kandev/apps/backend/internal/orchestrator/watcher/watcher.go

// Package watcher provides event subscription and dispatching for the Orchestrator.
package watcher

import (
	"context"
	"encoding/json"
	"sync"

	"go.uber.org/zap"

	"github.com/kandev/kandev/internal/agent/lifecycle"
	"github.com/kandev/kandev/internal/common/logger"
	"github.com/kandev/kandev/internal/events"
	"github.com/kandev/kandev/internal/events/bus"
	v1 "github.com/kandev/kandev/pkg/api/v1"
)

// TaskEventData contains data from task events
type TaskEventData struct {
	TaskID   string        `json:"task_id"`
	Task     *v1.Task      `json:"task,omitempty"`
	OldState *v1.TaskState `json:"old_state,omitempty"`
	NewState *v1.TaskState `json:"new_state,omitempty"`
}

// AgentEventData contains data from agent events
type AgentEventData struct {
	TaskID           string `json:"task_id"`
	SessionID        string `json:"session_id"`
	AgentExecutionID string `json:"agent_execution_id"`
	AgentProfileID   string `json:"agent_profile_id"`
	ExitCode         *int   `json:"exit_code,omitempty"`
	ErrorMessage     string `json:"error_message,omitempty"`
}

// ACPSessionEventData contains data from ACP session events
type ACPSessionEventData struct {
	TaskID           string `json:"task_id"`
	SessionID        string `json:"session_id"`
	AgentExecutionID string `json:"agent_execution_id"`
	ACPSessionID     string `json:"acp_session_id"`
}

// PermissionRequestData contains data from permission_request events
type PermissionRequestData struct {
	TaskID        string                   `json:"task_id"`
	TaskSessionID string                   `json:"session_id"`
	AgentID       string                   `json:"agent_id"`
	PendingID     string                   `json:"pending_id"`
	ToolCallID    string                   `json:"tool_call_id"`
	Title         string                   `json:"title"`
	Options       []map[string]interface{} `json:"options"`
	ActionType    string                   `json:"action_type"`
	ActionDetails map[string]interface{}   `json:"action_details"`
}

// GitEventData is an alias for lifecycle.GitEventPayload.
// Kept for backwards compatibility with existing handler signatures.
type GitEventData = lifecycle.GitEventPayload

// TaskMovedEventData contains data from task.moved events (manual step changes).
type TaskMovedEventData struct {
	TaskID          string `json:"task_id"`
	FromStepID      string `json:"from_step_id"`
	ToStepID        string `json:"to_step_id"`
	SessionID       string `json:"session_id"`
	WorkflowID      string `json:"workflow_id"`
	TaskDescription string `json:"task_description"`
}

// ContextWindowData contains data from context window events
type ContextWindowData struct {
	TaskID                 string  `json:"task_id"`
	TaskSessionID          string  `json:"session_id"`
	AgentID                string  `json:"agent_id"`
	ContextWindowSize      int64   `json:"context_window_size"`
	ContextWindowUsed      int64   `json:"context_window_used"`
	ContextWindowRemaining int64   `json:"context_window_remaining"`
	ContextEfficiency      float64 `json:"context_efficiency"`
	Timestamp              string  `json:"timestamp"`
}

// EventHandlers contains callbacks for different event types
type EventHandlers struct {
	// Task events
	OnTaskCreated      func(ctx context.Context, data TaskEventData)
	OnTaskUpdated      func(ctx context.Context, data TaskEventData)
	OnTaskStateChanged func(ctx context.Context, data TaskEventData)
	OnTaskDeleted      func(ctx context.Context, data TaskEventData)
	OnTaskMoved        func(ctx context.Context, data TaskMovedEventData)

	// Agent events
	OnAgentStarted      func(ctx context.Context, data AgentEventData)
	OnAgentRunning      func(ctx context.Context, data AgentEventData)
	OnAgentBootReady    func(ctx context.Context, data AgentEventData) // ACP session initialized; idle, no turn yet
	OnAgentReady        func(ctx context.Context, data AgentEventData) // Turn ended; agent idle waiting for follow-up
	OnAgentCompleted    func(ctx context.Context, data AgentEventData)
	OnAgentFailed       func(ctx context.Context, data AgentEventData)
	OnAgentStopped      func(ctx context.Context, data AgentEventData)
	OnACPSessionCreated func(ctx context.Context, data ACPSessionEventData)

	// Agent stream events (tool calls, message chunks, complete, etc.)
	OnAgentStreamEvent func(ctx context.Context, payload *lifecycle.AgentStreamEventPayload)

	// Permission request events
	OnPermissionRequest func(ctx context.Context, data PermissionRequestData)

	// Unified git events (status, commit, reset, snapshot)
	OnGitEvent func(ctx context.Context, data GitEventData)

	// Context window events
	OnContextWindowUpdated func(ctx context.Context, data ContextWindowData)
}

// Watcher subscribes to events and dispatches to handlers
type Watcher struct {
	eventBus bus.EventBus
	handlers EventHandlers
	logger   *logger.Logger
	queue    string

	subscriptions []bus.Subscription
	mu            sync.Mutex
	running       bool
}

// NewWatcher creates a new event watcher
func NewWatcher(eventBus bus.EventBus, handlers EventHandlers, queue string, log *logger.Logger) *Watcher {
	if queue == "" {
		queue = "orchestrator"
	}
	return &Watcher{
		eventBus:      eventBus,
		handlers:      handlers,
		logger:        log.WithFields(zap.String("component", "watcher")),
		queue:         queue,
		subscriptions: make([]bus.Subscription, 0),
	}
}

// Start begins watching for events
func (w *Watcher) Start(ctx context.Context) error {
	w.mu.Lock()
	defer w.mu.Unlock()

	if w.running {
		return nil
	}

	w.logger.Info("Starting event watcher")

	// Subscribe to task events
	if err := w.subscribeToTaskEvents(); err != nil {
		return err
	}

	// Subscribe to agent events
	if err := w.subscribeToAgentEvents(); err != nil {
		w.unsubscribeAll()
		return err
	}

	// Subscribe to ACP session events
	if err := w.subscribeToACPSessionEvents(); err != nil {
		w.unsubscribeAll()
		return err
	}

	// Subscribe to agent stream events
	if err := w.subscribeToAgentStreamEvents(); err != nil {
		w.unsubscribeAll()
		return err
	}

	// Subscribe to permission request events
	if err := w.subscribeToPermissionRequestEvents(); err != nil {
		w.unsubscribeAll()
		return err
	}

	// Subscribe to unified git events
	if err := w.subscribeToGitEvents(); err != nil {
		w.unsubscribeAll()
		return err
	}

	// Subscribe to context window events
	if err := w.subscribeToContextWindowEvents(); err != nil {
		w.unsubscribeAll()
		return err
	}

	w.running = true
	w.logger.Info("Event watcher started", zap.Int("subscriptions", len(w.subscriptions)))
	return nil
}

// Stop stops watching for events
func (w *Watcher) Stop() error {
	w.mu.Lock()
	defer w.mu.Unlock()

	if !w.running {
		return nil
	}

	w.logger.Info("Stopping event watcher")
	w.unsubscribeAll()
	w.running = false
	w.logger.Info("Event watcher stopped")
	return nil
}

// IsRunning returns true if the watcher is active
func (w *Watcher) IsRunning() bool {
	w.mu.Lock()
	defer w.mu.Unlock()
	return w.running
}

// unsubscribeAll removes all subscriptions (must be called with lock held)
func (w *Watcher) unsubscribeAll() {
	for _, sub := range w.subscriptions {
		if err := sub.Unsubscribe(); err != nil {
			w.logger.Error("Failed to unsubscribe", zap.Error(err))
		}
	}
	w.subscriptions = make([]bus.Subscription, 0)
}

// subscribeToTaskEvents subscribes to all task events
func (w *Watcher) subscribeToTaskEvents() error {
	taskEvents := []struct {
		subject string
		handler func(ctx context.Context, data TaskEventData)
	}{
		{events.TaskCreated, w.handlers.OnTaskCreated},
		{events.TaskUpdated, w.handlers.OnTaskUpdated},
		{events.TaskStateChanged, w.handlers.OnTaskStateChanged},
		{events.TaskDeleted, w.handlers.OnTaskDeleted},
	}

	for _, te := range taskEvents {
		if te.handler == nil {
			continue
		}
		handler := te.handler // capture for closure
		sub, err := w.eventBus.QueueSubscribe(te.subject, w.queue, w.createTaskEventHandler(handler))
		if err != nil {
			w.logger.Error("Failed to subscribe to task event",
				zap.String("subject", te.subject),
				zap.String("queue", w.queue),
				zap.Error(err))
			return err
		}
		w.subscriptions = append(w.subscriptions, sub)
	}

	// Subscribe to task.moved events (different data type from TaskEventData)
	if w.handlers.OnTaskMoved != nil {
		handler := w.handlers.OnTaskMoved
		sub, err := w.eventBus.QueueSubscribe(events.TaskMoved, w.queue, w.createTaskMovedEventHandler(handler))
		if err != nil {
			w.logger.Error("Failed to subscribe to task moved event",
				zap.String("subject", events.TaskMoved),
				zap.String("queue", w.queue),
				zap.Error(err))
			return err
		}
		w.subscriptions = append(w.subscriptions, sub)
	}

	return nil
}

// subscribeToAgentEvents subscribes to all agent events
func (w *Watcher) subscribeToAgentEvents() error {
	agentEvents := []struct {
		subject string
		handler func(ctx context.Context, data AgentEventData)
	}{
		{events.AgentStarted, w.handlers.OnAgentStarted},
		{events.AgentRunning, w.handlers.OnAgentRunning},
		{events.AgentBootReady, w.handlers.OnAgentBootReady},
		{events.AgentReady, w.handlers.OnAgentReady},
		{events.AgentCompleted, w.handlers.OnAgentCompleted},
		{events.AgentFailed, w.handlers.OnAgentFailed},
		{events.AgentStopped, w.handlers.OnAgentStopped},
	}

	for _, ae := range agentEvents {
		if ae.handler == nil {
			continue
		}
		handler := ae.handler // capture for closure
		sub, err := w.eventBus.QueueSubscribe(ae.subject, w.queue, w.createAgentEventHandler(handler))
		if err != nil {
			w.logger.Error("Failed to subscribe to agent event",
				zap.String("subject", ae.subject),
				zap.String("queue", w.queue),
				zap.Error(err))
			return err
		}
		w.subscriptions = append(w.subscriptions, sub)
	}
	return nil
}

// subscribeToACPSessionEvents subscribes to ACP session lifecycle events
func (w *Watcher) subscribeToACPSessionEvents() error {
	if w.handlers.OnACPSessionCreated == nil {
		return nil
	}

	sub, err := w.eventBus.QueueSubscribe(events.AgentACPSessionCreated, w.queue, w.createACPSessionEventHandler(w.handlers.OnACPSessionCreated))
	if err != nil {
		w.logger.Error("Failed to subscribe to ACP session event",
			zap.String("subject", events.AgentACPSessionCreated),
			zap.String("queue", w.queue),
			zap.Error(err))
		return err
	}
	w.subscriptions = append(w.subscriptions, sub)
	return nil
}

// subscribeToAgentStreamEvents subscribes to agent stream events using wildcard
func (w *Watcher) subscribeToAgentStreamEvents() error {
	if w.handlers.OnAgentStreamEvent == nil {
		return nil
	}

	// Use wildcard to subscribe to all agent stream events (agent.stream.*)
	subject := events.BuildAgentStreamWildcardSubject()

	// Use regular subscription (each instance needs all messages for WebSocket streaming)
	sub, err := w.eventBus.Subscribe(subject, w.createAgentStreamEventHandler())
	if err != nil {
		w.logger.Error("Failed to subscribe to agent stream events",
			zap.String("subject", subject),
			zap.Error(err))
		return err
	}
	w.subscriptions = append(w.subscriptions, sub)
	return nil
}

// createTaskEventHandler creates a bus.EventHandler for task events
func (w *Watcher) createTaskEventHandler(handler func(ctx context.Context, data TaskEventData)) bus.EventHandler {
	return func(ctx context.Context, event *bus.Event) error {
		var data TaskEventData
		if err := w.parseEventData(event.Data, &data); err != nil {
			w.logger.Error("Failed to parse task event data",
				zap.String("event_type", event.Type),
				zap.String("event_id", event.ID),
				zap.Error(err))
			return nil // Don't return error to continue processing other events
		}

		w.logger.Debug("Handling task event",
			zap.String("event_type", event.Type),
			zap.String("task_id", data.TaskID))

		handler(ctx, data)
		return nil
	}
}

// createTaskMovedEventHandler creates a bus.EventHandler for task.moved events
func (w *Watcher) createTaskMovedEventHandler(handler func(ctx context.Context, data TaskMovedEventData)) bus.EventHandler {
	return func(ctx context.Context, event *bus.Event) error {
		var data TaskMovedEventData
		if err := w.parseEventData(event.Data, &data); err != nil {
			w.logger.Error("Failed to parse task moved event data",
				zap.String("event_type", event.Type),
				zap.String("event_id", event.ID),
				zap.Error(err))
			return nil
		}

		w.logger.Debug("Handling task moved event",
			zap.String("task_id", data.TaskID),
			zap.String("from_step", data.FromStepID),
			zap.String("to_step", data.ToStepID))

		handler(ctx, data)
		return nil
	}
}

// createAgentEventHandler creates a bus.EventHandler for agent events
func (w *Watcher) createAgentEventHandler(handler func(ctx context.Context, data AgentEventData)) bus.EventHandler {
	return func(ctx context.Context, event *bus.Event) error {

		var data AgentEventData
		if err := w.parseEventData(event.Data, &data); err != nil {
			w.logger.Error("Failed to parse agent event data",
				zap.String("event_type", event.Type),
				zap.String("event_id", event.ID),
				zap.Error(err))
			return nil // Don't return error to continue processing other events
		}

		w.logger.Debug("Handling agent event",
			zap.String("event_type", event.Type),
			zap.String("task_id", data.TaskID),
			zap.String("agent_execution_id", data.AgentExecutionID))

		handler(ctx, data)
		return nil
	}
}

// createACPSessionEventHandler creates a bus.EventHandler for ACP session events
func (w *Watcher) createACPSessionEventHandler(handler func(ctx context.Context, data ACPSessionEventData)) bus.EventHandler {
	return func(ctx context.Context, event *bus.Event) error {
		var data ACPSessionEventData
		if err := w.parseEventData(event.Data, &data); err != nil {
			w.logger.Error("Failed to parse ACP session event data",
				zap.String("event_type", event.Type),
				zap.String("event_id", event.ID),
				zap.Error(err))
			return nil
		}

		w.logger.Debug("Handling ACP session event",
			zap.String("event_type", event.Type),
			zap.String("task_id", data.TaskID),
			zap.String("acp_session_id", data.ACPSessionID))

		handler(ctx, data)
		return nil
	}
}

// createAgentStreamEventHandler creates a bus.EventHandler for agent stream events
func (w *Watcher) createAgentStreamEventHandler() bus.EventHandler {
	return func(ctx context.Context, event *bus.Event) error {
		// Parse the agent stream event payload
		var payload lifecycle.AgentStreamEventPayload
		if err := w.parseEventData(event.Data, &payload); err != nil {
			w.logger.Error("Failed to parse agent stream event",
				zap.String("event_id", event.ID),
				zap.Error(err))
			return nil // Don't return error to continue processing other events
		}

		// Validate required fields
		if payload.TaskID == "" {
			w.logger.Warn("Agent stream event missing task_id",
				zap.String("event_id", event.ID))
			return nil
		}

		eventType := ""
		if payload.Data != nil {
			eventType = payload.Data.Type
		}

		w.logger.Debug("Handling agent stream event",
			zap.String("task_id", payload.TaskID),
			zap.String("session_id", payload.SessionID),
			zap.String("event_type", eventType))

		w.handlers.OnAgentStreamEvent(ctx, &payload)
		return nil
	}
}

// subscribeToPermissionRequestEvents subscribes to permission request events
func (w *Watcher) subscribeToPermissionRequestEvents() error {
	if w.handlers.OnPermissionRequest == nil {
		return nil
	}

	// Use wildcard to subscribe to all permission request events (permission_request.received.{session_id})
	subject := events.BuildPermissionRequestWildcardSubject()
	sub, err := w.eventBus.Subscribe(subject, w.createPermissionRequestHandler())
	if err != nil {
		w.logger.Error("Failed to subscribe to permission request events",
			zap.String("subject", subject),
			zap.Error(err))
		return err
	}
	w.subscriptions = append(w.subscriptions, sub)
	return nil
}

// createPermissionRequestHandler creates a bus.EventHandler for permission request events
func (w *Watcher) createPermissionRequestHandler() bus.EventHandler {
	return func(ctx context.Context, event *bus.Event) error {
		var data PermissionRequestData
		if err := w.parseEventData(event.Data, &data); err != nil {
			w.logger.Error("Failed to parse permission request event data",
				zap.String("event_type", event.Type),
				zap.String("event_id", event.ID),
				zap.Error(err))
			return nil
		}

		w.logger.Debug("Handling permission request event",
			zap.String("task_id", data.TaskID),
			zap.String("pending_id", data.PendingID),
			zap.String("title", data.Title))

		w.handlers.OnPermissionRequest(ctx, data)
		return nil
	}
}

// subscribeToGitEvents subscribes to unified git events
func (w *Watcher) subscribeToGitEvents() error {
	if w.handlers.OnGitEvent == nil {
		return nil
	}

	subject := events.BuildGitEventWildcardSubject()

	sub, err := w.eventBus.Subscribe(subject, w.createGitEventHandler())
	if err != nil {
		w.logger.Error("Failed to subscribe to git events",
			zap.String("subject", subject),
			zap.Error(err))
		return err
	}
	w.subscriptions = append(w.subscriptions, sub)
	return nil
}

// createGitEventHandler creates a bus.EventHandler for unified git events
func (w *Watcher) createGitEventHandler() bus.EventHandler {
	return func(ctx context.Context, event *bus.Event) error {
		var data GitEventData
		if err := w.parseEventData(event.Data, &data); err != nil {
			w.logger.Error("Failed to parse git event data",
				zap.String("event_type", event.Type),
				zap.String("event_id", event.ID),
				zap.Error(err))
			return nil
		}

		w.logger.Debug("Handling git event",
			zap.String("type", string(data.Type)),
			zap.String("task_id", data.TaskID),
			zap.String("session_id", data.SessionID))

		w.handlers.OnGitEvent(ctx, data)
		return nil
	}
}

// subscribeToContextWindowEvents subscribes to context window events
func (w *Watcher) subscribeToContextWindowEvents() error {
	if w.handlers.OnContextWindowUpdated == nil {
		return nil
	}

	// Use wildcard to subscribe to all context window events (context_window.updated.{session_id})
	subject := events.BuildContextWindowWildcardSubject()

	// Use regular subscription (each instance needs all messages)
	sub, err := w.eventBus.Subscribe(subject, w.createContextWindowHandler())
	if err != nil {
		w.logger.Error("Failed to subscribe to context window events",
			zap.String("subject", subject),
			zap.Error(err))
		return err
	}
	w.subscriptions = append(w.subscriptions, sub)
	return nil
}

// createContextWindowHandler creates a bus.EventHandler for context window events
func (w *Watcher) createContextWindowHandler() bus.EventHandler {
	return func(ctx context.Context, event *bus.Event) error {
		var data ContextWindowData
		if err := w.parseEventData(event.Data, &data); err != nil {
			w.logger.Error("Failed to parse context window event data",
				zap.String("event_type", event.Type),
				zap.String("event_id", event.ID),
				zap.Error(err))
			return nil // Don't return error to continue processing other events
		}

		w.logger.Debug("Handling context window event",
			zap.String("task_id", data.TaskID),
			zap.String("session_id", data.TaskSessionID),
			zap.Int64("size", data.ContextWindowSize),
			zap.Int64("used", data.ContextWindowUsed))

		w.handlers.OnContextWindowUpdated(ctx, data)
		return nil
	}
}

// parseEventData converts event data (map or struct) to a typed struct
func (w *Watcher) parseEventData(data interface{}, target interface{}) error {
	// Marshal to JSON and unmarshal to target type
	jsonData, err := json.Marshal(data)
	if err != nil {
		return err
	}
	return json.Unmarshal(jsonData, target)
}