import os
import json
import pytest
from app.core.render_engine import PythonRenderEngine

def test_render_engine_init():
    engine = PythonRenderEngine()
    assert engine.sample_rate == 44100

def test_bars_to_samples():
    engine = PythonRenderEngine()
    samples = engine.bars_to_samples(4.0, 120.0, 4)
    assert samples == 352800

def test_render_session_container_empty():
    engine = PythonRenderEngine()
    session = {"tracks": []}
    buf = engine.render_session_container(session, {}, 120.0, 4, 1000)
    assert buf.shape == (2, 1000)
    assert (buf == 0.0).all()

def test_render_project_bit_depth(tmp_path):
    """bit_depth 24/32 → WAV PCM_24/PCM_32; mặc định vẫn PCM_16."""
    import soundfile as sf
    engine = PythonRenderEngine()
    project = {
        "metadata": {"bpm": 120, "time_signature_numerator": 4},
        "main_session": {"length_bars": 1.0, "tracks": []},
        "section_store": {},
    }
    for bd, subtype in [(16, "PCM_16"), (24, "PCM_24"), (32, "PCM_32")]:
        out = str(tmp_path / f"render_{bd}.wav")
        engine.render_project(project, out, bit_depth=bd)
        assert sf.info(out).subtype == subtype