from dataclasses import dataclass
from pathlib import Path
from typing import Callable, Optional


@dataclass
class TranscriptionResult:
    success: bool
    text: str
    source: str  # "whisper" | "premium" | "none"


class Transcriber:
    """Wraps faster-whisper; injectable model_factory for tests."""

    def __init__(self, model_factory: Optional[Callable[[], object]] = None,
                 model_name: str = "large-v3", device: str = "cpu"):
        self._factory = model_factory
        self._model_name = model_name
        self._device = device
        self._model = None

    def _get_model(self):
        if self._factory is not None:
            return self._factory()
        if self._model is None:
            from faster_whisper import WhisperModel
            self._model = WhisperModel(self._model_name, device=self._device)
        return self._model

    def transcribe(self, audio_path: Path, premium_text: Optional[str] = None) -> TranscriptionResult:
        try:
            model = self._get_model()
            segments, _info = model.transcribe(str(audio_path), language="de", beam_size=5)
            text = " ".join(s.text.strip() for s in segments).strip()
            if text:
                return TranscriptionResult(True, text, "whisper")
        except Exception:
            pass
        if premium_text:
            return TranscriptionResult(True, premium_text, "premium")
        return TranscriptionResult(False, "", "none")