#include "stdafx.h"
#include "RuntimeHost.h"
#include "RuntimeParameterUtils.h"
#include "ShaderCompiler.h"
#include "ShaderPackageRegistry.h"

#include <algorithm>
#include <cmath>
#include <fstream>
#include <set>
#include <sstream>

namespace
{
std::string Trim(const std::string& text)
{
	std::size_t start = 0;
	while (start < text.size() && std::isspace(static_cast<unsigned char>(text[start])))
		++start;

	std::size_t end = text.size();
	while (end > start && std::isspace(static_cast<unsigned char>(text[end - 1])))
		--end;

	return text.substr(start, end - start);
}

bool IsFiniteNumber(double value)
{
	return std::isfinite(value) != 0;
}

std::string ToLowerCopy(std::string text)
{
	std::transform(text.begin(), text.end(), text.begin(),
		[](unsigned char ch) { return static_cast<char>(std::tolower(ch)); });
	return text;
}

std::string SimplifyControlKey(const std::string& text)
{
	std::string simplified;
	for (unsigned char ch : text)
	{
		if (std::isalnum(ch))
			simplified.push_back(static_cast<char>(std::tolower(ch)));
	}
	return simplified;
}

bool MatchesControlKey(const std::string& candidate, const std::string& key)
{
	return candidate == key || SimplifyControlKey(candidate) == SimplifyControlKey(key);
}

bool TryParseLayerIdNumber(const std::string& layerId, uint64_t& number)
{
	const std::string prefix = "layer-";
	if (layerId.rfind(prefix, 0) != 0 || layerId.size() == prefix.size())
		return false;

	uint64_t parsed = 0;
	for (std::size_t index = prefix.size(); index < layerId.size(); ++index)
	{
		const unsigned char ch = static_cast<unsigned char>(layerId[index]);
		if (!std::isdigit(ch))
			return false;
		parsed = parsed * 10 + static_cast<uint64_t>(ch - '0');
	}

	number = parsed;
	return true;
}

std::vector<double> JsonArrayToNumbers(const JsonValue& value)
{
	std::vector<double> numbers;
	for (const JsonValue& item : value.asArray())
	{
		if (item.isNumber())
			numbers.push_back(item.asNumber());
	}
	return numbers;
}

bool LooksLikePackagedRuntimeRoot(const std::filesystem::path& candidate)
{
	return std::filesystem::exists(candidate / "config" / "runtime-host.json") &&
		std::filesystem::exists(candidate / "runtime" / "templates" / "shader_wrapper.slang.in") &&
		std::filesystem::exists(candidate / "shaders");
}

bool LooksLikeRepoRoot(const std::filesystem::path& candidate)
{
	return std::filesystem::exists(candidate / "CMakeLists.txt") &&
		std::filesystem::exists(candidate / "apps" / "LoopThroughWithOpenGLCompositing");
}

std::filesystem::path FindRepoRootCandidate()
{
	std::vector<std::filesystem::path> rootsToTry;

	char currentDirectory[MAX_PATH] = {};
	if (GetCurrentDirectoryA(MAX_PATH, currentDirectory) > 0)
		rootsToTry.push_back(std::filesystem::path(currentDirectory));

	char modulePath[MAX_PATH] = {};
	DWORD moduleLength = GetModuleFileNameA(NULL, modulePath, MAX_PATH);
	if (moduleLength > 0 && moduleLength < MAX_PATH)
		rootsToTry.push_back(std::filesystem::path(modulePath).parent_path());

	for (const std::filesystem::path& startPath : rootsToTry)
	{
		std::filesystem::path candidate = startPath;
		for (int depth = 0; depth < 10 && !candidate.empty(); ++depth)
		{
			if (LooksLikePackagedRuntimeRoot(candidate) || LooksLikeRepoRoot(candidate))
				return candidate;

			candidate = candidate.parent_path();
		}
	}

	return std::filesystem::path();
}

std::string ShaderParameterTypeToString(ShaderParameterType type)
{
	switch (type)
	{
	case ShaderParameterType::Float: return "float";
	case ShaderParameterType::Vec2: return "vec2";
	case ShaderParameterType::Color: return "color";
	case ShaderParameterType::Boolean: return "bool";
	case ShaderParameterType::Enum: return "enum";
	case ShaderParameterType::Text: return "text";
	}
	return "unknown";
}

bool ParseTemporalHistorySource(const std::string& sourceName, TemporalHistorySource& source)
{
	if (sourceName == "source")
	{
		source = TemporalHistorySource::Source;
		return true;
	}
	if (sourceName == "preLayerInput")
	{
		source = TemporalHistorySource::PreLayerInput;
		return true;
	}
	return false;
}

bool ParseShaderParameterType(const std::string& typeName, ShaderParameterType& type)
{
	if (typeName == "float")
	{
		type = ShaderParameterType::Float;
		return true;
	}
	if (typeName == "vec2")
	{
		type = ShaderParameterType::Vec2;
		return true;
	}
	if (typeName == "color")
	{
		type = ShaderParameterType::Color;
		return true;
	}
	if (typeName == "bool")
	{
		type = ShaderParameterType::Boolean;
		return true;
	}
	if (typeName == "enum")
	{
		type = ShaderParameterType::Enum;
		return true;
	}
	if (typeName == "text")
	{
		type = ShaderParameterType::Text;
		return true;
	}
	return false;
}

bool TextureAssetsEqual(const std::vector<ShaderTextureAsset>& left, const std::vector<ShaderTextureAsset>& right)
{
	if (left.size() != right.size())
		return false;

	for (std::size_t index = 0; index < left.size(); ++index)
	{
		if (left[index].id != right[index].id ||
			left[index].path != right[index].path ||
			left[index].writeTime != right[index].writeTime)
		{
			return false;
		}
	}

	return true;
}

bool FontAssetsEqual(const std::vector<ShaderFontAsset>& left, const std::vector<ShaderFontAsset>& right)
{
	if (left.size() != right.size())
		return false;

	for (std::size_t index = 0; index < left.size(); ++index)
	{
		if (left[index].id != right[index].id ||
			left[index].path != right[index].path ||
			left[index].writeTime != right[index].writeTime)
		{
			return false;
		}
	}

	return true;
}

std::string ManifestPathMessage(const std::filesystem::path& manifestPath)
{
	return manifestPath.string();
}

bool RequireStringField(const JsonValue& object, const char* fieldName, std::string& value, const std::filesystem::path& manifestPath, std::string& error)
{
	const JsonValue* fieldValue = object.find(fieldName);
	if (!fieldValue || !fieldValue->isString())
	{
		error = "Shader manifest is missing required string '" + std::string(fieldName) + "' field: " + ManifestPathMessage(manifestPath);
		return false;
	}

	value = fieldValue->asString();
	return true;
}

bool RequireNonEmptyStringField(const JsonValue& object, const char* fieldName, std::string& value, const std::filesystem::path& manifestPath, std::string& error)
{
	if (!RequireStringField(object, fieldName, value, manifestPath, error))
		return false;
	if (Trim(value).empty())
	{
		error = "Shader manifest string '" + std::string(fieldName) + "' must not be empty: " + ManifestPathMessage(manifestPath);
		return false;
	}
	return true;
}

bool OptionalStringField(const JsonValue& object, const char* fieldName, std::string& value, const std::string& fallback, const std::filesystem::path& manifestPath, std::string& error)
{
	const JsonValue* fieldValue = object.find(fieldName);
	if (!fieldValue)
	{
		value = fallback;
		return true;
	}
	if (!fieldValue->isString())
	{
		error = "Shader manifest field '" + std::string(fieldName) + "' must be a string in: " + ManifestPathMessage(manifestPath);
		return false;
	}
	value = fieldValue->asString();
	return true;
}

bool OptionalArrayField(const JsonValue& object, const char* fieldName, const JsonValue*& value, const std::filesystem::path& manifestPath, std::string& error)
{
	value = object.find(fieldName);
	if (!value)
		return true;
	if (!value->isArray())
	{
		error = "Shader manifest '" + std::string(fieldName) + "' field must be an array in: " + ManifestPathMessage(manifestPath);
		return false;
	}
	return true;
}

bool OptionalObjectField(const JsonValue& object, const char* fieldName, const JsonValue*& value, const std::filesystem::path& manifestPath, std::string& error)
{
	value = object.find(fieldName);
	if (!value)
		return true;
	if (!value->isObject())
	{
		error = "Shader manifest '" + std::string(fieldName) + "' field must be an object in: " + ManifestPathMessage(manifestPath);
		return false;
	}
	return true;
}

bool NumberListFromJsonValue(const JsonValue& value, std::vector<double>& numbers, const std::string& fieldName, const std::filesystem::path& manifestPath, std::string& error)
{
	if (value.isNumber())
	{
		numbers.push_back(value.asNumber());
		return true;
	}
	if (value.isArray())
	{
		numbers = JsonArrayToNumbers(value);
		if (numbers.size() != value.asArray().size())
		{
			error = "Shader parameter field '" + fieldName + "' must contain only numbers in: " + ManifestPathMessage(manifestPath);
			return false;
		}
		return true;
	}

	error = "Shader parameter field '" + fieldName + "' must be a number or array of numbers in: " + ManifestPathMessage(manifestPath);
	return false;
}

bool ValidateShaderIdentifier(const std::string& identifier, const std::string& fieldName, const std::filesystem::path& manifestPath, std::string& error)
{
	if (identifier.empty() || !(std::isalpha(static_cast<unsigned char>(identifier.front())) || identifier.front() == '_'))
	{
		error = "Shader manifest field '" + fieldName + "' must be a valid shader identifier in: " + ManifestPathMessage(manifestPath);
		return false;
	}

	for (char ch : identifier)
	{
		const unsigned char unsignedCh = static_cast<unsigned char>(ch);
		if (!(std::isalnum(unsignedCh) || ch == '_'))
		{
			error = "Shader manifest field '" + fieldName + "' must be a valid shader identifier in: " + ManifestPathMessage(manifestPath);
			return false;
		}
	}

	return true;
}

bool ParseShaderMetadata(const JsonValue& manifestJson, ShaderPackage& shaderPackage, const std::filesystem::path& manifestPath, std::string& error)
{
	if (!RequireStringField(manifestJson, "id", shaderPackage.id, manifestPath, error) ||
		!RequireStringField(manifestJson, "name", shaderPackage.displayName, manifestPath, error) ||
		!OptionalStringField(manifestJson, "description", shaderPackage.description, "", manifestPath, error) ||
		!OptionalStringField(manifestJson, "category", shaderPackage.category, "", manifestPath, error) ||
		!OptionalStringField(manifestJson, "entryPoint", shaderPackage.entryPoint, "shadeVideo", manifestPath, error))
	{
		return false;
	}

	if (!ValidateShaderIdentifier(shaderPackage.entryPoint, "entryPoint", manifestPath, error))
		return false;

	shaderPackage.directoryPath = manifestPath.parent_path();
	shaderPackage.shaderPath = shaderPackage.directoryPath / "shader.slang";
	shaderPackage.manifestPath = manifestPath;
	return true;
}

bool ParseTextureAssets(const JsonValue& manifestJson, ShaderPackage& shaderPackage, const std::filesystem::path& manifestPath, std::string& error)
{
	const JsonValue* texturesValue = nullptr;
	if (!OptionalArrayField(manifestJson, "textures", texturesValue, manifestPath, error))
		return false;
	if (!texturesValue)
		return true;

	for (const JsonValue& textureJson : texturesValue->asArray())
	{
		if (!textureJson.isObject())
		{
			error = "Shader texture entry must be an object in: " + ManifestPathMessage(manifestPath);
			return false;
		}

		std::string textureId;
		std::string texturePath;
		if (!RequireNonEmptyStringField(textureJson, "id", textureId, manifestPath, error) ||
			!RequireNonEmptyStringField(textureJson, "path", texturePath, manifestPath, error))
		{
			error = "Shader texture is missing required 'id' or 'path' in: " + ManifestPathMessage(manifestPath);
			return false;
		}
		if (!ValidateShaderIdentifier(textureId, "textures[].id", manifestPath, error))
			return false;

		ShaderTextureAsset textureAsset;
		textureAsset.id = textureId;
		textureAsset.path = shaderPackage.directoryPath / texturePath;
		if (!std::filesystem::exists(textureAsset.path))
		{
			error = "Shader texture asset not found for package " + shaderPackage.id + ": " + textureAsset.path.string();
			return false;
		}

		textureAsset.writeTime = std::filesystem::last_write_time(textureAsset.path);
		shaderPackage.textureAssets.push_back(textureAsset);
	}

	return true;
}

bool ParseFontAssets(const JsonValue& manifestJson, ShaderPackage& shaderPackage, const std::filesystem::path& manifestPath, std::string& error)
{
	const JsonValue* fontsValue = nullptr;
	if (!OptionalArrayField(manifestJson, "fonts", fontsValue, manifestPath, error))
		return false;
	if (!fontsValue)
		return true;

	for (const JsonValue& fontJson : fontsValue->asArray())
	{
		if (!fontJson.isObject())
		{
			error = "Shader font entry must be an object in: " + ManifestPathMessage(manifestPath);
			return false;
		}

		std::string fontId;
		std::string fontPath;
		if (!RequireNonEmptyStringField(fontJson, "id", fontId, manifestPath, error) ||
			!RequireNonEmptyStringField(fontJson, "path", fontPath, manifestPath, error))
		{
			error = "Shader font is missing required 'id' or 'path' in: " + ManifestPathMessage(manifestPath);
			return false;
		}
		if (!ValidateShaderIdentifier(fontId, "fonts[].id", manifestPath, error))
			return false;

		ShaderFontAsset fontAsset;
		fontAsset.id = fontId;
		fontAsset.path = shaderPackage.directoryPath / fontPath;
		if (!std::filesystem::exists(fontAsset.path))
		{
			error = "Shader font asset not found for package " + shaderPackage.id + ": " + fontAsset.path.string();
			return false;
		}

		fontAsset.writeTime = std::filesystem::last_write_time(fontAsset.path);
		shaderPackage.fontAssets.push_back(fontAsset);
	}

	return true;
}

bool ParseTemporalSettings(const JsonValue& manifestJson, ShaderPackage& shaderPackage, unsigned maxTemporalHistoryFrames, const std::filesystem::path& manifestPath, std::string& error)
{
	const JsonValue* temporalValue = nullptr;
	if (!OptionalObjectField(manifestJson, "temporal", temporalValue, manifestPath, error))
		return false;
	if (!temporalValue)
		return true;

	const JsonValue* enabledValue = temporalValue->find("enabled");
	if (!enabledValue || !enabledValue->asBoolean(false))
		return true;

	std::string historySourceName;
	if (!RequireNonEmptyStringField(*temporalValue, "historySource", historySourceName, manifestPath, error))
	{
		error = "Temporal shader is missing required 'historySource' in: " + ManifestPathMessage(manifestPath);
		return false;
	}

	const JsonValue* historyLengthValue = temporalValue->find("historyLength");
	if (!historyLengthValue || !historyLengthValue->isNumber())
	{
		error = "Temporal shader is missing required numeric 'historyLength' in: " + ManifestPathMessage(manifestPath);
		return false;
	}

	TemporalHistorySource historySource = TemporalHistorySource::None;
	if (!ParseTemporalHistorySource(historySourceName, historySource))
	{
		error = "Unsupported temporal historySource '" + historySourceName + "' in: " + ManifestPathMessage(manifestPath);
		return false;
	}

	const double requestedHistoryLength = historyLengthValue->asNumber();
	if (!IsFiniteNumber(requestedHistoryLength) || requestedHistoryLength <= 0.0 || std::floor(requestedHistoryLength) != requestedHistoryLength)
	{
		error = "Temporal shader 'historyLength' must be a positive integer in: " + ManifestPathMessage(manifestPath);
		return false;
	}

	shaderPackage.temporal.enabled = true;
	shaderPackage.temporal.historySource = historySource;
	shaderPackage.temporal.requestedHistoryLength = static_cast<unsigned>(requestedHistoryLength);
	shaderPackage.temporal.effectiveHistoryLength = std::min(shaderPackage.temporal.requestedHistoryLength, maxTemporalHistoryFrames);
	return true;
}

bool ParseParameterNumberField(const JsonValue& parameterJson, const char* fieldName, std::vector<double>& values, const std::filesystem::path& manifestPath, std::string& error)
{
	if (const JsonValue* fieldValue = parameterJson.find(fieldName))
		return NumberListFromJsonValue(*fieldValue, values, fieldName, manifestPath, error);
	return true;
}

bool ParseParameterDefault(const JsonValue& parameterJson, ShaderParameterDefinition& definition, const std::filesystem::path& manifestPath, std::string& error)
{
	const JsonValue* defaultValue = parameterJson.find("default");
	if (!defaultValue)
		return true;

	if (definition.type == ShaderParameterType::Boolean)
	{
		if (!defaultValue->isBoolean())
		{
			error = "Boolean parameter default must be a boolean for: " + definition.id;
			return false;
		}
		definition.defaultBoolean = defaultValue->asBoolean(false);
		return true;
	}

	if (definition.type == ShaderParameterType::Enum)
	{
		if (!defaultValue->isString())
		{
			error = "Enum parameter default must be a string for: " + definition.id;
			return false;
		}
		definition.defaultEnumValue = defaultValue->asString();
		return true;
	}

	if (definition.type == ShaderParameterType::Text)
	{
		if (!defaultValue->isString())
		{
			error = "Text parameter default must be a string for: " + definition.id;
			return false;
		}
		definition.defaultTextValue = defaultValue->asString();
		return true;
	}

	return NumberListFromJsonValue(*defaultValue, definition.defaultNumbers, "default", manifestPath, error);
}

bool ParseParameterOptions(const JsonValue& parameterJson, ShaderParameterDefinition& definition, const std::filesystem::path& manifestPath, std::string& error)
{
	const JsonValue* optionsValue = nullptr;
	if (!OptionalArrayField(parameterJson, "options", optionsValue, manifestPath, error) || !optionsValue)
	{
		error = "Enum parameter is missing 'options' in: " + ManifestPathMessage(manifestPath);
		return false;
	}

	for (const JsonValue& optionJson : optionsValue->asArray())
	{
		if (!optionJson.isObject())
		{
			error = "Enum parameter option must be an object in: " + ManifestPathMessage(manifestPath);
			return false;
		}

		ShaderParameterOption option;
		if (!RequireStringField(optionJson, "value", option.value, manifestPath, error) ||
			!RequireStringField(optionJson, "label", option.label, manifestPath, error))
		{
			error = "Enum parameter option is missing 'value' or 'label' in: " + ManifestPathMessage(manifestPath);
			return false;
		}
		definition.enumOptions.push_back(option);
	}

	bool defaultFound = definition.defaultEnumValue.empty();
	for (const ShaderParameterOption& option : definition.enumOptions)
	{
		if (option.value == definition.defaultEnumValue)
		{
			defaultFound = true;
			break;
		}
	}

	if (!defaultFound)
	{
		error = "Enum parameter default is not present in its option list for: " + definition.id;
		return false;
	}

	return true;
}

bool ParseParameterDefinition(const JsonValue& parameterJson, ShaderParameterDefinition& definition, const std::filesystem::path& manifestPath, std::string& error)
{
	if (!parameterJson.isObject())
	{
		error = "Shader parameter entry must be an object in: " + ManifestPathMessage(manifestPath);
		return false;
	}

	std::string typeName;
	if (!RequireStringField(parameterJson, "id", definition.id, manifestPath, error) ||
		!RequireStringField(parameterJson, "label", definition.label, manifestPath, error) ||
		!RequireStringField(parameterJson, "type", typeName, manifestPath, error))
	{
		error = "Shader parameter is missing required fields in: " + ManifestPathMessage(manifestPath);
		return false;
	}

	if (!ParseShaderParameterType(typeName, definition.type))
	{
		error = "Unsupported parameter type '" + typeName + "' in: " + ManifestPathMessage(manifestPath);
		return false;
	}
	if (!ValidateShaderIdentifier(definition.id, "parameters[].id", manifestPath, error))
		return false;

	if (!ParseParameterDefault(parameterJson, definition, manifestPath, error) ||
		!ParseParameterNumberField(parameterJson, "min", definition.minNumbers, manifestPath, error) ||
		!ParseParameterNumberField(parameterJson, "max", definition.maxNumbers, manifestPath, error) ||
		!ParseParameterNumberField(parameterJson, "step", definition.stepNumbers, manifestPath, error))
	{
		return false;
	}

	if (definition.type == ShaderParameterType::Text)
	{
		if (const JsonValue* fontValue = parameterJson.find("font"))
		{
			if (!fontValue->isString())
			{
				error = "Text parameter 'font' must be a string for: " + definition.id;
				return false;
			}
			definition.fontId = fontValue->asString();
			if (!definition.fontId.empty() && !ValidateShaderIdentifier(definition.fontId, "parameters[].font", manifestPath, error))
				return false;
		}
		if (const JsonValue* maxLengthValue = parameterJson.find("maxLength"))
		{
			if (!maxLengthValue->isNumber() || maxLengthValue->asNumber() < 1.0 || maxLengthValue->asNumber() > 256.0)
			{
				error = "Text parameter 'maxLength' must be a number from 1 to 256 for: " + definition.id;
				return false;
			}
			definition.maxLength = static_cast<unsigned>(maxLengthValue->asNumber());
		}
	}

	if (definition.type == ShaderParameterType::Enum)
		return ParseParameterOptions(parameterJson, definition, manifestPath, error);

	return true;
}

bool ParseParameterDefinitions(const JsonValue& manifestJson, ShaderPackage& shaderPackage, const std::filesystem::path& manifestPath, std::string& error)
{
	const JsonValue* parametersValue = nullptr;
	if (!OptionalArrayField(manifestJson, "parameters", parametersValue, manifestPath, error))
		return false;
	if (!parametersValue)
		return true;

	for (const JsonValue& parameterJson : parametersValue->asArray())
	{
		ShaderParameterDefinition definition;
		if (!ParseParameterDefinition(parameterJson, definition, manifestPath, error))
			return false;
		shaderPackage.parameters.push_back(definition);
	}

	return true;
}
}

RuntimeHost::RuntimeHost()
	: mReloadRequested(false),
	mCompileSucceeded(false),
	mHasSignal(false),
	mSignalWidth(0),
	mSignalHeight(0),
	mFrameBudgetMilliseconds(0.0),
	mRenderMilliseconds(0.0),
	mSmoothedRenderMilliseconds(0.0),
	mServerPort(8080),
	mAutoReloadEnabled(true),
	mStartTime(std::chrono::steady_clock::now()),
	mLastScanTime(std::chrono::steady_clock::time_point::min()),
	mFrameCounter(0),
	mNextLayerId(0)
{
}

bool RuntimeHost::Initialize(std::string& error)
{
	try
	{
		std::lock_guard<std::mutex> lock(mMutex);

		if (!ResolvePaths(error))
			return false;
		if (!LoadConfig(error))
			return false;
		mShaderRoot = mRepoRoot / mConfig.shaderLibrary;
		if (!LoadPersistentState(error))
			return false;
		if (!ScanShaderPackages(error))
			return false;
		NormalizePersistentLayerIdsLocked();

		for (LayerPersistentState& layer : mPersistentState.layers)
		{
			auto shaderIt = mPackagesById.find(layer.shaderId);
			if (shaderIt != mPackagesById.end())
				EnsureLayerDefaultsLocked(layer, shaderIt->second);
		}

		if (mPersistentState.layers.empty() && !mPackageOrder.empty())
		{
			LayerPersistentState layer;
			layer.id = GenerateLayerId();
			layer.shaderId = mPackageOrder.front();
			layer.bypass = false;
			EnsureLayerDefaultsLocked(layer, mPackagesById[layer.shaderId]);
			mPersistentState.layers.push_back(layer);
		}

		mServerPort = mConfig.serverPort;
		mAutoReloadEnabled = mConfig.autoReload;
		mReloadRequested = true;
		mCompileMessage = "Waiting for shader compile.";
		return true;
	}
	catch (const std::exception& exception)
	{
		error = std::string("RuntimeHost::Initialize exception: ") + exception.what();
		return false;
	}
	catch (...)
	{
		error = "RuntimeHost::Initialize threw a non-standard exception.";
		return false;
	}
}

bool RuntimeHost::PollFileChanges(bool& registryChanged, bool& reloadRequested, std::string& error)
{
	try
	{
		std::lock_guard<std::mutex> lock(mMutex);
		registryChanged = false;
		reloadRequested = false;

		if (!mAutoReloadEnabled)
		{
			reloadRequested = mReloadRequested;
			return true;
		}

		const auto now = std::chrono::steady_clock::now();
		if (mLastScanTime != std::chrono::steady_clock::time_point::min() &&
			std::chrono::duration_cast<std::chrono::milliseconds>(now - mLastScanTime).count() < 250)
		{
			reloadRequested = mReloadRequested;
			return true;
		}

		mLastScanTime = now;

		std::string scanError;
		std::map<std::string, ShaderPackage> previousPackages = mPackagesById;
		std::vector<std::string> previousOrder = mPackageOrder;
		std::map<std::string, std::pair<std::filesystem::file_time_type, std::filesystem::file_time_type>> previousLayerShaderTimes;
		for (const LayerPersistentState& layer : mPersistentState.layers)
		{
			auto previous = previousPackages.find(layer.shaderId);
			if (previous != previousPackages.end())
				previousLayerShaderTimes[layer.id] = std::make_pair(previous->second.shaderWriteTime, previous->second.manifestWriteTime);
		}

		if (!ScanShaderPackages(scanError))
		{
			error = scanError;
			return false;
		}

		registryChanged = previousOrder != mPackageOrder;
		if (!registryChanged && previousPackages.size() == mPackagesById.size())
		{
			for (const auto& item : mPackagesById)
			{
				auto previous = previousPackages.find(item.first);
				if (previous == previousPackages.end())
				{
					registryChanged = true;
					break;
				}
				if (previous->second.shaderWriteTime != item.second.shaderWriteTime ||
					previous->second.manifestWriteTime != item.second.manifestWriteTime ||
					!TextureAssetsEqual(previous->second.textureAssets, item.second.textureAssets) ||
					!FontAssetsEqual(previous->second.fontAssets, item.second.fontAssets))
				{
					registryChanged = true;
					break;
				}
			}
		}

		for (LayerPersistentState& layer : mPersistentState.layers)
		{
			auto active = mPackagesById.find(layer.shaderId);
			auto previous = previousLayerShaderTimes.find(layer.id);
			if (active == mPackagesById.end())
				continue;
			EnsureLayerDefaultsLocked(layer, active->second);
			if (previous != previousLayerShaderTimes.end())
			{
				auto previousPackage = previousPackages.find(layer.shaderId);
				if (previous->second.first != active->second.shaderWriteTime ||
					previous->second.second != active->second.manifestWriteTime ||
					(previousPackage != previousPackages.end() &&
						(!TextureAssetsEqual(previousPackage->second.textureAssets, active->second.textureAssets) ||
							!FontAssetsEqual(previousPackage->second.fontAssets, active->second.fontAssets))))
				{
					mReloadRequested = true;
				}
			}
		}

		reloadRequested = mReloadRequested;
		return true;
	}
	catch (const std::exception& exception)
	{
		error = std::string("RuntimeHost::PollFileChanges exception: ") + exception.what();
		return false;
	}
	catch (...)
	{
		error = "RuntimeHost::PollFileChanges threw a non-standard exception.";
		return false;
	}
}

bool RuntimeHost::ManualReloadRequested()
{
	std::lock_guard<std::mutex> lock(mMutex);
	return mReloadRequested;
}

void RuntimeHost::ClearReloadRequest()
{
	std::lock_guard<std::mutex> lock(mMutex);
	mReloadRequested = false;
}

bool RuntimeHost::AddLayer(const std::string& shaderId, std::string& error)
{
	std::lock_guard<std::mutex> lock(mMutex);
	auto shaderIt = mPackagesById.find(shaderId);
	if (shaderIt == mPackagesById.end())
	{
		error = "Unknown shader id: " + shaderId;
		return false;
	}

	LayerPersistentState layer;
	layer.id = GenerateLayerId();
	layer.shaderId = shaderId;
	layer.bypass = false;
	EnsureLayerDefaultsLocked(layer, shaderIt->second);
	mPersistentState.layers.push_back(layer);
	mReloadRequested = true;
	return SavePersistentState(error);
}

bool RuntimeHost::RemoveLayer(const std::string& layerId, std::string& error)
{
	std::lock_guard<std::mutex> lock(mMutex);
	auto it = std::find_if(mPersistentState.layers.begin(), mPersistentState.layers.end(),
		[&layerId](const LayerPersistentState& layer) { return layer.id == layerId; });
	if (it == mPersistentState.layers.end())
	{
		error = "Unknown layer id: " + layerId;
		return false;
	}

	mPersistentState.layers.erase(it);
	mReloadRequested = true;
	return SavePersistentState(error);
}

bool RuntimeHost::MoveLayer(const std::string& layerId, int direction, std::string& error)
{
	std::lock_guard<std::mutex> lock(mMutex);
	auto it = std::find_if(mPersistentState.layers.begin(), mPersistentState.layers.end(),
		[&layerId](const LayerPersistentState& layer) { return layer.id == layerId; });
	if (it == mPersistentState.layers.end())
	{
		error = "Unknown layer id: " + layerId;
		return false;
	}

	const std::ptrdiff_t index = std::distance(mPersistentState.layers.begin(), it);
	const std::ptrdiff_t newIndex = index + direction;
	if (newIndex < 0 || newIndex >= static_cast<std::ptrdiff_t>(mPersistentState.layers.size()))
		return true;

	std::swap(mPersistentState.layers[index], mPersistentState.layers[newIndex]);
	mReloadRequested = true;
	return SavePersistentState(error);
}

bool RuntimeHost::MoveLayerToIndex(const std::string& layerId, std::size_t targetIndex, std::string& error)
{
	std::lock_guard<std::mutex> lock(mMutex);
	auto it = std::find_if(mPersistentState.layers.begin(), mPersistentState.layers.end(),
		[&layerId](const LayerPersistentState& layer) { return layer.id == layerId; });
	if (it == mPersistentState.layers.end())
	{
		error = "Unknown layer id: " + layerId;
		return false;
	}

	if (mPersistentState.layers.empty())
		return true;

	if (targetIndex >= mPersistentState.layers.size())
		targetIndex = mPersistentState.layers.size() - 1;

	const std::size_t sourceIndex = static_cast<std::size_t>(std::distance(mPersistentState.layers.begin(), it));
	if (sourceIndex == targetIndex)
		return true;

	LayerPersistentState movedLayer = *it;
	mPersistentState.layers.erase(mPersistentState.layers.begin() + static_cast<std::ptrdiff_t>(sourceIndex));
	mPersistentState.layers.insert(mPersistentState.layers.begin() + static_cast<std::ptrdiff_t>(targetIndex), movedLayer);
	mReloadRequested = true;
	return SavePersistentState(error);
}

bool RuntimeHost::SetLayerBypass(const std::string& layerId, bool bypassed, std::string& error)
{
	std::lock_guard<std::mutex> lock(mMutex);
	LayerPersistentState* layer = FindLayerById(layerId);
	if (!layer)
	{
		error = "Unknown layer id: " + layerId;
		return false;
	}

	layer->bypass = bypassed;
	mReloadRequested = true;
	return SavePersistentState(error);
}

bool RuntimeHost::SetLayerShader(const std::string& layerId, const std::string& shaderId, std::string& error)
{
	std::lock_guard<std::mutex> lock(mMutex);
	LayerPersistentState* layer = FindLayerById(layerId);
	if (!layer)
	{
		error = "Unknown layer id: " + layerId;
		return false;
	}

	auto shaderIt = mPackagesById.find(shaderId);
	if (shaderIt == mPackagesById.end())
	{
		error = "Unknown shader id: " + shaderId;
		return false;
	}

	layer->shaderId = shaderId;
	layer->parameterValues.clear();
	EnsureLayerDefaultsLocked(*layer, shaderIt->second);
	mReloadRequested = true;
	return SavePersistentState(error);
}

bool RuntimeHost::UpdateLayerParameter(const std::string& layerId, const std::string& parameterId, const JsonValue& newValue, std::string& error)
{
	std::lock_guard<std::mutex> lock(mMutex);

	LayerPersistentState* layer = FindLayerById(layerId);
	if (!layer)
	{
		error = "Unknown layer id: " + layerId;
		return false;
	}

	auto shaderIt = mPackagesById.find(layer->shaderId);
	if (shaderIt == mPackagesById.end())
	{
		error = "Unknown shader id: " + layer->shaderId;
		return false;
	}

	const ShaderPackage& shaderPackage = shaderIt->second;
	auto parameterIt = std::find_if(shaderPackage.parameters.begin(), shaderPackage.parameters.end(),
		[&parameterId](const ShaderParameterDefinition& definition) { return definition.id == parameterId; });
	if (parameterIt == shaderPackage.parameters.end())
	{
		error = "Unknown parameter id: " + parameterId;
		return false;
	}

	ShaderParameterValue normalized;
	if (!NormalizeAndValidateValue(*parameterIt, newValue, normalized, error))
		return false;

	layer->parameterValues[parameterId] = normalized;
	return SavePersistentState(error);
}

bool RuntimeHost::UpdateLayerParameterByControlKey(const std::string& layerKey, const std::string& parameterKey, const JsonValue& newValue, std::string& error)
{
	std::lock_guard<std::mutex> lock(mMutex);

	LayerPersistentState* matchedLayer = nullptr;
	const ShaderPackage* matchedPackage = nullptr;
	for (LayerPersistentState& layer : mPersistentState.layers)
	{
		auto shaderIt = mPackagesById.find(layer.shaderId);
		if (shaderIt == mPackagesById.end())
			continue;

		if (MatchesControlKey(layer.id, layerKey) || MatchesControlKey(shaderIt->second.id, layerKey) ||
			MatchesControlKey(shaderIt->second.displayName, layerKey))
		{
			matchedLayer = &layer;
			matchedPackage = &shaderIt->second;
			break;
		}
	}

	if (!matchedLayer || !matchedPackage)
	{
		error = "Unknown OSC layer key: " + layerKey;
		return false;
	}

	const auto parameterIt = std::find_if(matchedPackage->parameters.begin(), matchedPackage->parameters.end(),
		[&parameterKey](const ShaderParameterDefinition& definition)
		{
			return MatchesControlKey(definition.id, parameterKey) || MatchesControlKey(definition.label, parameterKey);
		});
	if (parameterIt == matchedPackage->parameters.end())
	{
		error = "Unknown OSC parameter key: " + parameterKey;
		return false;
	}

	ShaderParameterValue normalized;
	if (!NormalizeAndValidateValue(*parameterIt, newValue, normalized, error))
		return false;

	matchedLayer->parameterValues[parameterIt->id] = normalized;
	return SavePersistentState(error);
}

bool RuntimeHost::ResetLayerParameters(const std::string& layerId, std::string& error)
{
	std::lock_guard<std::mutex> lock(mMutex);

	LayerPersistentState* layer = FindLayerById(layerId);
	if (!layer)
	{
		error = "Unknown layer id: " + layerId;
		return false;
	}

	auto shaderIt = mPackagesById.find(layer->shaderId);
	if (shaderIt == mPackagesById.end())
	{
		error = "Unknown shader id: " + layer->shaderId;
		return false;
	}

	layer->parameterValues.clear();
	EnsureLayerDefaultsLocked(*layer, shaderIt->second);
	return SavePersistentState(error);
}

bool RuntimeHost::SaveStackPreset(const std::string& presetName, std::string& error) const
{
	std::lock_guard<std::mutex> lock(mMutex);
	const std::string safeStem = MakeSafePresetFileStem(presetName);
	if (safeStem.empty())
	{
		error = "Preset name must include at least one letter or number.";
		return false;
	}

	JsonValue root = JsonValue::MakeObject();
	root.set("version", JsonValue(1.0));
	root.set("name", JsonValue(Trim(presetName)));
	root.set("layers", SerializeLayerStackLocked());

	return WriteTextFile(mPresetRoot / (safeStem + ".json"), SerializeJson(root, true), error);
}

bool RuntimeHost::LoadStackPreset(const std::string& presetName, std::string& error)
{
	std::lock_guard<std::mutex> lock(mMutex);
	const std::string safeStem = MakeSafePresetFileStem(presetName);
	if (safeStem.empty())
	{
		error = "Preset name must include at least one letter or number.";
		return false;
	}

	const std::filesystem::path presetPath = mPresetRoot / (safeStem + ".json");
	std::string presetText = ReadTextFile(presetPath, error);
	if (presetText.empty())
		return false;

	JsonValue root;
	if (!ParseJson(presetText, root, error))
		return false;

	const JsonValue* layersValue = root.find("layers");
	if (!layersValue || !layersValue->isArray())
	{
		error = "Preset file is missing a valid 'layers' array.";
		return false;
	}

	std::vector<LayerPersistentState> nextLayers;
	if (!DeserializeLayerStackLocked(*layersValue, nextLayers, error))
		return false;

	if (nextLayers.empty())
	{
		error = "Preset does not contain any valid layers.";
		return false;
	}

	mPersistentState.layers = nextLayers;
	mReloadRequested = true;
	return SavePersistentState(error);
}

void RuntimeHost::SetCompileStatus(bool succeeded, const std::string& message)
{
	std::lock_guard<std::mutex> lock(mMutex);
	mCompileSucceeded = succeeded;
	mCompileMessage = message;
}

void RuntimeHost::SetSignalStatus(bool hasSignal, unsigned width, unsigned height, const std::string& modeName)
{
	std::lock_guard<std::mutex> lock(mMutex);
	mHasSignal = hasSignal;
	mSignalWidth = width;
	mSignalHeight = height;
	mSignalModeName = modeName;
}

void RuntimeHost::SetDeckLinkOutputStatus(const std::string& modelName, bool supportsInternalKeying, bool supportsExternalKeying,
	bool keyerInterfaceAvailable, bool externalKeyingRequested, bool externalKeyingActive, const std::string& statusMessage)
{
	std::lock_guard<std::mutex> lock(mMutex);
	mDeckLinkOutputStatus.modelName = modelName;
	mDeckLinkOutputStatus.supportsInternalKeying = supportsInternalKeying;
	mDeckLinkOutputStatus.supportsExternalKeying = supportsExternalKeying;
	mDeckLinkOutputStatus.keyerInterfaceAvailable = keyerInterfaceAvailable;
	mDeckLinkOutputStatus.externalKeyingRequested = externalKeyingRequested;
	mDeckLinkOutputStatus.externalKeyingActive = externalKeyingActive;
	mDeckLinkOutputStatus.statusMessage = statusMessage;
}

void RuntimeHost::SetPerformanceStats(double frameBudgetMilliseconds, double renderMilliseconds)
{
	std::lock_guard<std::mutex> lock(mMutex);
	mFrameBudgetMilliseconds = std::max(frameBudgetMilliseconds, 0.0);
	mRenderMilliseconds = std::max(renderMilliseconds, 0.0);
	if (mSmoothedRenderMilliseconds <= 0.0)
		mSmoothedRenderMilliseconds = mRenderMilliseconds;
	else
		mSmoothedRenderMilliseconds = mSmoothedRenderMilliseconds * 0.9 + mRenderMilliseconds * 0.1;
}

void RuntimeHost::AdvanceFrame()
{
	std::lock_guard<std::mutex> lock(mMutex);
	++mFrameCounter;
}

bool RuntimeHost::BuildLayerFragmentShaderSource(const std::string& layerId, std::string& fragmentShaderSource, std::string& error)
{
	try
	{
		ShaderPackage shaderPackage;
		{
			std::lock_guard<std::mutex> lock(mMutex);
			const LayerPersistentState* layer = FindLayerById(layerId);
			if (!layer)
			{
				error = "Unknown layer id: " + layerId;
				return false;
			}

			auto it = mPackagesById.find(layer->shaderId);
			if (it == mPackagesById.end())
			{
				error = "Unknown shader id: " + layer->shaderId;
				return false;
			}
			shaderPackage = it->second;
		}

		ShaderCompiler compiler(mRepoRoot, mWrapperPath, mGeneratedGlslPath, mPatchedGlslPath, mConfig.maxTemporalHistoryFrames);
		return compiler.BuildLayerFragmentShaderSource(shaderPackage, fragmentShaderSource, error);
	}
	catch (const std::exception& exception)
	{
		error = std::string("RuntimeHost::BuildLayerFragmentShaderSource exception: ") + exception.what();
		return false;
	}
	catch (...)
	{
		error = "RuntimeHost::BuildLayerFragmentShaderSource threw a non-standard exception.";
		return false;
	}
}

std::vector<RuntimeRenderState> RuntimeHost::GetLayerRenderStates(unsigned outputWidth, unsigned outputHeight) const
{
	std::lock_guard<std::mutex> lock(mMutex);
	std::vector<RuntimeRenderState> states;

	for (const LayerPersistentState& layer : mPersistentState.layers)
	{
		auto shaderIt = mPackagesById.find(layer.shaderId);
		if (shaderIt == mPackagesById.end())
			continue;

		RuntimeRenderState state;
		state.layerId = layer.id;
		state.shaderId = layer.shaderId;
		state.timeSeconds = std::chrono::duration_cast<std::chrono::duration<double>>(std::chrono::steady_clock::now() - mStartTime).count();
		state.frameCount = static_cast<double>(mFrameCounter);
		state.mixAmount = 1.0;
		state.bypass = layer.bypass ? 1.0 : 0.0;
		state.inputWidth = mSignalWidth;
		state.inputHeight = mSignalHeight;
		state.outputWidth = outputWidth;
		state.outputHeight = outputHeight;
		state.parameterDefinitions = shaderIt->second.parameters;
		state.textureAssets = shaderIt->second.textureAssets;
		state.fontAssets = shaderIt->second.fontAssets;
		state.isTemporal = shaderIt->second.temporal.enabled;
		state.temporalHistorySource = shaderIt->second.temporal.historySource;
		state.requestedTemporalHistoryLength = shaderIt->second.temporal.requestedHistoryLength;
		state.effectiveTemporalHistoryLength = shaderIt->second.temporal.effectiveHistoryLength;

		for (const ShaderParameterDefinition& definition : shaderIt->second.parameters)
		{
			ShaderParameterValue value = DefaultValueForDefinition(definition);
			auto valueIt = layer.parameterValues.find(definition.id);
			if (valueIt != layer.parameterValues.end())
				value = valueIt->second;
			state.parameterValues[definition.id] = value;
		}

		states.push_back(state);
	}

	return states;
}

std::string RuntimeHost::BuildStateJson() const
{
	return SerializeJson(BuildStateValue(), true);
}

void RuntimeHost::SetServerPort(unsigned short port)
{
	std::lock_guard<std::mutex> lock(mMutex);
	mServerPort = port;
}

bool RuntimeHost::LoadConfig(std::string& error)
{
	if (!std::filesystem::exists(mConfigPath))
		return true;

	std::string configText = ReadTextFile(mConfigPath, error);
	if (configText.empty())
		return false;

	JsonValue configJson;
	if (!ParseJson(configText, configJson, error))
		return false;

	if (const JsonValue* shaderLibraryValue = configJson.find("shaderLibrary"))
		mConfig.shaderLibrary = shaderLibraryValue->asString();
	if (const JsonValue* serverPortValue = configJson.find("serverPort"))
		mConfig.serverPort = static_cast<unsigned short>(serverPortValue->asNumber(mConfig.serverPort));
	if (const JsonValue* oscPortValue = configJson.find("oscPort"))
		mConfig.oscPort = static_cast<unsigned short>(oscPortValue->asNumber(mConfig.oscPort));
	if (const JsonValue* autoReloadValue = configJson.find("autoReload"))
		mConfig.autoReload = autoReloadValue->asBoolean(mConfig.autoReload);
	if (const JsonValue* maxTemporalHistoryFramesValue = configJson.find("maxTemporalHistoryFrames"))
	{
		const double configuredValue = maxTemporalHistoryFramesValue->asNumber(static_cast<double>(mConfig.maxTemporalHistoryFrames));
		mConfig.maxTemporalHistoryFrames = configuredValue <= 0.0 ? 0u : static_cast<unsigned>(configuredValue);
	}
	if (const JsonValue* enableExternalKeyingValue = configJson.find("enableExternalKeying"))
		mConfig.enableExternalKeying = enableExternalKeyingValue->asBoolean(mConfig.enableExternalKeying);
	if (const JsonValue* videoFormatValue = configJson.find("videoFormat"))
	{
		if (videoFormatValue->isString() && !videoFormatValue->asString().empty())
		{
			mConfig.inputVideoFormat = videoFormatValue->asString();
			mConfig.outputVideoFormat = videoFormatValue->asString();
		}
	}
	if (const JsonValue* frameRateValue = configJson.find("frameRate"))
	{
		if (frameRateValue->isString() && !frameRateValue->asString().empty())
		{
			mConfig.inputFrameRate = frameRateValue->asString();
			mConfig.outputFrameRate = frameRateValue->asString();
		}
		else if (frameRateValue->isNumber())
		{
			std::ostringstream stream;
			stream << frameRateValue->asNumber();
			mConfig.inputFrameRate = stream.str();
			mConfig.outputFrameRate = stream.str();
		}
	}
	if (const JsonValue* inputVideoFormatValue = configJson.find("inputVideoFormat"))
	{
		if (inputVideoFormatValue->isString() && !inputVideoFormatValue->asString().empty())
			mConfig.inputVideoFormat = inputVideoFormatValue->asString();
	}
	if (const JsonValue* inputFrameRateValue = configJson.find("inputFrameRate"))
	{
		if (inputFrameRateValue->isString() && !inputFrameRateValue->asString().empty())
			mConfig.inputFrameRate = inputFrameRateValue->asString();
		else if (inputFrameRateValue->isNumber())
		{
			std::ostringstream stream;
			stream << inputFrameRateValue->asNumber();
			mConfig.inputFrameRate = stream.str();
		}
	}
	if (const JsonValue* outputVideoFormatValue = configJson.find("outputVideoFormat"))
	{
		if (outputVideoFormatValue->isString() && !outputVideoFormatValue->asString().empty())
			mConfig.outputVideoFormat = outputVideoFormatValue->asString();
	}
	if (const JsonValue* outputFrameRateValue = configJson.find("outputFrameRate"))
	{
		if (outputFrameRateValue->isString() && !outputFrameRateValue->asString().empty())
			mConfig.outputFrameRate = outputFrameRateValue->asString();
		else if (outputFrameRateValue->isNumber())
		{
			std::ostringstream stream;
			stream << outputFrameRateValue->asNumber();
			mConfig.outputFrameRate = stream.str();
		}
	}

	mAutoReloadEnabled = mConfig.autoReload;
	return true;
}

bool RuntimeHost::LoadPersistentState(std::string& error)
{
	if (!std::filesystem::exists(mRuntimeStatePath))
		return true;

	std::string stateText = ReadTextFile(mRuntimeStatePath, error);
	if (stateText.empty())
		return false;

	JsonValue root;
	if (!ParseJson(stateText, root, error))
		return false;

	if (const JsonValue* layersValue = root.find("layers"))
	{
		for (const JsonValue& layerValue : layersValue->asArray())
		{
			if (!layerValue.isObject())
				continue;
			LayerPersistentState layer;
			if (const JsonValue* idValue = layerValue.find("id"))
				layer.id = idValue->asString();
			if (const JsonValue* shaderIdValue = layerValue.find("shaderId"))
				layer.shaderId = shaderIdValue->asString();
			if (const JsonValue* bypassValue = layerValue.find("bypass"))
				layer.bypass = bypassValue->asBoolean(false);
			else if (const JsonValue* enabledValue = layerValue.find("enabled"))
				layer.bypass = !enabledValue->asBoolean(true);

			if (const JsonValue* parameterValues = layerValue.find("parameterValues"))
			{
				for (const auto& parameterItem : parameterValues->asObject())
				{
					ShaderParameterValue value;
					const JsonValue& jsonValue = parameterItem.second;
					if (jsonValue.isBoolean())
						value.booleanValue = jsonValue.asBoolean();
					else if (jsonValue.isString())
						value.enumValue = jsonValue.asString();
					else if (jsonValue.isNumber())
						value.numberValues.push_back(jsonValue.asNumber());
					else if (jsonValue.isArray())
						value.numberValues = JsonArrayToNumbers(jsonValue);
					layer.parameterValues[parameterItem.first] = value;
				}
			}

			if (!layer.shaderId.empty())
				mPersistentState.layers.push_back(layer);
		}
	}
	else
	{
		// Migrate from the older single-shader state shape.
		std::string activeShaderId;
		if (const JsonValue* activeShaderValue = root.find("activeShaderId"))
			activeShaderId = activeShaderValue->asString();

		if (!activeShaderId.empty())
		{
			LayerPersistentState layer;
			layer.id = GenerateLayerId();
			layer.shaderId = activeShaderId;
			layer.bypass = false;

			if (const JsonValue* valuesByShader = root.find("parameterValuesByShader"))
			{
				const JsonValue* shaderValues = valuesByShader->find(activeShaderId);
				if (shaderValues)
				{
					for (const auto& parameterItem : shaderValues->asObject())
					{
						ShaderParameterValue value;
						const JsonValue& jsonValue = parameterItem.second;
						if (jsonValue.isBoolean())
							value.booleanValue = jsonValue.asBoolean();
						else if (jsonValue.isString())
							value.enumValue = jsonValue.asString();
						else if (jsonValue.isNumber())
							value.numberValues.push_back(jsonValue.asNumber());
						else if (jsonValue.isArray())
							value.numberValues = JsonArrayToNumbers(jsonValue);
						layer.parameterValues[parameterItem.first] = value;
					}
				}
			}

			mPersistentState.layers.push_back(layer);
		}
	}

	return true;
}

bool RuntimeHost::SavePersistentState(std::string& error) const
{
	JsonValue root = JsonValue::MakeObject();

	JsonValue layers = JsonValue::MakeArray();
	for (const LayerPersistentState& layer : mPersistentState.layers)
	{
		JsonValue layerValue = JsonValue::MakeObject();
		layerValue.set("id", JsonValue(layer.id));
		layerValue.set("shaderId", JsonValue(layer.shaderId));
		layerValue.set("bypass", JsonValue(layer.bypass));

		JsonValue parameterValues = JsonValue::MakeObject();
		auto packageIt = mPackagesById.find(layer.shaderId);
		for (const auto& parameterItem : layer.parameterValues)
		{
			const ShaderParameterDefinition* definition = nullptr;
			if (packageIt != mPackagesById.end())
			{
				for (const ShaderParameterDefinition& candidate : packageIt->second.parameters)
				{
					if (candidate.id == parameterItem.first)
					{
						definition = &candidate;
						break;
					}
				}
			}

			if (definition)
				parameterValues.set(parameterItem.first, SerializeParameterValue(*definition, parameterItem.second));
		}

		layerValue.set("parameterValues", parameterValues);
		layers.pushBack(layerValue);
	}
	root.set("layers", layers);

	return WriteTextFile(mRuntimeStatePath, SerializeJson(root, true), error);
}

bool RuntimeHost::ScanShaderPackages(std::string& error)
{
	std::map<std::string, ShaderPackage> packagesById;
	std::vector<std::string> packageOrder;
	ShaderPackageRegistry registry(mConfig.maxTemporalHistoryFrames);
	if (!registry.Scan(mShaderRoot, packagesById, packageOrder, error))
		return false;

	mPackagesById.swap(packagesById);
	mPackageOrder.swap(packageOrder);

	for (auto it = mPersistentState.layers.begin(); it != mPersistentState.layers.end();)
	{
		if (mPackagesById.find(it->shaderId) == mPackagesById.end())
			it = mPersistentState.layers.erase(it);
		else
			++it;
	}

	return true;
}

bool RuntimeHost::ParseShaderManifest(const std::filesystem::path& manifestPath, ShaderPackage& shaderPackage, std::string& error) const
{
	const std::string manifestText = ReadTextFile(manifestPath, error);
	if (manifestText.empty())
		return false;

	JsonValue manifestJson;
	if (!ParseJson(manifestText, manifestJson, error))
		return false;
	if (!manifestJson.isObject())
	{
		error = "Shader manifest root must be an object: " + manifestPath.string();
		return false;
	}

	if (!ParseShaderMetadata(manifestJson, shaderPackage, manifestPath, error))
		return false;

	if (!std::filesystem::exists(shaderPackage.shaderPath))
	{
		error = "Shader source not found for package " + shaderPackage.id + ": " + shaderPackage.shaderPath.string();
		return false;
	}

	shaderPackage.shaderWriteTime = std::filesystem::last_write_time(shaderPackage.shaderPath);
	shaderPackage.manifestWriteTime = std::filesystem::last_write_time(shaderPackage.manifestPath);

	return ParseTextureAssets(manifestJson, shaderPackage, manifestPath, error) &&
		ParseFontAssets(manifestJson, shaderPackage, manifestPath, error) &&
		ParseTemporalSettings(manifestJson, shaderPackage, mConfig.maxTemporalHistoryFrames, manifestPath, error) &&
		ParseParameterDefinitions(manifestJson, shaderPackage, manifestPath, error);
}

bool RuntimeHost::NormalizeAndValidateValue(const ShaderParameterDefinition& definition, const JsonValue& value, ShaderParameterValue& normalizedValue, std::string& error) const
{
	return NormalizeAndValidateParameterValue(definition, value, normalizedValue, error);
}

ShaderParameterValue RuntimeHost::DefaultValueForDefinition(const ShaderParameterDefinition& definition) const
{
	return ::DefaultValueForDefinition(definition);
}

void RuntimeHost::EnsureLayerDefaultsLocked(LayerPersistentState& layerState, const ShaderPackage& shaderPackage) const
{
	for (const ShaderParameterDefinition& definition : shaderPackage.parameters)
	{
		if (layerState.parameterValues.find(definition.id) == layerState.parameterValues.end())
			layerState.parameterValues[definition.id] = DefaultValueForDefinition(definition);
	}
}

std::string RuntimeHost::ReadTextFile(const std::filesystem::path& path, std::string& error) const
{
	std::ifstream input(path, std::ios::binary);
	if (!input)
	{
		error = "Could not open file: " + path.string();
		return std::string();
	}

	std::ostringstream buffer;
	buffer << input.rdbuf();
	return buffer.str();
}

bool RuntimeHost::WriteTextFile(const std::filesystem::path& path, const std::string& contents, std::string& error) const
{
	std::error_code fsError;
	std::filesystem::create_directories(path.parent_path(), fsError);

	const std::filesystem::path temporaryPath = path.string() + ".tmp";
	std::ofstream output(temporaryPath, std::ios::binary | std::ios::trunc);
	if (!output)
	{
		error = "Could not write file: " + temporaryPath.string();
		return false;
	}

	output << contents;
	output.close();
	if (!output.good())
	{
		error = "Could not finish writing file: " + temporaryPath.string();
		return false;
	}

	if (!MoveFileExA(temporaryPath.string().c_str(), path.string().c_str(), MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH))
	{
		const DWORD lastError = GetLastError();
		std::filesystem::remove(temporaryPath, fsError);
		error = "Could not replace file: " + path.string() + " (Win32 error " + std::to_string(lastError) + ")";
		return false;
	}

	return true;
}

bool RuntimeHost::ResolvePaths(std::string& error)
{
	mRepoRoot = FindRepoRootCandidate();
	if (mRepoRoot.empty())
	{
		error = "Could not locate the repository root from the current runtime path.";
		return false;
	}

	const std::filesystem::path builtUiRoot = mRepoRoot / "ui" / "dist";
	mUiRoot = std::filesystem::exists(builtUiRoot) ? builtUiRoot : (mRepoRoot / "ui");
	mDocsRoot = mRepoRoot / "docs";
	mConfigPath = mRepoRoot / "config" / "runtime-host.json";
	mShaderRoot = mRepoRoot / mConfig.shaderLibrary;
	mRuntimeRoot = mRepoRoot / "runtime";
	mPresetRoot = mRuntimeRoot / "stack_presets";
	mRuntimeStatePath = mRuntimeRoot / "runtime_state.json";
	mWrapperPath = mRuntimeRoot / "shader_cache" / "active_shader_wrapper.slang";
	mGeneratedGlslPath = mRuntimeRoot / "shader_cache" / "active_shader.raw.frag";
	mPatchedGlslPath = mRuntimeRoot / "shader_cache" / "active_shader.frag";

	std::error_code fsError;
	std::filesystem::create_directories(mRuntimeRoot / "shader_cache", fsError);
	std::filesystem::create_directories(mPresetRoot, fsError);
	return true;
}

JsonValue RuntimeHost::BuildStateValue() const
{
	std::lock_guard<std::mutex> lock(mMutex);

	JsonValue root = JsonValue::MakeObject();

	JsonValue app = JsonValue::MakeObject();
	app.set("serverPort", JsonValue(static_cast<double>(mServerPort)));
	app.set("oscPort", JsonValue(static_cast<double>(mConfig.oscPort)));
	app.set("autoReload", JsonValue(mAutoReloadEnabled));
	app.set("maxTemporalHistoryFrames", JsonValue(static_cast<double>(mConfig.maxTemporalHistoryFrames)));
	app.set("enableExternalKeying", JsonValue(mConfig.enableExternalKeying));
	app.set("inputVideoFormat", JsonValue(mConfig.inputVideoFormat));
	app.set("inputFrameRate", JsonValue(mConfig.inputFrameRate));
	app.set("outputVideoFormat", JsonValue(mConfig.outputVideoFormat));
	app.set("outputFrameRate", JsonValue(mConfig.outputFrameRate));
	root.set("app", app);

	JsonValue runtime = JsonValue::MakeObject();
	runtime.set("layerCount", JsonValue(static_cast<double>(mPersistentState.layers.size())));
	runtime.set("compileSucceeded", JsonValue(mCompileSucceeded));
	runtime.set("compileMessage", JsonValue(mCompileMessage));
	root.set("runtime", runtime);

	JsonValue video = JsonValue::MakeObject();
	video.set("hasSignal", JsonValue(mHasSignal));
	video.set("width", JsonValue(static_cast<double>(mSignalWidth)));
	video.set("height", JsonValue(static_cast<double>(mSignalHeight)));
	video.set("modeName", JsonValue(mSignalModeName));
	root.set("video", video);

	JsonValue deckLink = JsonValue::MakeObject();
	deckLink.set("modelName", JsonValue(mDeckLinkOutputStatus.modelName));
	deckLink.set("supportsInternalKeying", JsonValue(mDeckLinkOutputStatus.supportsInternalKeying));
	deckLink.set("supportsExternalKeying", JsonValue(mDeckLinkOutputStatus.supportsExternalKeying));
	deckLink.set("keyerInterfaceAvailable", JsonValue(mDeckLinkOutputStatus.keyerInterfaceAvailable));
	deckLink.set("externalKeyingRequested", JsonValue(mDeckLinkOutputStatus.externalKeyingRequested));
	deckLink.set("externalKeyingActive", JsonValue(mDeckLinkOutputStatus.externalKeyingActive));
	deckLink.set("statusMessage", JsonValue(mDeckLinkOutputStatus.statusMessage));
	root.set("decklink", deckLink);

	JsonValue performance = JsonValue::MakeObject();
	performance.set("frameBudgetMs", JsonValue(mFrameBudgetMilliseconds));
	performance.set("renderMs", JsonValue(mRenderMilliseconds));
	performance.set("smoothedRenderMs", JsonValue(mSmoothedRenderMilliseconds));
	performance.set("budgetUsedPercent", JsonValue(mFrameBudgetMilliseconds > 0.0 ? (mSmoothedRenderMilliseconds / mFrameBudgetMilliseconds) * 100.0 : 0.0));
	root.set("performance", performance);

	JsonValue shaderLibrary = JsonValue::MakeArray();
	for (const std::string& shaderId : mPackageOrder)
	{
		auto shaderIt = mPackagesById.find(shaderId);
		if (shaderIt == mPackagesById.end())
			continue;

		JsonValue shader = JsonValue::MakeObject();
		shader.set("id", JsonValue(shaderIt->second.id));
		shader.set("name", JsonValue(shaderIt->second.displayName));
		shader.set("description", JsonValue(shaderIt->second.description));
		shader.set("category", JsonValue(shaderIt->second.category));
		if (shaderIt->second.temporal.enabled)
		{
			JsonValue temporal = JsonValue::MakeObject();
			temporal.set("enabled", JsonValue(true));
			temporal.set("historySource", JsonValue(TemporalHistorySourceToString(shaderIt->second.temporal.historySource)));
			temporal.set("requestedHistoryLength", JsonValue(static_cast<double>(shaderIt->second.temporal.requestedHistoryLength)));
			temporal.set("effectiveHistoryLength", JsonValue(static_cast<double>(shaderIt->second.temporal.effectiveHistoryLength)));
			shader.set("temporal", temporal);
		}
		shaderLibrary.pushBack(shader);
	}
	root.set("shaders", shaderLibrary);

	JsonValue stackPresets = JsonValue::MakeArray();
	for (const std::string& presetName : GetStackPresetNamesLocked())
		stackPresets.pushBack(JsonValue(presetName));
	root.set("stackPresets", stackPresets);

	root.set("layers", SerializeLayerStackLocked());

	return root;
}

JsonValue RuntimeHost::SerializeLayerStackLocked() const
{
	JsonValue layers = JsonValue::MakeArray();
	for (const LayerPersistentState& layer : mPersistentState.layers)
	{
		auto shaderIt = mPackagesById.find(layer.shaderId);
		if (shaderIt == mPackagesById.end())
			continue;

		JsonValue layerValue = JsonValue::MakeObject();
		layerValue.set("id", JsonValue(layer.id));
		layerValue.set("shaderId", JsonValue(layer.shaderId));
		layerValue.set("shaderName", JsonValue(shaderIt->second.displayName));
		layerValue.set("bypass", JsonValue(layer.bypass));
		if (shaderIt->second.temporal.enabled)
		{
			JsonValue temporal = JsonValue::MakeObject();
			temporal.set("enabled", JsonValue(true));
			temporal.set("historySource", JsonValue(TemporalHistorySourceToString(shaderIt->second.temporal.historySource)));
			temporal.set("requestedHistoryLength", JsonValue(static_cast<double>(shaderIt->second.temporal.requestedHistoryLength)));
			temporal.set("effectiveHistoryLength", JsonValue(static_cast<double>(shaderIt->second.temporal.effectiveHistoryLength)));
			layerValue.set("temporal", temporal);
		}

		JsonValue parameters = JsonValue::MakeArray();
		for (const ShaderParameterDefinition& definition : shaderIt->second.parameters)
		{
			JsonValue parameter = JsonValue::MakeObject();
			parameter.set("id", JsonValue(definition.id));
			parameter.set("label", JsonValue(definition.label));
			parameter.set("type", JsonValue(ShaderParameterTypeToString(definition.type)));
			parameter.set("defaultValue", SerializeParameterValue(definition, DefaultValueForDefinition(definition)));

			if (!definition.minNumbers.empty())
			{
				JsonValue minValue = JsonValue::MakeArray();
				for (double number : definition.minNumbers)
					minValue.pushBack(JsonValue(number));
				parameter.set("min", minValue);
			}
			if (!definition.maxNumbers.empty())
			{
				JsonValue maxValue = JsonValue::MakeArray();
				for (double number : definition.maxNumbers)
					maxValue.pushBack(JsonValue(number));
				parameter.set("max", maxValue);
			}
			if (!definition.stepNumbers.empty())
			{
				JsonValue stepValue = JsonValue::MakeArray();
				for (double number : definition.stepNumbers)
					stepValue.pushBack(JsonValue(number));
				parameter.set("step", stepValue);
			}
			if (definition.type == ShaderParameterType::Enum)
			{
				JsonValue options = JsonValue::MakeArray();
				for (const ShaderParameterOption& option : definition.enumOptions)
				{
					JsonValue optionValue = JsonValue::MakeObject();
					optionValue.set("value", JsonValue(option.value));
					optionValue.set("label", JsonValue(option.label));
					options.pushBack(optionValue);
				}
				parameter.set("options", options);
			}
			if (definition.type == ShaderParameterType::Text)
			{
				parameter.set("maxLength", JsonValue(static_cast<double>(definition.maxLength)));
				if (!definition.fontId.empty())
					parameter.set("font", JsonValue(definition.fontId));
			}

			ShaderParameterValue value = DefaultValueForDefinition(definition);
			auto valueIt = layer.parameterValues.find(definition.id);
			if (valueIt != layer.parameterValues.end())
				value = valueIt->second;
			parameter.set("value", SerializeParameterValue(definition, value));
			parameters.pushBack(parameter);
		}

		layerValue.set("parameters", parameters);
		layers.pushBack(layerValue);
	}
	return layers;
}

bool RuntimeHost::DeserializeLayerStackLocked(const JsonValue& layersValue, std::vector<LayerPersistentState>& layers, std::string& error)
{
	for (const JsonValue& layerValue : layersValue.asArray())
	{
		if (!layerValue.isObject())
			continue;

		const JsonValue* shaderIdValue = layerValue.find("shaderId");
		if (!shaderIdValue)
			continue;

		const std::string shaderId = shaderIdValue->asString();
		auto shaderIt = mPackagesById.find(shaderId);
		if (shaderIt == mPackagesById.end())
		{
			error = "Preset references unknown shader id: " + shaderId;
			return false;
		}

		LayerPersistentState layer;
		layer.id = GenerateLayerId();
		layer.shaderId = shaderId;
		if (const JsonValue* bypassValue = layerValue.find("bypass"))
			layer.bypass = bypassValue->asBoolean(false);

		if (const JsonValue* parametersValue = layerValue.find("parameters"))
		{
			for (const JsonValue& parameterValue : parametersValue->asArray())
			{
				if (!parameterValue.isObject())
					continue;

				const JsonValue* parameterIdValue = parameterValue.find("id");
				const JsonValue* valueValue = parameterValue.find("value");
				if (!parameterIdValue || !valueValue)
					continue;

				const std::string parameterId = parameterIdValue->asString();
				auto definitionIt = std::find_if(shaderIt->second.parameters.begin(), shaderIt->second.parameters.end(),
					[&parameterId](const ShaderParameterDefinition& definition) { return definition.id == parameterId; });
				if (definitionIt == shaderIt->second.parameters.end())
					continue;

				ShaderParameterValue normalizedValue;
				if (!NormalizeAndValidateValue(*definitionIt, *valueValue, normalizedValue, error))
					return false;

				layer.parameterValues[parameterId] = normalizedValue;
			}
		}

		EnsureLayerDefaultsLocked(layer, shaderIt->second);
		layers.push_back(layer);
	}

	return true;
}

void RuntimeHost::NormalizePersistentLayerIdsLocked()
{
	std::set<std::string> usedIds;
	uint64_t maxLayerNumber = mNextLayerId;

	for (LayerPersistentState& layer : mPersistentState.layers)
	{
		uint64_t layerNumber = 0;
		const bool hasReusableId = !layer.id.empty() &&
			usedIds.find(layer.id) == usedIds.end() &&
			TryParseLayerIdNumber(layer.id, layerNumber);

		if (hasReusableId)
		{
			usedIds.insert(layer.id);
			maxLayerNumber = std::max(maxLayerNumber, layerNumber);
			continue;
		}

		do
		{
			++maxLayerNumber;
			layer.id = "layer-" + std::to_string(maxLayerNumber);
		}
		while (usedIds.find(layer.id) != usedIds.end());

		usedIds.insert(layer.id);
	}

	mNextLayerId = maxLayerNumber;
}

std::vector<std::string> RuntimeHost::GetStackPresetNamesLocked() const
{
	std::vector<std::string> presetNames;
	std::error_code fsError;
	if (!std::filesystem::exists(mPresetRoot, fsError))
		return presetNames;

	for (const auto& entry : std::filesystem::directory_iterator(mPresetRoot, fsError))
	{
		if (!entry.is_regular_file())
			continue;
		if (ToLowerCopy(entry.path().extension().string()) != ".json")
			continue;
		presetNames.push_back(entry.path().stem().string());
	}

	std::sort(presetNames.begin(), presetNames.end());
	return presetNames;
}

std::string RuntimeHost::MakeSafePresetFileStem(const std::string& presetName) const
{
	return ::MakeSafePresetFileStem(presetName);
}

JsonValue RuntimeHost::SerializeParameterValue(const ShaderParameterDefinition& definition, const ShaderParameterValue& value) const
{
	switch (definition.type)
	{
	case ShaderParameterType::Boolean:
		return JsonValue(value.booleanValue);
	case ShaderParameterType::Enum:
		return JsonValue(value.enumValue);
	case ShaderParameterType::Text:
		return JsonValue(value.textValue);
	case ShaderParameterType::Float:
		return JsonValue(value.numberValues.empty() ? 0.0 : value.numberValues.front());
	case ShaderParameterType::Vec2:
	case ShaderParameterType::Color:
	{
		JsonValue array = JsonValue::MakeArray();
		for (double number : value.numberValues)
			array.pushBack(JsonValue(number));
		return array;
	}
	}
	return JsonValue();
}

std::string RuntimeHost::TemporalHistorySourceToString(TemporalHistorySource source) const
{
	switch (source)
	{
	case TemporalHistorySource::Source:
		return "source";
	case TemporalHistorySource::PreLayerInput:
		return "preLayerInput";
	case TemporalHistorySource::None:
	default:
		return "none";
	}
}

RuntimeHost::LayerPersistentState* RuntimeHost::FindLayerById(const std::string& layerId)
{
	auto it = std::find_if(mPersistentState.layers.begin(), mPersistentState.layers.end(),
		[&layerId](const LayerPersistentState& layer) { return layer.id == layerId; });
	return it == mPersistentState.layers.end() ? nullptr : &*it;
}

const RuntimeHost::LayerPersistentState* RuntimeHost::FindLayerById(const std::string& layerId) const
{
	auto it = std::find_if(mPersistentState.layers.begin(), mPersistentState.layers.end(),
		[&layerId](const LayerPersistentState& layer) { return layer.id == layerId; });
	return it == mPersistentState.layers.end() ? nullptr : &*it;
}

std::string RuntimeHost::GenerateLayerId()
{
	while (true)
	{
		++mNextLayerId;
		const std::string candidate = "layer-" + std::to_string(mNextLayerId);
		if (!FindLayerById(candidate))
			return candidate;
	}
}