/*
Copyright IBM Corp. All Rights Reserved.

SPDX-License-Identifier: Apache-2.0
*/

package api

import (
	"crypto/x509"
	"encoding/base64"
	"encoding/json"
	"encoding/pem"
	"fmt"
	"time"

	"github.com/golang/protobuf/proto"
	cb "github.com/hyperledger/fabric-protos-go/common"
	"github.com/hyperledger/fabric-protos-go/msp"
	"github.com/hyperledger/fabric/gossip/common"
	"google.golang.org/grpc"
)

// MessageCryptoService is the contract between the gossip component and the
// peer's cryptographic layer and is used by the gossip component to verify,
// and authenticate remote peers and data they send, as well as to verify
// received blocks from the ordering service.
type MessageCryptoService interface {
	// GetPKIidOfCert returns the PKI-ID of a peer's identity
	// If any error occurs, the method return nil
	// This method does not validate peerIdentity.
	// This validation is supposed to be done appropriately during the execution flow.
	GetPKIidOfCert(peerIdentity PeerIdentityType) common.PKIidType

	// VerifyBlock returns nil if the block is properly signed, and the claimed seqNum is the
	// sequence number that the block's header contains.
	// else returns error
	VerifyBlock(channelID common.ChannelID, seqNum uint64, block *cb.Block) error

	// VerifyBlockAttestation does the same as VerifyBlock, except it assumes block.Data = nil. It therefore does not
	// compute the block.Data.Hash() and compare it to the block.Header.DataHash. This is used when the orderer
	// delivers a block with header & metadata only, as an attestation of block existence.
	VerifyBlockAttestation(channelID string, block *cb.Block) error

	// Sign signs msg with this peer's signing key and outputs
	// the signature if no error occurred.
	Sign(msg []byte) ([]byte, error)

	// Verify checks that signature is a valid signature of message under a peer's verification key.
	// If the verification succeeded, Verify returns nil meaning no error occurred.
	// If peerIdentity is nil, then the verification fails.
	Verify(peerIdentity PeerIdentityType, signature, message []byte) error

	// VerifyByChannel checks that signature is a valid signature of message
	// under a peer's verification key, but also in the context of a specific channel.
	// If the verification succeeded, Verify returns nil meaning no error occurred.
	// If peerIdentity is nil, then the verification fails.
	VerifyByChannel(channelID common.ChannelID, peerIdentity PeerIdentityType, signature, message []byte) error

	// ValidateIdentity validates the identity of a remote peer.
	// If the identity is invalid, revoked, expired it returns an error.
	// Else, returns nil
	ValidateIdentity(peerIdentity PeerIdentityType) error

	// Expiration returns:
	// - The time when the identity expires, nil
	//   In case it can expire
	// - A zero value time.Time, nil
	//   in case it cannot expire
	// - A zero value, error in case it cannot be
	//   determined if the identity can expire or not
	Expiration(peerIdentity PeerIdentityType) (time.Time, error)
}

// PeerIdentityInfo aggregates a peer's identity,
// and also additional metadata about it
type PeerIdentityInfo struct {
	PKIId        common.PKIidType
	Identity     PeerIdentityType
	Organization OrgIdentityType
}

// PeerIdentitySet aggregates a PeerIdentityInfo slice
type PeerIdentitySet []PeerIdentityInfo

// PeerIdentityFilter defines predicate function used to filter
// peer identities
type PeerIdentityFilter func(info PeerIdentityInfo) bool

// ByOrg sorts the PeerIdentitySet by organizations of its peers
func (pis PeerIdentitySet) ByOrg() map[string]PeerIdentitySet {
	m := make(map[string]PeerIdentitySet)
	for _, id := range pis {
		m[string(id.Organization)] = append(m[string(id.Organization)], id)
	}
	return m
}

// ByID sorts the PeerIdentitySet by PKI-IDs of its peers
func (pis PeerIdentitySet) ByID() map[string]PeerIdentityInfo {
	m := make(map[string]PeerIdentityInfo)
	for _, id := range pis {
		m[string(id.PKIId)] = id
	}
	return m
}

// Filter filters identities based on predicate, returns new  PeerIdentitySet
// with filtered ids.
func (pis PeerIdentitySet) Filter(filter PeerIdentityFilter) PeerIdentitySet {
	var result PeerIdentitySet
	for _, id := range pis {
		if filter(id) {
			result = append(result, id)
		}
	}
	return result
}

// PeerIdentityType is the peer's certificate
type PeerIdentityType []byte

// String returns a string representation of this PeerIdentityType
func (pit PeerIdentityType) String() string {
	base64Representation := base64.StdEncoding.EncodeToString(pit)
	sID := &msp.SerializedIdentity{}
	err := proto.Unmarshal(pit, sID)
	if err != nil {
		return fmt.Sprintf("non SerializedIdentity: %s", base64Representation)
	}

	bl, _ := pem.Decode(sID.IdBytes)
	if bl == nil {
		return fmt.Sprintf("non PEM encoded identity: %s", base64Representation)
	}

	cert, _ := x509.ParseCertificate(bl.Bytes)
	if cert == nil {
		return fmt.Sprintf("non x509 identity: %s", base64Representation)
	}
	m := make(map[string]interface{})
	m["MSP"] = sID.Mspid
	s := cert.Subject
	m["CN"] = s.CommonName
	m["OU"] = s.OrganizationalUnit
	m["L-ST-C"] = fmt.Sprintf("%s-%s-%s", s.Locality, s.StreetAddress, s.Country)
	i := cert.Issuer
	m["Issuer-CN"] = i.CommonName
	m["Issuer-OU"] = i.OrganizationalUnit
	m["Issuer-L-ST-C"] = fmt.Sprintf("%s-%s-%s", i.Locality, i.StreetAddress, i.Country)

	rawJSON, err := json.Marshal(m)
	if err != nil {
		return base64Representation
	}
	return string(rawJSON)
}

// PeerSuspector returns whether a peer with a given identity is suspected
// as being revoked, or its CA is revoked
type PeerSuspector func(identity PeerIdentityType) bool

// PeerSecureDialOpts returns the gRPC DialOptions to use for connection level
// security when communicating with remote peer endpoints
type PeerSecureDialOpts func() []grpc.DialOption

// PeerSignature defines a signature of a peer
// on a given message
type PeerSignature struct {
	Signature    []byte
	Message      []byte
	PeerIdentity PeerIdentityType
}