backend/tests/test_api.py

"""API integration tests."""

import pytest
import io
import numpy as np
import soundfile as sf
from fastapi.testclient import TestClient

from backend.main import app


@pytest.fixture
def client():
    """Create test client."""
    return TestClient(app)


def make_wav_bytes(audio: np.ndarray, sr: int) -> bytes:
    """Helper: encode numpy array to WAV bytes."""
    buf = io.BytesIO()
    sf.write(buf, audio, sr, format='WAV')
    buf.seek(0)
    return buf.read()


@pytest.fixture
def uploaded_session(client, sample_stems):
    """Upload stems and return session_id."""
    stems, sr = sample_stems
    files = []
    for name, audio in stems.items():
        wav_bytes = make_wav_bytes(audio, sr)
        files.append(("files", (f"{name}.wav", wav_bytes, "audio/wav")))

    response = client.post("/api/upload", files=files)
    assert response.status_code == 200
    return response.json()["session_id"]


def test_health_check(client):
    """Health endpoint should return healthy status."""
    response = client.get("/api/health")
    assert response.status_code == 200
    assert response.json()["status"] == "healthy"


def test_upload_returns_session(client, sample_stems):
    """Upload should return a valid session with stem names."""
    stems, sr = sample_stems
    files = []
    for name, audio in stems.items():
        wav_bytes = make_wav_bytes(audio, sr)
        files.append(("files", (f"{name}.wav", wav_bytes, "audio/wav")))

    response = client.post("/api/upload", files=files)
    assert response.status_code == 200
    data = response.json()
    assert "session_id" in data
    assert set(data["stems"]) == {"bass", "drums", "guitar"}


def test_detection_returns_bpm_and_key(client, uploaded_session):
    """Detection should return BPM and key."""
    response = client.post(f"/api/detect/{uploaded_session}")
    assert response.status_code == 200
    data = response.json()
    assert "bpm" in data
    assert "key" in data
    assert "mode" in data
    assert data["bpm"] > 0


def test_process_pitch_shift(client, uploaded_session):
    """Processing with pitch shift should succeed."""
    # First detect
    client.post(f"/api/detect/{uploaded_session}")
    # Then process
    response = client.post(f"/api/process/{uploaded_session}", json={
        "semitones": 2,
        "target_bpm": None
    })
    assert response.status_code == 200
    assert response.json()["success"] is True


def test_get_stem_after_processing(client, uploaded_session):
    """Should be able to fetch a processed stem as audio."""
    client.post(f"/api/detect/{uploaded_session}")
    client.post(f"/api/process/{uploaded_session}", json={"semitones": 2})

    response = client.get(f"/api/stem/{uploaded_session}/bass?processed=true")
    assert response.status_code == 200
    assert response.headers["content-type"] in ["audio/wav", "audio/x-wav"]


def test_invalid_session_404(client):
    """Requesting a nonexistent session should return 404."""
    response = client.post("/api/detect/nonexistent-id")
    assert response.status_code == 404


def test_upload_no_files_422(client):
    """Uploading with no files should return 422."""
    response = client.post("/api/upload", files=[])
    assert response.status_code == 422


def test_upload_non_wav_400(client):
    """Uploading non-WAV files should return 400."""
    files = [("files", ("test.txt", b"not audio", "text/plain"))]
    response = client.post("/api/upload", files=files)
    assert response.status_code == 400


def test_list_stems(client, uploaded_session):
    """Should be able to list all stems."""
    response = client.get(f"/api/stems/{uploaded_session}")
    assert response.status_code == 200
    data = response.json()
    assert "stems" in data
    assert len(data["stems"]) == 3


def test_get_original_stem(client, uploaded_session):
    """Should be able to fetch original stem without processing."""
    response = client.get(f"/api/stem/{uploaded_session}/bass?processed=false")
    assert response.status_code == 200


def test_get_nonexistent_stem_404(client, uploaded_session):
    """Requesting nonexistent stem should return 404."""
    response = client.get(f"/api/stem/{uploaded_session}/nonexistent")
    assert response.status_code == 404


def test_process_without_detection_400(client, uploaded_session):
    """Processing without detection should return 400."""
    response = client.post(f"/api/process/{uploaded_session}", json={
        "semitones": 2
    })
    assert response.status_code == 400


def test_upload_with_mix_file(client, sample_stems):
    """Upload with a mix file should recognize it."""
    stems, sr = sample_stems
    files = []
    for name, audio in stems.items():
        wav_bytes = make_wav_bytes(audio, sr)
        files.append(("files", (f"{name}.wav", wav_bytes, "audio/wav")))

    # Add a mix file
    mix_audio = np.sum([a for a in stems.values()], axis=0) / 3
    mix_bytes = make_wav_bytes(mix_audio.astype(np.float32), sr)
    files.append(("files", ("full_mix.wav", mix_bytes, "audio/wav")))

    response = client.post("/api/upload", files=files)
    assert response.status_code == 200
    data = response.json()
    assert data["has_full_mix"] is True