websocket_handler.py

"""
WebSocket Handler for Real-time STT/TTS
"""
from fastapi import WebSocket, WebSocketDisconnect, HTTPException
from typing import Dict, Any, Optional
import json
import asyncio
import base64
from datetime import datetime
import sys
import numpy as np
from enum import Enum

from session import Session, session_store
from config_provider import ConfigProvider
from chat_handler import handle_new_message, handle_parameter_followup
from stt_factory import STTFactory
from tts_factory import TTSFactory
from utils import log

# ========================= CONSTANTS =========================
SILENCE_THRESHOLD_MS = 2000
AUDIO_CHUNK_SIZE = 4096
ENERGY_THRESHOLD = 0.01

# ========================= ENUMS =========================
class ConversationState(Enum):
    IDLE = "idle"
    LISTENING = "listening"
    PROCESSING_STT = "processing_stt"
    PROCESSING_LLM = "processing_llm"
    PROCESSING_TTS = "processing_tts"
    PLAYING_AUDIO = "playing_audio"

# ========================= CLASSES =========================
class AudioBuffer:
    """Buffer for accumulating audio chunks"""
    def __init__(self):
        self.chunks = []
        self.total_size = 0
        
    def add_chunk(self, chunk_data: str):
        """Add base64 encoded audio chunk"""
        decoded = base64.b64decode(chunk_data)
        self.chunks.append(decoded)
        self.total_size += len(decoded)
        
    def get_audio(self) -> bytes:
        """Get concatenated audio data"""
        return b''.join(self.chunks)
        
    def clear(self):
        """Clear buffer"""
        self.chunks.clear()
        self.total_size = 0

class SilenceDetector:
    """Detect silence in audio stream"""
    def __init__(self, threshold_ms: int = SILENCE_THRESHOLD_MS, energy_threshold: float = ENERGY_THRESHOLD):
        self.threshold_ms = threshold_ms
        self.energy_threshold = energy_threshold
        self.silence_start = None
        self.sample_rate = 16000  # Default sample rate
        
    def is_silence(self, audio_chunk: bytes) -> bool:
        """Check if audio chunk is silence"""
        try:
            # Convert bytes to numpy array (assuming 16-bit PCM)
            audio_data = np.frombuffer(audio_chunk, dtype=np.int16)
            
            # Calculate RMS energy
            rms = np.sqrt(np.mean(audio_data**2))
            normalized_rms = rms / 32768.0  # Normalize for 16-bit audio
            
            return normalized_rms < self.energy_threshold
        except Exception as e:
            log(f"⚠️ Silence detection error: {e}")
            return False
    
    def update(self, audio_chunk: bytes) -> Optional[int]:
        """Update silence detection and return silence duration in ms"""
        is_silent = self.is_silence(audio_chunk)
        
        if is_silent:
            if self.silence_start is None:
                self.silence_start = datetime.now()
                log("🔇 Silence started")
            else:
                silence_duration = (datetime.now() - self.silence_start).total_seconds() * 1000
                return int(silence_duration)
        else:
            if self.silence_start is not None:
                log("🔊 Speech detected, silence broken")
            self.silence_start = None
            
        return 0

class BargeInHandler:
    """Handle barge-in (interruption) logic"""
    def __init__(self):
        self.interrupted_at_state: Optional[ConversationState] = None
        self.accumulated_text: str = ""
        self.pending_audio_chunks = []
        
    def handle_interruption(self, current_state: ConversationState):
        """Handle user interruption"""
        self.interrupted_at_state = current_state
        log(f"🛑 Barge-in detected at state: {current_state.value}")
        
    def should_preserve_context(self) -> bool:
        """Check if context should be preserved after interruption"""
        # Preserve context if interrupted during LLM or TTS processing
        return self.interrupted_at_state in [
            ConversationState.PROCESSING_LLM,
            ConversationState.PROCESSING_TTS,
            ConversationState.PLAYING_AUDIO
        ]

class ConversationManager:
    """Manage conversation state and flow"""
    def __init__(self, session: Session):
        self.session = session
        self.state = ConversationState.IDLE
        self.audio_buffer = AudioBuffer()
        self.silence_detector = SilenceDetector()
        self.barge_in_handler = BargeInHandler()
        self.stt_manager = None
        self.current_transcription = ""
        self.is_streaming = False
        
    async def initialize_stt(self):
        """Initialize STT provider"""
        try:
            self.stt_manager = STTFactory.create_provider()
            if self.stt_manager:
                config = ConfigProvider.get().global_config.stt_settings
                await self.stt_manager.start_streaming({
                    "language": config.get("language", "tr-TR"),
                    "interim_results": config.get("interim_results", True),
                    "single_utterance": False,  # Important for continuous listening
                    "enable_punctuation": config.get("enable_punctuation", True)
                })
                log("✅ STT manager initialized")
                return True
        except Exception as e:
            log(f"❌ Failed to initialize STT: {e}")
        return False
        
    def change_state(self, new_state: ConversationState):
        """Change conversation state"""
        old_state = self.state
        self.state = new_state
        log(f"📊 State change: {old_state.value} → {new_state.value}")
        
    def handle_barge_in(self):
        """Handle user interruption"""
        self.barge_in_handler.handle_interruption(self.state)
        self.change_state(ConversationState.LISTENING)
        
    def reset_audio_buffer(self):
        """Reset audio buffer for new utterance"""
        self.audio_buffer.clear()
        self.silence_detector.silence_start = None
        self.current_transcription = ""

# ========================= WEBSOCKET HANDLER =========================
async def websocket_endpoint(websocket: WebSocket, session_id: str):
    """Main WebSocket endpoint for real-time conversation"""
    await websocket.accept()
    log(f"🔌 WebSocket connected for session: {session_id}")
    
    # Get session
    session = session_store.get_session(session_id)
    if not session:
        await websocket.send_json({
            "type": "error",
            "message": "Session not found"
        })
        await websocket.close()
        return
        
    # Initialize conversation manager
    conversation = ConversationManager(session)
    
    # Initialize STT
    stt_initialized = await conversation.initialize_stt()
    if not stt_initialized:
        await websocket.send_json({
            "type": "error", 
            "message": "STT initialization failed"
        })
    
    try:
        while True:
            # Receive message
            message = await websocket.receive_json()
            message_type = message.get("type")
            
            if message_type == "audio_chunk":
                await handle_audio_chunk(websocket, conversation, message)
                
            elif message_type == "control":
                await handle_control_message(websocket, conversation, message)
                
            elif message_type == "ping":
                # Keep-alive ping
                await websocket.send_json({"type": "pong"})
                
    except WebSocketDisconnect:
        log(f"🔌 WebSocket disconnected for session: {session_id}")
        await cleanup_conversation(conversation)
    except Exception as e:
        log(f"❌ WebSocket error: {e}")
        await websocket.send_json({
            "type": "error",
            "message": str(e)
        })
        await cleanup_conversation(conversation)

# ========================= MESSAGE HANDLERS =========================
async def handle_audio_chunk(websocket: WebSocket, conversation: ConversationManager, message: Dict[str, Any]):
    """Handle incoming audio chunk"""
    try:
        audio_data = message.get("data")
        if not audio_data:
            return
            
        # Check for barge-in
        if conversation.state in [ConversationState.PLAYING_AUDIO, ConversationState.PROCESSING_TTS]:
            conversation.handle_barge_in()
            await websocket.send_json({
                "type": "control",
                "action": "stop_playback"
            })
            
        # Change state to listening if idle
        if conversation.state == ConversationState.IDLE:
            conversation.change_state(ConversationState.LISTENING)
            await websocket.send_json({
                "type": "state_change",
                "from": "idle",
                "to": "listening"
            })
            
        # Add to buffer
        conversation.audio_buffer.add_chunk(audio_data)
        
        # Decode for processing
        decoded_audio = base64.b64decode(audio_data)
        
        # Check silence
        silence_duration = conversation.silence_detector.update(decoded_audio)
        
        # Stream to STT if available
        if conversation.stt_manager and conversation.state == ConversationState.LISTENING:
            async for result in conversation.stt_manager.stream_audio(decoded_audio):
                # Send interim results
                await websocket.send_json({
                    "type": "transcription",
                    "text": result.text,
                    "is_final": result.is_final,
                    "confidence": result.confidence
                })
                
                if result.is_final:
                    conversation.current_transcription = result.text
                    
        # Check if user stopped speaking (2 seconds of silence)
        if silence_duration > SILENCE_THRESHOLD_MS and conversation.current_transcription:
            log(f"🔇 User stopped speaking after {silence_duration}ms of silence")
            await process_user_input(websocket, conversation)
            
    except Exception as e:
        log(f"❌ Audio chunk handling error: {e}")
        await websocket.send_json({
            "type": "error",
            "message": f"Audio processing error: {str(e)}"
        })

async def handle_control_message(websocket: WebSocket, conversation: ConversationManager, message: Dict[str, Any]):
    """Handle control messages"""
    action = message.get("action")
    
    if action == "start_session":
        # Session already started
        await websocket.send_json({
            "type": "session_started",
            "session_id": conversation.session.session_id
        })
        
    elif action == "end_session":
        # Clean up and close
        await cleanup_conversation(conversation)
        await websocket.close()
        
    elif action == "interrupt":
        # Handle explicit interrupt
        conversation.handle_barge_in()
        await websocket.send_json({
            "type": "control",
            "action": "interrupt_acknowledged"
        })
        
    elif action == "reset":
        # Reset conversation state
        conversation.reset_audio_buffer()
        conversation.change_state(ConversationState.IDLE)
        await websocket.send_json({
            "type": "state_change",
            "from": conversation.state.value,
            "to": "idle"
        })

# ========================= PROCESSING FUNCTIONS =========================
async def process_user_input(websocket: WebSocket, conversation: ConversationManager):
    """Process complete user input"""
    try:
        user_text = conversation.current_transcription
        if not user_text:
            conversation.reset_audio_buffer()
            conversation.change_state(ConversationState.IDLE)
            return
            
        log(f"💬 Processing user input: {user_text}")
        
        # Change state to processing
        conversation.change_state(ConversationState.PROCESSING_STT)
        await websocket.send_json({
            "type": "state_change",
            "from": "listening",
            "to": "processing_stt"
        })
        
        # Send final transcription
        await websocket.send_json({
            "type": "transcription",
            "text": user_text,
            "is_final": True,
            "confidence": 0.95
        })
        
        # Process with LLM
        conversation.change_state(ConversationState.PROCESSING_LLM)
        await websocket.send_json({
            "type": "state_change",
            "from": "processing_stt",
            "to": "processing_llm"
        })
        
        # Add to session history
        conversation.session.add_turn("user", user_text)
        
        # Get response based on session state
        if conversation.session.state == "await_param":
            response_text = await handle_parameter_followup(conversation.session, user_text)
        else:
            response_text = await handle_new_message(conversation.session, user_text)
            
        # Add response to history
        conversation.session.add_turn("assistant", response_text)
        
        # Send text response
        await websocket.send_json({
            "type": "assistant_response",
            "text": response_text
        })
        
        # Generate TTS if enabled
        tts_provider = TTSFactory.create_provider()
        if tts_provider:
            conversation.change_state(ConversationState.PROCESSING_TTS)
            await websocket.send_json({
                "type": "state_change",
                "from": "processing_llm",
                "to": "processing_tts"
            })
            
            # Generate audio
            audio_data = await tts_provider.synthesize(response_text)
            
            # Send audio in chunks
            chunk_size = 4096
            for i in range(0, len(audio_data), chunk_size):
                chunk = audio_data[i:i + chunk_size]
                await websocket.send_json({
                    "type": "tts_audio",
                    "data": base64.b64encode(chunk).decode('utf-8'),
                    "chunk_index": i // chunk_size,
                    "is_last": i + chunk_size >= len(audio_data)
                })
                
            conversation.change_state(ConversationState.PLAYING_AUDIO)
            await websocket.send_json({
                "type": "state_change",
                "from": "processing_tts",
                "to": "playing_audio"
            })
        else:
            # No TTS, go back to idle
            conversation.change_state(ConversationState.IDLE)
            await websocket.send_json({
                "type": "state_change",
                "from": "processing_llm",
                "to": "idle"
            })
            
        # Reset for next input
        conversation.reset_audio_buffer()
        
    except Exception as e:
        log(f"❌ Error processing user input: {e}")
        await websocket.send_json({
            "type": "error",
            "message": f"Processing error: {str(e)}"
        })
        conversation.reset_audio_buffer()
        conversation.change_state(ConversationState.IDLE)

# ========================= CLEANUP =========================
async def cleanup_conversation(conversation: ConversationManager):
    """Clean up conversation resources"""
    try:
        if conversation.stt_manager:
            await conversation.stt_manager.stop_streaming()
        log(f"🧹 Cleaned up conversation for session: {conversation.session.session_id}")
    except Exception as e:
        log(f"⚠️ Cleanup error: {e}")