/*
Copyright IBM Corp. All Rights Reserved.

SPDX-License-Identifier: Apache-2.0
*/

package msgprocessor

import (
	"fmt"

	"github.com/golang/protobuf/proto"
	"github.com/hyperledger/fabric/common/channelconfig"
	"github.com/hyperledger/fabric/common/configtx"
	"github.com/hyperledger/fabric/common/policies"
	"github.com/hyperledger/fabric/internal/pkg/identity"
	cb "github.com/hyperledger/fabric/protos/common"
	"github.com/hyperledger/fabric/protoutil"

	"github.com/pkg/errors"
)

// ChannelConfigTemplator can be used to generate config templates.
type ChannelConfigTemplator interface {
	// NewChannelConfig creates a new template configuration manager.
	NewChannelConfig(env *cb.Envelope) (channelconfig.Resources, error)
}

// SystemChannel implements the Processor interface for the system channel.
type SystemChannel struct {
	*StandardChannel
	templator ChannelConfigTemplator
}

// NewSystemChannel creates a new system channel message processor.
func NewSystemChannel(support StandardChannelSupport, templator ChannelConfigTemplator, filters *RuleSet) *SystemChannel {
	logger.Debugf("Creating system channel msg processor for channel %s", support.ChainID())
	return &SystemChannel{
		StandardChannel: NewStandardChannel(support, filters),
		templator:       templator,
	}
}

// CreateSystemChannelFilters creates the set of filters for the ordering system chain.
func CreateSystemChannelFilters(chainCreator ChainCreator, ledgerResources channelconfig.Resources) *RuleSet {
	ordererConfig, ok := ledgerResources.OrdererConfig()
	if !ok {
		logger.Panicf("Cannot create system channel filters without orderer config")
	}
	return NewRuleSet([]Rule{
		EmptyRejectRule,
		NewExpirationRejectRule(ledgerResources),
		NewSizeFilter(ordererConfig),
		NewSigFilter(policies.ChannelWriters, ledgerResources),
		NewSystemChannelFilter(ledgerResources, chainCreator),
	})
}

// ProcessNormalMsg handles normal messages, rejecting them if they are not bound for the system channel ID
// with ErrChannelDoesNotExist.
func (s *SystemChannel) ProcessNormalMsg(msg *cb.Envelope) (configSeq uint64, err error) {
	channelID, err := protoutil.ChannelID(msg)
	if err != nil {
		return 0, err
	}

	// For the StandardChannel message processing, we would not check the channel ID,
	// because the message processor is looked up by channel ID.
	// However, the system channel message processor is the catch all for messages
	// which do not correspond to an extant channel, so we must check it here.
	if channelID != s.support.ChainID() {
		return 0, ErrChannelDoesNotExist
	}

	return s.StandardChannel.ProcessNormalMsg(msg)
}

// ProcessConfigUpdateMsg handles messages of type CONFIG_UPDATE either for the system channel itself
// or, for channel creation.  In the channel creation case, the CONFIG_UPDATE is wrapped into a resulting
// ORDERER_TRANSACTION, and in the standard CONFIG_UPDATE case, a resulting CONFIG message
func (s *SystemChannel) ProcessConfigUpdateMsg(envConfigUpdate *cb.Envelope) (config *cb.Envelope, configSeq uint64, err error) {
	channelID, err := protoutil.ChannelID(envConfigUpdate)
	if err != nil {
		return nil, 0, err
	}

	logger.Debugf("Processing config update tx with system channel message processor for channel ID %s", channelID)

	if channelID == s.support.ChainID() {
		return s.StandardChannel.ProcessConfigUpdateMsg(envConfigUpdate)
	}

	// XXX we should check that the signature on the outer envelope is at least valid for some MSP in the system channel

	logger.Debugf("Processing channel create tx for channel %s on system channel %s", channelID, s.support.ChainID())

	// If the channel ID does not match the system channel, then this must be a channel creation transaction

	bundle, err := s.templator.NewChannelConfig(envConfigUpdate)
	if err != nil {
		return nil, 0, err
	}

	newChannelConfigEnv, err := bundle.ConfigtxValidator().ProposeConfigUpdate(envConfigUpdate)
	if err != nil {
		return nil, 0, errors.WithMessagef(err, "error validating channel creation transaction for new channel '%s', could not succesfully apply update to template configuration", channelID)
	}

	newChannelEnvConfig, err := protoutil.CreateSignedEnvelope(cb.HeaderType_CONFIG, channelID, s.support.Signer(), newChannelConfigEnv, msgVersion, epoch)
	if err != nil {
		return nil, 0, err
	}

	wrappedOrdererTransaction, err := protoutil.CreateSignedEnvelope(cb.HeaderType_ORDERER_TRANSACTION, s.support.ChainID(), s.support.Signer(), newChannelEnvConfig, msgVersion, epoch)
	if err != nil {
		return nil, 0, err
	}

	// We re-apply the filters here, especially for the size filter, to ensure that the transaction we
	// just constructed is not too large for our consenter.  It additionally reapplies the signature
	// check, which although not strictly necessary, is a good sanity check, in case the orderer
	// has not been configured with the right cert material.  The additional overhead of the signature
	// check is negligible, as this is the channel creation path and not the normal path.
	err = s.StandardChannel.filters.Apply(wrappedOrdererTransaction)
	if err != nil {
		return nil, 0, err
	}

	return wrappedOrdererTransaction, s.support.Sequence(), nil
}

// ProcessConfigMsg takes envelope of following two types:
//   - `HeaderType_CONFIG`: system channel itself is the target of config, we simply unpack `ConfigUpdate`
//     envelope from `LastUpdate` field and call `ProcessConfigUpdateMsg` on the underlying standard channel
//   - `HeaderType_ORDERER_TRANSACTION`: it's a channel creation message, we unpack `ConfigUpdate` envelope
//     and run `ProcessConfigUpdateMsg` on it
func (s *SystemChannel) ProcessConfigMsg(env *cb.Envelope) (*cb.Envelope, uint64, error) {
	payload, err := protoutil.UnmarshalPayload(env.Payload)
	if err != nil {
		return nil, 0, err
	}

	if payload.Header == nil {
		return nil, 0, fmt.Errorf("Abort processing config msg because no head was set")
	}

	if payload.Header.ChannelHeader == nil {
		return nil, 0, fmt.Errorf("Abort processing config msg because no channel header was set")
	}

	chdr, err := protoutil.UnmarshalChannelHeader(payload.Header.ChannelHeader)
	if err != nil {
		return nil, 0, fmt.Errorf("Abort processing config msg because channel header unmarshalling error: %s", err)
	}

	switch chdr.Type {
	case int32(cb.HeaderType_CONFIG):
		configEnvelope := &cb.ConfigEnvelope{}
		if err = proto.Unmarshal(payload.Data, configEnvelope); err != nil {
			return nil, 0, err
		}

		return s.StandardChannel.ProcessConfigUpdateMsg(configEnvelope.LastUpdate)

	case int32(cb.HeaderType_ORDERER_TRANSACTION):
		env, err := protoutil.UnmarshalEnvelope(payload.Data)
		if err != nil {
			return nil, 0, fmt.Errorf("Abort processing config msg because payload data unmarshalling error: %s", err)
		}

		configEnvelope := &cb.ConfigEnvelope{}
		_, err = protoutil.UnmarshalEnvelopeOfType(env, cb.HeaderType_CONFIG, configEnvelope)
		if err != nil {
			return nil, 0, fmt.Errorf("Abort processing config msg because payload data unmarshalling error: %s", err)
		}

		return s.ProcessConfigUpdateMsg(configEnvelope.LastUpdate)

	default:
		return nil, 0, fmt.Errorf("Panic processing config msg due to unexpected envelope type %s", cb.HeaderType_name[chdr.Type])
	}
}

// DefaultTemplatorSupport is the subset of the channel config required by the DefaultTemplator.
type DefaultTemplatorSupport interface {
	// ConsortiumsConfig returns the ordering system channel's Consortiums config.
	ConsortiumsConfig() (channelconfig.Consortiums, bool)

	// OrdererConfig returns the ordering configuration and whether the configuration exists
	OrdererConfig() (channelconfig.Orderer, bool)

	// ConfigtxValidator returns the configtx manager corresponding to the system channel's current config.
	ConfigtxValidator() configtx.Validator

	// Signer returns the local signer suitable for signing forwarded messages.
	Signer() identity.SignerSerializer
}

// DefaultTemplator implements the ChannelConfigTemplator interface and is the one used in production deployments.
type DefaultTemplator struct {
	support DefaultTemplatorSupport
}

// NewDefaultTemplator returns an instance of the DefaultTemplator.
func NewDefaultTemplator(support DefaultTemplatorSupport) *DefaultTemplator {
	return &DefaultTemplator{
		support: support,
	}
}

// NewChannelConfig creates a new template channel configuration based on the current config in the ordering system channel.
func (dt *DefaultTemplator) NewChannelConfig(envConfigUpdate *cb.Envelope) (channelconfig.Resources, error) {
	configUpdatePayload, err := protoutil.UnmarshalPayload(envConfigUpdate.Payload)
	if err != nil {
		return nil, fmt.Errorf("Failing initial channel config creation because of payload unmarshaling error: %s", err)
	}

	configUpdateEnv, err := configtx.UnmarshalConfigUpdateEnvelope(configUpdatePayload.Data)
	if err != nil {
		return nil, fmt.Errorf("Failing initial channel config creation because of config update envelope unmarshaling error: %s", err)
	}

	if configUpdatePayload.Header == nil {
		return nil, fmt.Errorf("Failed initial channel config creation because config update header was missing")
	}

	channelHeader, err := protoutil.UnmarshalChannelHeader(configUpdatePayload.Header.ChannelHeader)
	if err != nil {
		return nil, fmt.Errorf("Failed initial channel config creation because channel header was malformed: %s", err)
	}

	configUpdate, err := configtx.UnmarshalConfigUpdate(configUpdateEnv.ConfigUpdate)
	if err != nil {
		return nil, fmt.Errorf("Failing initial channel config creation because of config update unmarshaling error: %s", err)
	}

	if configUpdate.ChannelId != channelHeader.ChannelId {
		return nil, fmt.Errorf("Failing initial channel config creation: mismatched channel IDs: '%s' != '%s'", configUpdate.ChannelId, channelHeader.ChannelId)
	}

	if configUpdate.WriteSet == nil {
		return nil, fmt.Errorf("Config update has an empty writeset")
	}

	if configUpdate.WriteSet.Groups == nil || configUpdate.WriteSet.Groups[channelconfig.ApplicationGroupKey] == nil {
		return nil, fmt.Errorf("Config update has missing application group")
	}

	if uv := configUpdate.WriteSet.Groups[channelconfig.ApplicationGroupKey].Version; uv != 1 {
		return nil, fmt.Errorf("Config update for channel creation does not set application group version to 1, was %d", uv)
	}

	consortiumConfigValue, ok := configUpdate.WriteSet.Values[channelconfig.ConsortiumKey]
	if !ok {
		return nil, fmt.Errorf("Consortium config value missing")
	}

	consortium := &cb.Consortium{}
	err = proto.Unmarshal(consortiumConfigValue.Value, consortium)
	if err != nil {
		return nil, fmt.Errorf("Error reading unmarshaling consortium name: %s", err)
	}

	applicationGroup := protoutil.NewConfigGroup()
	consortiumsConfig, ok := dt.support.ConsortiumsConfig()
	if !ok {
		return nil, fmt.Errorf("The ordering system channel does not appear to support creating channels")
	}

	consortiumConf, ok := consortiumsConfig.Consortiums()[consortium.Name]
	if !ok {
		return nil, fmt.Errorf("Unknown consortium name: %s", consortium.Name)
	}

	policyKey := channelconfig.ChannelCreationPolicyKey
	if oc, ok := dt.support.OrdererConfig(); ok && oc.Capabilities().UseChannelCreationPolicyAsAdmins() {
		// To support the channel creation process, we use a copy of the Consortium's ChannelCreationPolicy
		// to govern modification of the application group.  We do this by creating a new policy in the
		// Application group (with a copy of the policy info from the consortium) and set the mod policy
		// of the Application group to the name of this policy.  Historically, the name chosen was
		// "ChannelCreationPolicy".  Because this name did not overlap with the default policy names, the
		// creation tx simply encoded the Readers/Writers/Admins policies in the write set at Version 0.
		// However, because there was no /Channel/Application/Admins policy in the template  config,
		// it made evaluating the /Channel/Admins policy impossible.  When the UseChannelCreationPolicyAsAdmins
		// capability is enabled, To allow the /Channel/Admins policy to evaluate normally, we now attempt
		// to use the standard policy name "Admins" instead of "ChannelCreationPolicy", when the user is
		// submitting a configtx generated by a newer version of configtxgen.  We detect if an old
		// configtxgen was used to generate the configtx if the /Channel/Application/Admins policy has a
		//version set to 0.  Otherwise, we use the newer behavior.
		applicationPolicies := configUpdate.WriteSet.Groups[channelconfig.ApplicationGroupKey].Policies
		if applicationPolicies != nil {
			if policy, ok := applicationPolicies[channelconfig.AdminsPolicyKey]; !ok || policy.Version != uint64(0) {
				policyKey = channelconfig.AdminsPolicyKey
			}
		}
	}
	applicationGroup.Policies[policyKey] = &cb.ConfigPolicy{
		Policy:    consortiumConf.ChannelCreationPolicy(),
		ModPolicy: policyKey,
	}
	applicationGroup.ModPolicy = policyKey

	// Get the current system channel config
	systemChannelGroup := dt.support.ConfigtxValidator().ConfigProto().ChannelGroup

	// If the consortium group has no members, allow the source request to have no members.  However,
	// if the consortium group has any members, there must be at least one member in the source request
	if len(systemChannelGroup.Groups[channelconfig.ConsortiumsGroupKey].Groups[consortium.Name].Groups) > 0 &&
		len(configUpdate.WriteSet.Groups[channelconfig.ApplicationGroupKey].Groups) == 0 {
		return nil, fmt.Errorf("Proposed configuration has no application group members, but consortium contains members")
	}

	// If the consortium has no members, allow the source request to contain arbitrary members
	// Otherwise, require that the supplied members are a subset of the consortium members
	if len(systemChannelGroup.Groups[channelconfig.ConsortiumsGroupKey].Groups[consortium.Name].Groups) > 0 {
		for orgName := range configUpdate.WriteSet.Groups[channelconfig.ApplicationGroupKey].Groups {
			consortiumGroup, ok := systemChannelGroup.Groups[channelconfig.ConsortiumsGroupKey].Groups[consortium.Name].Groups[orgName]
			if !ok {
				return nil, fmt.Errorf("Attempted to include a member which is not in the consortium")
			}
			applicationGroup.Groups[orgName] = proto.Clone(consortiumGroup).(*cb.ConfigGroup)
		}
	}

	channelGroup := protoutil.NewConfigGroup()

	// Copy the system channel Channel level config to the new config
	for key, value := range systemChannelGroup.Values {
		channelGroup.Values[key] = proto.Clone(value).(*cb.ConfigValue)
		if key == channelconfig.ConsortiumKey {
			// Do not set the consortium name, we do this later
			continue
		}
	}

	for key, policy := range systemChannelGroup.Policies {
		channelGroup.Policies[key] = proto.Clone(policy).(*cb.ConfigPolicy)
	}

	// Set the new config orderer group to the system channel orderer group and the application group to the new application group
	channelGroup.Groups[channelconfig.OrdererGroupKey] = proto.Clone(systemChannelGroup.Groups[channelconfig.OrdererGroupKey]).(*cb.ConfigGroup)
	channelGroup.Groups[channelconfig.ApplicationGroupKey] = applicationGroup
	channelGroup.Values[channelconfig.ConsortiumKey] = &cb.ConfigValue{
		Value:     protoutil.MarshalOrPanic(channelconfig.ConsortiumValue(consortium.Name).Value()),
		ModPolicy: channelconfig.AdminsPolicyKey,
	}

	// Non-backwards compatible bugfix introduced in v1.1
	// The capability check should be removed once v1.0 is deprecated
	if oc, ok := dt.support.OrdererConfig(); ok && oc.Capabilities().PredictableChannelTemplate() {
		channelGroup.ModPolicy = systemChannelGroup.ModPolicy
		zeroVersions(channelGroup)
	}

	bundle, err := channelconfig.NewBundle(channelHeader.ChannelId, &cb.Config{
		ChannelGroup: channelGroup,
	})

	if err != nil {
		return nil, err
	}

	return bundle, nil
}

// zeroVersions recursively iterates over a config tree, setting all versions to zero
func zeroVersions(cg *cb.ConfigGroup) {
	cg.Version = 0

	for _, value := range cg.Values {
		value.Version = 0
	}

	for _, policy := range cg.Policies {
		policy.Version = 0
	}

	for _, group := range cg.Groups {
		zeroVersions(group)
	}
}