"""Unit tests for src/server/image_utils.py"""
import base64
import cv2
import numpy as np
import pytest

from src.server.image_utils import decode_image, CLASS_COLORS


def _make_jpeg_bytes(width=64, height=64) -> bytes:
    """Create a minimal valid JPEG bytestring."""
    img = np.zeros((height, width, 3), dtype=np.uint8)
    img[10:50, 10:50] = (128, 64, 200)  # a coloured rectangle
    success, buf = cv2.imencode(".jpg", img)
    assert success
    return buf.tobytes()


class TestDecodeImage:
    def test_decodes_valid_jpeg_bytes(self):
        raw = _make_jpeg_bytes()
        img = decode_image(raw)
        assert img is not None
        assert img.ndim == 3

    def test_decodes_from_memoryview(self):
        raw = _make_jpeg_bytes()
        img = decode_image(memoryview(raw))
        assert img is not None

    def test_decodes_base64_encoded_jpeg(self):
        raw = _make_jpeg_bytes()
        encoded = base64.b64encode(raw)
        img = decode_image(encoded)
        assert img is not None

    def test_returns_none_for_garbage_bytes(self):
        img = decode_image(b"\x00\x01\x02\x03garbage")
        assert img is None

    def test_returns_none_for_empty_bytes(self):
        img = decode_image(b"")
        assert img is None

    def test_decoded_shape_matches_source(self):
        raw = _make_jpeg_bytes(width=80, height=60)
        img = decode_image(raw)
        assert img is not None
        # JPEG encoding may have minor dimension rounding; check order
        assert img.shape[0] == 60   # height
        assert img.shape[1] == 80   # width


class TestClassColors:
    def test_class_colors_are_bgr_tuples(self):
        for cls_id, color in CLASS_COLORS.items():
            assert isinstance(color, tuple)
            assert len(color) == 3
            assert all(0 <= c <= 255 for c in color)

    def test_known_class_ids_present(self):
        assert 0 in CLASS_COLORS
        assert 1 in CLASS_COLORS