#include "LayerStackStore.h"
#include "RuntimeStateJson.h"
#include "ShaderPackageCatalog.h"

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

namespace
{
int gFailures = 0;

void Expect(bool condition, const char* message)
{
	if (condition)
		return;

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

std::filesystem::path MakeTestRoot()
{
	const auto stamp = std::chrono::steady_clock::now().time_since_epoch().count();
	std::filesystem::path root = std::filesystem::temp_directory_path() / ("video-shader-runtime-subsystem-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;
}

void WriteShaderPackage(const std::filesystem::path& root, const std::string& directoryName, const std::string& manifest)
{
	const std::filesystem::path packageRoot = root / directoryName;
	WriteFile(packageRoot / "shader.json", manifest);
	WriteFile(packageRoot / "shader.slang", "float4 shadeVideo(float2 uv) { return float4(uv, 0.0, 1.0); }\n");
}

ShaderPackageCatalog BuildCatalog(const std::filesystem::path& root)
{
	ShaderPackageCatalog catalog;
	std::string error;
	Expect(catalog.Scan(root, 4, error), "shader package catalog scans test packages");
	Expect(error.empty(), "catalog scan does not report an error");
	return catalog;
}

void TestLayerDefaultsAndCrud()
{
	const std::filesystem::path root = MakeTestRoot();
	WriteShaderPackage(root, "alpha", R"({
		"id": "alpha",
		"name": "Alpha",
		"parameters": [
			{ "id": "gain", "label": "Gain", "type": "float", "default": 0.25, "min": 0, "max": 1 },
			{ "id": "enabled", "label": "Enabled", "type": "bool", "default": true }
		]
	})");
	WriteShaderPackage(root, "beta", R"({
		"id": "beta",
		"name": "Beta",
		"parameters": [
			{ "id": "mode", "label": "Mode", "type": "enum", "default": "soft", "options": [
				{ "value": "soft", "label": "Soft" },
				{ "value": "hard", "label": "Hard" }
			] }
		]
	})");

	ShaderPackageCatalog catalog = BuildCatalog(root);
	LayerStackStore layers;
	std::string error;
	Expect(layers.CreateLayer(catalog, "alpha", error), "layer store creates a layer for a known shader");
	Expect(layers.LayerCount() == 1, "created layer is stored");
	Expect(!layers.CreateLayer(catalog, "missing", error), "layer store rejects unknown shaders");

	LayerStackStore::StoredParameterSnapshot snapshot;
	Expect(layers.TryGetParameterById(catalog, layers.Layers()[0].id, "gain", snapshot, error), "parameter lookup by id succeeds");
	Expect(snapshot.currentValue.numberValues.size() == 1 && snapshot.currentValue.numberValues[0] == 0.25, "default float value is persisted");

	ShaderParameterValue value;
	value.numberValues = { 0.75 };
	Expect(layers.SetParameterValue(layers.Layers()[0].id, "gain", value, error), "parameter value can be updated");
	Expect(layers.TryGetParameterById(catalog, layers.Layers()[0].id, "gain", snapshot, error), "updated parameter can be read");
	Expect(snapshot.currentValue.numberValues.size() == 1 && snapshot.currentValue.numberValues[0] == 0.75, "updated float value is retained");

	Expect(layers.SetLayerShaderSelection(catalog, layers.Layers()[0].id, "beta", error), "layer shader selection can change");
	Expect(layers.Layers()[0].shaderId == "beta", "new shader id is stored");
	Expect(layers.TryGetParameterById(catalog, layers.Layers()[0].id, "mode", snapshot, error), "new shader defaults are applied");
	Expect(snapshot.currentValue.enumValue == "soft", "enum default is applied after shader change");

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

void TestMoveClassificationAndPresetLoad()
{
	const std::filesystem::path root = MakeTestRoot();
	WriteShaderPackage(root, "alpha", R"({
		"id": "alpha",
		"name": "Alpha",
		"parameters": [{ "id": "gain", "label": "Gain", "type": "float", "default": 0.5, "min": 0, "max": 1 }]
	})");
	WriteShaderPackage(root, "beta", R"({
		"id": "beta",
		"name": "Beta",
		"parameters": []
	})");

	ShaderPackageCatalog catalog = BuildCatalog(root);
	LayerStackStore layers;
	std::string error;
	Expect(layers.CreateLayer(catalog, "alpha", error), "first test layer is created");
	Expect(layers.CreateLayer(catalog, "beta", error), "second test layer is created");
	const std::string firstLayerId = layers.Layers()[0].id;
	const std::string secondLayerId = layers.Layers()[1].id;

	bool shouldMove = true;
	Expect(layers.ResolveLayerMove(firstLayerId, -1, shouldMove, error), "top layer move up is classified");
	Expect(!shouldMove, "top layer move up is a no-op");
	Expect(layers.ResolveLayerMove(firstLayerId, 1, shouldMove, error), "top layer move down is classified");
	Expect(shouldMove, "top layer move down should move");
	Expect(layers.MoveLayer(firstLayerId, 1, error), "top layer moves down");
	Expect(layers.Layers()[0].id == secondLayerId && layers.Layers()[1].id == firstLayerId, "layer order changed after move");

	JsonValue preset = layers.BuildStackPresetValue(catalog, "Look One");
	LayerStackStore loaded;
	Expect(loaded.LoadStackPresetValue(catalog, preset, error), "stack preset value loads into a fresh layer store");
	Expect(loaded.LayerCount() == 2, "loaded preset preserves layer count");
	Expect(loaded.Layers()[0].shaderId == "beta" && loaded.Layers()[1].shaderId == "alpha", "loaded preset preserves shader order");
	Expect(loaded.Layers()[0].id != secondLayerId, "loaded preset generates fresh layer ids");

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

void TestRuntimeStateJsonReadModelSerialization()
{
	ShaderPackage package;
	package.id = "alpha";
	package.displayName = "Alpha";
	package.feedback.enabled = true;
	package.feedback.writePassId = "main";
	package.temporal.enabled = true;
	package.temporal.historySource = TemporalHistorySource::Source;
	package.temporal.requestedHistoryLength = 3;
	package.temporal.effectiveHistoryLength = 3;

	ShaderParameterDefinition gain;
	gain.id = "gain";
	gain.label = "Gain";
	gain.type = ShaderParameterType::Float;
	gain.defaultNumbers = { 0.5 };
	gain.minNumbers = { 0.0 };
	gain.maxNumbers = { 1.0 };
	package.parameters.push_back(gain);

	LayerStackStore::LayerPersistentState layer;
	layer.id = "layer-1";
	layer.shaderId = "alpha";
	ShaderParameterValue gainValue;
	gainValue.numberValues = { 0.8 };
	layer.parameterValues["gain"] = gainValue;

	JsonValue layersJson = RuntimeStateJson::SerializeLayerStack({ layer }, { { "alpha", package } });
	Expect(layersJson.isArray() && layersJson.asArray().size() == 1, "runtime state layer serialization emits one layer");

	const JsonValue& layerJson = layersJson.asArray()[0];
	Expect(layerJson.find("shaderName") && layerJson.find("shaderName")->asString() == "Alpha", "serialized layer includes shader display name");
	Expect(layerJson.find("temporal") && layerJson.find("temporal")->isObject(), "serialized layer includes temporal metadata");
	Expect(layerJson.find("feedback") && layerJson.find("feedback")->isObject(), "serialized layer includes feedback metadata");

	const JsonValue* parameters = layerJson.find("parameters");
	Expect(parameters && parameters->isArray() && parameters->asArray().size() == 1, "serialized layer includes parameter metadata");
	const JsonValue* value = parameters->asArray()[0].find("value");
	Expect(value && value->asNumber() == 0.8, "serialized parameter includes current value");
}
}

int main()
{
	TestLayerDefaultsAndCrud();
	TestMoveClassificationAndPresetLoad();
	TestRuntimeStateJsonReadModelSerialization();

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

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