backend/app/routers/samples.py

"""Sample audio listing & download endpoints."""
from __future__ import annotations

import contextlib

import soundfile as sf
from fastapi import APIRouter, HTTPException
from fastapi.responses import FileResponse

from app.config import settings
from app.schemas.response import SampleAudio, SamplesResponse
from app.utils.samples import SAMPLES, sample_by_id, sample_path

router = APIRouter()


def _duration_safe(path) -> float | None:
    if not path.exists():
        return None
    with contextlib.suppress(Exception):
        info = sf.info(str(path))
        return float(info.frames) / float(info.samplerate)
    return None


@router.get("/samples", response_model=SamplesResponse)
async def list_samples() -> SamplesResponse:
    out = []
    for s in SAMPLES:
        path = sample_path(s["filename"])
        out.append(
            SampleAudio(
                sample_id=s["sample_id"],
                filename=s["filename"],
                label=s["label"],
                description=s["description"],
                duration_seconds=_duration_safe(path),
                url=f"{settings.api_prefix}/samples/{s['sample_id']}/download",
            )
        )
    return SamplesResponse(samples=out)


@router.get("/samples/{sample_id}/download")
async def download_sample(sample_id: str):
    s = sample_by_id(sample_id)
    if s is None:
        raise HTTPException(status_code=404, detail="Unknown sample.")
    path = sample_path(s["filename"])
    if not path.exists():
        raise HTTPException(
            status_code=404,
            detail=(
                f"Sample file '{s['filename']}' not present on the server. "
                "Add real WAV files under data/sample_audios/ to enable this endpoint."
            ),
        )
    return FileResponse(str(path), media_type="audio/wav", filename=s["filename"])