import os
import pytest
from app.processing import create_layered_curves_dxf

# Create a dedicated directory for test outputs
TEST_OUTPUT_DIR = "test_outputs"
os.makedirs(TEST_OUTPUT_DIR, exist_ok=True)

import trimesh

@pytest.fixture
def create_dummy_mesh_file(tmp_path):
    """
    Creates a simple, valid mesh file for testing using trimesh.
    Returns the path to the file.
    """
    # Create a simple box primitive using trimesh
    mesh = trimesh.creation.box()
    file_path = tmp_path / "dummy_box.stl"
    
    # Export the mesh to a file
    mesh.export(file_path)
    
    return str(file_path)

def test_processing_function_runs_and_creates_output(create_dummy_mesh_file):
    """
    Tests that the core DXF generation function runs without errors and
    produces a non-empty output file.
    """
    input_file = create_dummy_mesh_file
    output_file = os.path.join(TEST_OUTPUT_DIR, "output.dxf")

    # The function is a generator, so we consume it to run it.
    # We wrap it in list() to execute all the yields.
    try:
        # We need to iterate through the generator to make it execute
        for _ in create_layered_curves_dxf(input_file, output_file):
            pass
    except Exception as e:
        pytest.fail(f"Processing function raised an unexpected exception: {e}")

    # Check that the output file was created and is not empty
    assert os.path.exists(output_file), "Output file was not created."
    assert os.path.getsize(output_file) > 0, "Output file is empty."