/*
Copyright IBM Corp. All Rights Reserved.

SPDX-License-Identifier: Apache-2.0
*/

package comm

import (
	"crypto/tls"
	"crypto/x509"
	"encoding/pem"
	"fmt"
	"os"
	"sync"
	"time"

	"github.com/hyperledger/fabric/common/flogging"
	"github.com/hyperledger/fabric/core/config"
	"github.com/spf13/viper"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials"
	"google.golang.org/grpc/grpclog"
)

const defaultTimeout = time.Second * 3

var commLogger = flogging.MustGetLogger("comm")
var caSupport *CASupport
var once sync.Once

// CASupport type manages certificate authorities scoped by channel
type CASupport struct {
	sync.RWMutex
	AppRootCAsByChain     map[string][][]byte
	OrdererRootCAsByChain map[string][][]byte
	ClientRootCAs         [][]byte
	ServerRootCAs         [][]byte
}

// GetCASupport returns the signleton CASupport instance
func GetCASupport() *CASupport {

	once.Do(func() {
		caSupport = &CASupport{
			AppRootCAsByChain:     make(map[string][][]byte),
			OrdererRootCAsByChain: make(map[string][][]byte),
		}
	})
	return caSupport
}

// GetServerRootCAs returns the PEM-encoded root certificates for all of the
// application and orderer organizations defined for all chains.  The root
// certificates returned should be used to set the trusted server roots for
// TLS clients.
func (cas *CASupport) GetServerRootCAs() (appRootCAs, ordererRootCAs [][]byte) {
	cas.RLock()
	defer cas.RUnlock()

	appRootCAs = [][]byte{}
	ordererRootCAs = [][]byte{}

	for _, appRootCA := range cas.AppRootCAsByChain {
		appRootCAs = append(appRootCAs, appRootCA...)
	}

	for _, ordererRootCA := range cas.OrdererRootCAsByChain {
		ordererRootCAs = append(ordererRootCAs, ordererRootCA...)
	}

	// also need to append statically configured root certs
	appRootCAs = append(appRootCAs, cas.ServerRootCAs...)
	return appRootCAs, ordererRootCAs
}

// GetDeliverServiceCredentials returns GRPC transport credentials for given channel to be used by GRPC
// clients which communicate with ordering service endpoints.
// If the channel isn't found, error is returned.
func (cas *CASupport) GetDeliverServiceCredentials(channelID string) (credentials.TransportCredentials, error) {
	cas.RLock()
	defer cas.RUnlock()

	var creds credentials.TransportCredentials
	var tlsConfig = &tls.Config{}
	var certPool = x509.NewCertPool()

	rootCACerts, exists := cas.OrdererRootCAsByChain[channelID]
	if !exists {
		commLogger.Errorf("Attempted to obtain root CA certs of a non existent channel: %s", channelID)
		return nil, fmt.Errorf("didn't find any root CA certs for channel %s", channelID)
	}

	for _, cert := range rootCACerts {
		block, _ := pem.Decode(cert)
		if block != nil {
			cert, err := x509.ParseCertificate(block.Bytes)
			if err == nil {
				certPool.AddCert(cert)
			} else {
				commLogger.Warningf("Failed to add root cert to credentials (%s)", err)
			}
		} else {
			commLogger.Warning("Failed to add root cert to credentials")
		}
	}
	tlsConfig.RootCAs = certPool
	creds = credentials.NewTLS(tlsConfig)
	return creds, nil
}

// GetPeerCredentials returns GRPC transport credentials for use by GRPC
// clients which communicate with remote peer endpoints.
func (cas *CASupport) GetPeerCredentials(tlsCert tls.Certificate) credentials.TransportCredentials {
	var creds credentials.TransportCredentials
	var tlsConfig = &tls.Config{
		Certificates: []tls.Certificate{tlsCert},
	}
	var certPool = x509.NewCertPool()
	// loop through the orderer CAs
	roots, _ := cas.GetServerRootCAs()
	for _, root := range roots {
		block, _ := pem.Decode(root)
		if block != nil {
			cert, err := x509.ParseCertificate(block.Bytes)
			if err == nil {
				certPool.AddCert(cert)
			} else {
				commLogger.Warningf("Failed to add root cert to credentials (%s)", err)
			}
		} else {
			commLogger.Warning("Failed to add root cert to credentials")
		}
	}
	tlsConfig.RootCAs = certPool
	creds = credentials.NewTLS(tlsConfig)
	return creds
}

// GetClientRootCAs returns the PEM-encoded root certificates for all of the
// application and orderer organizations defined for all chains.  The root
// certificates returned should be used to set the trusted client roots for
// TLS servers.
func (cas *CASupport) GetClientRootCAs() (appRootCAs, ordererRootCAs [][]byte) {
	cas.RLock()
	defer cas.RUnlock()

	appRootCAs = [][]byte{}
	ordererRootCAs = [][]byte{}

	for _, appRootCA := range cas.AppRootCAsByChain {
		appRootCAs = append(appRootCAs, appRootCA...)
	}

	for _, ordererRootCA := range cas.OrdererRootCAsByChain {
		ordererRootCAs = append(ordererRootCAs, ordererRootCA...)
	}

	// also need to append statically configured root certs
	appRootCAs = append(appRootCAs, cas.ClientRootCAs...)
	return appRootCAs, ordererRootCAs
}

func getEnv(key, def string) string {
	val := os.Getenv(key)
	if len(val) > 0 {
		return val
	} else {
		return def
	}
}

func GetPeerTestingAddress(port string) string {
	return getEnv("UNIT_TEST_PEER_IP", "localhost") + ":" + port
}

// NewClientConnectionWithAddress Returns a new grpc.ClientConn to the given address.
func NewClientConnectionWithAddress(peerAddress string, block bool, tslEnabled bool, creds credentials.TransportCredentials) (*grpc.ClientConn, error) {
	var opts []grpc.DialOption
	if tslEnabled {
		opts = append(opts, grpc.WithTransportCredentials(creds))
	} else {
		opts = append(opts, grpc.WithInsecure())
	}
	opts = append(opts, grpc.WithTimeout(defaultTimeout))
	if block {
		opts = append(opts, grpc.WithBlock())
	}
	opts = append(opts, grpc.WithDefaultCallOptions(grpc.MaxCallRecvMsgSize(MaxRecvMsgSize()),
		grpc.MaxCallSendMsgSize(MaxSendMsgSize())))
	conn, err := grpc.Dial(peerAddress, opts...)
	if err != nil {
		return nil, err
	}
	return conn, err
}

// InitTLSForPeer returns TLS credentials for peer
func InitTLSForPeer() credentials.TransportCredentials {
	var sn string
	if viper.GetString("peer.tls.serverhostoverride") != "" {
		sn = viper.GetString("peer.tls.serverhostoverride")
	}
	var creds credentials.TransportCredentials
	if config.GetPath("peer.tls.rootcert.file") != "" {
		var err error
		creds, err = credentials.NewClientTLSFromFile(config.GetPath("peer.tls.rootcert.file"), sn)
		if err != nil {
			grpclog.Fatalf("Failed to create TLS credentials %v", err)
		}
	} else {
		creds = credentials.NewClientTLSFromCert(nil, sn)
	}
	return creds
}