/*
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 ledger

import (
	"github.com/golang/protobuf/proto"
	commonledger "github.com/hyperledger/fabric/common/ledger"
	"github.com/hyperledger/fabric/protos/common"
	"github.com/hyperledger/fabric/protos/ledger/rwset"
	"github.com/hyperledger/fabric/protos/peer"
)

// PeerLedgerProvider provides handle to ledger instances
type PeerLedgerProvider interface {
	Initialize(statelisteners StateListeners)
	// Create creates a new ledger with the given genesis block.
	// This function guarantees that the creation of ledger and committing the genesis block would an atomic action
	// The chain id retrieved from the genesis block is treated as a ledger id
	Create(genesisBlock *common.Block) (PeerLedger, error)
	// Open opens an already created ledger
	Open(ledgerID string) (PeerLedger, error)
	// Exists tells whether the ledger with given id exists
	Exists(ledgerID string) (bool, error)
	// List lists the ids of the existing ledgers
	List() ([]string, error)
	// Close closes the PeerLedgerProvider
	Close()
}

// PeerLedger differs from the OrdererLedger in that PeerLedger locally maintain a bitmask
// that tells apart valid transactions from invalid ones
type PeerLedger interface {
	commonledger.Ledger
	// GetTransactionByID retrieves a transaction by id
	GetTransactionByID(txID string) (*peer.ProcessedTransaction, error)
	// GetBlockByHash returns a block given it's hash
	GetBlockByHash(blockHash []byte) (*common.Block, error)
	// GetBlockByTxID returns a block which contains a transaction
	GetBlockByTxID(txID string) (*common.Block, error)
	// GetTxValidationCodeByTxID returns reason code of transaction validation
	GetTxValidationCodeByTxID(txID string) (peer.TxValidationCode, error)
	// NewTxSimulator gives handle to a transaction simulator.
	// A client can obtain more than one 'TxSimulator's for parallel execution.
	// Any snapshoting/synchronization should be performed at the implementation level if required
	NewTxSimulator(txid string) (TxSimulator, error)
	// NewQueryExecutor gives handle to a query executor.
	// A client can obtain more than one 'QueryExecutor's for parallel execution.
	// Any synchronization should be performed at the implementation level if required
	NewQueryExecutor() (QueryExecutor, error)
	// NewHistoryQueryExecutor gives handle to a history query executor.
	// A client can obtain more than one 'HistoryQueryExecutor's for parallel execution.
	// Any synchronization should be performed at the implementation level if required
	NewHistoryQueryExecutor() (HistoryQueryExecutor, error)
	// GetPvtDataAndBlockByNum returns the block and the corresponding pvt data.
	// The pvt data is filtered by the list of 'ns/collections' supplied
	// A nil filter does not filter any results and causes retrieving all the pvt data for the given blockNum
	GetPvtDataAndBlockByNum(blockNum uint64, filter PvtNsCollFilter) (*BlockAndPvtData, error)
	// GetPvtDataByNum returns only the pvt data  corresponding to the given block number
	// The pvt data is filtered by the list of 'ns/collections' supplied in the filter
	// A nil filter does not filter any results and causes retrieving all the pvt data for the given blockNum
	GetPvtDataByNum(blockNum uint64, filter PvtNsCollFilter) ([]*TxPvtData, error)
	// CommitWithPvtData commits the block and the corresponding pvt data in an atomic operation
	CommitWithPvtData(blockAndPvtdata *BlockAndPvtData) error
	// Purge removes private read-writes set generated by endorsers at block height lesser than
	// a given maxBlockNumToRetain. In other words, Purge only retains private read-write sets
	// that were generated at block height of maxBlockNumToRetain or higher.
	PurgePrivateData(maxBlockNumToRetain uint64) error
	// PrivateDataMinBlockNum returns the lowest retained endorsement block height
	PrivateDataMinBlockNum() (uint64, error)
	//Prune prunes the blocks/transactions that satisfy the given policy
	Prune(policy commonledger.PrunePolicy) error
}

// ValidatedLedger represents the 'final ledger' after filtering out invalid transactions from PeerLedger.
// Post-v1
type ValidatedLedger interface {
	commonledger.Ledger
}

// QueryExecutor executes the queries
// Get* methods are for supporting KV-based data model. ExecuteQuery method is for supporting a rich datamodel and query support
//
// ExecuteQuery method in the case of a rich data model is expected to support queries on
// latest state, historical state and on the intersection of state and transactions
type QueryExecutor interface {
	// GetState gets the value for given namespace and key. For a chaincode, the namespace corresponds to the chaincodeId
	GetState(namespace string, key string) ([]byte, error)
	// GetStateMultipleKeys gets the values for multiple keys in a single call
	GetStateMultipleKeys(namespace string, keys []string) ([][]byte, error)
	// GetStateRangeScanIterator returns an iterator that contains all the key-values between given key ranges.
	// startKey is included in the results and endKey is excluded. An empty startKey refers to the first available key
	// and an empty endKey refers to the last available key. For scanning all the keys, both the startKey and the endKey
	// can be supplied as empty strings. However, a full scan should be used judiciously for performance reasons.
	// The returned ResultsIterator contains results of type *KV which is defined in protos/ledger/queryresult.
	GetStateRangeScanIterator(namespace string, startKey string, endKey string) (commonledger.ResultsIterator, error)
	// ExecuteQuery executes the given query and returns an iterator that contains results of type specific to the underlying data store.
	// Only used for state databases that support query
	// For a chaincode, the namespace corresponds to the chaincodeId
	// The returned ResultsIterator contains results of type *KV which is defined in protos/ledger/queryresult.
	ExecuteQuery(namespace, query string) (commonledger.ResultsIterator, error)
	// GetPrivateData gets the value of a private data item identified by a tuple <namespace, collection, key>
	GetPrivateData(namespace, collection, key string) ([]byte, error)
	// GetPrivateDataMultipleKeys gets the values for the multiple private data items in a single call
	GetPrivateDataMultipleKeys(namespace, collection string, keys []string) ([][]byte, error)
	// GetPrivateDataRangeScanIterator returns an iterator that contains all the key-values between given key ranges.
	// startKey is included in the results and endKey is excluded. An empty startKey refers to the first available key
	// and an empty endKey refers to the last available key. For scanning all the keys, both the startKey and the endKey
	// can be supplied as empty strings. However, a full scan shuold be used judiciously for performance reasons.
	// The returned ResultsIterator contains results of type *KV which is defined in protos/ledger/queryresult.
	GetPrivateDataRangeScanIterator(namespace, collection, startKey, endKey string) (commonledger.ResultsIterator, error)
	// ExecuteQuery executes the given query and returns an iterator that contains results of type specific to the underlying data store.
	// Only used for state databases that support query
	// For a chaincode, the namespace corresponds to the chaincodeId
	// The returned ResultsIterator contains results of type *KV which is defined in protos/ledger/queryresult.
	ExecuteQueryOnPrivateData(namespace, collection, query string) (commonledger.ResultsIterator, error)
	// Done releases resources occupied by the QueryExecutor
	Done()
}

// HistoryQueryExecutor executes the history queries
type HistoryQueryExecutor interface {
	// GetHistoryForKey retrieves the history of values for a key.
	// The returned ResultsIterator contains results of type *KeyModification which is defined in protos/ledger/queryresult.
	GetHistoryForKey(namespace string, key string) (commonledger.ResultsIterator, error)
}

// TxSimulator simulates a transaction on a consistent snapshot of the 'as recent state as possible'
// Set* methods are for supporting KV-based data model. ExecuteUpdate method is for supporting a rich datamodel and query support
type TxSimulator interface {
	QueryExecutor
	// SetState sets the given value for the given namespace and key. For a chaincode, the namespace corresponds to the chaincodeId
	SetState(namespace string, key string, value []byte) error
	// DeleteState deletes the given namespace and key
	DeleteState(namespace string, key string) error
	// SetMultipleKeys sets the values for multiple keys in a single call
	SetStateMultipleKeys(namespace string, kvs map[string][]byte) error
	// ExecuteUpdate for supporting rich data model (see comments on QueryExecutor above)
	ExecuteUpdate(query string) error
	// SetPrivateData sets the given value to a key in the private data state represented by the tuple <namespace, collection, key>
	SetPrivateData(namespace, collection, key string, value []byte) error
	// SetPrivateDataMultipleKeys sets the values for multiple keys in the private data space in a single call
	SetPrivateDataMultipleKeys(namespace, collection string, kvs map[string][]byte) error
	// DeletePrivateData deletes the given tuple <namespace, collection, key> from private data
	DeletePrivateData(namespace, collection, key string) error
	// GetTxSimulationResults encapsulates the results of the transaction simulation.
	// This should contain enough detail for
	// - The update in the state that would be caused if the transaction is to be committed
	// - The environment in which the transaction is executed so as to be able to decide the validity of the environment
	//   (at a later time on a different peer) during committing the transactions
	// Different ledger implementation (or configurations of a single implementation) may want to represent the above two pieces
	// of information in different way in order to support different data-models or optimize the information representations.
	// Returned type 'TxSimulationResults' contains the simulation results for both the public data and the private data.
	// The public data simulation results are expected to be used as in V1 while the private data simulation results are expected
	// to be used by the gossip to disseminate this to the other endorsers (in phase-2 of sidedb)
	GetTxSimulationResults() (*TxSimulationResults, error)
}

// TxPvtData encapsulates the transaction number and pvt write-set for a transaction
type TxPvtData struct {
	SeqInBlock uint64
	WriteSet   *rwset.TxPvtReadWriteSet
}

// MissingPrivateData represents a private RWSet
// that isn't present among the private data passed
// to the ledger at the commit of the corresponding block
type MissingPrivateData struct {
	TxId       string
	SeqInBlock int
	Namespace  string
	Collection string
}

// BlockAndPvtData encapsulates the block and a map that contains the tuples <seqInBlock, *TxPvtData>
// The map is expected to contain the entries only for the transactions that has associated pvt data
type BlockAndPvtData struct {
	Block        *common.Block
	BlockPvtData map[uint64]*TxPvtData
	Missing      []MissingPrivateData
}

// PvtCollFilter represents the set of the collection names (as keys of the map with value 'true')
type PvtCollFilter map[string]bool

// PvtNsCollFilter specifies the tuple <namespace, PvtCollFilter>
type PvtNsCollFilter map[string]PvtCollFilter

// NewPvtNsCollFilter constructs an empty PvtNsCollFilter
func NewPvtNsCollFilter() PvtNsCollFilter {
	return make(map[string]PvtCollFilter)
}

// Has returns true if the pvtdata includes the data for collection <ns,coll>
func (pvtdata *TxPvtData) Has(ns string, coll string) bool {
	if pvtdata.WriteSet == nil {
		return false
	}
	for _, nsdata := range pvtdata.WriteSet.NsPvtRwset {
		if nsdata.Namespace == ns {
			for _, colldata := range nsdata.CollectionPvtRwset {
				if colldata.CollectionName == coll {
					return true
				}
			}
		}
	}
	return false
}

// Add adds a namespace-collection tuple to the filter
func (filter PvtNsCollFilter) Add(ns string, coll string) {
	collFilter, ok := filter[ns]
	if !ok {
		collFilter = make(map[string]bool)
		filter[ns] = collFilter
	}
	collFilter[coll] = true
}

// Has returns true if the filter has the entry for tuple namespace-collection
func (filter PvtNsCollFilter) Has(ns string, coll string) bool {
	collFilter, ok := filter[ns]
	if !ok {
		return false
	}
	return collFilter[coll]
}

// TxSimulationResults captures the details of the simulation results
// the field 'SimulationBlkHt' captures the approximate height of the blockchain on which
// the transaction is simulated - this is used to decide when to expire the 'PvtDataSimulationResults' from transient storage
type TxSimulationResults struct {
	PubSimulationResults *rwset.TxReadWriteSet
	PvtSimulationResults *rwset.TxPvtReadWriteSet
	SimulationBlkHt      uint64
}

// GetPubSimulationBytes returns the serialized bytes of public readwrite set
func (txSim *TxSimulationResults) GetPubSimulationBytes() ([]byte, error) {
	return proto.Marshal(txSim.PubSimulationResults)
}

// GetPvtSimulationBytes returns the serialized bytes of private readwrite set
func (txSim *TxSimulationResults) GetPvtSimulationBytes() ([]byte, error) {
	if !txSim.ContainsPvtWrites() {
		return nil, nil
	}
	return proto.Marshal(txSim.PvtSimulationResults)
}

// ContainsPvtWrites returns true if the simulation results include the private writes
func (txSim *TxSimulationResults) ContainsPvtWrites() bool {
	return txSim.PvtSimulationResults != nil
}

// StateListener allows a custom code for performing additional stuff upon state change
// for a perticular namespace against which the listener is registered.
// This helps to perform custom tasks other than the state updates.
// A ledger implemetation is expected to invoke Function `HandleStateUpdates` once per block and
// the `stateUpdates` parameter passed to the function captures the state changes caused by the block
// for the namespace. The actual data type of stateUpdates depends on the data model enabled.
// For instance, for KV data model, the actual type would be proto message
// `github.com/hyperledger/fabric/protos/ledger/rwset/kvrwset.KVWrite`
// Function `HandleStateUpdates` is expected to be invoked before block is committed and if this
// function returns an error, the ledger implementation is expected to halt block commit operation
// and result in a panic
type StateListener interface {
	HandleStateUpdates(ledgerID string, stateUpdates StateUpdates) error
}

// StateUpdates is the generic type to represent the state updates
type StateUpdates interface{}

// StateListeners maintains the association between a namespace to its corresponding listener
type StateListeners map[string]StateListener