Monogame-Extended/tests/MonoGame.Extended.Tests/Tilemaps/TilemapTilesetCollectionTests.cs

using System;
using System.Linq;
using Microsoft.Xna.Framework.Graphics;
using MonoGame.Extended.Tilemaps;

namespace MonoGame.Extended.Tests;

public sealed class TilemapTilesetCollectionTests
{
    private Texture2D CreateDummyTexture()
    {
        // TODO: setup with xvfb later
        return null;
    }

    [Fact]
    public void Count_InitiallyZero()
    {
        var collection = new TilemapTilesetCollection();
        Assert.Empty(collection);
    }

    [Fact]
    public void Indexer_ReturnsCorrectTileset()
    {
        var collection = new TilemapTilesetCollection();
        var tileset1 = new TilemapTileset("Tileset1", CreateDummyTexture(), 32, 32, 100, 10);
        var tileset2 = new TilemapTileset("Tileset2", CreateDummyTexture(), 32, 32, 50, 5);

        collection.Add(tileset1);
        collection.Add(tileset2);

        Assert.Equal(tileset1, collection[0]);
        Assert.Equal(tileset2, collection[1]);
    }

    [Fact]
    public void GetTilesetForGid_WithSingleTileset_ReturnsCorrectTileset()
    {
        var collection = new TilemapTilesetCollection();
        var tileset = new TilemapTileset("Tileset", CreateDummyTexture(), 32, 32, 100, 10);
        tileset.FirstGlobalId = 1;
        collection.Add(tileset);

        var result = collection.GetTilesetForGid(50);

        Assert.Equal(tileset, result);
    }

    [Fact]
    public void GetTilesetForGid_WithMultipleTilesets_ReturnsCorrectTileset()
    {
        var collection = new TilemapTilesetCollection();

        var tileset1 = new TilemapTileset("Tileset1", CreateDummyTexture(), 32, 32, 100, 10);
        tileset1.FirstGlobalId = 1;

        var tileset2 = new TilemapTileset("Tileset2", CreateDummyTexture(), 32, 32, 50, 5);
        // After tileset1
        tileset2.FirstGlobalId = 101;

        var tileset3 = new TilemapTileset("Tileset3", CreateDummyTexture(), 32, 32, 25, 5);
        // After tileset2
        tileset3.FirstGlobalId = 151;

        collection.Add(tileset1);
        collection.Add(tileset2);
        collection.Add(tileset3);

        Assert.Equal(tileset1, collection.GetTilesetForGid(1)); // Fist tile of tileset1
        Assert.Equal(tileset1, collection.GetTilesetForGid(50)); // Mid tileset 1
        Assert.Equal(tileset1, collection.GetTilesetForGid(100)); // Last tile of tileset1

        Assert.Equal(tileset2, collection.GetTilesetForGid(101)); // First tile of tileset2
        Assert.Equal(tileset2, collection.GetTilesetForGid(125)); // Mid of tileset2
        Assert.Equal(tileset2, collection.GetTilesetForGid(150)); // Last tile of tileset2

        Assert.Equal(tileset3, collection.GetTilesetForGid(151)); // First tile of tileset3
        Assert.Equal(tileset3, collection.GetTilesetForGid(175)); // Last tile of tileset3
    }

    [Fact]
    public void GetTilesetForGid_WithGidBeforeFirstTileset_ReturnsNull()
    {
        var collection = new TilemapTilesetCollection();
        var tileset = new TilemapTileset("Tileset", CreateDummyTexture(), 32, 32, 100, 10);
        tileset.FirstGlobalId = 10;
        collection.Add(tileset);

        var result = collection.GetTilesetForGid(5);

        Assert.Null(result);
    }

    [Fact]
    public void GetTilesetForGid_WithEmptyCollection_ReturnsNull()
    {
        var collection = new TilemapTilesetCollection();
        var result = collection.GetTilesetForGid(1);
        Assert.Null(result);
    }

    [Fact]
    public void GetLocalId_WithValidGid_ReturnsCorrectLocalId()
    {
        var collection = new TilemapTilesetCollection();
        var tileset = new TilemapTileset("Tileset", CreateDummyTexture(), 32, 32, 100, 10);
        tileset.FirstGlobalId = 1;
        collection.Add(tileset);

        var localId = collection.GetLocalId(50, out var outTileset);

        // 50 - 1 = 49
        Assert.Equal(49, localId);
        Assert.Equal(tileset, outTileset);
    }

    [Fact]
    public void GetLocalId_WithFirstGid_ReturnsZero()
    {
        var collection = new TilemapTilesetCollection();
        var tileset = new TilemapTileset("Tileset", CreateDummyTexture(), 32, 32, 100, 10);
        tileset.FirstGlobalId = 100;
        collection.Add(tileset);

        var localId = collection.GetLocalId(100, out var outTileset);

        // 100 - 100 = 0
        Assert.Equal(0, localId);
        Assert.Equal(tileset, outTileset);
    }

    [Fact]
    public void GetLocalId_WithMultipleTilesets_ReturnsCorrectLocalId()
    {
        var collection = new TilemapTilesetCollection();

        var tileset1 = new TilemapTileset("Tileset1", CreateDummyTexture(), 32, 32, 100, 10);
        tileset1.FirstGlobalId = 1;

        var tileset2 = new TilemapTileset("Tileset2", CreateDummyTexture(), 32, 32, 50, 5);
        tileset2.FirstGlobalId = 101;

        collection.Add(tileset1);
        collection.Add(tileset2);

        var localId1 = collection.GetLocalId(50, out var outTileset1);
        var localId2 = collection.GetLocalId(125, out var outTileset2);

        // Assert
        Assert.Equal(49, localId1);
        Assert.Equal(tileset1, outTileset1);

        Assert.Equal(24, localId2);
        Assert.Equal(tileset2, outTileset2);
    }

    [Fact]
    public void GetLocalId_WithInvalidGid_ThrowsInvalidOperationException()
    {
        var collection = new TilemapTilesetCollection();
        var tileset = new TilemapTileset("Tileset", CreateDummyTexture(), 32, 32, 100, 10);
        tileset.FirstGlobalId = 10;
        collection.Add(tileset);

        Assert.Throws<InvalidOperationException>(() => collection.GetLocalId(5, out _));
    }

    [Fact]
    public void Enumeration_ReturnsAllTilesets()
    {
        var collection = new TilemapTilesetCollection();
        var tileset1 = new TilemapTileset("Tileset1", CreateDummyTexture(), 32, 32, 100, 10);
        var tileset2 = new TilemapTileset("Tileset2", CreateDummyTexture(), 32, 32, 50, 5);

        collection.Add(tileset1);
        collection.Add(tileset2);

        var list = collection.ToList();

        Assert.Equal(2, list.Count);
        Assert.Contains(tileset1, list);
        Assert.Contains(tileset2, list);
    }
}