/*
Copyright IBM Corp. 2017 All Rights Reserved.

SPDX-License-Identifier: Apache-2.0
*/

package cluster

import (
	"bytes"
	"encoding/pem"
	"sync/atomic"

	"github.com/hyperledger/fabric/core/comm"
	"github.com/pkg/errors"
	"google.golang.org/grpc"
)

// ConnByCertMap maps certificates represented as strings
// to gRPC connections
type ConnByCertMap map[string]*grpc.ClientConn

// Lookup looks up a certificate and returns the connection that was mapped
// to the certificate, and whether it was found or not
func (cbc ConnByCertMap) Lookup(cert []byte) (*grpc.ClientConn, bool) {
	conn, ok := cbc[string(cert)]
	return conn, ok
}

// Put associates the given connection to the certificate
func (cbc ConnByCertMap) Put(cert []byte, conn *grpc.ClientConn) {
	cbc[string(cert)] = conn
}

// Remove removes the connection that is associated to the given certificate
func (cbc ConnByCertMap) Remove(cert []byte) {
	delete(cbc, string(cert))
}

// MemberMapping defines NetworkMembers by their ID
type MemberMapping map[uint64]*Stub

// Put inserts the given stub to the MemberMapping
func (mp MemberMapping) Put(stub *Stub) {
	mp[stub.ID] = stub
}

// ByID retrieves the Stub with the given ID from the MemberMapping
func (mp MemberMapping) ByID(ID uint64) *Stub {
	return mp[ID]
}

// LookupByClientCert retrieves a Stub with the given client certificate
func (mp MemberMapping) LookupByClientCert(cert []byte) *Stub {
	for _, stub := range mp {
		if bytes.Equal(stub.ClientTLSCert, cert) {
			return stub
		}
	}
	return nil
}

// ServerCertificates returns a set of the server certificates
// represented as strings
func (mp MemberMapping) ServerCertificates() StringSet {
	res := make(StringSet)
	for _, member := range mp {
		res[string(member.ServerTLSCert)] = struct{}{}
	}
	return res
}

// StringSet is a set of strings
type StringSet map[string]struct{}

// union adds the elements of the given set to the StringSet
func (ss StringSet) union(set StringSet) {
	for k := range set {
		ss[k] = struct{}{}
	}
}

// subtract removes all elements in the given set from the StringSet
func (ss StringSet) subtract(set StringSet) {
	for k := range set {
		delete(ss, k)
	}
}

// PredicateDialer creates gRPC connections
// that are only established if the given predicate
// is fulfilled
type PredicateDialer struct {
	Config atomic.Value
}

// NewTLSPinningDialer creates a new PredicateDialer
func NewTLSPinningDialer(config comm.ClientConfig) *PredicateDialer {
	d := &PredicateDialer{}
	d.SetConfig(config)
	return d
}

// SetConfig sets the configuration of the PredicateDialer
func (dialer *PredicateDialer) SetConfig(config comm.ClientConfig) {
	configCopy := comm.ClientConfig{
		Timeout: config.Timeout,
		SecOpts: &comm.SecureOptions{},
		KaOpts:  &comm.KeepaliveOptions{},
	}
	// Explicitly copy configuration
	if config.SecOpts != nil {
		*configCopy.SecOpts = *config.SecOpts
	}
	if config.KaOpts != nil {
		*configCopy.KaOpts = *config.KaOpts
	} else {
		configCopy.KaOpts = nil
	}

	dialer.Config.Store(configCopy)
}

// Dial creates a new gRPC connection that can only be established, if the remote node's
// certificate chain satisfy verifyFunc
func (dialer *PredicateDialer) Dial(address string, verifyFunc RemoteVerifier) (*grpc.ClientConn, error) {
	cfg := dialer.Config.Load().(comm.ClientConfig)
	cfg.SecOpts.VerifyCertificate = verifyFunc
	client, err := comm.NewGRPCClient(cfg)
	if err != nil {
		return nil, errors.WithStack(err)
	}
	return client.NewConnection(address, "")
}

// DERtoPEM returns a PEM representation of the DER
// encoded certificate
func DERtoPEM(der []byte) string {
	return string(pem.EncodeToMemory(&pem.Block{
		Type:  "CERTIFICATE",
		Bytes: der,
	}))
}