using System;

using UnityEngine;

using NUnit.Framework;

namespace Framework.Geometry.Lines.Fitting {

 	/// <summary>Verifies that the 2D line fitter is working correctly</summary>
	[TestFixture]
	public static class Line2FitterTest {

		/// <summary>
		///   Verifies that attempting to fit a line to no points results in a default line
		/// </summary>
		[Test]
		public static void NoPointsResultInDefaultLine() {
			var noPoints = new Vector2[0];
			Line2 fittedLine = Line2Fitter.Fit(noPoints);

			Assert.That(fittedLine.Offset, Is.EqualTo(Vector2.zero));
			Assert.That(fittedLine.Direction, Is.EqualTo(Vector2.right));
		}

		/// <summary>
		///   Verifies that fitting a line to a single point produces a horizontal line
		/// </summary>
		[Test]
		public static void SinglePointResultsInHorizontalLine() {
			var singlePoint = new Vector2[] { new Vector2(1.2f, 3.4f) };
			Line2 fittedLine = Line2Fitter.Fit(singlePoint);

			Assert.That(fittedLine.Offset, Is.EqualTo(singlePoint[0]));
			Assert.That(fittedLine.Direction, Is.EqualTo(Vector2.right));
		}

		/// <summary>
		///   Verifies that fitting a bunch of points all on top of each other produces
		///   a horizontal line
		/// </summary>
		[Test]
		public static void ClumpedPointsResultInHorizontalLine() {
			var clumpedPoints = new Vector2[] {
				new Vector2(1.2f, 3.4f),
				new Vector2(1.2f, 3.4f),
				new Vector2(1.2f, 3.4f),
				new Vector2(1.2f, 3.4f)
			};
			Line2 fittedLine = Line2Fitter.Fit(clumpedPoints);

			Assert.That(fittedLine.Offset, Is.EqualTo(clumpedPoints[0]));
			Assert.That(fittedLine.Direction, Is.EqualTo(Vector2.right));
		}

		/// <summary>
		///   Verifies that fitting a line to a series in a flat row builds a horizontal line
		/// </summary>
		[Test]
		public static void FlatHorizontalLineCanBeFitted() {
			var horizontalPoints = new Vector2[] {
				new Vector2(4.0f, 5.0f),
				new Vector2(9.0f, 5.0f),
				new Vector2(14.0f, 5.0f),
				new Vector2(21.0f, 5.0f)
			};
			Line2 fittedLine = Line2Fitter.Fit(horizontalPoints);

			Assert.That(fittedLine.Direction, Is.EqualTo(Vector2.right));
			Assert.That(fittedLine.Offset, Is.EqualTo(new Vector2(0.0f, 5.0f)));
		}

		/// <summary>
		///   Verifies that fitting a line to a series in a flat column builds a vertical line
		/// </summary>
		[Test]
		public static void FlatVerticalLineCanBeFitted() {
			var verticalPoints = new Vector2[] {
				new Vector2(5.0f, 4.0f),
				new Vector2(5.0f, 9.0f),
				new Vector2(5.0f, 14.0f),
				new Vector2(5.0f, 21.0f)
			};
			Line2 fittedLine = Line2Fitter.Fit(verticalPoints);

			Assert.That(fittedLine.Direction, Is.EqualTo(Vector2.up));
			Assert.That(fittedLine.Offset, Is.EqualTo(new Vector2(5.0f, 0.0f)));
		}

	}

} // namespace Framework.Geometry.Lines.Fitting