/*
Copyright IBM Corp. 2016 All Rights Reserved.

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 rwsetutil

import (
	"bytes"

	"github.com/golang/protobuf/proto"
	"github.com/hyperledger/fabric-protos-go/ledger/rwset"
	"github.com/hyperledger/fabric-protos-go/ledger/rwset/kvrwset"
	"github.com/hyperledger/fabric/core/ledger/internal/version"
	"github.com/hyperledger/fabric/core/ledger/util"
)

/////////////////////////////////////////////////////////////////
// Messages related to PUBLIC read-write set
/////////////////////////////////////////////////////////////////

// TxRwSet acts as a proxy of 'rwset.TxReadWriteSet' proto message and helps constructing Read-write set specifically for KV data model
type TxRwSet struct {
	NsRwSets []*NsRwSet
}

// NsRwSet encapsulates 'kvrwset.KVRWSet' proto message for a specific name space (chaincode)
type NsRwSet struct {
	NameSpace        string
	KvRwSet          *kvrwset.KVRWSet
	CollHashedRwSets []*CollHashedRwSet
}

// CollHashedRwSet encapsulates 'kvrwset.HashedRWSet' proto message for a specific collection
type CollHashedRwSet struct {
	CollectionName string
	HashedRwSet    *kvrwset.HashedRWSet
	PvtRwSetHash   []byte
}

// GetPvtDataHash returns the PvtRwSetHash for a given namespace and collection
func (txRwSet *TxRwSet) GetPvtDataHash(ns, coll string) []byte {
	// we could build and use a map to reduce the number of lookup
	// in the future call. However, we decided to defer such optimization
	// due to the following assumptions (mainly to avoid additional LOC).
	// we assume that the number of namespaces and collections in a txRWSet
	// to be very minimal (in a single digit),
	for _, nsRwSet := range txRwSet.NsRwSets {
		if nsRwSet.NameSpace != ns {
			continue
		}
		return nsRwSet.getPvtDataHash(coll)
	}
	return nil
}

func (nsRwSet *NsRwSet) getPvtDataHash(coll string) []byte {
	for _, collHashedRwSet := range nsRwSet.CollHashedRwSets {
		if collHashedRwSet.CollectionName != coll {
			continue
		}
		return collHashedRwSet.PvtRwSetHash
	}
	return nil
}

/////////////////////////////////////////////////////////////////
// Messages related to PRIVATE read-write set
/////////////////////////////////////////////////////////////////

// TxPvtRwSet represents 'rwset.TxPvtReadWriteSet' proto message
type TxPvtRwSet struct {
	NsPvtRwSet []*NsPvtRwSet
}

// NsPvtRwSet represents 'rwset.NsPvtReadWriteSet' proto message
type NsPvtRwSet struct {
	NameSpace     string
	CollPvtRwSets []*CollPvtRwSet
}

// CollPvtRwSet encapsulates 'kvrwset.KVRWSet' proto message for a private rwset for a specific collection
// KvRwSet in a private RwSet should not contain range query info
type CollPvtRwSet struct {
	CollectionName string
	KvRwSet        *kvrwset.KVRWSet
}

/////////////////////////////////////////////////////////////////
// FUNCTIONS for converting messages to/from proto bytes
/////////////////////////////////////////////////////////////////

// ToProtoBytes constructs TxReadWriteSet proto message and serializes using protobuf Marshal
func (txRwSet *TxRwSet) ToProtoBytes() ([]byte, error) {
	var protoMsg *rwset.TxReadWriteSet
	var err error
	if protoMsg, err = txRwSet.toProtoMsg(); err != nil {
		return nil, err
	}
	return proto.Marshal(protoMsg)
}

// FromProtoBytes deserializes protobytes into TxReadWriteSet proto message and populates 'TxRwSet'
func (txRwSet *TxRwSet) FromProtoBytes(protoBytes []byte) error {
	protoMsg := &rwset.TxReadWriteSet{}
	var err error
	var txRwSetTemp *TxRwSet
	if err = proto.Unmarshal(protoBytes, protoMsg); err != nil {
		return err
	}
	if txRwSetTemp, err = TxRwSetFromProtoMsg(protoMsg); err != nil {
		return err
	}
	txRwSet.NsRwSets = txRwSetTemp.NsRwSets
	return nil
}

// ToProtoBytes constructs 'TxPvtReadWriteSet' proto message and serializes using protobuf Marshal
func (txPvtRwSet *TxPvtRwSet) ToProtoBytes() ([]byte, error) {
	var protoMsg *rwset.TxPvtReadWriteSet
	var err error
	if protoMsg, err = txPvtRwSet.ToProtoMsg(); err != nil {
		return nil, err
	}
	return proto.Marshal(protoMsg)
}

// FromProtoBytes deserializes protobytes into 'TxPvtReadWriteSet' proto message and populates 'TxPvtRwSet'
func (txPvtRwSet *TxPvtRwSet) FromProtoBytes(protoBytes []byte) error {
	protoMsg := &rwset.TxPvtReadWriteSet{}
	var err error
	var txPvtRwSetTemp *TxPvtRwSet
	if err = proto.Unmarshal(protoBytes, protoMsg); err != nil {
		return err
	}
	if txPvtRwSetTemp, err = TxPvtRwSetFromProtoMsg(protoMsg); err != nil {
		return err
	}
	txPvtRwSet.NsPvtRwSet = txPvtRwSetTemp.NsPvtRwSet
	return nil
}

func (txRwSet *TxRwSet) toProtoMsg() (*rwset.TxReadWriteSet, error) {
	protoMsg := &rwset.TxReadWriteSet{DataModel: rwset.TxReadWriteSet_KV}
	var nsRwSetProtoMsg *rwset.NsReadWriteSet
	var err error
	for _, nsRwSet := range txRwSet.NsRwSets {
		if nsRwSetProtoMsg, err = nsRwSet.toProtoMsg(); err != nil {
			return nil, err
		}
		protoMsg.NsRwset = append(protoMsg.NsRwset, nsRwSetProtoMsg)
	}
	return protoMsg, nil
}

// TxRwSetFromProtoMsg transforms the proto message into a struct for ease of use
func TxRwSetFromProtoMsg(protoMsg *rwset.TxReadWriteSet) (*TxRwSet, error) {
	txRwSet := &TxRwSet{}
	var nsRwSet *NsRwSet
	var err error
	for _, nsRwSetProtoMsg := range protoMsg.NsRwset {
		if nsRwSet, err = nsRwSetFromProtoMsg(nsRwSetProtoMsg); err != nil {
			return nil, err
		}
		txRwSet.NsRwSets = append(txRwSet.NsRwSets, nsRwSet)
	}
	return txRwSet, nil
}

func (nsRwSet *NsRwSet) toProtoMsg() (*rwset.NsReadWriteSet, error) {
	var err error
	protoMsg := &rwset.NsReadWriteSet{Namespace: nsRwSet.NameSpace}
	if protoMsg.Rwset, err = proto.Marshal(nsRwSet.KvRwSet); err != nil {
		return nil, err
	}

	var collHashedRwSetProtoMsg *rwset.CollectionHashedReadWriteSet
	for _, collHashedRwSet := range nsRwSet.CollHashedRwSets {
		if collHashedRwSetProtoMsg, err = collHashedRwSet.toProtoMsg(); err != nil {
			return nil, err
		}
		protoMsg.CollectionHashedRwset = append(protoMsg.CollectionHashedRwset, collHashedRwSetProtoMsg)
	}
	return protoMsg, nil
}

func nsRwSetFromProtoMsg(protoMsg *rwset.NsReadWriteSet) (*NsRwSet, error) {
	nsRwSet := &NsRwSet{NameSpace: protoMsg.Namespace, KvRwSet: &kvrwset.KVRWSet{}}
	if err := proto.Unmarshal(protoMsg.Rwset, nsRwSet.KvRwSet); err != nil {
		return nil, err
	}
	var err error
	var collHashedRwSet *CollHashedRwSet
	for _, collHashedRwSetProtoMsg := range protoMsg.CollectionHashedRwset {
		if collHashedRwSet, err = collHashedRwSetFromProtoMsg(collHashedRwSetProtoMsg); err != nil {
			return nil, err
		}
		nsRwSet.CollHashedRwSets = append(nsRwSet.CollHashedRwSets, collHashedRwSet)
	}
	return nsRwSet, nil
}

func (collHashedRwSet *CollHashedRwSet) toProtoMsg() (*rwset.CollectionHashedReadWriteSet, error) {
	var err error
	protoMsg := &rwset.CollectionHashedReadWriteSet{
		CollectionName: collHashedRwSet.CollectionName,
		PvtRwsetHash:   collHashedRwSet.PvtRwSetHash,
	}
	if protoMsg.HashedRwset, err = proto.Marshal(collHashedRwSet.HashedRwSet); err != nil {
		return nil, err
	}
	return protoMsg, nil
}

func collHashedRwSetFromProtoMsg(protoMsg *rwset.CollectionHashedReadWriteSet) (*CollHashedRwSet, error) {
	colHashedRwSet := &CollHashedRwSet{
		CollectionName: protoMsg.CollectionName,
		PvtRwSetHash:   protoMsg.PvtRwsetHash,
		HashedRwSet:    &kvrwset.HashedRWSet{},
	}
	if err := proto.Unmarshal(protoMsg.HashedRwset, colHashedRwSet.HashedRwSet); err != nil {
		return nil, err
	}
	return colHashedRwSet, nil
}

// NumCollections returns the number of collections present in the TxRwSet
func (txRwSet *TxRwSet) NumCollections() int {
	if txRwSet == nil {
		return 0
	}
	numColls := 0
	for _, nsRwset := range txRwSet.NsRwSets {
		for range nsRwset.CollHashedRwSets {
			numColls++
		}
	}
	return numColls
}

///////////////////////////////////////////////////////////////////////////////
// functions for private read-write set
///////////////////////////////////////////////////////////////////////////////

// ToToProtoMsg transforms the struct into equivalent proto message
func (txPvtRwSet *TxPvtRwSet) ToProtoMsg() (*rwset.TxPvtReadWriteSet, error) {
	protoMsg := &rwset.TxPvtReadWriteSet{DataModel: rwset.TxReadWriteSet_KV}
	var nsProtoMsg *rwset.NsPvtReadWriteSet
	var err error
	for _, nsPvtRwSet := range txPvtRwSet.NsPvtRwSet {
		if nsProtoMsg, err = nsPvtRwSet.toProtoMsg(); err != nil {
			return nil, err
		}
		protoMsg.NsPvtRwset = append(protoMsg.NsPvtRwset, nsProtoMsg)
	}
	return protoMsg, nil
}

// TxPvtRwSetFromProtoMsg transforms the proto message into a struct for ease of use
func TxPvtRwSetFromProtoMsg(protoMsg *rwset.TxPvtReadWriteSet) (*TxPvtRwSet, error) {
	txPvtRwset := &TxPvtRwSet{}
	var nsPvtRwSet *NsPvtRwSet
	var err error
	for _, nsRwSetProtoMsg := range protoMsg.NsPvtRwset {
		if nsPvtRwSet, err = nsPvtRwSetFromProtoMsg(nsRwSetProtoMsg); err != nil {
			return nil, err
		}
		txPvtRwset.NsPvtRwSet = append(txPvtRwset.NsPvtRwSet, nsPvtRwSet)
	}
	return txPvtRwset, nil
}

func (nsPvtRwSet *NsPvtRwSet) toProtoMsg() (*rwset.NsPvtReadWriteSet, error) {
	protoMsg := &rwset.NsPvtReadWriteSet{Namespace: nsPvtRwSet.NameSpace}
	var err error
	var collPvtRwSetProtoMsg *rwset.CollectionPvtReadWriteSet
	for _, collPvtRwSet := range nsPvtRwSet.CollPvtRwSets {
		if collPvtRwSetProtoMsg, err = collPvtRwSet.toProtoMsg(); err != nil {
			return nil, err
		}
		protoMsg.CollectionPvtRwset = append(protoMsg.CollectionPvtRwset, collPvtRwSetProtoMsg)
	}
	return protoMsg, err
}

func nsPvtRwSetFromProtoMsg(protoMsg *rwset.NsPvtReadWriteSet) (*NsPvtRwSet, error) {
	nsPvtRwSet := &NsPvtRwSet{NameSpace: protoMsg.Namespace}
	for _, collPvtRwSetProtoMsg := range protoMsg.CollectionPvtRwset {
		var err error
		var collPvtRwSet *CollPvtRwSet
		if collPvtRwSet, err = collPvtRwSetFromProtoMsg(collPvtRwSetProtoMsg); err != nil {
			return nil, err
		}
		nsPvtRwSet.CollPvtRwSets = append(nsPvtRwSet.CollPvtRwSets, collPvtRwSet)
	}
	return nsPvtRwSet, nil
}

func (collPvtRwSet *CollPvtRwSet) toProtoMsg() (*rwset.CollectionPvtReadWriteSet, error) {
	var err error
	protoMsg := &rwset.CollectionPvtReadWriteSet{CollectionName: collPvtRwSet.CollectionName}
	if protoMsg.Rwset, err = proto.Marshal(collPvtRwSet.KvRwSet); err != nil {
		return nil, err
	}
	return protoMsg, nil
}

func collPvtRwSetFromProtoMsg(protoMsg *rwset.CollectionPvtReadWriteSet) (*CollPvtRwSet, error) {
	collPvtRwSet := &CollPvtRwSet{CollectionName: protoMsg.CollectionName, KvRwSet: &kvrwset.KVRWSet{}}
	if err := proto.Unmarshal(protoMsg.Rwset, collPvtRwSet.KvRwSet); err != nil {
		return nil, err
	}
	return collPvtRwSet, nil
}

// NewKVRead helps constructing proto message kvrwset.KVRead
func NewKVRead(key string, version *version.Height) *kvrwset.KVRead {
	return &kvrwset.KVRead{Key: key, Version: newProtoVersion(version)}
}

// NewVersion helps converting proto message kvrwset.Version to version.Height
func NewVersion(protoVersion *kvrwset.Version) *version.Height {
	if protoVersion == nil {
		return nil
	}
	return version.NewHeight(protoVersion.BlockNum, protoVersion.TxNum)
}

func newProtoVersion(height *version.Height) *kvrwset.Version {
	if height == nil {
		return nil
	}
	return &kvrwset.Version{BlockNum: height.BlockNum, TxNum: height.TxNum}
}

func newKVWrite(key string, value []byte) *kvrwset.KVWrite {
	return &kvrwset.KVWrite{Key: key, IsDelete: len(value) == 0, Value: value}
}

func newPvtKVReadHash(key string, version *version.Height) *kvrwset.KVReadHash {
	return &kvrwset.KVReadHash{KeyHash: util.ComputeStringHash(key), Version: newProtoVersion(version)}
}

func newPvtKVWriteAndHash(key string, value []byte) (*kvrwset.KVWrite, *kvrwset.KVWriteHash) {
	kvWrite := newKVWrite(key, value)
	var keyHash, valueHash []byte
	keyHash = util.ComputeStringHash(key)
	if !kvWrite.IsDelete {
		valueHash = util.ComputeHash(value)
	}
	return kvWrite, &kvrwset.KVWriteHash{KeyHash: keyHash, IsDelete: kvWrite.IsDelete, ValueHash: valueHash}
}

// IsKVWriteDelete returns true if the kvWrite indicates a delete operation. See FAB-18386 for details.
func IsKVWriteDelete(kvWrite *kvrwset.KVWrite) bool {
	return kvWrite.IsDelete || len(kvWrite.Value) == 0
}

var (
	hashOfZeroLengthByteArray = util.ComputeHash([]byte{})
)

// IsKVWriteHashDelete returns true if the kvWriteHash indicates a delete operation. See FAB-18386 for details.
func IsKVWriteHashDelete(kvWriteHash *kvrwset.KVWriteHash) bool {
	return kvWriteHash.IsDelete || len(kvWriteHash.ValueHash) == 0 || bytes.Equal(hashOfZeroLengthByteArray, kvWriteHash.ValueHash)
}
