import pytest
from openpyxl import Workbook
import io
from core.renderer import ExcelRenderer
from PIL import Image

@pytest.fixture
def sample_excel_bytes():
    wb = Workbook()
    ws = wb.active
    ws.title = "TestSheet"
    ws['A1'] = "Hello"
    ws['B1'] = "World"
    ws['A2'] = 123
    ws['B2'] = 456.78
    
    # Add some color
    from openpyxl.styles import PatternFill
    fill = PatternFill(start_color="FFFF0000", end_color="FFFF0000", fill_type="solid")
    ws['A1'].fill = fill
    
    out = io.BytesIO()
    wb.save(out)
    out.seek(0)
    return out.getvalue()

def test_renderer_initialization(sample_excel_bytes):
    renderer = ExcelRenderer(sample_excel_bytes)
    assert renderer is not None

def test_render_to_bytes(sample_excel_bytes):
    renderer = ExcelRenderer(sample_excel_bytes)
    img_bytes = renderer.render_to_bytes(sheet_name="TestSheet")
    
    assert isinstance(img_bytes, bytes)
    assert len(img_bytes) > 0
    
    # Verify it's a valid image
    img = Image.open(io.BytesIO(img_bytes))
    assert img.format == "PNG"
    assert img.width > 0
    assert img.height > 0

def test_render_invalid_sheet(sample_excel_bytes):
    renderer = ExcelRenderer(sample_excel_bytes)
    with pytest.raises(ValueError, match="Sheet 'NonExistent' not found"):
        renderer.render_to_bytes(sheet_name="NonExistent")