import pyaudio
import threading

from .config import AUDIO_INPUT_DEVICE_INDEX, AUDIO_INPUT_DEVICE_NAME


class AudioManager:
    _instance = None
    _lock = threading.Lock()

    def __new__(cls):
        with cls._lock:
            if cls._instance is None:
                cls._instance = super(AudioManager, cls).__new__(cls)
                cls._instance.pa = pyaudio.PyAudio()
                cls._instance._input_device_index = None
                cls._instance._input_device_resolved = False
                print("🔊 AudioManager: PyAudio initialized (Global)")
            return cls._instance

    def get_pyaudio(self):
        return self.pa

    def get_input_device_index(self):
        """
        Returns PortAudio input device index or None (let PortAudio pick default).
        Raises a RuntimeError with a helpful message if no input devices exist.
        """
        if self._input_device_resolved:
            return self._input_device_index

        self._input_device_index = self._resolve_input_device_index()
        self._input_device_resolved = True
        return self._input_device_index

    def _resolve_input_device_index(self):
        if self.pa is None:
            return None

        device_count = int(self.pa.get_device_count() or 0)

        def is_input_device(idx: int) -> bool:
            try:
                info = self.pa.get_device_info_by_index(idx)
            except Exception:
                return False
            return int(info.get("maxInputChannels") or 0) > 0

        if AUDIO_INPUT_DEVICE_INDEX is not None:
            idx = int(AUDIO_INPUT_DEVICE_INDEX)
            if 0 <= idx < device_count and is_input_device(idx):
                return idx
            raise RuntimeError(
                "Audio input initialization failed: invalid AUDIO_INPUT_DEVICE_INDEX="
                f"{AUDIO_INPUT_DEVICE_INDEX}. Available input devices:\n"
                + self.describe_input_devices()
            )

        if AUDIO_INPUT_DEVICE_NAME:
            needle = AUDIO_INPUT_DEVICE_NAME.lower()
            for idx in range(device_count):
                if not is_input_device(idx):
                    continue
                try:
                    name = str(self.pa.get_device_info_by_index(idx).get("name") or "")
                except Exception:
                    continue
                if needle in name.lower():
                    return idx

            raise RuntimeError(
                "Audio input initialization failed: could not find an input device "
                f"matching AUDIO_INPUT_DEVICE_NAME={AUDIO_INPUT_DEVICE_NAME!r}. "
                "Available input devices:\n"
                + self.describe_input_devices()
            )

        # Default input device (if PortAudio has one).
        try:
            default_info = self.pa.get_default_input_device_info()
            default_idx = int(default_info.get("index"))
            if 0 <= default_idx < device_count and is_input_device(default_idx):
                return default_idx
        except Exception:
            pass

        # Fallback: first input device.
        for idx in range(device_count):
            if is_input_device(idx):
                return idx

        raise RuntimeError(
            "Audio input initialization failed: no input devices found. "
            "Check microphone connection and PipeWire/PulseAudio. "
            "PortAudio devices:\n"
            + self.describe_input_devices()
        )

    def describe_input_devices(self, limit: int = 20) -> str:
        if self.pa is None:
            return "<PyAudio not initialized>"

        items = []
        count = int(self.pa.get_device_count() or 0)
        for idx in range(count):
            try:
                info = self.pa.get_device_info_by_index(idx)
            except Exception:
                continue
            max_in = int(info.get("maxInputChannels") or 0)
            if max_in <= 0:
                continue
            name = str(info.get("name") or "").strip()
            items.append(f"[{idx}] {name} (in={max_in})")
            if len(items) >= limit:
                break
        return "\n".join(items) if items else "<no input devices>"

    def cleanup(self):
        if self.pa:
            self.pa.terminate()
            self.pa = None


def get_audio_manager():
    return AudioManager()