using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Reflection;
using UnityEngine;
using UnityEditor;
using UnityEngine.Rendering;
using UnityEngine.ScriptableRenderLoop;
using NUnit.Framework;

[TestFixture]
public class ShaderGeneratorTests
{
	struct FailureTypes
	{
		// Non-primitive type in nested struct
		internal struct NestedWithNonPrimitiveType
		{
			public struct Data
			{
				public string s;
			}
			public Data contents;
		}

		// Unsupported primitive type in nested struct
		internal struct UnsupportedPrimitiveType
		{
			public struct Data
			{
				public IntPtr intPtr;
			}
			public Data contents;
		}

		// Mixed types in nested struct
		internal struct MixedTypesInNestedStruct
		{
			public struct Data
			{
				public float f;
				public int i;
			}
			public Data contents;
		}

		// More than 4 primitive fields in nested struct
		internal struct TooManyFields
		{
			public struct Data
			{
				public float f1, f2, f3, f4, f5;
			}
			public Data contents;
		}

		// Merge failure due to incompatible types
		internal struct MergeIncompatibleTypes
		{
			public float f;
			public Vector2 v;
			public int i;
		}

		// Merge failure due to register boundary crossing
		internal struct MergeCrossBoundary
		{
			public Vector2 u;
			public Vector3 v;
		}
	}

	// @TODO:  should probably switch to exceptions...
	static bool HasErrorString(List<string> errors, string errorSubstring)
	{
		if (errors == null)
			return false;

		bool foundError = false;
		foreach (var error in errors)
		{
			if (error.IndexOf(errorSubstring) >= 0)
			{
				foundError = true;
				break;
			}
		}

		return foundError;
	}

	[Test(Description = "Disallow non-primitive types in nested structs")]
    public void Fail_NestedWithNonPrimitiveType()
	{
		string source;
		List<string> errors;

		bool success = CSharpToHLSL.GenerateHLSL(typeof(FailureTypes.NestedWithNonPrimitiveType), new GenerateHLSL(PackingRules.Exact), out source, out errors);
		Assert.IsFalse(success);
		Assert.IsTrue(HasErrorString(errors, "contains a non-primitive field type"));
	}

	[Test(Description = "Check for unsupported types in primitive structs")]
    public void Fail_UnsupportedPrimitiveType()
	{
		string source;
		List<string> errors;

		bool success = CSharpToHLSL.GenerateHLSL(typeof(FailureTypes.UnsupportedPrimitiveType), new GenerateHLSL(PackingRules.Exact), out source, out errors);
		Assert.IsFalse(success);
		Assert.IsTrue(HasErrorString(errors, "contains an unsupported field type"));
	}

	[Test(Description = "Disallow mixed types in nested structs")]
	public void Fail_MixedTypesInNestedStruct()
	{
		string source;
		List<string> errors;

		bool success = CSharpToHLSL.GenerateHLSL(typeof(FailureTypes.MixedTypesInNestedStruct), new GenerateHLSL(PackingRules.Exact), out source, out errors);
		Assert.IsFalse(success);
		Assert.IsTrue(HasErrorString(errors, "contains mixed basic types"));
	}

	[Test(Description = "Disallow more than 16 bytes worth of fields in nested structs")]
    public void Fail_TooManyFields()
	{
		string source;
		List<string> errors;

		bool success = CSharpToHLSL.GenerateHLSL(typeof(FailureTypes.TooManyFields), new GenerateHLSL(PackingRules.Exact), out source, out errors);
		Assert.IsFalse(success);
		Assert.IsTrue(HasErrorString(errors, "more than 4 fields"));
	}

	[Test(Description = "Disallow merging incompatible types when doing aggressive packing")]
    public void Fail_MergeIncompatibleTypes()
	{
		string source;
		List<string> errors;

		bool success = CSharpToHLSL.GenerateHLSL(typeof(FailureTypes.MergeIncompatibleTypes), new GenerateHLSL(PackingRules.Aggressive), out source, out errors);
		Assert.IsFalse(success);
		Assert.IsTrue(HasErrorString(errors, "incompatible types"));
	}

	[Test(Description = "Disallow placing fields across register boundaries when merging")]
    public void Fail_MergeCrossBoundary()
	{
		string source;
		List<string> errors;

		bool success = CSharpToHLSL.GenerateHLSL(typeof(FailureTypes.MergeCrossBoundary), new GenerateHLSL(PackingRules.Aggressive), out source, out errors);
		Assert.IsFalse(success);
		Assert.IsTrue(HasErrorString(errors, "cross register boundary"));
	}

}