using System;
using System.Drawing;
using NUnit.Framework;

namespace Developpez.Dotnet.Drawing.Tests
{
    [TestFixture]
    public class ColorExtensionsTests
    {
        [Test]
        public void Test_RgbToHsv_And_Back_Gives_Original_Color()
        {
            var expected = Color.FromArgb(42, 99, 123);
            var hsv = expected.ToHsv();
            var actual = hsv.ToRgb();
            Assert.AreEqual(actual, expected);
        }

        [Test]
        public void Test_HsvToRgb_And_Back_Gives_Original_Color()
        {
            var expected = new HsvColor(198.0, 0.66, 0.5);
            var rgb = expected.ToRgb();
            var actual = rgb.ToHsv();
            Assert.IsTrue(AlmostEqual(actual, expected), "Expected {0}, but was {1}", expected, actual);
        }

        [Test]
        public void Test_RgbToHsl_And_Back_Gives_Original_Color()
        {
            var expected = Color.FromArgb(42, 99, 123);
            var hsl = expected.ToHsl();
            var actual = hsl.ToRgb();
            Assert.AreEqual(actual, expected);
        }

        [Test]
        public void Test_HslToRgb_And_Back_Gives_Original_Color()
        {
            var expected = new HslColor(120.0, 1.0, 0.5);
            var rgb = expected.ToRgb();
            var actual = rgb.ToHsl();
            Assert.IsTrue(AlmostEqual(actual, expected), "Expected {0}, but was {1}", expected, actual);
        }

        static bool AlmostEqual(HsvColor a, HsvColor b)
        {
            double dh = Math.Abs(a.H - b.H);
            double ds = Math.Abs(a.S - b.S);
            double dv = Math.Abs(a.V - b.V);
            return dh < 1.0 && ds < 1.0 && dv < 1.0;
        }

        static bool AlmostEqual(HslColor a, HslColor b)
        {
            double dh = Math.Abs(a.H - b.H);
            double ds = Math.Abs(a.S - b.S);
            double dl = Math.Abs(a.L - b.L);
            return dh < 1.0 && ds < 1.0 && dl < 1.0;
        }
    }
}