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import logging
import threading
import queue
import time
import numpy as np
import pyaudiowpatch as pyaudio

log = logging.getLogger("LiveTrans.Audio")

DEVICE_CHECK_INTERVAL = 2.0  # seconds


def list_output_devices():
    """Return list of WASAPI output device names."""
    pa = pyaudio.PyAudio()
    devices = []
    wasapi_idx = None
    for i in range(pa.get_host_api_count()):
        info = pa.get_host_api_info_by_index(i)
        if "WASAPI" in info["name"]:
            wasapi_idx = info["index"]
            break
    if wasapi_idx is not None:
        for i in range(pa.get_device_count()):
            dev = pa.get_device_info_by_index(i)
            if (dev["hostApi"] == wasapi_idx
                    and dev["maxOutputChannels"] > 0
                    and not dev.get("isLoopbackDevice", False)):
                devices.append(dev["name"])
    pa.terminate()
    return devices


class AudioCapture:
    """Capture system audio via WASAPI loopback using pyaudiowpatch."""

    def __init__(self, device=None, sample_rate=16000, chunk_duration=0.5):
        self.sample_rate = sample_rate
        self.chunk_duration = chunk_duration
        self.audio_queue = queue.Queue(maxsize=100)
        self._stream = None
        self._running = False
        self._device_name = device
        self._pa = pyaudio.PyAudio()
        self._read_thread = None
        self._native_channels = 2
        self._native_rate = 44100
        self._current_device_name = None
        self._lock = threading.Lock()

    def _get_wasapi_info(self):
        for i in range(self._pa.get_host_api_count()):
            info = self._pa.get_host_api_info_by_index(i)
            if "WASAPI" in info["name"]:
                return info
        return None

    def _get_default_output_name(self):
        wasapi_info = self._get_wasapi_info()
        if wasapi_info is None:
            return None
        default_idx = wasapi_info["defaultOutputDevice"]
        default_dev = self._pa.get_device_info_by_index(default_idx)
        return default_dev["name"]

    @staticmethod
    def _query_current_default():
        """Create a fresh PA instance to get the actual current default device."""
        pa = pyaudio.PyAudio()
        try:
            for i in range(pa.get_host_api_count()):
                info = pa.get_host_api_info_by_index(i)
                if "WASAPI" in info["name"]:
                    default_idx = info["defaultOutputDevice"]
                    dev = pa.get_device_info_by_index(default_idx)
                    return dev["name"]
        finally:
            pa.terminate()
        return None

    def _find_loopback_device(self):
        """Find WASAPI loopback device for the default output."""
        wasapi_info = self._get_wasapi_info()
        if wasapi_info is None:
            raise RuntimeError("WASAPI host API not found")

        default_output_idx = wasapi_info["defaultOutputDevice"]
        default_output = self._pa.get_device_info_by_index(default_output_idx)
        log.info(f"Default output: {default_output['name']}")

        target_name = self._device_name or default_output["name"]

        for i in range(self._pa.get_device_count()):
            dev = self._pa.get_device_info_by_index(i)
            if dev["hostApi"] == wasapi_info["index"] and dev.get("isLoopbackDevice", False):
                if target_name in dev["name"]:
                    return dev

        # Fallback: any loopback device
        for i in range(self._pa.get_device_count()):
            dev = self._pa.get_device_info_by_index(i)
            if dev.get("isLoopbackDevice", False):
                return dev

        raise RuntimeError("No WASAPI loopback device found")

    def _open_stream(self):
        """Open stream for current default loopback device."""
        loopback_dev = self._find_loopback_device()
        self._native_channels = loopback_dev["maxInputChannels"]
        self._native_rate = int(loopback_dev["defaultSampleRate"])
        self._current_device_name = loopback_dev["name"]

        log.info(f"Loopback device: {loopback_dev['name']}")
        log.info(f"Native: {self._native_rate}Hz, {self._native_channels}ch -> {self.sample_rate}Hz mono")

        native_chunk = int(self._native_rate * self.chunk_duration)

        self._stream = self._pa.open(
            format=pyaudio.paFloat32,
            channels=self._native_channels,
            rate=self._native_rate,
            input=True,
            input_device_index=loopback_dev["index"],
            frames_per_buffer=native_chunk,
        )

    def _close_stream(self):
        if self._stream:
            try:
                self._stream.stop_stream()
                self._stream.close()
            except Exception:
                pass
            self._stream = None

    def set_device(self, device_name):
        """Change capture device at runtime. None = system default."""
        if device_name == self._device_name:
            return
        log.info(f"Audio device changed: {self._device_name} -> {device_name}")
        self._device_name = device_name
        if self._running:
            self._restart_stream()

    def _restart_stream(self):
        """Restart stream with new default device."""
        with self._lock:
            self._close_stream()
            # Refresh device list
            self._pa.terminate()
            self._pa = pyaudio.PyAudio()
            self._open_stream()

    def _read_loop(self):
        """Synchronous read loop in a background thread."""
        last_device_check = time.monotonic()

        while self._running:
            # Auto-switch only when using system default
            now = time.monotonic()
            if now - last_device_check > DEVICE_CHECK_INTERVAL:
                last_device_check = now
                if self._device_name is None:
                    try:
                        current_default = self._query_current_default()
                        if current_default and self._current_device_name and \
                           current_default not in self._current_device_name:
                            log.info(f"System default output changed: "
                                     f"{self._current_device_name} -> {current_default}")
                            log.info("Restarting audio capture for new device...")
                            self._restart_stream()
                            log.info(f"Audio capture restarted on: {self._current_device_name}")
                    except Exception as e:
                        log.warning(f"Device check error: {e}")

            native_chunk = int(self._native_rate * self.chunk_duration)
            try:
                with self._lock:
                    if not self._stream:
                        continue
                    data = self._stream.read(native_chunk, exception_on_overflow=False)
            except Exception as e:
                log.warning(f"Read error (device may have changed): {e}")
                try:
                    time.sleep(0.5)
                    self._restart_stream()
                    log.info("Stream restarted after read error")
                except Exception as re:
                    log.error(f"Restart failed: {re}")
                    time.sleep(1)
                continue

            audio = np.frombuffer(data, dtype=np.float32)

            # Mix to mono
            if self._native_channels > 1:
                audio = audio.reshape(-1, self._native_channels).mean(axis=1)

            # Resample to target rate
            if self._native_rate != self.sample_rate:
                ratio = self.sample_rate / self._native_rate
                n_out = int(len(audio) * ratio)
                indices = np.arange(n_out) / ratio
                indices = np.clip(indices, 0, len(audio) - 1)
                idx_floor = indices.astype(np.int64)
                idx_ceil = np.minimum(idx_floor + 1, len(audio) - 1)
                frac = (indices - idx_floor).astype(np.float32)
                audio = audio[idx_floor] * (1 - frac) + audio[idx_ceil] * frac

            try:
                self.audio_queue.put_nowait(audio)
            except queue.Full:
                self.audio_queue.get_nowait()  # Drop oldest
                self.audio_queue.put_nowait(audio)

    def start(self):
        self._open_stream()
        self._running = True
        self._read_thread = threading.Thread(target=self._read_loop, daemon=True)
        self._read_thread.start()
        log.info("Audio capture started")

    def stop(self):
        self._running = False
        if self._read_thread:
            self._read_thread.join(timeout=3)
        self._close_stream()
        log.info("Audio capture stopped")

    def get_audio(self, timeout=1.0):
        try:
            return self.audio_queue.get(timeout=timeout)
        except queue.Empty:
            return None

    def __del__(self):
        if self._pa:
            self._pa.terminate()