package api

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/url"
	"strings"
	"sync"
	"sync/atomic"
	"time"

	accountdomain "git.ipao.vip/rogee/creator-hub/internal/account"
	"git.ipao.vip/rogee/creator-hub/internal/creator"
	hub "git.ipao.vip/rogee/creator-hub/internal/environment"
	"github.com/sirupsen/logrus"
)

const creatorEventReconcileInterval = 10 * time.Second

type creatorGatewayEvent struct {
	DeliveryID     string                     `json:"delivery_id,omitempty"`
	Generation     string                     `json:"generation,omitempty"`
	Kind           string                     `json:"kind"`
	Reason         string                     `json:"reason,omitempty"`
	Continuity     string                     `json:"continuity,omitempty"`
	BoundaryAt     string                     `json:"boundary_at,omitempty"`
	BoundarySource string                     `json:"boundary_source,omitempty"`
	Baseline       bool                       `json:"baseline,omitempty"`
	Notice         *creatorGatewayEventNotice `json:"notice,omitempty"`
}

type creatorGatewayEventNotice struct {
	EventKey          string `json:"event_key"`
	EventType         string `json:"event_type"`
	InteractorUID     string `json:"interactor_uid"`
	CommentID         string `json:"comment_id"`
	WorkID            string `json:"work_id"`
	MessageType       string `json:"message_type,omitempty"`
	MessageText       string `json:"message_text,omitempty"`
	PlatformEventAt   string `json:"platform_event_at,omitempty"`
	GatewayReceivedAt string `json:"gateway_received_at,omitempty"`
}

type creatorEventBinding struct {
	accountID    string
	uid          string
	env          hub.EnvironmentContext
	gateway      hub.Gateway
	hubStore     *hub.Store
	sessionToken string
}

type creatorUpdateHub struct {
	mu          sync.Mutex
	subscribers map[chan struct{}]struct{}
}

var creatorUpdates = &creatorUpdateHub{subscribers: make(map[chan struct{}]struct{})}

func (h *creatorUpdateHub) subscribe() (<-chan struct{}, func()) {
	channel := make(chan struct{}, 1)
	h.mu.Lock()
	h.subscribers[channel] = struct{}{}
	h.mu.Unlock()
	return channel, func() {
		h.mu.Lock()
		if _, ok := h.subscribers[channel]; ok {
			delete(h.subscribers, channel)
			close(channel)
		}
		h.mu.Unlock()
	}
}

func (h *creatorUpdateHub) publish() {
	h.mu.Lock()
	defer h.mu.Unlock()
	for channel := range h.subscribers {
		select {
		case channel <- struct{}{}:
		default:
		}
	}
}

func creatorListenerGeneration(env hub.EnvironmentContext) string {
	return fmt.Sprintf("%s:%s:%d", env.RuntimeID, env.RuntimeNetworkID, env.BindingVersion)
}

var creatorListenerSessionNonce atomic.Uint64

func creatorListenerSessionToken(env hub.EnvironmentContext) string {
	return fmt.Sprintf("%s/%d-%d", creatorListenerGeneration(env), time.Now().UnixNano(), creatorListenerSessionNonce.Add(1))
}

func listenerBoundaryPointer(value time.Time) *time.Time {
	if value.IsZero() {
		return nil
	}
	value = value.UTC()
	return &value
}

func persistCreatorListenerState(ctx context.Context, store *creator.Store, binding creatorEventBinding, status, reason string, boundaryAt *time.Time, deliveryID string) {
	if store == nil {
		return
	}
	if _, err := store.UpsertListenerState(ctx, creator.ListenerState{
		AccountID:      binding.accountID,
		Platform:       creator.PlatformDouyin,
		Generation:     creatorListenerGeneration(binding.env),
		SessionToken:   binding.sessionToken,
		Status:         status,
		BoundaryAt:     boundaryAt,
		LastDeliveryID: deliveryID,
		Reason:         reason,
	}); err != nil {
		logrus.WithError(err).WithField("account_id", binding.accountID).Warn("creator listener state persistence failed")
	}
}

func (binding creatorEventBinding) key() string {
	return fmt.Sprintf("%s\x00%s\x00%s\x00%d\x00%s\x00%s\x00%s\x00%s", binding.gateway.Name, binding.gateway.Endpoint, binding.gateway.Token, binding.env.BindingVersion, binding.env.RuntimeID, binding.env.RuntimeNetworkID, binding.env.Exit.ID, binding.uid)
}

type creatorEventListenerHandle struct {
	cancel context.CancelFunc
	done   chan struct{}
	key    string
}

type creatorEventListenerManager struct {
	mu    sync.Mutex
	items map[string]creatorEventListenerHandle
}

func RunCreatorEventListeners(ctx context.Context, store *creator.Store, phaseAStore *accountdomain.Store, hubStore *hub.Store, executor creator.ActionExecutor, generator creator.TextGenerator) {
	manager := &creatorEventListenerManager{items: map[string]creatorEventListenerHandle{}}
	ticker := time.NewTicker(creatorEventReconcileInterval)
	defer ticker.Stop()
	defer manager.close()
	for {
		if err := manager.reconcile(ctx, store, phaseAStore, hubStore, executor, generator); err != nil && ctx.Err() == nil {
			logrus.WithField("service", "control-plane").WithError(err).Warn("creator event listener reconciliation failed")
		}
		select {
		case <-ctx.Done():
			return
		case <-ticker.C:
		}
	}
}

func (manager *creatorEventListenerManager) reconcile(ctx context.Context, store *creator.Store, phaseAStore *accountdomain.Store, hubStore *hub.Store, executor creator.ActionExecutor, generator creator.TextGenerator) error {
	if store == nil || phaseAStore == nil || hubStore == nil {
		return creator.ErrUnavailable
	}
	if recovered, err := store.RecoverStaleProcessing(ctx, time.Now().UTC()); err != nil {
		return err
	} else if recovered > 0 {
		logrus.WithField("count", recovered).Warn("recovered stale creator operations as uncertain")
	}
	accounts, err := phaseAStore.ListAccounts(ctx)
	if err != nil {
		return err
	}
	desired := make(map[string]creatorEventBinding)
	for _, account := range accounts {
		if account.Platform != creator.PlatformDouyin || account.AuthorizationStatus != "authorized" {
			continue
		}
		profile, profileErr := store.GetAccountProfile(ctx, account.ID)
		if profileErr != nil {
			logrus.WithError(profileErr).WithField("account_id", account.ID).Warn("creator event listener account profile unavailable")
			continue
		}
		if profile.LoginStatus != "logged_in" {
			continue
		}
		if !creatorEventUID(profile.PlatformAccountKey) {
			logrus.WithField("account_id", account.ID).Warn("creator event listener account UID is unavailable")
			continue
		}
		environment, environmentErr := hubStore.GetEnvironmentContextForAccount(ctx, account.ID)
		if environmentErr != nil {
			logrus.WithError(environmentErr).WithField("account_id", account.ID).Warn("creator event listener environment unavailable")
			continue
		}
		if environment.RuntimeID == "" || environment.RuntimeNetworkID == "" || environment.BindingVersion <= 0 {
			continue
		}
		gateway, gatewayErr := hubStore.GetGateway(ctx, environment.Gateway)
		if gatewayErr != nil {
			logrus.WithError(gatewayErr).WithField("account_id", account.ID).Warn("creator event listener gateway unavailable")
			continue
		}
		desired[account.ID] = creatorEventBinding{accountID: account.ID, uid: profile.PlatformAccountKey, env: environment, gateway: gateway, hubStore: hubStore}
	}

	var stopping []creatorEventListenerHandle
	manager.mu.Lock()
	for accountID, current := range manager.items {
		binding, ok := desired[accountID]
		if ok && current.key == binding.key() {
			state, stateErr := store.GetListenerState(ctx, accountID)
			if stateErr != nil || !state.Invalidated {
				continue
			}
		}
		current.cancel()
		delete(manager.items, accountID)
		stopping = append(stopping, current)
	}
	manager.mu.Unlock()
	for _, current := range stopping {
		<-current.done
	}

	manager.mu.Lock()
	defer manager.mu.Unlock()
	for accountID, binding := range desired {
		if _, ok := manager.items[accountID]; ok {
			continue
		}
		listenerContext, cancel := context.WithCancel(ctx)
		done := make(chan struct{})
		listenerBinding := binding
		manager.items[accountID] = creatorEventListenerHandle{cancel: cancel, done: done, key: binding.key()}
		go func() {
			defer close(done)
			runCreatorEventListener(listenerContext, store, listenerBinding, executor, generator)
		}()
	}
	return nil
}

func (manager *creatorEventListenerManager) close() {
	manager.mu.Lock()
	handles := make([]creatorEventListenerHandle, 0, len(manager.items))
	for accountID, current := range manager.items {
		current.cancel()
		handles = append(handles, current)
		delete(manager.items, accountID)
	}
	manager.mu.Unlock()
	for _, current := range handles {
		<-current.done
	}
}

func runCreatorEventListener(ctx context.Context, store *creator.Store, binding creatorEventBinding, executor creator.ActionExecutor, generator creator.TextGenerator) {
	binding.sessionToken = creatorListenerSessionToken(binding.env)
	path := "/v1/browsers/" + url.PathEscape(binding.env.Alias) + "/douyin/events"
	generation := gatewayGenerationPayload(binding.env)
	useCtx, runtimeUse, err := beginRuntimeUseForEnvironment(ctx, binding.hubStore, binding.env, "listener", "creator-listener-"+binding.accountID)
	if err != nil {
		persistCreatorListenerState(context.WithoutCancel(ctx), store, binding, "error", "runtime use unavailable: "+err.Error(), nil, "")
		return
	}
	ctx = useCtx
	defer func() {
		if releaseErr := runtimeUse.Close(); releaseErr != nil {
			logrus.WithError(releaseErr).WithField("account_id", binding.accountID).Error("creator listener runtime use release failed")
		}
	}()
	startPayload := make(map[string]any, len(generation)+1)
	for key, value := range generation {
		startPayload[key] = value
	}
	startPayload["expected_uid"] = binding.uid
	persistCreatorListenerState(ctx, store, binding, "starting", "等待平台边界标记", nil, "")
	defer func() {
		stopCreatorEventListener(binding.accountID, binding.gateway, path, generation)
		persistCreatorListenerState(context.WithoutCancel(ctx), store, binding, "stopped", "监听已停止", nil, "")
	}()

	backoff := time.Second
	for ctx.Err() == nil {
		status, _, err := gatewayCall(ctx, binding.gateway, http.MethodPost, path, startPayload, 30*time.Second)
		if err != nil || status != http.StatusOK {
			if err == nil {
				err = fmt.Errorf("gateway returned HTTP %d", status)
			}
			logrus.WithError(err).WithField("account_id", binding.accountID).Warn("creator event listener start failed")
			persistCreatorListenerState(ctx, store, binding, "error", err.Error(), nil, "")
			if !waitCreatorEventBackoff(ctx, backoff) {
				return
			}
			backoff *= 2
			if backoff > 30*time.Second {
				backoff = 30 * time.Second
			}
			continue
		}
		backoff = time.Second
		// Every successful start creates a new boundary. Events observed before
		// its marker remain historical even when the previous poll loop was ready.
		ready := false
		var boundaryAt time.Time
		for ctx.Err() == nil {
			status, body, err := gatewayCall(ctx, binding.gateway, http.MethodGet, path+"?limit=100&wait=25", generation, 35*time.Second)
			if err != nil || status != http.StatusOK {
				if err == nil {
					err = fmt.Errorf("gateway returned HTTP %d", status)
				}
				logrus.WithError(err).WithField("account_id", binding.accountID).Warn("creator event listener poll failed")
				persistCreatorListenerState(ctx, store, binding, "gap", err.Error(), listenerBoundaryPointer(boundaryAt), "")
				break
			}
			var events []creatorGatewayEvent
			if err := json.Unmarshal(body, &events); err != nil {
				logrus.WithError(err).WithField("account_id", binding.accountID).Warn("creator event listener response is invalid")
				persistCreatorListenerState(ctx, store, binding, "gap", "监听响应无法解析: "+err.Error(), listenerBoundaryPointer(boundaryAt), "")
				break
			}
			for _, event := range events {
				if event.Kind == "baseline" {
					parsedBoundary, boundaryReady, reason := creatorGatewayBoundary(event)
					boundaryAt, ready = parsedBoundary, boundaryReady
					status := "gap"
					if ready {
						status, reason = "ready", ""
					}
					persistCreatorListenerState(ctx, store, binding, status, reason, listenerBoundaryPointer(boundaryAt), event.DeliveryID)
				} else if event.Kind == "open" || event.Kind == "error" || event.Kind == "close" || event.Kind == "reconnected" {
					// A transport event never proves continuity. Only the explicit
					// boundary marker permits automatic writes again.
					ready = false
					persistCreatorListenerState(ctx, store, binding, "gap", event.Reason, listenerBoundaryPointer(boundaryAt), event.DeliveryID)
				}
				if event.Kind == "notice" {
					if needsBaseline, reason := creatorGatewayEventNeedsBaseline(event, ready); needsBaseline {
						event.Baseline = true
						event.Reason = reason
					} else if creatorEventBeforeBoundary(event, boundaryAt) {
						event.Baseline = true
						event.Reason = "平台事件早于监听边界"
					}
					status := "gap"
					reason := event.Reason
					if ready && !event.Baseline {
						status, reason = "ready", ""
					}
					persistCreatorListenerState(ctx, store, binding, status, reason, listenerBoundaryPointer(boundaryAt), event.DeliveryID)
				}
				handleCreatorGatewayEvent(ctx, store, binding, event, executor, generator)
			}
		}
		if !waitCreatorEventBackoff(ctx, backoff) {
			return
		}
		backoff *= 2
		if backoff > 30*time.Second {
			backoff = 30 * time.Second
		}
	}
}

func stopCreatorEventListener(accountID string, gateway hub.Gateway, path string, generation map[string]any) {
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	if status, _, err := gatewayCall(ctx, gateway, http.MethodDelete, path, generation, 5*time.Second); err != nil || status != http.StatusNoContent {
		if err == nil {
			err = fmt.Errorf("gateway returned HTTP %d", status)
		}
		logrus.WithError(err).WithField("account_id", accountID).Warn("creator event listener stop failed")
	}
}

func waitCreatorEventBackoff(ctx context.Context, delay time.Duration) bool {
	timer := time.NewTimer(delay)
	defer timer.Stop()
	select {
	case <-ctx.Done():
		return false
	case <-timer.C:
		return true
	}
}

func pathForCreatorEvent(environment hub.EnvironmentContext) string {
	return "/v1/browsers/" + url.PathEscape(environment.Alias) + "/douyin/events"
}

func handleCreatorGatewayEvent(ctx context.Context, store *creator.Store, binding creatorEventBinding, event creatorGatewayEvent, executor creator.ActionExecutor, generator creator.TextGenerator) {
	ack := func() {
		if event.DeliveryID == "" {
			return
		}
		// Acknowledgement is deliberately detached from the listener poll loop:
		// receipt and event classification must not be serialized behind a slow
		// gateway request. The gateway keeps the delivery until this succeeds.
		go func(deliveryID string) {
			ackCtx, cancel := context.WithTimeout(context.WithoutCancel(ctx), 5*time.Second)
			defer cancel()
			ackPath := pathForCreatorEvent(binding.env)
			status, _, ackErr := gatewayCall(ackCtx, binding.gateway, http.MethodGet, ackPath+"?ack="+url.QueryEscape(deliveryID)+"&limit=1&wait=0", gatewayGenerationPayload(binding.env), 5*time.Second)
			if ackErr != nil || status != http.StatusOK {
				if ackErr == nil {
					ackErr = fmt.Errorf("gateway returned HTTP %d", status)
				}
				logrus.WithError(ackErr).WithField("account_id", binding.accountID).Warn("creator event acknowledgement failed")
			}
		}(event.DeliveryID)
	}
	switch event.Kind {
	case "error":
		logrus.WithFields(logrus.Fields{"account_id": binding.accountID, "reason": event.Reason, "continuity": event.Continuity}).Warn("creator event listener reported an error")
		ack()
		return
	case "reconnected":
		logrus.WithField("account_id", binding.accountID).Warn("creator event listener reconnected")
		ack()
		return
	case "open", "baseline":
		ack()
		return
	case "close":
		logrus.WithField("account_id", binding.accountID).Warn("creator event listener connection closed")
		ack()
		return
	case "notice":
	default:
		logrus.WithFields(logrus.Fields{"account_id": binding.accountID, "kind": event.Kind}).Warn("creator event listener returned an unknown event")
		ack()
		return
	}
	if event.Notice == nil {
		logrus.WithField("account_id", binding.accountID).Warn("creator event listener notice is missing")
		ack()
		return
	}
	input, err := creatorEventFromGatewayNotice(binding.accountID, *event.Notice)
	if err != nil {
		logrus.WithError(err).WithField("account_id", binding.accountID).Warn("creator event listener notice was rejected")
		ack()
		return
	}
	input.Baseline = event.Baseline
	input.BaselineReason = event.Reason
	input.Generation = strings.TrimSpace(event.Generation)
	if input.Generation == "" {
		input.Generation = creatorListenerGeneration(binding.env)
	}
	selfEvent := binding.uid != "" && input.InteractorUID == binding.uid
	if selfEvent {
		input.Baseline = true
		input.BaselineReason = "接收账号主动行为"
	}
	if input.GatewayReceivedAt == nil {
		receivedAt := time.Now().UTC()
		input.GatewayReceivedAt = &receivedAt
	}
	if input.PlatformEventAt == nil {
		input.Baseline = true
		input.BaselineReason = "缺少平台事件时间"
	}
	if store == nil {
		return
	}
	// Receipt is durable before the potentially slow action. This prevents an
	// executor outage from erasing the platform notification and lets polling
	// continue while a prior action is still in flight.
	received, err := store.RecordEvent(ctx, input)
	if err != nil {
		logrus.WithError(err).WithFields(logrus.Fields{"account_id": binding.accountID, "event_key": input.EventKey}).Warn("creator event receipt failed")
		return
	}
	creatorUpdates.publish()
	if input.EventType == "dm" && input.InteractorUID != "" {
		messageAt := input.PlatformEventAt
		if messageAt == nil {
			receivedAt := input.ReceivedAt
			if receivedAt.IsZero() {
				receivedAt = time.Now().UTC()
			}
			messageAt = &receivedAt
		}
		direction, sentState := "inbound", "received"
		if selfEvent {
			direction, sentState = "outbound", "succeeded"
		}
		savedMessage, _, messageErr := store.SaveMessage(ctx, creator.MessageInput{Platform: input.Platform, AccountID: input.ReceivingAccountID, PeerUID: input.InteractorUID, PlatformMessageKey: input.EventKey, Direction: direction, MessageType: input.MessageType, Text: input.MessageText, SentState: sentState, MessageAt: messageAt})
		if messageErr != nil {
			logrus.WithError(messageErr).WithFields(logrus.Fields{"account_id": binding.accountID, "event_key": input.EventKey}).Warn("creator direct message persistence failed")
			return
		}
		if selfEvent {
			if err := store.LinkMessageOperation(ctx, savedMessage.ID, input.EventKey); err != nil {
				logrus.WithError(err).WithFields(logrus.Fields{"account_id": binding.accountID, "event_key": input.EventKey}).Warn("creator outbound direct message correlation failed")
				return
			}
		}
	}
	// The event is now durable. An action may be slow or unavailable, but that
	// must not hold ingestion or cause the same receipt to be fetched forever.
	ack()
	if input.Baseline || received.Event.State != "received" {
		return
	}
	go func() {
		result, processErr := store.ProcessAutomaticEvent(ctx, input, executor, generator)
		if processErr != nil {
			logrus.WithError(processErr).WithFields(logrus.Fields{"account_id": binding.accountID, "event_key": input.EventKey}).Warn("creator event processing failed")
			return
		}
		logrus.WithFields(logrus.Fields{"account_id": binding.accountID, "event_key": input.EventKey, "event_type": input.EventType, "state": result.Event.State}).Info("creator event processed")
		creatorUpdates.publish()
	}()
}

func creatorGatewayBoundary(event creatorGatewayEvent) (time.Time, bool, string) {
	if event.BoundarySource != "douyin_identity_extra_now" {
		return time.Time{}, false, "平台边界来源未验证"
	}
	if event.BoundaryAt == "" {
		return time.Time{}, false, "平台边界无效"
	}
	parsedBoundary, err := time.Parse(time.RFC3339Nano, event.BoundaryAt)
	if err != nil {
		return time.Time{}, false, "平台边界无效"
	}
	return parsedBoundary.UTC(), true, ""
}

func creatorEventBeforeBoundary(event creatorGatewayEvent, boundaryAt time.Time) bool {
	if boundaryAt.IsZero() || event.Notice == nil {
		return false
	}
	platformAt, err := time.Parse(time.RFC3339Nano, event.Notice.PlatformEventAt)
	return err != nil || !platformAt.After(boundaryAt)
}

func creatorGatewayEventNeedsBaseline(event creatorGatewayEvent, ready bool) (bool, string) {
	if event.Baseline {
		if event.Reason != "" {
			return true, event.Reason
		}
		return true, "监听基线"
	}
	if !ready {
		return true, "监听边界未确认"
	}
	if event.Notice == nil || strings.TrimSpace(event.Notice.PlatformEventAt) == "" {
		return true, "缺少平台事件时间"
	}
	return false, ""
}

func creatorEventFromGatewayNotice(accountID string, notice creatorGatewayEventNotice) (creator.InteractionEvent, error) {
	if accountID == "" || !creatorEventID(notice.EventKey) || !creator.ValidEventType(notice.EventType) {
		return creator.InteractionEvent{}, creator.ErrInvalid
	}
	if notice.InteractorUID != "" && !creatorEventUID(notice.InteractorUID) {
		return creator.InteractionEvent{}, creator.ErrInvalid
	}
	if (notice.CommentID != "" && !creatorEventID(notice.CommentID)) || (notice.WorkID != "" && !creatorEventID(notice.WorkID)) {
		return creator.InteractionEvent{}, creator.ErrInvalid
	}
	messageType := strings.TrimSpace(notice.MessageType)
	if messageType == "" {
		messageType = creator.MessageTypeText
	}
	if !creator.ValidMessageType(messageType) {
		return creator.InteractionEvent{}, creator.ErrInvalid
	}
	result := creator.InteractionEvent{Platform: creator.PlatformDouyin, ReceivingAccountID: accountID, EventKey: notice.EventKey, EventType: notice.EventType, InteractorUID: notice.InteractorUID, CommentID: notice.CommentID, WorkID: notice.WorkID, MessageType: messageType, MessageText: strings.TrimSpace(notice.MessageText)}
	if strings.TrimSpace(notice.PlatformEventAt) != "" {
		at, err := time.Parse(time.RFC3339Nano, notice.PlatformEventAt)
		if err != nil {
			return creator.InteractionEvent{}, fmt.Errorf("invalid platform event time: %w", err)
		}
		at = at.UTC()
		result.PlatformEventAt = &at
	}
	if strings.TrimSpace(notice.GatewayReceivedAt) != "" {
		receivedAt, err := time.Parse(time.RFC3339Nano, notice.GatewayReceivedAt)
		if err != nil {
			return creator.InteractionEvent{}, fmt.Errorf("invalid gateway receipt time: %w", err)
		}
		receivedAt = receivedAt.UTC()
		result.GatewayReceivedAt = &receivedAt
	}
	return result, nil
}

func creatorEventUID(value string) bool {
	return creatorEventDigits(value, 20)
}

func creatorEventID(value string) bool {
	return creatorEventDigits(value, 64)
}

func creatorEventDigits(value string, max int) bool {
	if value == "" || len(value) > max || value[0] < '1' || value[0] > '9' {
		return false
	}
	for _, char := range value[1:] {
		if char < '0' || char > '9' {
			return false
		}
	}
	return true
}