// PicoClaw - Ultra-lightweight personal AI agent
// Inspired by and based on nanobot: https://github.com/HKUDS/nanobot
// License: MIT
//
// Copyright (c) 2026 PicoClaw contributors

package channels

import (
	"context"
	"errors"
	"fmt"
	"math"
	"net/http"
	"sync"
	"time"

	"golang.org/x/time/rate"

	"github.com/sipeed/picoclaw/pkg/bus"
	"github.com/sipeed/picoclaw/pkg/config"
	"github.com/sipeed/picoclaw/pkg/constants"
	"github.com/sipeed/picoclaw/pkg/health"
	"github.com/sipeed/picoclaw/pkg/logger"
	"github.com/sipeed/picoclaw/pkg/media"
)

const (
	defaultChannelQueueSize = 16
	defaultRateLimit        = 10 // default 10 msg/s
	maxRetries              = 3
	rateLimitDelay          = 1 * time.Second
	baseBackoff             = 500 * time.Millisecond
	maxBackoff              = 8 * time.Second

	janitorInterval = 10 * time.Second
	typingStopTTL   = 5 * time.Minute
	placeholderTTL  = 10 * time.Minute
)

// typingEntry wraps a typing stop function with a creation timestamp for TTL eviction.
type typingEntry struct {
	stop      func()
	createdAt time.Time
}

// reactionEntry wraps a reaction undo function with a creation timestamp for TTL eviction.
type reactionEntry struct {
	undo      func()
	createdAt time.Time
}

// placeholderEntry wraps a placeholder ID with a creation timestamp for TTL eviction.
type placeholderEntry struct {
	id        string
	createdAt time.Time
}

// channelRateConfig maps channel name to per-second rate limit.
var channelRateConfig = map[string]float64{
	"telegram": 20,
	"discord":  1,
	"slack":    1,
	"matrix":   2,
	"line":     10,
	"qq":       5,
	"irc":      2,
}

type channelWorker struct {
	ch         Channel
	queue      chan bus.OutboundMessage
	mediaQueue chan bus.OutboundMediaMessage
	done       chan struct{}
	mediaDone  chan struct{}
	limiter    *rate.Limiter
}

type Manager struct {
	channels      map[string]Channel
	workers       map[string]*channelWorker
	bus           *bus.MessageBus
	config        *config.Config
	mediaStore    media.MediaStore
	dispatchTask  *asyncTask
	mux           *dynamicServeMux
	httpServer    *http.Server
	mu            sync.RWMutex
	placeholders  sync.Map          // "channel:chatID" → placeholderID (string)
	typingStops   sync.Map          // "channel:chatID" → func()
	reactionUndos sync.Map          // "channel:chatID" → reactionEntry
	streamActive  sync.Map          // "channel:chatID" → true (set when streamer.Finalize sent the message)
	channelHashes map[string]string // channel name → config hash
}

type asyncTask struct {
	cancel context.CancelFunc
}

// RecordPlaceholder registers a placeholder message for later editing.
// Implements PlaceholderRecorder.
func (m *Manager) RecordPlaceholder(channel, chatID, placeholderID string) {
	key := channel + ":" + chatID
	m.placeholders.Store(key, placeholderEntry{id: placeholderID, createdAt: time.Now()})
}

// SendPlaceholder sends a "Thinking…" placeholder for the given channel/chatID
// and records it for later editing. Returns true if a placeholder was sent.
func (m *Manager) SendPlaceholder(ctx context.Context, channel, chatID string) bool {
	m.mu.RLock()
	ch, ok := m.channels[channel]
	m.mu.RUnlock()
	if !ok {
		return false
	}
	pc, ok := ch.(PlaceholderCapable)
	if !ok {
		return false
	}
	phID, err := pc.SendPlaceholder(ctx, chatID)
	if err != nil || phID == "" {
		return false
	}
	m.RecordPlaceholder(channel, chatID, phID)
	return true
}

// RecordTypingStop registers a typing stop function for later invocation.
// Implements PlaceholderRecorder.
func (m *Manager) RecordTypingStop(channel, chatID string, stop func()) {
	key := channel + ":" + chatID
	entry := typingEntry{stop: stop, createdAt: time.Now()}
	if previous, loaded := m.typingStops.Swap(key, entry); loaded {
		if oldEntry, ok := previous.(typingEntry); ok && oldEntry.stop != nil {
			oldEntry.stop()
		}
	}
}

// InvokeTypingStop invokes the registered typing stop function for the given channel and chatID.
// It is safe to call even when no typing indicator is active (no-op).
// Used by the agent loop to stop typing when processing completes (success, error, or panic),
// regardless of whether an outbound message is published.
func (m *Manager) InvokeTypingStop(channel, chatID string) {
	key := channel + ":" + chatID
	if v, loaded := m.typingStops.LoadAndDelete(key); loaded {
		if entry, ok := v.(typingEntry); ok {
			entry.stop()
		}
	}
}

// RecordReactionUndo registers a reaction undo function for later invocation.
// Implements PlaceholderRecorder.
func (m *Manager) RecordReactionUndo(channel, chatID string, undo func()) {
	key := channel + ":" + chatID
	m.reactionUndos.Store(key, reactionEntry{undo: undo, createdAt: time.Now()})
}

// preSend handles typing stop, reaction undo, and placeholder editing before sending a message.
// Returns true if the message was already delivered (skip Send).
func (m *Manager) preSend(ctx context.Context, name string, msg bus.OutboundMessage, ch Channel) bool {
	key := name + ":" + msg.ChatID

	// 1. Stop typing
	if v, loaded := m.typingStops.LoadAndDelete(key); loaded {
		if entry, ok := v.(typingEntry); ok {
			entry.stop() // idempotent, safe
		}
	}

	// 2. Undo reaction
	if v, loaded := m.reactionUndos.LoadAndDelete(key); loaded {
		if entry, ok := v.(reactionEntry); ok {
			entry.undo() // idempotent, safe
		}
	}

	// 3. If a stream already finalized this message, delete the placeholder and skip send
	if _, loaded := m.streamActive.LoadAndDelete(key); loaded {
		if v, loaded := m.placeholders.LoadAndDelete(key); loaded {
			if entry, ok := v.(placeholderEntry); ok && entry.id != "" {
				// Prefer deleting the placeholder (cleaner UX than editing to same content)
				if deleter, ok := ch.(MessageDeleter); ok {
					deleter.DeleteMessage(ctx, msg.ChatID, entry.id) // best effort
				} else if editor, ok := ch.(MessageEditor); ok {
					editor.EditMessage(ctx, msg.ChatID, entry.id, msg.Content) // fallback
				}
			}
		}
		return true
	}

	// 4. Try editing placeholder
	if v, loaded := m.placeholders.LoadAndDelete(key); loaded {
		if entry, ok := v.(placeholderEntry); ok && entry.id != "" {
			if editor, ok := ch.(MessageEditor); ok {
				if err := editor.EditMessage(ctx, msg.ChatID, entry.id, msg.Content); err == nil {
					return true // edited successfully, skip Send
				}
				// edit failed → fall through to normal Send
			}
		}
	}

	return false
}

// preSendMedia handles typing stop, reaction undo, and placeholder cleanup
// before sending media attachments. Unlike preSend for text messages, media
// delivery never edits the placeholder because there is no text payload to
// replace it with; it only attempts to delete the placeholder when possible.
func (m *Manager) preSendMedia(ctx context.Context, name string, msg bus.OutboundMediaMessage, ch Channel) {
	key := name + ":" + msg.ChatID

	// 1. Stop typing
	if v, loaded := m.typingStops.LoadAndDelete(key); loaded {
		if entry, ok := v.(typingEntry); ok {
			entry.stop() // idempotent, safe
		}
	}

	// 2. Undo reaction
	if v, loaded := m.reactionUndos.LoadAndDelete(key); loaded {
		if entry, ok := v.(reactionEntry); ok {
			entry.undo() // idempotent, safe
		}
	}

	// 3. Clear any finalized stream marker for this chat before media delivery.
	m.streamActive.LoadAndDelete(key)

	// 4. Delete placeholder if present.
	if v, loaded := m.placeholders.LoadAndDelete(key); loaded {
		if entry, ok := v.(placeholderEntry); ok && entry.id != "" {
			if deleter, ok := ch.(MessageDeleter); ok {
				deleter.DeleteMessage(ctx, msg.ChatID, entry.id) // best effort
			}
		}
	}
}

func NewManager(cfg *config.Config, messageBus *bus.MessageBus, store media.MediaStore) (*Manager, error) {
	m := &Manager{
		channels:      make(map[string]Channel),
		workers:       make(map[string]*channelWorker),
		bus:           messageBus,
		config:        cfg,
		mediaStore:    store,
		channelHashes: make(map[string]string),
	}

	// Register as streaming delegate so the agent loop can obtain streamers
	messageBus.SetStreamDelegate(m)

	if err := m.initChannels(&cfg.Channels); err != nil {
		return nil, err
	}

	// Store initial config hashes for all channels
	m.channelHashes = toChannelHashes(cfg)

	return m, nil
}

// GetStreamer implements bus.StreamDelegate.
// It checks if the named channel supports streaming and returns a Streamer.
func (m *Manager) GetStreamer(ctx context.Context, channelName, chatID string) (bus.Streamer, bool) {
	m.mu.RLock()
	ch, exists := m.channels[channelName]
	m.mu.RUnlock()

	if !exists {
		return nil, false
	}

	sc, ok := ch.(StreamingCapable)
	if !ok {
		return nil, false
	}

	streamer, err := sc.BeginStream(ctx, chatID)
	if err != nil {
		logger.DebugCF("channels", "Streaming unavailable, falling back to placeholder", map[string]any{
			"channel": channelName,
			"error":   err.Error(),
		})
		return nil, false
	}

	// Mark streamActive on Finalize so preSend knows to clean up the placeholder
	key := channelName + ":" + chatID
	return &finalizeHookStreamer{
		Streamer:   streamer,
		onFinalize: func() { m.streamActive.Store(key, true) },
	}, true
}

// finalizeHookStreamer wraps a Streamer to run a hook on Finalize.
type finalizeHookStreamer struct {
	Streamer
	onFinalize func()
}

func (s *finalizeHookStreamer) Finalize(ctx context.Context, content string) error {
	if err := s.Streamer.Finalize(ctx, content); err != nil {
		return err
	}
	s.onFinalize()
	return nil
}

// initChannel is a helper that looks up a factory by name and creates the channel.
func (m *Manager) initChannel(name, displayName string) {
	f, ok := getFactory(name)
	if !ok {
		logger.WarnCF("channels", "Factory not registered", map[string]any{
			"channel": displayName,
		})
		return
	}
	logger.DebugCF("channels", "Attempting to initialize channel", map[string]any{
		"channel": displayName,
	})
	ch, err := f(m.config, m.bus)
	if err != nil {
		logger.ErrorCF("channels", "Failed to initialize channel", map[string]any{
			"channel": displayName,
			"error":   err.Error(),
		})
	} else {
		// Inject MediaStore if channel supports it
		if m.mediaStore != nil {
			if setter, ok := ch.(interface{ SetMediaStore(s media.MediaStore) }); ok {
				setter.SetMediaStore(m.mediaStore)
			}
		}
		// Inject PlaceholderRecorder if channel supports it
		if setter, ok := ch.(interface{ SetPlaceholderRecorder(r PlaceholderRecorder) }); ok {
			setter.SetPlaceholderRecorder(m)
		}
		// Inject owner reference so BaseChannel.HandleMessage can auto-trigger typing/reaction
		if setter, ok := ch.(interface{ SetOwner(ch Channel) }); ok {
			setter.SetOwner(ch)
		}
		m.channels[name] = ch
		logger.InfoCF("channels", "Channel enabled successfully", map[string]any{
			"channel": displayName,
		})
	}
}

func (m *Manager) initChannels(channels *config.ChannelsConfig) error {
	logger.InfoC("channels", "Initializing channel manager")

	if channels.Telegram.Enabled && channels.Telegram.Token.String() != "" {
		m.initChannel("telegram", "Telegram")
	}

	if channels.WhatsApp.Enabled {
		waCfg := channels.WhatsApp
		if waCfg.UseNative {
			m.initChannel("whatsapp_native", "WhatsApp Native")
		} else if waCfg.BridgeURL != "" {
			m.initChannel("whatsapp", "WhatsApp")
		}
	}

	if channels.Feishu.Enabled {
		m.initChannel("feishu", "Feishu")
	}

	if channels.Discord.Enabled && channels.Discord.Token.String() != "" {
		m.initChannel("discord", "Discord")
	}

	if channels.MaixCam.Enabled {
		m.initChannel("maixcam", "MaixCam")
	}

	if channels.QQ.Enabled {
		m.initChannel("qq", "QQ")
	}

	if channels.DingTalk.Enabled && channels.DingTalk.ClientID != "" {
		m.initChannel("dingtalk", "DingTalk")
	}

	if channels.Slack.Enabled && channels.Slack.BotToken.String() != "" {
		m.initChannel("slack", "Slack")
	}

	if channels.Matrix.Enabled &&
		m.config.Channels.Matrix.Homeserver != "" &&
		m.config.Channels.Matrix.UserID != "" &&
		m.config.Channels.Matrix.AccessToken.String() != "" {
		m.initChannel("matrix", "Matrix")
	}

	if channels.LINE.Enabled && channels.LINE.ChannelAccessToken.String() != "" {
		m.initChannel("line", "LINE")
	}

	if channels.OneBot.Enabled && channels.OneBot.WSUrl != "" {
		m.initChannel("onebot", "OneBot")
	}

	if channels.WeCom.Enabled && channels.WeCom.BotID != "" && channels.WeCom.Secret.String() != "" {
		m.initChannel("wecom", "WeCom")
	}

	if channels.Weixin.Enabled && channels.Weixin.Token.String() != "" {
		m.initChannel("weixin", "Weixin")
	}

	if channels.Pico.Enabled && channels.Pico.Token.String() != "" {
		m.initChannel("pico", "Pico")
	}

	if channels.PicoClient.Enabled && channels.PicoClient.URL != "" {
		m.initChannel("pico_client", "Pico Client")
	}

	if channels.IRC.Enabled && channels.IRC.Server != "" {
		m.initChannel("irc", "IRC")
	}

	logger.InfoCF("channels", "Channel initialization completed", map[string]any{
		"enabled_channels": len(m.channels),
	})

	return nil
}

// SetupHTTPServer creates a shared HTTP server with the given listen address.
// It registers health endpoints from the health server and discovers channels
// that implement WebhookHandler and/or HealthChecker to register their handlers.
func (m *Manager) SetupHTTPServer(addr string, healthServer *health.Server) {
	m.mux = newDynamicServeMux()

	// Register health endpoints
	if healthServer != nil {
		healthServer.RegisterOnMux(m.mux)
	}

	// Discover and register webhook handlers and health checkers
	m.registerHTTPHandlersLocked()

	m.httpServer = &http.Server{
		Addr:         addr,
		Handler:      m.mux,
		ReadTimeout:  30 * time.Second,
		WriteTimeout: 30 * time.Second,
	}
}

// registerHTTPHandlersLocked registers webhook and health-check handlers for
// all channels currently in m.channels. Caller must hold m.mu (or ensure
// exclusive access).
func (m *Manager) registerHTTPHandlersLocked() {
	for name, ch := range m.channels {
		m.registerChannelHTTPHandler(name, ch)
	}
}

// registerChannelHTTPHandler registers the webhook/health handlers for a
// single channel onto m.mux.
func (m *Manager) registerChannelHTTPHandler(name string, ch Channel) {
	if wh, ok := ch.(WebhookHandler); ok {
		m.mux.Handle(wh.WebhookPath(), wh)
		logger.InfoCF("channels", "Webhook handler registered", map[string]any{
			"channel": name,
			"path":    wh.WebhookPath(),
		})
	}
	if hc, ok := ch.(HealthChecker); ok {
		m.mux.HandleFunc(hc.HealthPath(), hc.HealthHandler)
		logger.InfoCF("channels", "Health endpoint registered", map[string]any{
			"channel": name,
			"path":    hc.HealthPath(),
		})
	}
}

// unregisterChannelHTTPHandler removes the webhook/health handlers for a
// single channel from m.mux.
func (m *Manager) unregisterChannelHTTPHandler(name string, ch Channel) {
	if wh, ok := ch.(WebhookHandler); ok {
		m.mux.Unhandle(wh.WebhookPath())
		logger.InfoCF("channels", "Webhook handler unregistered", map[string]any{
			"channel": name,
			"path":    wh.WebhookPath(),
		})
	}
	if hc, ok := ch.(HealthChecker); ok {
		m.mux.Unhandle(hc.HealthPath())
		logger.InfoCF("channels", "Health endpoint unregistered", map[string]any{
			"channel": name,
			"path":    hc.HealthPath(),
		})
	}
}

func (m *Manager) StartAll(ctx context.Context) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	if len(m.channels) == 0 {
		logger.WarnC("channels", "No channels enabled")
	}

	logger.InfoC("channels", "Starting all channels")

	dispatchCtx, cancel := context.WithCancel(ctx)
	m.dispatchTask = &asyncTask{cancel: cancel}

	for name, channel := range m.channels {
		logger.InfoCF("channels", "Starting channel", map[string]any{
			"channel": name,
		})
		if err := channel.Start(ctx); err != nil {
			logger.ErrorCF("channels", "Failed to start channel", map[string]any{
				"channel": name,
				"error":   err.Error(),
			})
			continue
		}
		// Lazily create worker only after channel starts successfully
		w := newChannelWorker(name, channel)
		m.workers[name] = w
		go m.runWorker(dispatchCtx, name, w)
		go m.runMediaWorker(dispatchCtx, name, w)
	}

	// Start the dispatcher that reads from the bus and routes to workers
	go m.dispatchOutbound(dispatchCtx)
	go m.dispatchOutboundMedia(dispatchCtx)

	// Start the TTL janitor that cleans up stale typing/placeholder entries
	go m.runTTLJanitor(dispatchCtx)

	// Start shared HTTP server if configured
	if m.httpServer != nil {
		go func() {
			logger.InfoCF("channels", "Shared HTTP server listening", map[string]any{
				"addr": m.httpServer.Addr,
			})
			if err := m.httpServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
				logger.FatalCF("channels", "Shared HTTP server error", map[string]any{
					"error": err.Error(),
				})
			}
		}()
	}

	logger.InfoC("channels", "All channels started")
	return nil
}

func (m *Manager) StopAll(ctx context.Context) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	logger.InfoC("channels", "Stopping all channels")

	// Shutdown shared HTTP server first
	if m.httpServer != nil {
		shutdownCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
		defer cancel()
		if err := m.httpServer.Shutdown(shutdownCtx); err != nil {
			logger.ErrorCF("channels", "Shared HTTP server shutdown error", map[string]any{
				"error": err.Error(),
			})
		}
		m.httpServer = nil
	}

	// Cancel dispatcher
	if m.dispatchTask != nil {
		m.dispatchTask.cancel()
		m.dispatchTask = nil
	}

	// Close all worker queues and wait for them to drain
	for _, w := range m.workers {
		if w != nil {
			close(w.queue)
		}
	}
	for _, w := range m.workers {
		if w != nil {
			<-w.done
		}
	}
	// Close all media worker queues and wait for them to drain
	for _, w := range m.workers {
		if w != nil {
			close(w.mediaQueue)
		}
	}
	for _, w := range m.workers {
		if w != nil {
			<-w.mediaDone
		}
	}

	// Stop all channels
	for name, channel := range m.channels {
		logger.InfoCF("channels", "Stopping channel", map[string]any{
			"channel": name,
		})
		if err := channel.Stop(ctx); err != nil {
			logger.ErrorCF("channels", "Error stopping channel", map[string]any{
				"channel": name,
				"error":   err.Error(),
			})
		}
	}

	logger.InfoC("channels", "All channels stopped")
	return nil
}

// newChannelWorker creates a channelWorker with a rate limiter configured
// for the given channel name.
func newChannelWorker(name string, ch Channel) *channelWorker {
	rateVal := float64(defaultRateLimit)
	if r, ok := channelRateConfig[name]; ok {
		rateVal = r
	}
	burst := int(math.Max(1, math.Ceil(rateVal/2)))

	return &channelWorker{
		ch:         ch,
		queue:      make(chan bus.OutboundMessage, defaultChannelQueueSize),
		mediaQueue: make(chan bus.OutboundMediaMessage, defaultChannelQueueSize),
		done:       make(chan struct{}),
		mediaDone:  make(chan struct{}),
		limiter:    rate.NewLimiter(rate.Limit(rateVal), burst),
	}
}

// runWorker processes outbound messages for a single channel.
// Message processing follows this order:
//  1. SplitByMarker (if enabled in config) - LLM semantic marker-based splitting
//  2. SplitMessage - channel-specific length-based splitting (MaxMessageLength)
func (m *Manager) runWorker(ctx context.Context, name string, w *channelWorker) {
	defer close(w.done)
	for {
		select {
		case msg, ok := <-w.queue:
			if !ok {
				return
			}
			maxLen := 0
			if mlp, ok := w.ch.(MessageLengthProvider); ok {
				maxLen = mlp.MaxMessageLength()
			}

			// Collect all message chunks to send
			var chunks []string

			// Step 1: Try marker-based splitting if enabled
			if m.config != nil && m.config.Agents.Defaults.SplitOnMarker {
				if markerChunks := SplitByMarker(msg.Content); len(markerChunks) > 1 {
					for _, chunk := range markerChunks {
						chunks = append(chunks, splitByLength(chunk, maxLen)...)
					}
				}
			}

			// Step 2: Fallback to length-based splitting if no chunks from marker
			if len(chunks) == 0 {
				chunks = splitByLength(msg.Content, maxLen)
			}

			// Step 3: Send all chunks
			for _, chunk := range chunks {
				chunkMsg := msg
				chunkMsg.Content = chunk
				m.sendWithRetry(ctx, name, w, chunkMsg)
			}
		case <-ctx.Done():
			return
		}
	}
}

// splitByLength splits content by maxLen if needed, otherwise returns single chunk.
func splitByLength(content string, maxLen int) []string {
	if maxLen > 0 && len([]rune(content)) > maxLen {
		return SplitMessage(content, maxLen)
	}
	return []string{content}
}

// sendWithRetry sends a message through the channel with rate limiting and
// retry logic. It classifies errors to determine the retry strategy:
//   - ErrNotRunning / ErrSendFailed: permanent, no retry
//   - ErrRateLimit: fixed delay retry
//   - ErrTemporary / unknown: exponential backoff retry
func (m *Manager) sendWithRetry(ctx context.Context, name string, w *channelWorker, msg bus.OutboundMessage) {
	// Rate limit: wait for token
	if err := w.limiter.Wait(ctx); err != nil {
		// ctx canceled, shutting down
		return
	}

	// Pre-send: stop typing and try to edit placeholder
	if m.preSend(ctx, name, msg, w.ch) {
		return // placeholder was edited successfully, skip Send
	}

	var lastErr error
	for attempt := 0; attempt <= maxRetries; attempt++ {
		lastErr = w.ch.Send(ctx, msg)
		if lastErr == nil {
			return
		}

		// Permanent failures — don't retry
		if errors.Is(lastErr, ErrNotRunning) || errors.Is(lastErr, ErrSendFailed) {
			break
		}

		// Last attempt exhausted — don't sleep
		if attempt == maxRetries {
			break
		}

		// Rate limit error — fixed delay
		if errors.Is(lastErr, ErrRateLimit) {
			select {
			case <-time.After(rateLimitDelay):
				continue
			case <-ctx.Done():
				return
			}
		}

		// ErrTemporary or unknown error — exponential backoff
		backoff := min(time.Duration(float64(baseBackoff)*math.Pow(2, float64(attempt))), maxBackoff)
		select {
		case <-time.After(backoff):
		case <-ctx.Done():
			return
		}
	}

	// All retries exhausted or permanent failure
	logger.ErrorCF("channels", "Send failed", map[string]any{
		"channel": name,
		"chat_id": msg.ChatID,
		"error":   lastErr.Error(),
		"retries": maxRetries,
	})
}

func dispatchLoop[M any](
	ctx context.Context,
	m *Manager,
	ch <-chan M,
	getChannel func(M) string,
	enqueue func(context.Context, *channelWorker, M) bool,
	startMsg, stopMsg, unknownMsg, noWorkerMsg string,
) {
	logger.InfoC("channels", startMsg)

	for {
		select {
		case <-ctx.Done():
			logger.InfoC("channels", stopMsg)
			return

		case msg, ok := <-ch:
			if !ok {
				logger.InfoC("channels", stopMsg)
				return
			}

			channel := getChannel(msg)

			// Silently skip internal channels
			if constants.IsInternalChannel(channel) {
				continue
			}

			m.mu.RLock()
			_, exists := m.channels[channel]
			w, wExists := m.workers[channel]
			m.mu.RUnlock()

			if !exists {
				logger.WarnCF("channels", unknownMsg, map[string]any{"channel": channel})
				continue
			}

			if wExists && w != nil {
				if !enqueue(ctx, w, msg) {
					return
				}
			} else if exists {
				logger.WarnCF("channels", noWorkerMsg, map[string]any{"channel": channel})
			}
		}
	}
}

func (m *Manager) dispatchOutbound(ctx context.Context) {
	dispatchLoop(
		ctx, m,
		m.bus.OutboundChan(),
		func(msg bus.OutboundMessage) string { return msg.Channel },
		func(ctx context.Context, w *channelWorker, msg bus.OutboundMessage) bool {
			select {
			case w.queue <- msg:
				return true
			case <-ctx.Done():
				return false
			}
		},
		"Outbound dispatcher started",
		"Outbound dispatcher stopped",
		"Unknown channel for outbound message",
		"Channel has no active worker, skipping message",
	)
}

func (m *Manager) dispatchOutboundMedia(ctx context.Context) {
	dispatchLoop(
		ctx, m,
		m.bus.OutboundMediaChan(),
		func(msg bus.OutboundMediaMessage) string { return msg.Channel },
		func(ctx context.Context, w *channelWorker, msg bus.OutboundMediaMessage) bool {
			select {
			case w.mediaQueue <- msg:
				return true
			case <-ctx.Done():
				return false
			}
		},
		"Outbound media dispatcher started",
		"Outbound media dispatcher stopped",
		"Unknown channel for outbound media message",
		"Channel has no active worker, skipping media message",
	)
}

// runMediaWorker processes outbound media messages for a single channel.
func (m *Manager) runMediaWorker(ctx context.Context, name string, w *channelWorker) {
	defer close(w.mediaDone)
	for {
		select {
		case msg, ok := <-w.mediaQueue:
			if !ok {
				return
			}
			_ = m.sendMediaWithRetry(ctx, name, w, msg)
		case <-ctx.Done():
			return
		}
	}
}

// sendMediaWithRetry sends a media message through the channel with rate limiting and
// retry logic. It returns nil on success, or the last error after retries,
// including when the channel does not support MediaSender.
func (m *Manager) sendMediaWithRetry(
	ctx context.Context,
	name string,
	w *channelWorker,
	msg bus.OutboundMediaMessage,
) error {
	ms, ok := w.ch.(MediaSender)
	if !ok {
		err := fmt.Errorf("channel %q does not support media sending", name)
		logger.WarnCF("channels", "Channel does not support MediaSender", map[string]any{
			"channel": name,
			"error":   err.Error(),
		})
		return err
	}

	// Rate limit: wait for token
	if err := w.limiter.Wait(ctx); err != nil {
		return err
	}

	// Pre-send: stop typing and clean up any placeholder before sending media.
	m.preSendMedia(ctx, name, msg, w.ch)

	var lastErr error
	for attempt := 0; attempt <= maxRetries; attempt++ {
		lastErr = ms.SendMedia(ctx, msg)
		if lastErr == nil {
			return nil
		}

		// Permanent failures — don't retry
		if errors.Is(lastErr, ErrNotRunning) || errors.Is(lastErr, ErrSendFailed) {
			break
		}

		// Last attempt exhausted — don't sleep
		if attempt == maxRetries {
			break
		}

		// Rate limit error — fixed delay
		if errors.Is(lastErr, ErrRateLimit) {
			select {
			case <-time.After(rateLimitDelay):
				continue
			case <-ctx.Done():
				return ctx.Err()
			}
		}

		// ErrTemporary or unknown error — exponential backoff
		backoff := min(time.Duration(float64(baseBackoff)*math.Pow(2, float64(attempt))), maxBackoff)
		select {
		case <-time.After(backoff):
		case <-ctx.Done():
			return ctx.Err()
		}
	}

	// All retries exhausted or permanent failure
	logger.ErrorCF("channels", "SendMedia failed", map[string]any{
		"channel": name,
		"chat_id": msg.ChatID,
		"error":   lastErr.Error(),
		"retries": maxRetries,
	})
	return lastErr
}

// runTTLJanitor periodically scans the typingStops and placeholders maps
// and evicts entries that have exceeded their TTL. This prevents memory
// accumulation when outbound paths fail to trigger preSend (e.g. LLM errors).
func (m *Manager) runTTLJanitor(ctx context.Context) {
	ticker := time.NewTicker(janitorInterval)
	defer ticker.Stop()

	for {
		select {
		case <-ctx.Done():
			return
		case now := <-ticker.C:
			m.typingStops.Range(func(key, value any) bool {
				if entry, ok := value.(typingEntry); ok {
					if now.Sub(entry.createdAt) > typingStopTTL {
						if _, loaded := m.typingStops.LoadAndDelete(key); loaded {
							entry.stop() // idempotent, safe
						}
					}
				}
				return true
			})
			m.reactionUndos.Range(func(key, value any) bool {
				if entry, ok := value.(reactionEntry); ok {
					if now.Sub(entry.createdAt) > typingStopTTL {
						if _, loaded := m.reactionUndos.LoadAndDelete(key); loaded {
							entry.undo() // idempotent, safe
						}
					}
				}
				return true
			})
			m.placeholders.Range(func(key, value any) bool {
				if entry, ok := value.(placeholderEntry); ok {
					if now.Sub(entry.createdAt) > placeholderTTL {
						m.placeholders.Delete(key)
					}
				}
				return true
			})
		}
	}
}

func (m *Manager) GetChannel(name string) (Channel, bool) {
	m.mu.RLock()
	defer m.mu.RUnlock()
	channel, ok := m.channels[name]
	return channel, ok
}

func (m *Manager) GetStatus() map[string]any {
	m.mu.RLock()
	defer m.mu.RUnlock()

	status := make(map[string]any)
	for name, channel := range m.channels {
		status[name] = map[string]any{
			"enabled": true,
			"running": channel.IsRunning(),
		}
	}
	return status
}

func (m *Manager) GetEnabledChannels() []string {
	m.mu.RLock()
	defer m.mu.RUnlock()

	names := make([]string, 0, len(m.channels))
	for name := range m.channels {
		names = append(names, name)
	}
	return names
}

// Reload updates the config reference without restarting channels.
// This is used when channel config hasn't changed but other parts of the config have.
func (m *Manager) Reload(ctx context.Context, cfg *config.Config) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	// Save old config so we can revert on error.
	oldConfig := m.config

	// Update config early: initChannel uses m.config via factory(m.config, m.bus).
	m.config = cfg

	list := toChannelHashes(cfg)
	added, removed := compareChannels(m.channelHashes, list)

	deferFuncs := make([]func(), 0, len(removed)+len(added))
	for _, name := range removed {
		// Stop all channels
		channel := m.channels[name]
		logger.InfoCF("channels", "Stopping channel", map[string]any{
			"channel": name,
		})
		if err := channel.Stop(ctx); err != nil {
			logger.ErrorCF("channels", "Error stopping channel", map[string]any{
				"channel": name,
				"error":   err.Error(),
			})
		}
		deferFuncs = append(deferFuncs, func() {
			m.UnregisterChannel(name)
		})
	}
	dispatchCtx, cancel := context.WithCancel(ctx)
	m.dispatchTask = &asyncTask{cancel: cancel}
	cc, err := toChannelConfig(cfg, added)
	if err != nil {
		logger.ErrorC("channels", fmt.Sprintf("toChannelConfig error: %v", err))
		m.config = oldConfig
		cancel()
		return err
	}
	err = m.initChannels(cc)
	if err != nil {
		logger.ErrorC("channels", fmt.Sprintf("initChannels error: %v", err))
		m.config = oldConfig
		cancel()
		return err
	}
	for _, name := range added {
		channel := m.channels[name]
		logger.InfoCF("channels", "Starting channel", map[string]any{
			"channel": name,
		})
		if err := channel.Start(ctx); err != nil {
			logger.ErrorCF("channels", "Failed to start channel", map[string]any{
				"channel": name,
				"error":   err.Error(),
			})
			continue
		}
		// Lazily create worker only after channel starts successfully
		w := newChannelWorker(name, channel)
		m.workers[name] = w
		go m.runWorker(dispatchCtx, name, w)
		go m.runMediaWorker(dispatchCtx, name, w)
		deferFuncs = append(deferFuncs, func() {
			m.RegisterChannel(name, channel)
		})
	}

	// Commit hashes only on full success.
	m.channelHashes = list
	go func() {
		for _, f := range deferFuncs {
			f()
		}
	}()
	return nil
}

func (m *Manager) RegisterChannel(name string, channel Channel) {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.channels[name] = channel
	if m.mux != nil {
		m.registerChannelHTTPHandler(name, channel)
	}
}

func (m *Manager) UnregisterChannel(name string) {
	m.mu.Lock()
	defer m.mu.Unlock()
	if ch, ok := m.channels[name]; ok && m.mux != nil {
		m.unregisterChannelHTTPHandler(name, ch)
	}
	if w, ok := m.workers[name]; ok && w != nil {
		close(w.queue)
		<-w.done
		close(w.mediaQueue)
		<-w.mediaDone
	}
	delete(m.workers, name)
	delete(m.channels, name)
}

// SendMessage sends an outbound message synchronously through the channel
// worker's rate limiter and retry logic. It blocks until the message is
// delivered (or all retries are exhausted), which preserves ordering when
// a subsequent operation depends on the message having been sent.
func (m *Manager) SendMessage(ctx context.Context, msg bus.OutboundMessage) error {
	m.mu.RLock()
	_, exists := m.channels[msg.Channel]
	w, wExists := m.workers[msg.Channel]
	m.mu.RUnlock()

	if !exists {
		return fmt.Errorf("channel %s not found", msg.Channel)
	}
	if !wExists || w == nil {
		return fmt.Errorf("channel %s has no active worker", msg.Channel)
	}

	maxLen := 0
	if mlp, ok := w.ch.(MessageLengthProvider); ok {
		maxLen = mlp.MaxMessageLength()
	}
	if maxLen > 0 && len([]rune(msg.Content)) > maxLen {
		for _, chunk := range SplitMessage(msg.Content, maxLen) {
			chunkMsg := msg
			chunkMsg.Content = chunk
			m.sendWithRetry(ctx, msg.Channel, w, chunkMsg)
		}
	} else {
		m.sendWithRetry(ctx, msg.Channel, w, msg)
	}
	return nil
}

// SendMedia sends outbound media synchronously through the channel worker's
// rate limiter and retry logic. It blocks until the media is delivered (or all
// retries are exhausted), which preserves ordering when later agent behavior
// depends on actual media delivery.
func (m *Manager) SendMedia(ctx context.Context, msg bus.OutboundMediaMessage) error {
	m.mu.RLock()
	_, exists := m.channels[msg.Channel]
	w, wExists := m.workers[msg.Channel]
	m.mu.RUnlock()

	if !exists {
		return fmt.Errorf("channel %s not found", msg.Channel)
	}
	if !wExists || w == nil {
		return fmt.Errorf("channel %s has no active worker", msg.Channel)
	}

	return m.sendMediaWithRetry(ctx, msg.Channel, w, msg)
}

func (m *Manager) SendToChannel(ctx context.Context, channelName, chatID, content string) error {
	m.mu.RLock()
	_, exists := m.channels[channelName]
	w, wExists := m.workers[channelName]
	m.mu.RUnlock()

	if !exists {
		return fmt.Errorf("channel %s not found", channelName)
	}

	msg := bus.OutboundMessage{
		Channel: channelName,
		ChatID:  chatID,
		Content: content,
	}

	if wExists && w != nil {
		select {
		case w.queue <- msg:
			return nil
		case <-ctx.Done():
			return ctx.Err()
		}
	}

	// Fallback: direct send (should not happen)
	channel, _ := m.channels[channelName]
	return channel.Send(ctx, msg)
}