using System;
using System.Utility;
using NUnit.Framework;

namespace Chernobyl.Graphics
{
    [TestFixture, Description("Tests for the ColorHsla type.")]
    public class ColorHslaTests
    {
        ColorHsla _color = new ColorHsla(.91, 1, .44, .5);

        #region RGBA Conversion

        [Test, Description("Ensures that RGBA to HSLA conversion works.")]
        public void RgbaToHsla()
        {
            // Color 1
            {
                var rgba1 = new ColorRgba(224, 0, 120, 127);
                var hsla1 = (ColorHsla)rgba1;
                hsla1.Round(2).IsEqualTo(new ColorHsla(.91, 1, .44, .5), "color 1");
            }

            // Color 2
            {
                var rgba1 = new ColorRgba(214, 174, 174, 45);
                var hsla1 = (ColorHsla)rgba1;
                hsla1.Round(2).IsEqualTo(new ColorHsla(0, .33, .76, .18), "color 2");
            }
        }

        [Test, Description("Ensures that HSLA to RGBA conversion works.")]
        public void HslaToRgba()
        {
            // Color 1
            {
                var hsla1 = new ColorHsla(.91, 1, .44, .5);
                var rgba1 = (ColorRgba)hsla1;
                rgba1.IsEqualTo(new ColorRgba(224, 0, 121, 127), "color 1");
            }

            // Color 2
            {
                var hsla1 = new ColorHsla(0, .33, .76, .18);
                var rgba1 = (ColorRgba)hsla1;
                rgba1.IsEqualTo(new ColorRgba(214, 174, 174, 45), "color 2");
            }
        }

        #endregion

        #region Darken

        [Test, Description(".Darken returns correct result.")]
        public void Darken()
        {
            _color.Darken(.20).IsEqualTo(new ColorHsla(.91, 1, .24, .5), "HSLA");
            _color.Darken(.50).IsEqualTo(new ColorHsla(.91, 1, 0, .5), "HSLA");
        }

        [Test, Description(".Darken throws if given out of range argument.")]
        public void DarkenThrows()
        {
            Assert.Throws<ArgumentOutOfRangeException>(() => _color.Darken(1.1));
            Assert.Throws<ArgumentOutOfRangeException>(() => _color.Darken(-.1));
        }

        #endregion

        #region Lighten

        [Test, Description(".Lighten returns correct result.")]
        public void Lighten()
        {
            _color.Lighten(.20).IsEqualTo(new ColorHsla(.91, 1, .64, .5), "HSLA");
            _color.Lighten(.60).IsEqualTo(new ColorHsla(.91, 1, 1.0, .5), "HSLA");
        }

        [Test, Description(".Lighten throws if given out of range argument.")]
        public void LightenThrows()
        {
            Assert.Throws<ArgumentOutOfRangeException>(() => _color.Lighten(1.1));
            Assert.Throws<ArgumentOutOfRangeException>(() => _color.Lighten(-.1));
        }

        #endregion

        #region Lerp

        [Test, Description(".Lerp returns correct result.")]
        public void Lerp()
        {
            var start = new ColorHsla(0, 0, 0, 0);
            var end = new ColorHsla(1, 1, 1, 1);
            var actual = new[]
            {
                start.Lerp(end, 0.0),
                start.Lerp(end, 0.4),
                start.Lerp(end, 0.8),
                start.Lerp(end, 1.0)
            };
            actual.IsEqualTo(new[]
            {
                new ColorHsla(0.0, 0.0, 0.0, 0.0),
                new ColorHsla(0.4, 0.4, 0.4, 0.4),
                new ColorHsla(0.8, 0.8, 0.8, 0.8),
                new ColorHsla(1.0, 1.0, 1.0, 1.0)
            }, "Lerp Results");
        }

        [Test, Description(".Lerp throws when amount is less than 0.")]
        public void LerpThrowsWhenAmountIsLessThanZero() =>
            Assert.Throws<ArgumentOutOfRangeException>(() => _color.Lerp(new ColorHsla(1, 1, 1, 1), -0.1));

        [Test, Description(".Lerp throws when amount is greater than 1.")]
        public void LerpThrowsWhenAmountIsGreaterThanZero() =>
            Assert.Throws<ArgumentOutOfRangeException>(() => _color.Lerp(new ColorHsla(1, 1, 1, 1), 1.1));

        #endregion
    }
}