package types

import (
	"context"
	"fmt"
	"strings"

	"github.com/tendermint/tendermint/abci/types"
	"github.com/tendermint/tendermint/libs/log"
	tmpubsub "github.com/tendermint/tendermint/libs/pubsub"
	"github.com/tendermint/tendermint/libs/service"
)

const defaultCapacity = 0

type EventBusSubscriber interface {
	Subscribe(ctx context.Context, subscriber string, query tmpubsub.Query, outCapacity ...int) (Subscription, error)
	Unsubscribe(ctx context.Context, args tmpubsub.UnsubscribeArgs) error
	UnsubscribeAll(ctx context.Context, subscriber string) error

	NumClients() int
	NumClientSubscriptions(clientID string) int
}

type Subscription interface {
	ID() string
	Out() <-chan tmpubsub.Message
	Canceled() <-chan struct{}
	Err() error
}

// EventBus is a common bus for all events going through the system. All calls
// are proxied to underlying pubsub server. All events must be published using
// EventBus to ensure correct data types.
type EventBus struct {
	service.BaseService
	pubsub *tmpubsub.Server
}

// NewEventBus returns a new event bus.
func NewEventBus() *EventBus {
	return NewEventBusWithBufferCapacity(defaultCapacity)
}

// NewEventBusWithBufferCapacity returns a new event bus with the given buffer capacity.
func NewEventBusWithBufferCapacity(cap int) *EventBus {
	// capacity could be exposed later if needed
	pubsub := tmpubsub.NewServer(tmpubsub.BufferCapacity(cap))
	b := &EventBus{pubsub: pubsub}
	b.BaseService = *service.NewBaseService(nil, "EventBus", b)
	return b
}

func (b *EventBus) SetLogger(l log.Logger) {
	b.BaseService.SetLogger(l)
	b.pubsub.SetLogger(l.With("module", "pubsub"))
}

func (b *EventBus) OnStart() error {
	return b.pubsub.Start()
}

func (b *EventBus) OnStop() {
	if err := b.pubsub.Stop(); err != nil {
		b.pubsub.Logger.Error("error trying to stop eventBus", "error", err)
	}
}

func (b *EventBus) NumClients() int {
	return b.pubsub.NumClients()
}

func (b *EventBus) NumClientSubscriptions(clientID string) int {
	return b.pubsub.NumClientSubscriptions(clientID)
}

func (b *EventBus) Subscribe(
	ctx context.Context,
	subscriber string,
	query tmpubsub.Query,
	outCapacity ...int,
) (Subscription, error) {
	return b.pubsub.Subscribe(ctx, subscriber, query, outCapacity...)
}

// This method can be used for a local consensus explorer and synchronous
// testing. Do not use for for public facing / untrusted subscriptions!
func (b *EventBus) SubscribeUnbuffered(
	ctx context.Context,
	subscriber string,
	query tmpubsub.Query,
) (Subscription, error) {
	return b.pubsub.SubscribeUnbuffered(ctx, subscriber, query)
}

func (b *EventBus) Unsubscribe(ctx context.Context, args tmpubsub.UnsubscribeArgs) error {
	return b.pubsub.Unsubscribe(ctx, args)
}

func (b *EventBus) UnsubscribeAll(ctx context.Context, subscriber string) error {
	return b.pubsub.UnsubscribeAll(ctx, subscriber)
}

func (b *EventBus) Publish(eventValue string, eventData TMEventData) error {
	// no explicit deadline for publishing events
	ctx := context.Background()

	tokens := strings.Split(EventTypeKey, ".")
	event := types.Event{
		Type: tokens[0],
		Attributes: []types.EventAttribute{
			{
				Key:   tokens[1],
				Value: eventValue,
			},
		},
	}

	return b.pubsub.PublishWithEvents(ctx, eventData, []types.Event{event})
}

func (b *EventBus) PublishEventNewBlock(data EventDataNewBlock) error {
	// no explicit deadline for publishing events
	ctx := context.Background()
	events := append(data.ResultBeginBlock.Events, data.ResultEndBlock.Events...)

	// add Tendermint-reserved new block event
	events = append(events, EventNewBlock)

	return b.pubsub.PublishWithEvents(ctx, data, events)
}

func (b *EventBus) PublishEventNewBlockHeader(data EventDataNewBlockHeader) error {
	// no explicit deadline for publishing events
	ctx := context.Background()
	events := append(data.ResultBeginBlock.Events, data.ResultEndBlock.Events...)

	// add Tendermint-reserved new block header event
	events = append(events, EventNewBlockHeader)

	return b.pubsub.PublishWithEvents(ctx, data, events)
}

func (b *EventBus) PublishEventNewEvidence(evidence EventDataNewEvidence) error {
	return b.Publish(EventNewEvidenceValue, evidence)
}

func (b *EventBus) PublishEventVote(data EventDataVote) error {
	return b.Publish(EventVoteValue, data)
}

func (b *EventBus) PublishEventValidBlock(data EventDataRoundState) error {
	return b.Publish(EventValidBlockValue, data)
}

// PublishEventTx publishes tx event with events from Result. Note it will add
// predefined keys (EventTypeKey, TxHashKey). Existing events with the same keys
// will be overwritten.
func (b *EventBus) PublishEventTx(data EventDataTx) error {
	// no explicit deadline for publishing events
	ctx := context.Background()
	events := data.Result.Events

	// add Tendermint-reserved events
	events = append(events, EventTx)

	tokens := strings.Split(TxHashKey, ".")
	events = append(events, types.Event{
		Type: tokens[0],
		Attributes: []types.EventAttribute{
			{
				Key:   tokens[1],
				Value: fmt.Sprintf("%X", Tx(data.Tx).Hash()),
			},
		},
	})

	tokens = strings.Split(TxHeightKey, ".")
	events = append(events, types.Event{
		Type: tokens[0],
		Attributes: []types.EventAttribute{
			{
				Key:   tokens[1],
				Value: fmt.Sprintf("%d", data.Height),
			},
		},
	})

	return b.pubsub.PublishWithEvents(ctx, data, events)
}

func (b *EventBus) PublishEventNewRoundStep(data EventDataRoundState) error {
	return b.Publish(EventNewRoundStepValue, data)
}

func (b *EventBus) PublishEventTimeoutPropose(data EventDataRoundState) error {
	return b.Publish(EventTimeoutProposeValue, data)
}

func (b *EventBus) PublishEventTimeoutWait(data EventDataRoundState) error {
	return b.Publish(EventTimeoutWaitValue, data)
}

func (b *EventBus) PublishEventNewRound(data EventDataNewRound) error {
	return b.Publish(EventNewRoundValue, data)
}

func (b *EventBus) PublishEventCompleteProposal(data EventDataCompleteProposal) error {
	return b.Publish(EventCompleteProposalValue, data)
}

func (b *EventBus) PublishEventPolka(data EventDataRoundState) error {
	return b.Publish(EventPolkaValue, data)
}

func (b *EventBus) PublishEventUnlock(data EventDataRoundState) error {
	return b.Publish(EventUnlockValue, data)
}

func (b *EventBus) PublishEventRelock(data EventDataRoundState) error {
	return b.Publish(EventRelockValue, data)
}

func (b *EventBus) PublishEventLock(data EventDataRoundState) error {
	return b.Publish(EventLockValue, data)
}

func (b *EventBus) PublishEventValidatorSetUpdates(data EventDataValidatorSetUpdates) error {
	return b.Publish(EventValidatorSetUpdatesValue, data)
}

//-----------------------------------------------------------------------------
type NopEventBus struct{}

func (NopEventBus) Subscribe(
	ctx context.Context,
	subscriber string,
	query tmpubsub.Query,
	out chan<- interface{},
) error {
	return nil
}

func (NopEventBus) Unsubscribe(ctx context.Context, args tmpubsub.UnsubscribeArgs) error {
	return nil
}

func (NopEventBus) UnsubscribeAll(ctx context.Context, subscriber string) error {
	return nil
}

func (NopEventBus) PublishEventNewBlock(data EventDataNewBlock) error {
	return nil
}

func (NopEventBus) PublishEventNewBlockHeader(data EventDataNewBlockHeader) error {
	return nil
}

func (NopEventBus) PublishEventNewEvidence(evidence EventDataNewEvidence) error {
	return nil
}

func (NopEventBus) PublishEventVote(data EventDataVote) error {
	return nil
}

func (NopEventBus) PublishEventTx(data EventDataTx) error {
	return nil
}

func (NopEventBus) PublishEventNewRoundStep(data EventDataRoundState) error {
	return nil
}

func (NopEventBus) PublishEventTimeoutPropose(data EventDataRoundState) error {
	return nil
}

func (NopEventBus) PublishEventTimeoutWait(data EventDataRoundState) error {
	return nil
}

func (NopEventBus) PublishEventNewRound(data EventDataRoundState) error {
	return nil
}

func (NopEventBus) PublishEventCompleteProposal(data EventDataRoundState) error {
	return nil
}

func (NopEventBus) PublishEventPolka(data EventDataRoundState) error {
	return nil
}

func (NopEventBus) PublishEventUnlock(data EventDataRoundState) error {
	return nil
}

func (NopEventBus) PublishEventRelock(data EventDataRoundState) error {
	return nil
}

func (NopEventBus) PublishEventLock(data EventDataRoundState) error {
	return nil
}

func (NopEventBus) PublishEventValidatorSetUpdates(data EventDataValidatorSetUpdates) error {
	return nil
}