/*
Copyright IBM Corp. All Rights Reserved.

SPDX-License-Identifier: Apache-2.0
*/

package lifecycle

import (
	"strconv"

	"github.com/golang/protobuf/proto"
	"github.com/hyperledger/fabric-protos-go/peer"
	"github.com/hyperledger/fabric/common/chaincode"
	"github.com/hyperledger/fabric/common/policies"
	"github.com/hyperledger/fabric/protoutil"
	"github.com/pkg/errors"
)

// LegacyMetadataProvider provides metadata for a lscc-defined chaincode
// on a specific channel.
type LegacyMetadataProvider interface {
	Metadata(channel string, cc string, collections ...string) *chaincode.Metadata
}

// ChaincodeInfoProvider provides metadata for a _lifecycle-defined
// chaincode on a specific channel
type ChaincodeInfoProvider interface {
	// ChaincodeInfo returns the chaincode definition and its install info.
	// An error is returned only if either the channel or the chaincode do not exist.
	ChaincodeInfo(channelID, name string) (*LocalChaincodeInfo, error)
}

// ChannelPolicyReferenceProvider is used to determine if a set of signature is valid and complies with a policy
type ChannelPolicyReferenceProvider interface {
	// NewPolicy creates a new policy based on the policy bytes
	NewPolicy(channelID, channelConfigPolicyReference string) (policies.Policy, error)
}

type channelPolicyReferenceProviderImpl struct {
	ChannelConfigSource
}

// NewPolicy implements the method of the same name of the ChannelPolicyReferenceProvider interface
func (c *channelPolicyReferenceProviderImpl) NewPolicy(channelID, channelConfigPolicyReference string) (policies.Policy, error) {
	cc := c.GetStableChannelConfig(channelID)
	pm := cc.PolicyManager()
	p, ok := pm.GetPolicy(channelConfigPolicyReference)
	if !ok {
		return nil, errors.Errorf("could not retrieve policy for reference '%s' on channel '%s'", channelConfigPolicyReference, channelID)
	}

	return p, nil
}

// NewMetadataProvider returns a new MetadataProvider instance
func NewMetadataProvider(cip ChaincodeInfoProvider, lmp LegacyMetadataProvider, ccs ChannelConfigSource) *MetadataProvider {
	return &MetadataProvider{
		ChaincodeInfoProvider:  cip,
		LegacyMetadataProvider: lmp,
		ChannelPolicyReferenceProvider: &channelPolicyReferenceProviderImpl{
			ChannelConfigSource: ccs,
		},
	}
}

type MetadataProvider struct {
	ChaincodeInfoProvider          ChaincodeInfoProvider
	LegacyMetadataProvider         LegacyMetadataProvider
	ChannelPolicyReferenceProvider ChannelPolicyReferenceProvider
}

func (mp *MetadataProvider) toSignaturePolicyEnvelope(channelID string, policyBytes []byte) ([]byte, error) {
	p := &peer.ApplicationPolicy{}
	err := proto.Unmarshal(policyBytes, p)
	if err != nil {
		return nil, errors.Wrap(err, "failed to unmarshal ApplicationPolicy bytes")
	}

	switch policy := p.Type.(type) {
	case *peer.ApplicationPolicy_SignaturePolicy:
		return protoutil.MarshalOrPanic(policy.SignaturePolicy), nil
	case *peer.ApplicationPolicy_ChannelConfigPolicyReference:
		p, err := mp.ChannelPolicyReferenceProvider.NewPolicy(channelID, policy.ChannelConfigPolicyReference)
		if err != nil {
			return nil, errors.WithMessagef(err, "could not retrieve policy for reference '%s' on channel '%s'", policy.ChannelConfigPolicyReference, channelID)
		}

		cp, ok := p.(policies.Converter)
		if !ok {
			return nil, errors.Errorf("policy with reference '%s' on channel '%s' is not convertible to SignaturePolicyEnvelope", policy.ChannelConfigPolicyReference, channelID)
		}

		spe, err := cp.Convert()
		if err != nil {
			return nil, errors.WithMessagef(err, "error converting policy with reference '%s' on channel '%s' to SignaturePolicyEnvelope", policy.ChannelConfigPolicyReference, channelID)
		}

		return proto.Marshal(spe)
	default:
		// this will only happen if a new policy type is added to the oneof
		return nil, errors.Errorf("unsupported policy type %T on channel '%s'", policy, channelID)
	}
}

// Metadata implements the metadata retriever support interface for service discovery
func (mp *MetadataProvider) Metadata(channel string, ccName string, collections ...string) *chaincode.Metadata {
	ccInfo, err := mp.ChaincodeInfoProvider.ChaincodeInfo(channel, ccName)
	if err != nil {
		logger.Debugf("chaincode '%s' on channel '%s' not defined in _lifecycle. requesting metadata from lscc", ccName, channel)
		// fallback to legacy metadata via cclifecycle
		return mp.LegacyMetadataProvider.Metadata(channel, ccName, collections...)
	}

	spe, err := mp.toSignaturePolicyEnvelope(channel, ccInfo.Definition.ValidationInfo.ValidationParameter)
	if err != nil {
		logger.Errorf("could not convert policy for chaincode '%s' on channel '%s', err '%s'", ccName, channel, err)
		return nil
	}

	// report the sequence as the version to service discovery since
	// the version is no longer required to change when updating any
	// part of the chaincode definition
	ccMetadata := &chaincode.Metadata{
		Name:               ccName,
		Version:            strconv.FormatInt(ccInfo.Definition.Sequence, 10),
		Policy:             spe,
		CollectionPolicies: map[string][]byte{},
		CollectionsConfig:  ccInfo.Definition.Collections,
	}

	if ccInfo.Definition.Collections == nil {
		return ccMetadata
	}

	// process any existing collection endorsement policies
	for _, collectionName := range collections {
		for _, conf := range ccInfo.Definition.Collections.Config {
			staticCollConfig := conf.GetStaticCollectionConfig()
			if staticCollConfig == nil {
				continue
			}
			if staticCollConfig.Name == collectionName {
				if staticCollConfig.EndorsementPolicy != nil {
					ep := protoutil.MarshalOrPanic(staticCollConfig.EndorsementPolicy)
					cspe, err := mp.toSignaturePolicyEnvelope(channel, ep)
					if err != nil {
						logger.Errorf("could not convert collection policy for chaincode '%s' collection '%s' on channel '%s', err '%s'", ccName, collectionName, channel, err)
						return nil
					}
					ccMetadata.CollectionPolicies[collectionName] = cspe
				}
			}
		}
	}

	return ccMetadata
}