/*
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 lockbasedtxmgr

import (
	"errors"
	"fmt"

	commonledger "github.com/hyperledger/fabric/common/ledger"
	"github.com/hyperledger/fabric/core/ledger"
	"github.com/hyperledger/fabric/core/ledger/kvledger/txmgmt/rwsetutil"
	"github.com/hyperledger/fabric/core/ledger/kvledger/txmgmt/txmgr"
)

// LockBasedTxSimulator is a transaction simulator used in `LockBasedTxMgr`
type lockBasedTxSimulator struct {
	lockBasedQueryExecutor
	rwsetBuilder            *rwsetutil.RWSetBuilder
	writePerformed          bool
	pvtdataQueriesPerformed bool
}

func newLockBasedTxSimulator(txmgr *LockBasedTxMgr, txid string) (*lockBasedTxSimulator, error) {
	rwsetBuilder := rwsetutil.NewRWSetBuilder()
	helper := &queryHelper{txmgr: txmgr, rwsetBuilder: rwsetBuilder}
	logger.Debugf("constructing new tx simulator txid = [%s]", txid)
	return &lockBasedTxSimulator{lockBasedQueryExecutor{helper, txid}, rwsetBuilder, false, false}, nil
}

// GetState implements method in interface `ledger.TxSimulator`
func (s *lockBasedTxSimulator) GetState(ns string, key string) ([]byte, error) {
	return s.helper.getState(ns, key)
}

// SetState implements method in interface `ledger.TxSimulator`
func (s *lockBasedTxSimulator) SetState(ns string, key string, value []byte) error {
	if err := s.helper.checkDone(); err != nil {
		return err
	}
	if err := s.checkBeforeWrite(); err != nil {
		return err
	}
	if err := s.helper.txmgr.db.ValidateKey(key); err != nil {
		return err
	}
	s.rwsetBuilder.AddToWriteSet(ns, key, value)
	return nil
}

// DeleteState implements method in interface `ledger.TxSimulator`
func (s *lockBasedTxSimulator) DeleteState(ns string, key string) error {
	return s.SetState(ns, key, nil)
}

// SetStateMultipleKeys implements method in interface `ledger.TxSimulator`
func (s *lockBasedTxSimulator) SetStateMultipleKeys(namespace string, kvs map[string][]byte) error {
	for k, v := range kvs {
		if err := s.SetState(namespace, k, v); err != nil {
			return err
		}
	}
	return nil
}

// SetPrivateData implements method in interface `ledger.TxSimulator`
func (s *lockBasedTxSimulator) SetPrivateData(ns, coll, key string, value []byte) error {
	if err := s.helper.checkDone(); err != nil {
		return err
	}
	if err := s.checkBeforeWrite(); err != nil {
		return err
	}
	if err := s.helper.txmgr.db.ValidateKey(key); err != nil {
		return err
	}
	s.writePerformed = true
	return s.rwsetBuilder.AddToPvtAndHashedWriteSet(ns, coll, key, value)
}

// DeletePrivateData implements method in interface `ledger.TxSimulator`
func (s *lockBasedTxSimulator) DeletePrivateData(ns, coll, key string) error {
	return s.SetPrivateData(ns, coll, key, nil)
}

// SetPrivateDataMultipleKeys implements method in interface `ledger.TxSimulator`
func (s *lockBasedTxSimulator) SetPrivateDataMultipleKeys(ns, coll string, kvs map[string][]byte) error {
	for k, v := range kvs {
		if err := s.SetPrivateData(ns, coll, k, v); err != nil {
			return err
		}
	}
	return nil
}

// GetPrivateDataRangeScanIterator implements method in interface `ledger.TxSimulator`
func (s *lockBasedTxSimulator) GetPrivateDataRangeScanIterator(namespace, collection, startKey, endKey string) (commonledger.ResultsIterator, error) {
	if err := s.checkBeforePvtdataQueries(); err != nil {
		return nil, err
	}
	return s.lockBasedQueryExecutor.GetPrivateDataRangeScanIterator(namespace, collection, startKey, endKey)
}

// ExecuteQueryOnPrivateData implements method in interface `ledger.TxSimulator`
func (s *lockBasedTxSimulator) ExecuteQueryOnPrivateData(namespace, collection, query string) (commonledger.ResultsIterator, error) {
	if err := s.checkBeforePvtdataQueries(); err != nil {
		return nil, err
	}
	return s.lockBasedQueryExecutor.ExecuteQueryOnPrivateData(namespace, collection, query)
}

// GetTxSimulationResults implements method in interface `ledger.TxSimulator`
func (s *lockBasedTxSimulator) GetTxSimulationResults() (*ledger.TxSimulationResults, error) {
	logger.Debugf("Simulation completed, getting simulation results")
	s.Done()
	if s.helper.err != nil {
		return nil, s.helper.err
	}
	return s.rwsetBuilder.GetTxSimulationResults()
}

// ExecuteUpdate implements method in interface `ledger.TxSimulator`
func (s *lockBasedTxSimulator) ExecuteUpdate(query string) error {
	return errors.New("Not supported")
}

func (s *lockBasedTxSimulator) checkBeforeWrite() error {
	if s.pvtdataQueriesPerformed {
		return &txmgr.ErrUnsupportedTransaction{
			Msg: fmt.Sprintf("Tx [%s]: Transaction has already performed queries on pvt data. Writes are not allowed", s.txid),
		}
	}
	s.writePerformed = true
	return nil
}

func (s *lockBasedTxSimulator) checkBeforePvtdataQueries() error {
	if s.writePerformed {
		return &txmgr.ErrUnsupportedTransaction{
			Msg: fmt.Sprintf("Tx [%s]: Queries on pvt data is supported only in a read-only transaction", s.txid),
		}
	}
	s.pvtdataQueriesPerformed = true
	return nil
}