using System;
using Microsoft.Xna.Framework.Graphics;
using MLEM.Data;
using MLEM.Textures;
using NUnit.Framework;

namespace Tests {
    public class TexturePackerTests {

        private Texture2D testTexture;
        private Texture2D disposedTestTexture;
        private TestGame game;

        [SetUp]
        public void SetUp() {
            this.game = TestGame.Create();
            this.testTexture = new Texture2D(this.game.GraphicsDevice, 256, 256);
            this.disposedTestTexture = new Texture2D(this.game.GraphicsDevice, 16, 16);
        }

        [TearDown]
        public void TearDown() {
            this.game?.Dispose();
            this.testTexture?.Dispose();
            this.disposedTestTexture?.Dispose();
        }

        [Test]
        public void TestPacking() {
            using var packer = new RuntimeTexturePacker();
            for (var i = 0; i < 5; i++) {
                var width = 16 * (i + 1);
                packer.Add(new TextureRegion(this.testTexture, 0, 0, width, 64), r => {
                    Assert.AreEqual(r.Width, width);
                    Assert.AreEqual(r.Height, 64);
                });
            }
            packer.Pack(this.game.GraphicsDevice);
            Assert.AreEqual(packer.PackedTexture.Width, 16 + 32 + 48 + 64 + 80);
            Assert.AreEqual(packer.PackedTexture.Height, 64);
        }

        [Test]
        public void TestDisposal() {
            using var packer = new RuntimeTexturePacker(128, disposeTextures: true);
            packer.Add(new TextureRegion(this.disposedTestTexture), TexturePackerTests.StubResult);
            packer.Add(new TextureRegion(this.disposedTestTexture, 0, 0, 8, 8), TexturePackerTests.StubResult);
            packer.Pack(this.game.GraphicsDevice);
            Assert.True(this.disposedTestTexture.IsDisposed);
            Assert.False(packer.PackedTexture.IsDisposed);
        }

        [Test]
        public void TestBounds() {
            // test forced max width
            using var packer = new RuntimeTexturePacker(128);
            Assert.Throws<InvalidOperationException>(() => {
                packer.Add(new TextureRegion(this.testTexture, 0, 0, 256, 128), TexturePackerTests.StubResult);
            });

            // test auto-expanding width
            using var packer2 = new RuntimeTexturePacker(128, true);
            Assert.DoesNotThrow(() => {
                packer2.Add(new TextureRegion(this.testTexture, 0, 0, 256, 128), TexturePackerTests.StubResult);
            });
            packer2.Pack(this.game.GraphicsDevice);

            // test power of two forcing
            using var packer3 = new RuntimeTexturePacker(128, forcePowerOfTwo: true);
            packer3.Add(new TextureRegion(this.testTexture, 0, 0, 37, 170), TexturePackerTests.StubResult);
            packer3.Pack(this.game.GraphicsDevice);
            Assert.AreEqual(64, packer3.PackedTexture.Width);
            Assert.AreEqual(256, packer3.PackedTexture.Height);

            // test square forcing
            using var packer4 = new RuntimeTexturePacker(128, forceSquare: true);
            packer4.Add(new TextureRegion(this.testTexture, 0, 0, 37, 170), TexturePackerTests.StubResult);
            packer4.Pack(this.game.GraphicsDevice);
            Assert.AreEqual(170, packer4.PackedTexture.Width);
            Assert.AreEqual(170, packer4.PackedTexture.Height);
        }

        [Test]
        public void TestPackMultipleTimes() {
            using var packer = new RuntimeTexturePacker(1024);

            // pack the first time
            var results = 0;
            for (var i = 0; i < 10; i++)
                packer.Add(new TextureRegion(this.testTexture, 0, 0, 64, 64), _ => results++);
            packer.Pack(this.game.GraphicsDevice);
            Assert.AreEqual(10, results);

            // pack without resizing
            packer.Add(new TextureRegion(this.testTexture, 0, 0, 0, 0), _ => results++);
            packer.Pack(this.game.GraphicsDevice);
            Assert.AreEqual(11, results);

            // pack and force a resize
            packer.Add(new TextureRegion(this.testTexture, 0, 0, 64, 64), _ => results++);
            packer.Pack(this.game.GraphicsDevice);
            // all callbacks are called again, so we add 11 again, as well as the callback we just added
            Assert.AreEqual(2 * 11 + 1, results);
        }

        private static void StubResult(TextureRegion region) {}

    }
}