using System;
using System.Collections;
using System.Collections.Generic;
using BracerLib.Utility;
using NUnit.Framework;
using UnityEngine;

namespace BracerLib.Tests.Utility
{
    public class TriangulatorTest : TestBase
    {
        private static IEnumerable AreaValueTests()
        {
            var points = new List<Vector2>();

            yield return new TestCaseData(points.ToArray(), 0f).SetName("No points to calculate");

            points.AddRange(new[]
            {
                Vector2.one,
                new Vector2(5f, 7f),
                new Vector2(-2f, 8f)
            });

            yield return new TestCaseData(points.ToArray(), 23f).SetName("Area of a triangle");

            points.Add(new Vector2(3f, 5f));

            yield return new TestCaseData(points.ToArray(), 10f).SetName("Area of a quad");
        }

        private static IEnumerable InsideTrianglePointsTest()
        {
            yield return new TestCaseData(
                Vector2.zero,
                new Vector2(3f, 3f),
                new Vector2(3f, 0f),
                new Vector2(2f, 1f),
                true
            ).SetName("Point inside triangle");

            yield return new TestCaseData(
                Vector2.zero,
                new Vector2(3f, 3f),
                new Vector2(3f, 0f),
                new Vector2(1f, 0f),
                true
            ).SetName("Point on the line");

            yield return new TestCaseData(
                Vector2.zero,
                new Vector2(3f, 3f),
                new Vector2(3f, 0f),
                new Vector2(3f, 0f),
                false
            ).SetName("Point is one of triangle points");

            yield return new TestCaseData(
                Vector2.zero,
                new Vector2(3f, 3f),
                new Vector2(3f, 0f),
                new Vector2(-2f, 1f),
                false
            ).SetName("Point outside triangle");
        }

        private static IEnumerable TriangulatePointsTest()
        {
            yield return new TestCaseData(
                new[]
                {
                    Vector2.zero,
                    Vector2.right,
                    Vector2.right + Vector2.up,
                    Vector2.up,
                    Vector2.left + Vector2.up,
                    Vector2.left
                },
                new[] { 5,3,2,2,0,5,5,4,3,2,1,0 }
            ).SetName("Positive triangulation");

            yield return new TestCaseData(
                new[]
                {
                    Vector2.zero,
                    Vector2.right,
                    Vector2.right + Vector2.down,
                    Vector2.down,
                    Vector2.left + Vector2.down,
                    Vector2.left
                },
                new[] { 1,3,4,4,0,1,1,2,3,4,5,0 }
            ).SetName("Negative triangulation");

            yield return new TestCaseData(
                new[] { Vector2.zero, Vector2.right },
                Array.Empty<int>()
            ).SetName("Empty triangulation");
        }

        [Test]
        [TestCaseSource(nameof(AreaValueTests))]
        public void AreaCalculatesCorrectly(Vector2[] points, float expected)
        {
            var result = Triangulator.Area(points);
            Assert.AreEqual(expected, result);
        }

        [Test]
        [TestCaseSource(nameof(InsideTrianglePointsTest))]
        public void PointsInsideTriangleCorrectly(Vector2 a, Vector2 b, Vector2 c, Vector2 p, bool expected)
        {
            var result = Triangulator.InsideTriangle(a, b, c, p);
            Assert.AreEqual(expected, result);
        }

        [Test]
        [TestCaseSource(nameof(TriangulatePointsTest))]
        public void TriangulatePoints(Vector2[] points, int[] expected)
        {
            var result = Triangulator.Triangulate(points);
            Assert.AreEqual(expected.Length, result.Length);
            for (var i = 0; i < result.Length; i++)
            {
                Assert.AreEqual(expected[i], result[i]);
            }
        }
    }
}