/*
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 multichain

import (
	"github.com/hyperledger/fabric/common/config"
	"github.com/hyperledger/fabric/common/configtx"
	configtxapi "github.com/hyperledger/fabric/common/configtx/api"
	"github.com/hyperledger/fabric/orderer/ledger"
	cb "github.com/hyperledger/fabric/protos/common"
	"github.com/hyperledger/fabric/protos/utils"
	"github.com/op/go-logging"

	"github.com/hyperledger/fabric/common/crypto"
)

var logger = logging.MustGetLogger("orderer/multichain")

// Manager coordinates the creation and access of chains
type Manager interface {
	// GetChain retrieves the chain support for a chain (and whether it exists)
	GetChain(chainID string) (ChainSupport, bool)

	// SystemChannelID returns the channel ID for the system channel
	SystemChannelID() string
}

type configResources struct {
	configtxapi.Manager
}

func (cr *configResources) SharedConfig() config.Orderer {
	return cr.OrdererConfig()
}

type ledgerResources struct {
	*configResources
	ledger ledger.ReadWriter
}

type multiLedger struct {
	chains          map[string]*chainSupport
	consenters      map[string]Consenter
	ledgerFactory   ledger.Factory
	signer          crypto.LocalSigner
	systemChannelID string
}

func getConfigTx(reader ledger.Reader) *cb.Envelope {
	lastBlock := ledger.GetBlock(reader, reader.Height()-1)
	index, err := utils.GetLastConfigIndexFromBlock(lastBlock)
	if err != nil {
		logger.Panicf("Chain did not have appropriately encoded last config in its latest block: %s", err)
	}
	configBlock := ledger.GetBlock(reader, index)
	if configBlock == nil {
		logger.Panicf("Config block does not exist")
	}

	return utils.ExtractEnvelopeOrPanic(configBlock, 0)
}

// NewManagerImpl produces an instance of a Manager
func NewManagerImpl(ledgerFactory ledger.Factory, consenters map[string]Consenter, signer crypto.LocalSigner) Manager {
	ml := &multiLedger{
		chains:        make(map[string]*chainSupport),
		ledgerFactory: ledgerFactory,
		consenters:    consenters,
		signer:        signer,
	}

	existingChains := ledgerFactory.ChainIDs()
	for _, chainID := range existingChains {
		rl, err := ledgerFactory.GetOrCreate(chainID)
		if err != nil {
			logger.Fatalf("Ledger factory reported chainID %s but could not retrieve it: %s", chainID, err)
		}
		configTx := getConfigTx(rl)
		if configTx == nil {
			logger.Fatalf("Could not find config transaction for chain %s", chainID)
		}
		ledgerResources := ml.newLedgerResources(configTx)
		chainID := ledgerResources.ChainID()

		if ledgerResources.SharedConfig().ChainCreationPolicyNames() != nil {
			if ml.systemChannelID != "" {
				logger.Fatalf("There appear to be two system chains %s and %s", ml.systemChannelID, chainID)
			}
			chain := newChainSupport(createSystemChainFilters(ml, ledgerResources),
				ledgerResources,
				consenters,
				signer)
			logger.Infof("Starting with system channel: %s and orderer type %s", chainID, chain.SharedConfig().ConsensusType())
			ml.chains[string(chainID)] = chain
			ml.systemChannelID = chainID
			// We delay starting this chain, as it might try to copy and replace the chains map via newChain before the map is fully built
			defer chain.start()
		} else {
			logger.Debugf("Starting chain: %x", chainID)
			chain := newChainSupport(createStandardFilters(ledgerResources),
				ledgerResources,
				consenters,
				signer)
			ml.chains[string(chainID)] = chain
			chain.start()
		}

	}

	if ml.systemChannelID == "" {
		logger.Panicf("No system chain found")
	}

	return ml
}

func (ml *multiLedger) SystemChannelID() string {
	return ml.systemChannelID
}

// GetChain retrieves the chain support for a chain (and whether it exists)
func (ml *multiLedger) GetChain(chainID string) (ChainSupport, bool) {
	cs, ok := ml.chains[chainID]
	return cs, ok
}

func (ml *multiLedger) newLedgerResources(configTx *cb.Envelope) *ledgerResources {
	initializer := configtx.NewInitializer()
	configManager, err := configtx.NewManagerImpl(configTx, initializer, nil)
	if err != nil {
		logger.Fatalf("Error creating configtx manager and handlers: %s", err)
	}

	chainID := configManager.ChainID()

	ledger, err := ml.ledgerFactory.GetOrCreate(chainID)
	if err != nil {
		logger.Fatalf("Error getting ledger for %s", chainID)
	}

	return &ledgerResources{
		configResources: &configResources{Manager: configManager},
		ledger:          ledger,
	}
}

func (ml *multiLedger) newChain(configtx *cb.Envelope) {
	ledgerResources := ml.newLedgerResources(configtx)
	ledgerResources.ledger.Append(ledger.CreateNextBlock(ledgerResources.ledger, []*cb.Envelope{configtx}))

	// Copy the map to allow concurrent reads from broadcast/deliver while the new chainSupport is
	newChains := make(map[string]*chainSupport)
	for key, value := range ml.chains {
		newChains[key] = value
	}

	cs := newChainSupport(createStandardFilters(ledgerResources), ledgerResources, ml.consenters, ml.signer)
	chainID := ledgerResources.ChainID()

	logger.Infof("Created and starting new chain %s", chainID)

	newChains[string(chainID)] = cs
	cs.start()

	ml.chains = newChains
}

func (ml *multiLedger) channelsCount() int {
	return len(ml.chains)
}