8ShroudedKeyBag(asn1Data, password []byte) (privateKey interface{}, err error) {
	pkinfo := new(encryptedPrivateKeyInfo)
	if err = unmarshal(asn1Data, pkinfo); err != nil {
		return nil, errors.New("pkcs12: error decoding PKCS#8 shrouded key bag: " + err.Error())
	}

	pkData, err := pbDecrypt(pkinfo, password)
	if err != nil {
		return nil, errors.New("pkcs12: error decrypting PKCS#8 shrouded key bag: " + err.Error())
	}

	ret := new(asn1.RawValue)
	if err = unmarshal(pkData, ret); err != nil {
		return nil, errors.New("pkcs12: error unmarshalling decrypted private key: " + err.Error())
	}

	if privateKey, err = x509.ParsePKCS8PrivateKey(pkData); err != nil {
		return nil, errors.New("pkcs12: error parsing PKCS#8 private key: " + err.Error())
	}

	return privateKey, nil
}

func decodeCertBag(asn1Data []byte) (x509Certificates []byte, err error) {
	bag := new(certBag)
	if err := unmarshal(asn1Data, bag); err != nil {
		return nil, errors.New("pkcs12: error decoding cert bag: " + err.Error())
	}
	if !bag.Id.Equal(oidCertTypeX509Certificate) {
		return nil, NotImplementedError("only X509 certificates are supported")
	}
	return bag.Data, nil
}
