#include "RuntimeLayerModel.h"

#include <chrono>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <string>

namespace
{
int gFailures = 0;

void Expect(bool condition, const std::string& message)
{
	if (condition)
		return;

	++gFailures;
	std::cerr << "FAIL: " << message << "\n";
}

std::filesystem::path MakeTestRoot()
{
	const auto stamp = std::chrono::steady_clock::now().time_since_epoch().count();
	const std::filesystem::path root = std::filesystem::temp_directory_path() / ("render-cadence-layer-model-tests-" + std::to_string(stamp));
	std::filesystem::create_directories(root);
	return root;
}

void WriteFile(const std::filesystem::path& path, const std::string& contents)
{
	std::filesystem::create_directories(path.parent_path());
	std::ofstream output(path, std::ios::binary);
	output << contents;
}

RenderCadenceCompositor::SupportedShaderCatalog MakeCatalog(std::filesystem::path& root)
{
	root = MakeTestRoot();
	WriteFile(root / "solid" / "shader.slang", "float4 shadeVideo(float2 uv) { return float4(uv, 0.0, 1.0); }\n");
	WriteFile(root / "solid" / "shader.json", R"({
		"id": "solid",
		"name": "Solid",
		"description": "Solid test shader",
		"category": "Tests",
		"entryPoint": "shadeVideo",
		"parameters": [
			{ "id": "gain", "label": "Gain", "type": "float", "default": 0.5 }
		]
	})");

	RenderCadenceCompositor::SupportedShaderCatalog catalog;
	std::string error;
	Expect(catalog.Load(root, 4, error), error.empty() ? "catalog loads test shader" : error);
	return catalog;
}

void TestSingleLayerLifecycle()
{
	std::filesystem::path root;
	RenderCadenceCompositor::SupportedShaderCatalog catalog = MakeCatalog(root);

	RenderCadenceCompositor::RuntimeLayerModel model;
	std::string error;
	Expect(model.InitializeSingleLayer(catalog, "solid", error), "model initializes a supported startup shader");
	Expect(model.FirstLayerId() == "runtime-layer-1", "startup layer id is stable");

	Expect(model.MarkBuildStarted(model.FirstLayerId(), "build started", error), "build start updates the layer");
	RenderCadenceCompositor::RuntimeLayerModelSnapshot snapshot = model.Snapshot();
	Expect(snapshot.displayLayers.size() == 1, "snapshot exposes the display layer");
	Expect(snapshot.displayLayers[0].buildState == RenderCadenceCompositor::RuntimeLayerBuildState::Pending, "started layer is pending");
	Expect(!snapshot.displayLayers[0].renderReady, "started layer is not render-ready yet");

	RuntimeShaderArtifact artifact;
	artifact.shaderId = "solid";
	artifact.displayName = "Solid";
	artifact.fragmentShaderSource = "void main(){}";
	artifact.message = "build ready";
	Expect(model.MarkBuildReady(artifact, error), "ready artifact updates the matching layer");

	snapshot = model.Snapshot();
	Expect(snapshot.compileSucceeded, "ready layer reports compile success");
	Expect(snapshot.displayLayers[0].buildState == RenderCadenceCompositor::RuntimeLayerBuildState::Ready, "ready layer is marked ready");
	Expect(snapshot.displayLayers[0].renderReady, "ready layer exposes render readiness");
	Expect(snapshot.renderLayers.size() == 1, "ready layer produces one render layer artifact");
	Expect(snapshot.renderLayers[0].artifact.shaderId == "solid", "render layer carries the artifact");

	std::filesystem::remove_all(root);
}

void TestRejectsUnsupportedStartupShader()
{
	std::filesystem::path root;
	RenderCadenceCompositor::SupportedShaderCatalog catalog = MakeCatalog(root);

	RenderCadenceCompositor::RuntimeLayerModel model;
	std::string error;
	Expect(!model.InitializeSingleLayer(catalog, "missing", error), "model rejects unsupported shader ids");
	Expect(!error.empty(), "unsupported shader rejection explains the problem");
	Expect(model.Snapshot().displayLayers.empty(), "rejected startup shader leaves no display layer");

	std::filesystem::remove_all(root);
}

void TestBuildFailureStaysDisplaySide()
{
	std::filesystem::path root;
	RenderCadenceCompositor::SupportedShaderCatalog catalog = MakeCatalog(root);

	RenderCadenceCompositor::RuntimeLayerModel model;
	std::string error;
	Expect(model.InitializeSingleLayer(catalog, "solid", error), "model initializes for failure test");
	Expect(model.MarkBuildFailed(model.FirstLayerId(), "compile failed", error), "build failure updates the layer");

	const RenderCadenceCompositor::RuntimeLayerModelSnapshot snapshot = model.Snapshot();
	Expect(!snapshot.compileSucceeded, "failed layer reports compile failure");
	Expect(snapshot.displayLayers[0].buildState == RenderCadenceCompositor::RuntimeLayerBuildState::Failed, "failed layer is marked failed");
	Expect(!snapshot.displayLayers[0].renderReady, "failed layer is not render-ready");
	Expect(snapshot.renderLayers.empty(), "failed layer does not produce a render artifact");

	std::filesystem::remove_all(root);
}

void TestAddAndRemoveLayers()
{
	std::filesystem::path root;
	RenderCadenceCompositor::SupportedShaderCatalog catalog = MakeCatalog(root);

	RenderCadenceCompositor::RuntimeLayerModel model;
	std::string error;
	std::string firstLayerId;
	std::string secondLayerId;
	Expect(model.AddLayer(catalog, "solid", firstLayerId, error), "first layer can be added");
	Expect(model.AddLayer(catalog, "solid", secondLayerId, error), "second layer can be added");
	Expect(firstLayerId != secondLayerId, "added layers receive distinct ids");
	Expect(model.Snapshot().displayLayers.size() == 2, "added layers appear in display snapshot");

	Expect(model.RemoveLayer(firstLayerId, error), "existing layer can be removed");
	RenderCadenceCompositor::RuntimeLayerModelSnapshot snapshot = model.Snapshot();
	Expect(snapshot.displayLayers.size() == 1, "removed layer leaves snapshot");
	Expect(snapshot.displayLayers[0].id == secondLayerId, "remaining layer identity is preserved");
	Expect(!model.RemoveLayer(firstLayerId, error), "removed layer cannot be removed twice");

	std::filesystem::remove_all(root);
}

void TestLayerControlsUpdateDisplayAndRenderModels()
{
	std::filesystem::path root;
	RenderCadenceCompositor::SupportedShaderCatalog catalog = MakeCatalog(root);

	RenderCadenceCompositor::RuntimeLayerModel model;
	std::string error;
	std::string firstLayerId;
	std::string secondLayerId;
	Expect(model.AddLayer(catalog, "solid", firstLayerId, error), "first control layer can be added");
	Expect(model.AddLayer(catalog, "solid", secondLayerId, error), "second control layer can be added");

	Expect(model.SetLayerBypass(firstLayerId, true, error), "bypass can be set");
	Expect(model.ReorderLayer(firstLayerId, 1, error), "layer can be reordered");
	RenderCadenceCompositor::RuntimeLayerModelSnapshot snapshot = model.Snapshot();
	Expect(snapshot.displayLayers[1].id == firstLayerId, "reordered layer moves to requested index");
	Expect(snapshot.displayLayers[1].bypass, "bypass state is visible in read model");

	JsonValue gainValue(0.75);
	Expect(model.UpdateParameter(firstLayerId, "gain", gainValue, error), "parameter value can be updated");
	snapshot = model.Snapshot();
	Expect(snapshot.displayLayers[1].parameterValues.at("gain").numberValues.front() == 0.75, "updated parameter value is visible");

	RuntimeShaderArtifact artifact;
	artifact.layerId = firstLayerId;
	artifact.shaderId = "solid";
	artifact.displayName = "Solid";
	artifact.fragmentShaderSource = "void main(){}";
	artifact.parameterDefinitions = snapshot.displayLayers[1].parameterDefinitions;
	artifact.message = "build ready";
	Expect(model.MarkBuildReady(artifact, error), "ready artifact keeps layer parameter state");
	snapshot = model.Snapshot();
	Expect(snapshot.renderLayers.size() == 1, "ready layer produces render model");
	Expect(snapshot.renderLayers[0].bypass, "render model carries bypass state");
	Expect(snapshot.renderLayers[0].artifact.parameterValues.at("gain").numberValues.front() == 0.75, "render artifact carries updated parameter value");

	Expect(model.ResetParameters(firstLayerId, error), "parameters can reset to defaults");
	snapshot = model.Snapshot();
	Expect(snapshot.displayLayers[1].parameterValues.at("gain").numberValues.front() == 0.5, "reset restores default value");

	std::filesystem::remove_all(root);
}
}

int main()
{
	TestSingleLayerLifecycle();
	TestRejectsUnsupportedStartupShader();
	TestBuildFailureStaysDisplaySide();
	TestAddAndRemoveLayers();
	TestLayerControlsUpdateDisplayAndRenderModels();

	if (gFailures != 0)
	{
		std::cerr << gFailures << " RenderCadenceCompositorRuntimeLayerModel test failure(s).\n";
		return 1;
	}

	std::cout << "RenderCadenceCompositorRuntimeLayerModel tests passed.\n";
	return 0;
}