/*
Copyright IBM Corp. 2017 All Rights Reserved.

SPDX-License-Identifier: Apache-2.0
*/

// Package msgprocessor provides the implementations for processing of the assorted message
// types which may arrive in the system through Broadcast.
package msgprocessor

import (
	"errors"

	"github.com/hyperledger/fabric/common/flogging"
	cb "github.com/hyperledger/fabric/protos/common"
)

const (
	pkgLogID = "orderer/common/msgprocessor"

	// These should eventually be derived from the channel support once enabled
	msgVersion = int32(0)
	epoch      = 0
)

var logger = flogging.MustGetLogger(pkgLogID)

// ErrChannelDoesNotExist is returned by the system channel for transactions which
// are not for the system channel ID and are not attempting to create a new channel
var ErrChannelDoesNotExist = errors.New("channel does not exist")

// ErrPermissionDenied is returned by errors which are caused by transactions
// which are not permitted due to an authorization failure.
var ErrPermissionDenied = errors.New("permission denied")

// Classification represents the possible message types for the system.
type Classification int

const (
	// NormalMsg is the class of standard (endorser or otherwise non-config) messages.
	// Messages of this type should be processed by ProcessNormalMsg.
	NormalMsg Classification = iota

	// ConfigUpdateMsg indicates messages of type CONFIG_UPDATE.
	// Messages of this type should be processed by ProcessConfigUpdateMsg.
	ConfigUpdateMsg

	// ConfigMsg indicates message of type ORDERER_TRANSACTION or CONFIG.
	// Messages of this type should be processed by ProcessConfigMsg
	ConfigMsg
)

// Processor provides the methods necessary to classify and process any message which
// arrives through the Broadcast interface.
type Processor interface {
	// ClassifyMsg inspects the message header to determine which type of processing is necessary
	ClassifyMsg(chdr *cb.ChannelHeader) Classification

	// ProcessNormalMsg will check the validity of a message based on the current configuration.  It returns the current
	// configuration sequence number and nil on success, or an error if the message is not valid
	ProcessNormalMsg(env *cb.Envelope) (configSeq uint64, err error)

	// ProcessConfigUpdateMsg will attempt to apply the config update to the current configuration, and if successful
	// return the resulting config message and the configSeq the config was computed from.  If the config update message
	// is invalid, an error is returned.
	ProcessConfigUpdateMsg(env *cb.Envelope) (config *cb.Envelope, configSeq uint64, err error)

	// ProcessConfigMsg takes message of type `ORDERER_TX` or `CONFIG`, unpack the ConfigUpdate envelope embedded
	// in it, and call `ProcessConfigUpdateMsg` to produce new Config message of the same type as original message.
	// This method is used to re-validate and reproduce config message, if it's deemed not to be valid anymore.
	ProcessConfigMsg(env *cb.Envelope) (*cb.Envelope, uint64, error)
}