package renderer

import (
	"context"
	"fmt"
)

// Service controls Unreal Engine avatar rendering
type Service interface {
	StartSession(ctx context.Context, sessionID string) error
	StopSession(ctx context.Context, sessionID string) error
	SendAnimationParams(ctx context.Context, sessionID string, params *AnimationParams) error
	GetVideoStream(ctx context.Context, sessionID string) (string, error) // Returns WebRTC stream URL
}

// AnimationParams contains animation parameters for the avatar
type AnimationParams struct {
	Visemes     []VisemeEvent
	Expressions *ExpressionParams
	Gestures    []GestureEvent
	Gaze        *GazeParams
}

// VisemeEvent represents a viseme (lip shape) event
type VisemeEvent struct {
	Viseme    string
	StartTime float64
	EndTime   float64
	Intensity float64
}

// ExpressionParams contains facial expression parameters
type ExpressionParams struct {
	Valence float64 // -1.0 to 1.0
	Arousal float64 // 0.0 to 1.0
	Emotion string  // e.g., "happy", "neutral", "concerned"
}

// GestureEvent represents a gesture event
type GestureEvent struct {
	Type      string  // e.g., "nod", "point", "wave"
	StartTime float64
	Duration  float64
	Intensity float64
}

// GazeParams contains gaze/head tracking parameters
type GazeParams struct {
	TargetX float64
	TargetY float64
	TargetZ float64
}

// PixelStreamingService implements avatar rendering using Unreal PixelStreaming
type PixelStreamingService struct {
	unrealInstances map[string]*UnrealInstance
}

// UnrealInstance represents a running Unreal Engine instance
type UnrealInstance struct {
	SessionID   string
	ProcessID   int
	StreamURL   string
	Status      string // "starting", "running", "stopping", "stopped"
}

// NewPixelStreamingService creates a new PixelStreaming service
func NewPixelStreamingService() *PixelStreamingService {
	return &PixelStreamingService{
		unrealInstances: make(map[string]*UnrealInstance),
	}
}

// StartSession starts an Unreal instance for a session
func (s *PixelStreamingService) StartSession(ctx context.Context, sessionID string) error {
	// TODO: Launch Unreal Engine with PixelStreaming enabled
	// This would involve:
	// 1. Starting Unreal Engine process with command-line args for PixelStreaming
	// 2. Configuring the instance for the session
	// 3. Getting the WebRTC stream URL
	// 4. Storing instance info

	instance := &UnrealInstance{
		SessionID: sessionID,
		Status:    "starting",
	}

	s.unrealInstances[sessionID] = instance

	// Simulate instance startup
	instance.Status = "running"
	instance.StreamURL = fmt.Sprintf("ws://localhost:8888/stream/%s", sessionID)

	return nil
}

// StopSession stops an Unreal instance
func (s *PixelStreamingService) StopSession(ctx context.Context, sessionID string) error {
	instance, ok := s.unrealInstances[sessionID]
	if !ok {
		return fmt.Errorf("instance not found for session: %s", sessionID)
	}

	instance.Status = "stopping"
	// TODO: Terminate Unreal Engine process
	instance.Status = "stopped"
	delete(s.unrealInstances, sessionID)

	return nil
}

// SendAnimationParams sends animation parameters to Unreal
func (s *PixelStreamingService) SendAnimationParams(ctx context.Context, sessionID string, params *AnimationParams) error {
	instance, ok := s.unrealInstances[sessionID]
	if !ok {
		return fmt.Errorf("instance not found for session: %s", sessionID)
	}

	// TODO: Send parameters via WebSocket or HTTP to Unreal PixelStreaming plugin
	// This would involve:
	// 1. Serializing AnimationParams to JSON
	// 2. Sending to Unreal instance's control endpoint
	// 3. Unreal receives and applies to avatar

	_ = instance // Use instance

	return nil
}

// GetVideoStream returns the WebRTC stream URL for a session
func (s *PixelStreamingService) GetVideoStream(ctx context.Context, sessionID string) (string, error) {
	instance, ok := s.unrealInstances[sessionID]
	if !ok {
		return "", fmt.Errorf("instance not found for session: %s", sessionID)
	}

	if instance.Status != "running" {
		return "", fmt.Errorf("instance not running for session: %s", sessionID)
	}

	return instance.StreamURL, nil
}