/*
Copyright IBM Corp. 2017 All Rights Reserved.

SPDX-License-Identifier: Apache-2.0
*/

package deliverclient

import (
	"math"

	"github.com/hyperledger/fabric/common/util"
	"github.com/hyperledger/fabric/core/comm"
	"github.com/hyperledger/fabric/core/deliverservice/blocksprovider"
	"github.com/hyperledger/fabric/internal/pkg/identity"
	"github.com/hyperledger/fabric/protos/common"
	"github.com/hyperledger/fabric/protos/orderer"
	"github.com/hyperledger/fabric/protoutil"
)

type blocksRequester struct {
	tls     bool
	chainID string
	client  blocksprovider.BlocksDeliverer
	signer  identity.SignerSerializer
}

func (b *blocksRequester) RequestBlocks(ledgerInfoProvider blocksprovider.LedgerInfo) error {
	height, err := ledgerInfoProvider.LedgerHeight()
	if err != nil {
		logger.Errorf("Can't get ledger height for channel %s from committer [%s]", b.chainID, err)
		return err
	}

	if height > 0 {
		logger.Debugf("Starting deliver with block [%d] for channel %s", height, b.chainID)
		if err := b.seekLatestFromCommitter(height); err != nil {
			return err
		}
	} else {
		logger.Debugf("Starting deliver with oldest block for channel %s", b.chainID)
		if err := b.seekOldest(); err != nil {
			return err
		}
	}

	return nil
}

func (b *blocksRequester) getTLSCertHash() []byte {
	if b.tls {
		return util.ComputeSHA256(comm.GetCredentialSupport().GetClientCertificate().Certificate[0])
	}
	return nil
}

func (b *blocksRequester) seekOldest() error {
	seekInfo := &orderer.SeekInfo{
		Start:    &orderer.SeekPosition{Type: &orderer.SeekPosition_Oldest{Oldest: &orderer.SeekOldest{}}},
		Stop:     &orderer.SeekPosition{Type: &orderer.SeekPosition_Specified{Specified: &orderer.SeekSpecified{Number: math.MaxUint64}}},
		Behavior: orderer.SeekInfo_BLOCK_UNTIL_READY,
	}

	//TODO- epoch and msgVersion may need to be obtained for nowfollowing usage in orderer/configupdate/configupdate.go
	msgVersion := int32(0)
	epoch := uint64(0)
	tlsCertHash := b.getTLSCertHash()
	env, err := protoutil.CreateSignedEnvelopeWithTLSBinding(
		common.HeaderType_DELIVER_SEEK_INFO,
		b.chainID,
		b.signer,
		seekInfo,
		msgVersion,
		epoch,
		tlsCertHash,
	)
	if err != nil {
		return err
	}
	return b.client.Send(env)
}

func (b *blocksRequester) seekLatestFromCommitter(height uint64) error {
	seekInfo := &orderer.SeekInfo{
		Start:    &orderer.SeekPosition{Type: &orderer.SeekPosition_Specified{Specified: &orderer.SeekSpecified{Number: height}}},
		Stop:     &orderer.SeekPosition{Type: &orderer.SeekPosition_Specified{Specified: &orderer.SeekSpecified{Number: math.MaxUint64}}},
		Behavior: orderer.SeekInfo_BLOCK_UNTIL_READY,
	}

	//TODO- epoch and msgVersion may need to be obtained for nowfollowing usage in orderer/configupdate/configupdate.go
	msgVersion := int32(0)
	epoch := uint64(0)
	tlsCertHash := b.getTLSCertHash()
	env, err := protoutil.CreateSignedEnvelopeWithTLSBinding(
		common.HeaderType_DELIVER_SEEK_INFO,
		b.chainID,
		b.signer,
		seekInfo,
		msgVersion,
		epoch,
		tlsCertHash,
	)
	if err != nil {
		return err
	}
	return b.client.Send(env)
}