/*
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 peer

import (
	"runtime/debug"
	"time"

	"github.com/golang/protobuf/proto"
	"github.com/hyperledger/fabric/common/deliver"
	"github.com/hyperledger/fabric/common/flogging"
	"github.com/hyperledger/fabric/core/aclmgmt/resources"
	"github.com/hyperledger/fabric/core/ledger/util"
	"github.com/hyperledger/fabric/protos/common"
	"github.com/hyperledger/fabric/protos/peer"
	"github.com/hyperledger/fabric/protos/utils"
	"github.com/pkg/errors"
	"github.com/spf13/viper"
)

const pkgLogID = "common/deliverevents"

var logger = flogging.MustGetLogger(pkgLogID)

// PolicyCheckerProvider provides the corresponding policy checker for a
// given resource name
type PolicyCheckerProvider func(resourceName string) deliver.PolicyCheckerFunc

// server holds the dependencies necessary to create a deliver server
type server struct {
	dh                    *deliver.Handler
	policyCheckerProvider PolicyCheckerProvider
}

// blockResponseSender structure used to send block responses
type blockResponseSender struct {
	peer.Deliver_DeliverServer
}

// SendStatusResponse generates status reply proto message
func (brs *blockResponseSender) SendStatusResponse(status common.Status) error {
	reply := &peer.DeliverResponse{
		Type: &peer.DeliverResponse_Status{Status: status},
	}
	return brs.Send(reply)
}

// SendBlockResponse generates deliver response with block message
func (brs *blockResponseSender) SendBlockResponse(block *common.Block) error {
	response := &peer.DeliverResponse{
		Type: &peer.DeliverResponse_Block{Block: block},
	}
	return brs.Send(response)
}

// filteredBlockResponseSender structure used to send filtered block responses
type filteredBlockResponseSender struct {
	peer.Deliver_DeliverFilteredServer
}

func (fbrs *filteredBlockResponseSender) SendStatusResponse(status common.Status) error {
	response := &peer.DeliverResponse{
		Type: &peer.DeliverResponse_Status{Status: status},
	}
	return fbrs.Send(response)
}

// SendBlockResponse generates deliver response with block message
func (fbrs *filteredBlockResponseSender) SendBlockResponse(block *common.Block) error {
	// Generates filtered block response
	b := blockEvent(*block)
	filteredBlock, err := b.toFilteredBlock()
	if err != nil {
		logger.Warningf("Failed to generate filtered block due to: %s", err)
		return fbrs.SendStatusResponse(common.Status_BAD_REQUEST)
	}
	response := &peer.DeliverResponse{
		Type: &peer.DeliverResponse_FilteredBlock{FilteredBlock: filteredBlock},
	}
	return fbrs.Send(response)
}

// transactionActions aliasing for peer.TransactionAction pointers slice
type transactionActions []*peer.TransactionAction

// blockEvent an alias for common.Block structure, used to
// extend with auxiliary functionality
type blockEvent common.Block

// Deliver sends a stream of blocks to a client after commitment
func (s *server) DeliverFiltered(srv peer.Deliver_DeliverFilteredServer) error {
	logger.Debugf("Starting new DeliverFiltered handler")
	defer dumpStacktraceOnPanic()
	// getting policy checker based on resources.Event_FilteredBlock resource name
	deliverServer := &deliver.Server{
		Receiver:      srv,
		PolicyChecker: s.policyCheckerProvider(resources.Event_FilteredBlock),
		ResponseSender: &filteredBlockResponseSender{
			Deliver_DeliverFilteredServer: srv,
		},
	}
	return s.dh.Handle(srv.Context(), deliverServer)
}

// Deliver sends a stream of blocks to a client after commitment
func (s *server) Deliver(srv peer.Deliver_DeliverServer) (err error) {
	logger.Debugf("Starting new Deliver handler")
	defer dumpStacktraceOnPanic()
	// getting policy checker based on resources.Event_Block resource name
	deliverServer := &deliver.Server{
		PolicyChecker: s.policyCheckerProvider(resources.Event_Block),
		Receiver:      srv,
		ResponseSender: &blockResponseSender{
			Deliver_DeliverServer: srv,
		},
	}
	return s.dh.Handle(srv.Context(), deliverServer)
}

// NewDeliverEventsServer creates a peer.Deliver server to deliver block and
// filtered block events
func NewDeliverEventsServer(mutualTLS bool, policyCheckerProvider PolicyCheckerProvider, chainManager deliver.ChainManager) peer.DeliverServer {
	timeWindow := viper.GetDuration("peer.authentication.timewindow")
	if timeWindow == 0 {
		defaultTimeWindow := 15 * time.Minute
		logger.Warningf("`peer.authentication.timewindow` not set; defaulting to %s", defaultTimeWindow)
		timeWindow = defaultTimeWindow
	}
	return &server{
		dh: deliver.NewHandler(chainManager, timeWindow, mutualTLS),
		policyCheckerProvider: policyCheckerProvider,
	}
}

func (s *server) sendProducer(srv peer.Deliver_DeliverFilteredServer) func(msg proto.Message) error {
	return func(msg proto.Message) error {
		response, ok := msg.(*peer.DeliverResponse)
		if !ok {
			logger.Errorf("received wrong response type, expected response type peer.DeliverResponse")
			return errors.New("expected response type peer.DeliverResponse")
		}
		return srv.Send(response)
	}
}

func (block *blockEvent) toFilteredBlock() (*peer.FilteredBlock, error) {
	filteredBlock := &peer.FilteredBlock{
		Number: block.Header.Number,
	}

	txsFltr := util.TxValidationFlags(block.Metadata.Metadata[common.BlockMetadataIndex_TRANSACTIONS_FILTER])
	for txIndex, ebytes := range block.Data.Data {
		var env *common.Envelope
		var err error

		if ebytes == nil {
			logger.Debugf("got nil data bytes for tx index %d, "+
				"block num %d", txIndex, block.Header.Number)
			continue
		}

		env, err = utils.GetEnvelopeFromBlock(ebytes)
		if err != nil {
			logger.Errorf("error getting tx from block, %s", err)
			continue
		}

		// get the payload from the envelope
		payload, err := utils.GetPayload(env)
		if err != nil {
			return nil, errors.WithMessage(err, "could not extract payload from envelope")
		}

		if payload.Header == nil {
			logger.Debugf("transaction payload header is nil, %d, block num %d",
				txIndex, block.Header.Number)
			continue
		}
		chdr, err := utils.UnmarshalChannelHeader(payload.Header.ChannelHeader)
		if err != nil {
			return nil, err
		}

		filteredBlock.ChannelId = chdr.ChannelId

		filteredTransaction := &peer.FilteredTransaction{
			Txid:             chdr.TxId,
			Type:             common.HeaderType(chdr.Type),
			TxValidationCode: txsFltr.Flag(txIndex),
		}

		if filteredTransaction.Type == common.HeaderType_ENDORSER_TRANSACTION {
			tx, err := utils.GetTransaction(payload.Data)
			if err != nil {
				return nil, errors.WithMessage(err, "error unmarshal transaction payload for block event")
			}

			filteredTransaction.Data, err = transactionActions(tx.Actions).toFilteredActions()
			if err != nil {
				logger.Errorf(err.Error())
				return nil, err
			}
		}

		filteredBlock.FilteredTransactions = append(filteredBlock.FilteredTransactions, filteredTransaction)
	}

	return filteredBlock, nil
}

func (ta transactionActions) toFilteredActions() (*peer.FilteredTransaction_TransactionActions, error) {
	transactionActions := &peer.FilteredTransactionActions{}
	for _, action := range ta {
		chaincodeActionPayload, err := utils.GetChaincodeActionPayload(action.Payload)
		if err != nil {
			return nil, errors.WithMessage(err, "error unmarshal transaction action payload for block event")
		}

		if chaincodeActionPayload.Action == nil {
			logger.Debugf("chaincode action, the payload action is nil, skipping")
			continue
		}
		propRespPayload, err := utils.GetProposalResponsePayload(chaincodeActionPayload.Action.ProposalResponsePayload)
		if err != nil {
			return nil, errors.WithMessage(err, "error unmarshal proposal response payload for block event")
		}

		caPayload, err := utils.GetChaincodeAction(propRespPayload.Extension)
		if err != nil {
			return nil, errors.WithMessage(err, "error unmarshal chaincode action for block event")
		}

		ccEvent, err := utils.GetChaincodeEvents(caPayload.Events)
		if err != nil {
			return nil, errors.WithMessage(err, "error unmarshal chaincode event for block event")
		}

		if ccEvent.GetChaincodeId() != "" {
			filteredAction := &peer.FilteredChaincodeAction{
				ChaincodeEvent: &peer.ChaincodeEvent{
					TxId:        ccEvent.TxId,
					ChaincodeId: ccEvent.ChaincodeId,
					EventName:   ccEvent.EventName,
				},
			}
			transactionActions.ChaincodeActions = append(transactionActions.ChaincodeActions, filteredAction)
		}
	}
	return &peer.FilteredTransaction_TransactionActions{
		TransactionActions: transactionActions,
	}, nil
}

func dumpStacktraceOnPanic() {
	func() {
		if r := recover(); r != nil {
			logger.Criticalf("Deliver client triggered panic: %s\n%s", r, debug.Stack())
		}
		logger.Debugf("Closing Deliver stream")
	}()
}