package governance

import (
	"context"
	"errors"
	"fmt"

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/innerring/metrics"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/morph/client"
	frostfscontract "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/morph/client/frostfs"
	nmClient "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/morph/client/netmap"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/morph/event"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/morph/event/rolemanagement"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger"
	"github.com/nspcc-dev/neo-go/pkg/core/native"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
	"github.com/nspcc-dev/neo-go/pkg/util"
	"github.com/panjf2000/ants/v2"
)

// ProcessorPoolSize limits the pool size for governance Processor. Processor manages
// governance sync tasks. This process must not be interrupted by other sync
// operation, so we limit the pool size for the processor to one.
const ProcessorPoolSize = 1

type (
	// AlphabetState is a callback interface for innerring global state.
	AlphabetState interface {
		IsAlphabet(context.Context) bool
	}
)

// VoteValidatorPrm groups parameters of the VoteForSidechainValidator
// operation.
type VoteValidatorPrm struct {
	Validators keys.PublicKeys
	Hash       *util.Uint256 // hash of the transaction that triggered voting
}

// Voter is a callback interface for alphabet contract voting.
type Voter interface {
	VoteForSidechainValidator(context.Context, VoteValidatorPrm) error
}

type (
	// EpochState is a callback interface for innerring global state.
	EpochState interface {
		EpochCounter() uint64
	}

	// IRFetcher is a callback interface for innerring keys.
	// Implementation must take into account availability of
	// the notary contract.
	IRFetcher interface {
		InnerRingKeys() (keys.PublicKeys, error)
	}

	FrostFSClient interface {
		AlphabetUpdate(ctx context.Context, p frostfscontract.AlphabetUpdatePrm) error
	}

	NetmapClient interface {
		UpdateInnerRing(p nmClient.UpdateIRPrm) error
	}

	MainnetClient interface {
		NeoFSAlphabetList() (res keys.PublicKeys, err error)
		GetDesignateHash() util.Uint160
	}

	MorphClient interface {
		Committee() (res keys.PublicKeys, err error)
		UpdateNeoFSAlphabetList(ctx context.Context, prm client.UpdateAlphabetListPrm) error
		UpdateNotaryList(ctx context.Context, prm client.UpdateNotaryListPrm) error
	}

	// Processor of events related to governance in the network.
	Processor struct {
		log           *logger.Logger
		metrics       metrics.Register
		pool          *ants.Pool
		frostfsClient FrostFSClient

		alphabetState AlphabetState
		epochState    EpochState
		voter         Voter
		irFetcher     IRFetcher

		mainnetClient MainnetClient
		morphClient   MorphClient

		designate util.Uint160
	}

	// Params of the processor constructor.
	Params struct {
		Log     *logger.Logger
		Metrics metrics.Register

		AlphabetState AlphabetState
		EpochState    EpochState
		Voter         Voter
		IRFetcher     IRFetcher

		MorphClient   MorphClient
		MainnetClient MainnetClient
		FrostFSClient FrostFSClient
	}
)

// New creates a balance contract processor instance.
func New(p *Params) (*Processor, error) {
	switch {
	case p.Log == nil:
		return nil, errors.New("ir/governance: logger is not set")
	case p.MainnetClient == nil:
		return nil, errors.New("ir/governance: neo:mainnet client is not set")
	case p.MorphClient == nil:
		return nil, errors.New("ir/governance: neo:sidechain client is not set")
	case p.AlphabetState == nil:
		return nil, errors.New("ir/governance: global state is not set")
	case p.EpochState == nil:
		return nil, errors.New("ir/governance: global state is not set")
	case p.Voter == nil:
		return nil, errors.New("ir/governance: global state is not set")
	case p.IRFetcher == nil:
		return nil, errors.New("ir/governance: innerring keys fetcher is not set")
	}

	pool, err := ants.NewPool(ProcessorPoolSize, ants.WithNonblocking(true))
	if err != nil {
		return nil, fmt.Errorf("ir/governance: can't create worker pool: %w", err)
	}

	metricsRegister := p.Metrics
	if metricsRegister == nil {
		metricsRegister = metrics.DefaultRegister{}
	}

	// result is cached by neo-go, so we can pre-calc it
	designate := p.MainnetClient.GetDesignateHash()

	return &Processor{
		log:           p.Log,
		metrics:       metricsRegister,
		pool:          pool,
		frostfsClient: p.FrostFSClient,
		alphabetState: p.AlphabetState,
		epochState:    p.EpochState,
		voter:         p.Voter,
		irFetcher:     p.IRFetcher,
		mainnetClient: p.MainnetClient,
		morphClient:   p.MorphClient,
		designate:     designate,
	}, nil
}

// ListenerNotificationHandlers for the 'event.Listener' event producer.
func (gp *Processor) ListenerNotificationHandlers() []event.NotificationHandlerInfo {
	return []event.NotificationHandlerInfo{
		{
			Contract: gp.designate,
			Type:     event.TypeFromString(native.DesignationEventName),
			Parser:   rolemanagement.ParseDesignate,
			Handlers: []event.Handler{gp.HandleAlphabetSync},
		},
	}
}

// ListenerNotaryParsers for the 'event.Listener' event producer.
func (gp *Processor) ListenerNotaryParsers() []event.NotaryParserInfo {
	return nil
}

// ListenerNotaryHandlers for the 'event.Listener' event producer.
func (gp *Processor) ListenerNotaryHandlers() []event.NotaryHandlerInfo {
	return nil
}