/*
Copyright IBM Corp. 2017 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 ledgerstorage

import (
	"fmt"
	"sync"

	"github.com/hyperledger/fabric/core/ledger/pvtdatapolicy"

	"github.com/hyperledger/fabric/common/ledger/blkstorage"
	"github.com/hyperledger/fabric/common/ledger/blkstorage/fsblkstorage"
	"github.com/hyperledger/fabric/core/ledger"
	"github.com/hyperledger/fabric/core/ledger/ledgerconfig"
	"github.com/hyperledger/fabric/core/ledger/pvtdatastorage"
	"github.com/hyperledger/fabric/protos/common"
)

// Provider encapusaltes two providers 1) block store provider and 2) and pvt data store provider
type Provider struct {
	blkStoreProvider     blkstorage.BlockStoreProvider
	pvtdataStoreProvider pvtdatastorage.Provider
}

// Store encapsulates two stores 1) block store and pvt data store
type Store struct {
	blkstorage.BlockStore
	pvtdataStore pvtdatastorage.Store
	rwlock       *sync.RWMutex
}

// NewProvider returns the handle to the provider
func NewProvider() *Provider {
	// Initialize the block storage
	attrsToIndex := []blkstorage.IndexableAttr{
		blkstorage.IndexableAttrBlockHash,
		blkstorage.IndexableAttrBlockNum,
		blkstorage.IndexableAttrTxID,
		blkstorage.IndexableAttrBlockNumTranNum,
		blkstorage.IndexableAttrBlockTxID,
		blkstorage.IndexableAttrTxValidationCode,
	}
	indexConfig := &blkstorage.IndexConfig{AttrsToIndex: attrsToIndex}
	blockStoreProvider := fsblkstorage.NewProvider(
		fsblkstorage.NewConf(ledgerconfig.GetBlockStorePath(), ledgerconfig.GetMaxBlockfileSize()),
		indexConfig)

	pvtStoreProvider := pvtdatastorage.NewProvider()
	return &Provider{blockStoreProvider, pvtStoreProvider}
}

// Open opens the store
func (p *Provider) Open(ledgerid string) (*Store, error) {
	var blockStore blkstorage.BlockStore
	var pvtdataStore pvtdatastorage.Store
	var err error

	if blockStore, err = p.blkStoreProvider.OpenBlockStore(ledgerid); err != nil {
		return nil, err
	}
	if pvtdataStore, err = p.pvtdataStoreProvider.OpenStore(ledgerid); err != nil {
		return nil, err
	}
	store := &Store{blockStore, pvtdataStore, &sync.RWMutex{}}
	if err := store.init(); err != nil {
		return nil, err
	}
	return store, nil
}

// Close closes the provider
func (p *Provider) Close() {
	p.blkStoreProvider.Close()
	p.pvtdataStoreProvider.Close()
}

// Init initializes store with essential configurations
func (s *Store) Init(btlPolicy pvtdatapolicy.BTLPolicy) {
	s.pvtdataStore.Init(btlPolicy)
}

// CommitWithPvtData commits the block and the corresponding pvt data in an atomic operation
func (s *Store) CommitWithPvtData(blockAndPvtdata *ledger.BlockAndPvtData) error {
	s.rwlock.Lock()
	defer s.rwlock.Unlock()
	var pvtdata []*ledger.TxPvtData
	for _, v := range blockAndPvtdata.BlockPvtData {
		pvtdata = append(pvtdata, v)
	}
	if err := s.pvtdataStore.Prepare(blockAndPvtdata.Block.Header.Number, pvtdata); err != nil {
		return err
	}
	if err := s.AddBlock(blockAndPvtdata.Block); err != nil {
		s.pvtdataStore.Rollback()
		return err
	}
	return s.pvtdataStore.Commit()
}

// GetPvtDataAndBlockByNum returns the block and the corresponding pvt data.
// The pvt data is filtered by the list of 'collections' supplied
func (s *Store) GetPvtDataAndBlockByNum(blockNum uint64, filter ledger.PvtNsCollFilter) (*ledger.BlockAndPvtData, error) {
	s.rwlock.RLock()
	defer s.rwlock.RUnlock()

	var block *common.Block
	var pvtdata []*ledger.TxPvtData
	var err error
	if block, err = s.RetrieveBlockByNumber(blockNum); err != nil {
		return nil, err
	}
	if pvtdata, err = s.getPvtDataByNumWithoutLock(blockNum, filter); err != nil {
		return nil, err
	}
	return &ledger.BlockAndPvtData{Block: block, BlockPvtData: constructPvtdataMap(pvtdata)}, nil
}

// 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
func (s *Store) GetPvtDataByNum(blockNum uint64, filter ledger.PvtNsCollFilter) ([]*ledger.TxPvtData, error) {
	s.rwlock.RLock()
	defer s.rwlock.RUnlock()
	return s.getPvtDataByNumWithoutLock(blockNum, filter)
}

// getPvtDataByNumWithoutLock returns only the pvt data  corresponding to the given block number.
// This function does not acquire a readlock and it is expected that in most of the circumstances, the caller
// posesses a read lock on `s.rwlock`
func (s *Store) getPvtDataByNumWithoutLock(blockNum uint64, filter ledger.PvtNsCollFilter) ([]*ledger.TxPvtData, error) {
	var pvtdata []*ledger.TxPvtData
	var err error
	if pvtdata, err = s.pvtdataStore.GetPvtDataByBlockNum(blockNum, filter); err != nil {
		return nil, err
	}
	return pvtdata, nil
}

// init first invokes function `initFromExistingBlockchain`
// in order to check whether the pvtdata store is present because of an upgrade
// of peer from 1.0 and need to be updated with the existing blockchain. If, this is
// not the case then this init will invoke function `syncPvtdataStoreWithBlockStore`
// to follow the normal course
func (s *Store) init() error {
	var initialized bool
	var err error
	if initialized, err = s.initPvtdataStoreFromExistingBlockchain(); err != nil || initialized {
		return err
	}
	return s.syncPvtdataStoreWithBlockStore()
}

// initPvtdataStoreFromExistingBlockchain updates the initial state of the pvtdata store
// if an existing block store has a blockchain and the pvtdata store is empty.
// This situation is expected to happen when a peer is upgrated from version 1.0
// and an existing blockchain is present that was generated with version 1.0.
// Under this scenario, the pvtdata store is brought upto the point as if it has
// processed exisitng blocks with no pvt data. This function returns true if the
// above mentioned condition is found to be true and pvtdata store is successfully updated
func (s *Store) initPvtdataStoreFromExistingBlockchain() (bool, error) {
	var bcInfo *common.BlockchainInfo
	var pvtdataStoreEmpty bool
	var err error

	if bcInfo, err = s.BlockStore.GetBlockchainInfo(); err != nil {
		return false, err
	}
	if pvtdataStoreEmpty, err = s.pvtdataStore.IsEmpty(); err != nil {
		return false, err
	}
	if pvtdataStoreEmpty && bcInfo.Height > 0 {
		if err = s.pvtdataStore.InitLastCommittedBlock(bcInfo.Height - 1); err != nil {
			return false, err
		}
		return true, nil
	}
	return false, nil
}

// syncPvtdataStoreWithBlockStore checks whether the block storage and pvt data store are in sync
// this is called when the store instance is constructed and handed over for the use.
// this check whether there is a pending batch (possibly from a previous system crash)
// of pvt data that was not committed. If a pending batch exists, the check is made
// whether the associated block was successfully committed in the block storage (before the crash)
// or not. If the block was committed, the private data batch is committed
// otherwise, the pvt data batch is rolledback
func (s *Store) syncPvtdataStoreWithBlockStore() error {
	var pendingPvtbatch bool
	var err error
	if pendingPvtbatch, err = s.pvtdataStore.HasPendingBatch(); err != nil {
		return err
	}
	if !pendingPvtbatch {
		return nil
	}
	var bcInfo *common.BlockchainInfo
	var pvtdataStoreHt uint64

	if bcInfo, err = s.GetBlockchainInfo(); err != nil {
		return err
	}
	if pvtdataStoreHt, err = s.pvtdataStore.LastCommittedBlockHeight(); err != nil {
		return err
	}

	if bcInfo.Height == pvtdataStoreHt {
		return s.pvtdataStore.Rollback()
	}

	if bcInfo.Height == pvtdataStoreHt+1 {
		return s.pvtdataStore.Commit()
	}

	return fmt.Errorf("This is not expected. blockStoreHeight=%d, pvtdataStoreHeight=%d", bcInfo.Height, pvtdataStoreHt)
}

func constructPvtdataMap(pvtdata []*ledger.TxPvtData) map[uint64]*ledger.TxPvtData {
	if pvtdata == nil {
		return nil
	}
	m := make(map[uint64]*ledger.TxPvtData)
	for _, pvtdatum := range pvtdata {
		m[pvtdatum.SeqInBlock] = pvtdatum
	}
	return m
}