transcribe/transcription.py

import logging 
import time
import functools
import json
import logging
import time
from enum import Enum
from typing import List, Optional
import numpy as np
from .server import ServeClientBase
from .whisper_llm_serve import PyWhiperCppServe
from .vad import VoiceActivityDetector
from urllib.parse import urlparse, parse_qsl
from websockets.exceptions import ConnectionClosed
from websockets.sync.server import serve
from uuid import uuid1


logging.basicConfig(level=logging.INFO)


class ClientManager:
    def __init__(self, max_clients=4, max_connection_time=600):
        """
        Initializes the ClientManager with specified limits on client connections and connection durations.

        Args:
            max_clients (int, optional): The maximum number of simultaneous client connections allowed. Defaults to 4.
            max_connection_time (int, optional): The maximum duration (in seconds) a client can stay connected. Defaults
                                                 to 600 seconds (10 minutes).
        """
        self.clients = {}
        self.start_times = {}
        self.max_clients = max_clients
        self.max_connection_time = max_connection_time

    def add_client(self, websocket, client):
        """
        Adds a client and their connection start time to the tracking dictionaries.

        Args:
            websocket: The websocket associated with the client to add.
            client: The client object to be added and tracked.
        """
        self.clients[websocket] = client
        self.start_times[websocket] = time.time()

    def get_client(self, websocket):
        """
        Retrieves a client associated with the given websocket.

        Args:
            websocket: The websocket associated with the client to retrieve.

        Returns:
            The client object if found, False otherwise.
        """
        if websocket in self.clients:
            return self.clients[websocket]
        return False

    def remove_client(self, websocket):
        """
        Removes a client and their connection start time from the tracking dictionaries. Performs cleanup on the
        client if necessary.

        Args:
            websocket: The websocket associated with the client to be removed.
        """
        client = self.clients.pop(websocket, None)
        if client:
            client.cleanup()
        self.start_times.pop(websocket, None)

    def get_wait_time(self):
        """
        Calculates the estimated wait time for new clients based on the remaining connection times of current clients.

        Returns:
            The estimated wait time in minutes for new clients to connect. Returns 0 if there are available slots.
        """
        wait_time = None
        for start_time in self.start_times.values():
            current_client_time_remaining = self.max_connection_time - (time.time() - start_time)
            if wait_time is None or current_client_time_remaining < wait_time:
                wait_time = current_client_time_remaining
        return wait_time / 60 if wait_time is not None else 0

    def is_server_full(self, websocket, options):
        """
        Checks if the server is at its maximum client capacity and sends a wait message to the client if necessary.

        Args:
            websocket: The websocket of the client attempting to connect.
            options: A dictionary of options that may include the client's unique identifier.

        Returns:
            True if the server is full, False otherwise.
        """
        if len(self.clients) >= self.max_clients:
            wait_time = self.get_wait_time()
            response = {"uid": options["uid"], "status": "WAIT", "message": wait_time}
            websocket.send(json.dumps(response))
            return True
        return False

    def is_client_timeout(self, websocket):
        """
        Checks if a client has exceeded the maximum allowed connection time and disconnects them if so, issuing a warning.

        Args:
            websocket: The websocket associated with the client to check.

        Returns:
            True if the client's connection time has exceeded the maximum limit, False otherwise.
        """
        elapsed_time = time.time() - self.start_times[websocket]
        if elapsed_time >= self.max_connection_time:
            self.clients[websocket].disconnect()
            logging.warning(f"Client with uid '{self.clients[websocket].client_uid}' disconnected due to overtime.")
            return True
        return False


class BackendType(Enum):
    PYWHISPERCPP = "pywhispercpp"

    @staticmethod
    def valid_types() -> List[str]:
        return [backend_type.value for backend_type in BackendType]

    @staticmethod
    def is_valid(backend: str) -> bool:
        return backend in BackendType.valid_types()

    def is_pywhispercpp(self) -> bool:
        return self == BackendType.PYWHISPERCPP


class TranscriptionServer:
    RATE = 16000

    def __init__(self):
        self.client_manager = None
        self.no_voice_activity_chunks = 0
        self.single_model = False

    def initialize_client(
            self, websocket, options
    ):
        client: Optional[ServeClientBase] = None

        if self.backend.is_pywhispercpp():
            client = PyWhiperCppServe(
                websocket,
                language=options["language"],
                client_uid=options["uid"],
            )
            logging.info("Running pywhispercpp backend.")

        if client is None:
            raise ValueError(f"Backend type {self.backend.value} not recognised or not handled.")

        self.client_manager.add_client(websocket, client)

    def get_audio_from_websocket(self, websocket):
        """
        Receives audio buffer from websocket and creates a numpy array out of it.

        Args:
            websocket: The websocket to receive audio from.

        Returns:
            A numpy array containing the audio.
        """
        frame_data = websocket.recv()
        if frame_data == b"END_OF_AUDIO":
            return False
        return np.frombuffer(frame_data, dtype=np.int16).astype(np.float32) / 32768.0
        # return np.frombuffer(frame_data, dtype=np.float32)


    def handle_new_connection(self, websocket):
        query_parameters_dict = dict(parse_qsl(urlparse(websocket.request.path).query))
        from_lang, to_lang = query_parameters_dict.get('from'), query_parameters_dict.get('to')

        try:
            logging.info("New client connected")
            options = websocket.recv()
            try:
                options = json.loads(options)
            except Exception as e:
                options = {"language": from_lang, "uid": str(uuid1())}
            if self.client_manager is None:
                max_clients = options.get('max_clients', 4)
                max_connection_time = options.get('max_connection_time', 600)
                self.client_manager = ClientManager(max_clients, max_connection_time)

            if self.client_manager.is_server_full(websocket, options):
                websocket.close()
                return False  # Indicates that the connection should not continue

            if self.backend.is_pywhispercpp():
                self.vad_detector = VoiceActivityDetector(frame_rate=self.RATE)

            self.initialize_client(websocket, options)
            if from_lang and to_lang:
                self.set_lang(websocket, from_lang, to_lang)
                logging.info(f"Source lange: {from_lang}  -> Dst lange: {to_lang}")
            return True
        except json.JSONDecodeError:
            logging.error("Failed to decode JSON from client")
            return False
        except ConnectionClosed:
            logging.info("Connection closed by client")
            return False
        except Exception as e:
            logging.error(f"Error during new connection initialization: {str(e)}")
            return False

    def process_audio_frames(self, websocket):
        frame_np = self.get_audio_from_websocket(websocket)
        client = self.client_manager.get_client(websocket)

        # TODO Vad has some problem, it will be blocking process loop
        # if frame_np is False:
        #     if self.backend.is_pywhispercpp():
        #         client.set_eos(True)
        #     return False

        # if self.backend.is_pywhispercpp():
        #     voice_active = self.voice_activity(websocket, frame_np)
        #     if voice_active:
        #         self.no_voice_activity_chunks = 0
        #         client.set_eos(False)
        #     if self.use_vad and not voice_active:
        #         return True

        client.add_frames(frame_np)
        return True
    
    def set_lang(self, websocket, src_lang, dst_lang):
        client = self.client_manager.get_client(websocket)
        if isinstance(client, PyWhiperCppServe):
            client.set_lang(src_lang, dst_lang)

    def recv_audio(self,
                   websocket,
                   backend: BackendType = BackendType.PYWHISPERCPP):

        self.backend = backend
        if not self.handle_new_connection(websocket):
            return
       

        try:
            while not self.client_manager.is_client_timeout(websocket):
                if not self.process_audio_frames(websocket):
                    break
        except ConnectionClosed:
            logging.info("Connection closed by client")
        except Exception as e:
            logging.error(f"Unexpected error: {str(e)}")
        finally:
            if self.client_manager.get_client(websocket):
                self.cleanup(websocket)
                websocket.close()
            del websocket

    def run(self,
            host,
            port=9090,
            backend="pywhispercpp"):
        """
        Run the transcription server.

        Args:
            host (str): The host address to bind the server.
            port (int): The port number to bind the server.
        """

        if not BackendType.is_valid(backend):
            raise ValueError(f"{backend} is not a valid backend type. Choose backend from {BackendType.valid_types()}")

        with serve(
                functools.partial(
                    self.recv_audio,
                    backend=BackendType(backend),
                ),
                host,
                port
        ) as server:
            server.serve_forever()

    def voice_activity(self, websocket, frame_np):
        """
        Evaluates the voice activity in a given audio frame and manages the state of voice activity detection.

        This method uses the configured voice activity detection (VAD) model to assess whether the given audio frame
        contains speech. If the VAD model detects no voice activity for more than three consecutive frames,
        it sets an end-of-speech (EOS) flag for the associated client. This method aims to efficiently manage
        speech detection to improve subsequent processing steps.

        Args:
            websocket: The websocket associated with the current client. Used to retrieve the client object
                    from the client manager for state management.
            frame_np (numpy.ndarray): The audio frame to be analyzed. This should be a NumPy array containing
                                    the audio data for the current frame.

        Returns:
            bool: True if voice activity is detected in the current frame, False otherwise. When returning False
                after detecting no voice activity for more than three consecutive frames, it also triggers the
                end-of-speech (EOS) flag for the client.
        """
        if not self.vad_detector(frame_np):
            self.no_voice_activity_chunks += 1
            if self.no_voice_activity_chunks > 3:
                client = self.client_manager.get_client(websocket)
                if not client.eos:
                    client.set_eos(True)
                time.sleep(0.1)  # Sleep 100m; wait some voice activity.
            return False
        return True

    def cleanup(self, websocket):
        """
        Cleans up resources associated with a given client's websocket.

        Args:
            websocket: The websocket associated with the client to be cleaned up.
        """
        if self.client_manager.get_client(websocket):
            self.client_manager.remove_client(websocket)