"""PipeWire/Pulse microphone capture through the local ffmpeg binary."""

from __future__ import annotations

import subprocess
from collections.abc import Iterator

import numpy as np

from mic_clipper.vad import FRAME_SAMPLES


class AudioInputUnavailable(RuntimeError):
    """The dynamic Pulse default source could not supply another frame."""


class PulseAudioInput:
    """Yield fixed 16 kHz mono float PCM frames from Pulse's `default` source."""

    @staticmethod
    def command() -> list[str]:
        return [
            "ffmpeg",
            "-nostdin",
            "-hide_banner",
            "-loglevel",
            "error",
            "-f",
            "pulse",
            "-sample_rate",
            "16000",
            "-channels",
            "1",
            "-i",
            "default",
            "-ac",
            "1",
            "-ar",
            "16000",
            "-f",
            "f32le",
            "pipe:1",
        ]

    def frames(self) -> Iterator[np.ndarray]:
        process = subprocess.Popen(
            self.command(),
            stdin=subprocess.DEVNULL,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
        )
        assert process.stdout is not None
        assert process.stderr is not None
        try:
            while True:
                payload = process.stdout.read(FRAME_SAMPLES * np.dtype("<f4").itemsize)
                if len(payload) != FRAME_SAMPLES * np.dtype("<f4").itemsize:
                    error = process.stderr.read(4096).decode("utf-8", errors="replace").strip()
                    return_code = process.wait()
                    detail = f": {error}" if error else ""
                    raise AudioInputUnavailable(
                        f"ffmpeg Pulse input ended with exit code {return_code}{detail}"
                    )
                yield np.frombuffer(payload, dtype="<f4").copy()
        finally:
            if process.poll() is None:
                process.terminate()
                try:
                    process.wait(timeout=5)
                except subprocess.TimeoutExpired:
                    process.kill()
                    process.wait()