"""
单元测试：图片处理工具函数

测试 utils/image_utils.py 中的图片处理函数。
"""

import pytest
from PIL import Image
from utils.image_utils import (
    inches_to_pixels,
    pixels_to_inches,
    apply_fit_mode,
    create_canvas_with_background,
)


class TestUnitConversion:
    """测试单位转换函数"""

    def test_inches_to_pixels_default_dpi(self):
        """测试英寸转像素（默认 96 DPI）"""
        assert inches_to_pixels(1) == 96
        assert inches_to_pixels(2) == 192
        assert inches_to_pixels(0.5) == 48

    def test_inches_to_pixels_custom_dpi(self):
        """测试英寸转像素（自定义 DPI）"""
        assert inches_to_pixels(1, dpi=72) == 72
        assert inches_to_pixels(2, dpi=150) == 300
        assert inches_to_pixels(0.5, dpi=300) == 150

    def test_pixels_to_inches_default_dpi(self):
        """测试像素转英寸（默认 96 DPI）"""
        assert pixels_to_inches(96) == 1.0
        assert pixels_to_inches(192) == 2.0
        assert pixels_to_inches(48) == 0.5

    def test_pixels_to_inches_custom_dpi(self):
        """测试像素转英寸（自定义 DPI）"""
        assert pixels_to_inches(72, dpi=72) == 1.0
        assert pixels_to_inches(300, dpi=150) == 2.0


class TestApplyFitMode:
    """测试图片适配模式函数"""

    @pytest.fixture
    def test_image(self):
        """创建测试图片（100x100）"""
        return Image.new("RGB", (100, 100), color="red")

    def test_stretch_mode(self, test_image):
        """测试 stretch 模式"""
        result = apply_fit_mode(test_image, (200, 150), "stretch")
        assert result.size == (200, 150)

    def test_contain_mode_wider_box(self, test_image):
        """测试 contain 模式（box 更宽）"""
        result = apply_fit_mode(test_image, (200, 100), "contain")
        # 图片应该适配到高度，宽度保持比例
        assert result.size == (100, 100)

    def test_contain_mode_taller_box(self, test_image):
        """测试 contain 模式（box 更高）"""
        result = apply_fit_mode(test_image, (100, 200), "contain")
        # 图片应该适配到宽度，高度保持比例
        assert result.size == (100, 100)

    def test_cover_mode_wider_box(self, test_image):
        """测试 cover 模式（box 更宽）"""
        result = apply_fit_mode(test_image, (200, 100), "cover")
        # 图片应该覆盖整个 box
        assert result.size == (200, 100)

    def test_cover_mode_taller_box(self, test_image):
        """测试 cover 模式（box 更高）"""
        result = apply_fit_mode(test_image, (100, 200), "cover")
        # 图片应该覆盖整个 box
        assert result.size == (100, 200)

    def test_center_mode(self, test_image):
        """测试 center 模式"""
        result = apply_fit_mode(test_image, (200, 150), "center")
        # center 模式保持原始尺寸
        assert result.size == (100, 100)

    def test_invalid_mode(self, test_image):
        """测试无效的 fit 模式"""
        with pytest.raises(ValueError, match="不支持的 fit 模式"):
            apply_fit_mode(test_image, (200, 150), "invalid")


class TestCreateCanvas:
    """测试画布创建函数"""

    def test_create_canvas_with_white_background(self):
        """测试创建白色背景画布"""
        canvas = create_canvas_with_background((200, 150), "#ffffff")
        assert canvas.size == (200, 150)
        assert canvas.mode == "RGB"
        # 检查中心像素是白色
        assert canvas.getpixel((100, 75)) == (255, 255, 255)

    def test_create_canvas_with_colored_background(self):
        """测试创建彩色背景画布"""
        canvas = create_canvas_with_background((200, 150), "#ff0000")
        assert canvas.size == (200, 150)
        # 检查中心像素是红色
        assert canvas.getpixel((100, 75)) == (255, 0, 0)

    def test_create_canvas_with_short_hex(self):
        """测试创建画布（短格式十六进制颜色）"""
        canvas = create_canvas_with_background((100, 100), "#f00")
        # 检查中心像素是红色
        assert canvas.getpixel((50, 50)) == (255, 0, 0)

    def test_create_canvas_with_invalid_color(self):
        """测试无效颜色格式"""
        with pytest.raises(ValueError, match="无效的颜色格式"):
            create_canvas_with_background((100, 100), "invalid")