from pathlib import Path
import os
import sys
import threading
import logging
import wave
import json
import subprocess
import shutil

try:
    from vosk import Model, KaldiRecognizer
except Exception:
    Model = None
    KaldiRecognizer = None


class FFmpegConverter:
    """Utility to convert audio files using ffmpeg."""

    @staticmethod
    def convert_mp3_to_wav(src: Path, dest: Path) -> None:
        cmd = [
            "ffmpeg",
            "-y",
            "-i",
            str(src),
            "-ac",
            "1",
            "-ar",
            "16000",
            "-vn",
            "-f",
            "wav",
            str(dest),
        ]
        subprocess.run(cmd, check=True)


class VoskModelManager:
    """Loads a Vosk model and provides transcription methods.

    Loading captures model stderr into Python logs to show progress.
    """

    def __init__(self, model_path: Path):
        self.logger = logging.getLogger("vosk.model_manager")
        if Model is None or KaldiRecognizer is None:
            raise RuntimeError("vosk is not installed in runtime")
        self.model = self._load_model_with_progress(model_path)

    def _load_model_with_progress(self, path: Path):
        logger = logging.getLogger("vosk.loader")
        r_fd, w_fd = os.pipe()
        saved_stderr_fd = os.dup(sys.stderr.fileno())
        os.dup2(w_fd, sys.stderr.fileno())

        def _reader(fd):
            with os.fdopen(fd, "rb") as fh:
                for raw in iter(fh.readline, b""):
                    try:
                        logger.info(raw.decode(errors="ignore").rstrip())
                    except Exception:
                        pass

        reader_thread = threading.Thread(target=_reader, args=(r_fd,), daemon=True)
        reader_thread.start()

        try:
            model = Model(str(path))
        finally:
            try:
                os.dup2(saved_stderr_fd, sys.stderr.fileno())
            except Exception:
                pass
            try:
                os.close(saved_stderr_fd)
            except Exception:
                pass
            reader_thread.join(timeout=2)

        return model

    def transcribe_wav(self, wav_path: Path) -> str:
        if not wav_path.exists():
            raise FileNotFoundError(wav_path)
        try:
            with wave.open(str(wav_path), "rb") as wf:
                if wf.getnchannels() != 1:
                    raise ValueError("Audio must be mono (1 channel)")
                recognizer = KaldiRecognizer(self.model, wf.getframerate())
                while True:
                    data = wf.readframes(4000)
                    if not data:
                        break
                    recognizer.AcceptWaveform(data)
                result = json.loads(recognizer.FinalResult())
                return result.get("text", "")
        except wave.Error as e:
            raise ValueError(f"Invalid WAV file: {e}")