/*-
 * Copyright 2019 Square 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,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package generator

import (
	"crypto/x509"
	"encoding/pem"
	"errors"

	"github.com/go-jose/go-jose/v4"
)

func LoadJSONWebKey(json []byte, pub bool) (*jose.JSONWebKey, error) {
	var jwk jose.JSONWebKey
	err := jwk.UnmarshalJSON(json)
	if err != nil {
		return nil, err
	}
	if !jwk.Valid() {
		return nil, errors.New("invalid JWK key")
	}
	if jwk.IsPublic() != pub {
		return nil, errors.New("priv/pub JWK key mismatch")
	}
	return &jwk, nil
}

// LoadPublicKey loads a public key from PEM/DER/JWK-encoded data.
func LoadPublicKey(data []byte) (interface{}, error) {
	input := data

	block, _ := pem.Decode(data)
	if block != nil {
		input = block.Bytes
	}

	// Try to load SubjectPublicKeyInfo
	pub, err0 := x509.ParsePKIXPublicKey(input)
	if err0 == nil {
		return pub, nil
	}

	cert, err1 := x509.ParseCertificate(input)
	if err1 == nil {
		return cert.PublicKey, nil
	}

	jwk, err2 := LoadJSONWebKey(data, true)
	if err2 == nil {
		return jwk, nil
	}

	return nil, errors.New("parse error, invalid public key")
}

// LoadPrivateKey loads a private key from PEM/DER/JWK-encoded data.
func LoadPrivateKey(data []byte) (interface{}, error) {
	input := data

	block, _ := pem.Decode(data)
	if block != nil {
		input = block.Bytes
	}

	var priv interface{}
	priv, err0 := x509.ParsePKCS1PrivateKey(input)
	if err0 == nil {
		return priv, nil
	}

	priv, err1 := x509.ParsePKCS8PrivateKey(input)
	if err1 == nil {
		return priv, nil
	}

	priv, err2 := x509.ParseECPrivateKey(input)
	if err2 == nil {
		return priv, nil
	}

	jwk, err3 := LoadJSONWebKey(input, false)
	if err3 == nil {
		return jwk, nil
	}

	return nil, errors.New("parse error, invalid private key")
}
