"""Voice co-creation session storage helpers."""

from __future__ import annotations

from pathlib import Path

from app.core.config import settings


def session_storage_dir(session_id: str) -> Path:
    """Return the storage directory for one voice session."""

    return Path(settings.voice_session_storage_dir) / session_id


def build_turn_user_audio_path(session_id: str, turn_index: int, suffix: str) -> Path:
    """Build the persisted path for one user-uploaded turn audio file."""

    normalized_suffix = suffix.lstrip(".") or "webm"
    return session_storage_dir(session_id) / f"turn-{turn_index:03d}-user.{normalized_suffix}"


def build_turn_assistant_audio_path(session_id: str, turn_index: int) -> Path:
    """Build the persisted path for one generated assistant turn audio file."""

    return session_storage_dir(session_id) / f"turn-{turn_index:03d}-assistant.mp3"


def write_session_audio(path: Path, audio_data: bytes) -> str:
    """Persist session audio bytes atomically and return the saved path."""

    path.parent.mkdir(parents=True, exist_ok=True)
    temp_path = path.with_suffix(f"{path.suffix}.tmp")
    temp_path.write_bytes(audio_data)
    temp_path.replace(path)
    return str(path)


def read_session_audio(audio_path: str) -> bytes:
    """Read persisted session audio bytes."""

    return Path(audio_path).read_bytes()


def session_audio_exists(audio_path: str | None) -> bool:
    """Whether one stored session audio file currently exists."""

    return bool(audio_path) and Path(audio_path).is_file()