Split workflow into multiple files, fix unity build

27 files changed, 687 insertions, 526 deletions

diff --git a/3rdparty/imgui-node-editor/CMakeLists.txt b/3rdparty/imgui-node-editor/CMakeLists.txt
index 2730a8e..47199dc 100644
--- a/3rdparty/imgui-node-editor/CMakeLists.txt
+++ b/3rdparty/imgui-node-editor/CMakeLists.txt
@@ -1,6 +1,7 @@
 file(GLOB IMGUI_NODE_EDITOR_SOURCES *.cpp)
 
 add_library(imgui-node-editor ${IMGUI_NODE_EDITOR_SOURCES})
+set_target_properties(imgui-node-editor PROPERTIES UNITY_BUILD OFF)
 target_include_directories(imgui-node-editor PRIVATE
 	${CMAKE_SOURCE_DIR}/3rdparty/imgui-node-editor
 	${CMAKE_SOURCE_DIR}/3rdparty/imgui
diff --git a/3rdparty/imgui/CMakeLists.txt b/3rdparty/imgui/CMakeLists.txt
index de80f9a..bf09c56 100644
--- a/3rdparty/imgui/CMakeLists.txt
+++ b/3rdparty/imgui/CMakeLists.txt
@@ -5,6 +5,7 @@ file(GLOB IMGUI_SOURCES *.cpp)
 # the build flags twice both in here and in core/CMakeLists.txt
 
 add_library(imgui ${IMGUI_SOURCES})
+set_target_properties(imgui PROPERTIES UNITY_BUILD OFF)
 target_include_directories(imgui
 PRIVATE
 	${CMAKE_SOURCE_DIR}/3rdparty/imgui
diff --git a/3rdparty/implot/CMakeLists.txt b/3rdparty/implot/CMakeLists.txt
index 6b92b02..4fae8f2 100644
--- a/3rdparty/implot/CMakeLists.txt
+++ b/3rdparty/implot/CMakeLists.txt
@@ -1,6 +1,7 @@
 file(GLOB IMPLOT_SOURCES *.cpp)
 
 add_library(implot ${IMPLOT_SOURCES})
+set_target_properties(implot PROPERTIES UNITY_BUILD OFF)
 target_include_directories(implot PRIVATE
 	${CMAKE_SOURCE_DIR}/3rdparty/implot
 	${CMAKE_SOURCE_DIR}/3rdparty/imgui
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0517e4c..2fecd26 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.18)
 project(Cplt LANGUAGES CXX)
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
diff --git a/core/CMakeLists.txt b/core/CMakeLists.txt
index efa43ed..ccb5aeb 100644
--- a/core/CMakeLists.txt
+++ b/core/CMakeLists.txt
@@ -14,13 +14,13 @@ elseif(APPLE)
 	option(BUILD_CORE_WITH_METAL_BACKEND ON)
 endif()
 
-function(add_source_group GROUP_NAME)
-	set(${GROUP_NAME} ${ARGN} PARENT_SCOPE)
+macro(add_source_group GROUP_NAME)
+	set(${GROUP_NAME} ${ARGN})
 	set_source_files_properties(${ARGN}
-		PROPERTIES
+	PROPERTIES
 		UNITY_GROUP "${GROUP_NAME}"
 	)
-endfunction()
+endmacro()
 
 set(ENTRYPOINT_MODULE_SOURCES
 	src/Entrypoint/main.cpp
@@ -33,16 +33,30 @@ set(ENTRYPOINT_MODULE_SOURCES
 )
 
 add_source_group(MODEL_MODULE_SOURCES
-	src/Model/EvaluatedValue.cpp
 	src/Model/Filter.cpp
 	src/Model/GlobalStates.cpp
 	src/Model/Items.cpp
 	src/Model/Project.cpp
 	src/Model/TransactionsModel.cpp
-	src/Model/Workflow.cpp
-	src/Model/WorkflowNodes.cpp
 )
 
+add_source_group(MODEL_WORKFLOW_MODULE_SOURCES
+	src/Model/Workflow/Evaluation.cpp
+	src/Model/Workflow/Value.cpp
+	src/Model/Workflow/Workflow.cpp
+)
+
+add_source_group(MODEL_WORKFLOW_NODES_MODULE_SOURCES
+	src/Model/Workflow/Nodes/DocumentNodes.cpp
+	src/Model/Workflow/Nodes/UserInputNodes.cpp
+	src/Model/Workflow/Nodes/NumericNodes.cpp
+	src/Model/Workflow/Nodes/TextNodes.cpp
+)
+
+add_source_group(MODEL_WORKFLOW_VALUES_MODULE_SOURCES
+	src/Model/Workflow/Values/BasicValues.cpp
+	)
+
 add_source_group(UI_MODULE_SOURCES
 	src/UI/Localization.cpp
 	src/UI/States.cpp
@@ -80,6 +94,9 @@ function(add_executable_variant TARGET_NAME)
 	add_executable(${TARGET_NAME}
 		${ENTRYPOINT_MODULE_SOURCES}
 		${MODEL_MODULE_SOURCES}
+		${MODEL_WORKFLOW_MODULE_SOURCES}
+		${MODEL_WORKFLOW_NODES_MODULE_SOURCES}
+		${MODEL_WORKFLOW_VALUES_MODULE_SOURCES}
 		${UI_MODULE_SOURCES}
 		${UTILS_MODULE_SOURCES}
 		${UTILS_DIALOG_MODULE_SOURCES}
@@ -187,13 +204,9 @@ function(add_executable_variant TARGET_NAME)
 		endif()
 	endif()
 
-	if(BUILD_CORE_WITH_UNITY_BUILD)
+	if(CMAKE_UNITY_BUILD)
 		message("CpltCore: - using unity build")
-		set_target_properties(${TARGET_NAME}
-		PROPERTIES
-			UNITY_BUILD ON
-			UNITY_BUILD_MODE GROUP
-		)
+		set_target_properties(${TARGET_NAME} PROPERTIES UNITY_BUILD_MODE GROUP)
 	else()
 		message("CpltCore: - using regular build")
 	endif()
diff --git a/core/src/Model/Workflow/Evaluation.cpp b/core/src/Model/Workflow/Evaluation.cpp
new file mode 100644
index 0000000..111d34e
--- /dev/null
+++ b/core/src/Model/Workflow/Evaluation.cpp
@@ -0,0 +1,183 @@
+#include "Evaluation.hpp"
+
+#include <queue>
+
+namespace {
+enum class EvaluationStatus {
+	Unevaluated,
+	Success,
+	Failed,
+};
+} // namespace
+
+struct WorkflowEvaluationContext::RuntimeNode {
+	EvaluationStatus Status = EvaluationStatus::Unevaluated;
+};
+
+struct WorkflowEvaluationContext::RuntimeConnection {
+	std::unique_ptr<BaseValue> Value;
+
+	bool IsAvailableValue() const {
+		return Value != nullptr;
+	}
+};
+
+WorkflowEvaluationContext::WorkflowEvaluationContext(Workflow& workflow)
+	: mWorkflow{ &workflow } {
+	mRuntimeNodes.resize(workflow.mNodes.size());
+	mRuntimeConnections.resize(workflow.mConnections.size());
+}
+
+BaseValue* WorkflowEvaluationContext::GetConnectionValue(size_t id, bool constant) {
+	if (constant) {
+		return mWorkflow->GetConstantById(id);
+	} else {
+		return mRuntimeConnections[id].Value.get();
+	}
+}
+
+BaseValue* WorkflowEvaluationContext::GetConnectionValue(const WorkflowNode::InputPin& inputPin) {
+	if (inputPin.IsConnected()) {
+		return GetConnectionValue(inputPin.Connection, inputPin.IsConstantConnection());
+	} else {
+		return nullptr;
+	}
+}
+
+void WorkflowEvaluationContext::SetConnectionValue(size_t id, std::unique_ptr<BaseValue> value) {
+	mRuntimeConnections[id].Value = std::move(value);
+}
+
+void WorkflowEvaluationContext::SetConnectionValue(const WorkflowNode::OutputPin& outputPin, std::unique_ptr<BaseValue> value) {
+	if (outputPin.IsConnected()) {
+		SetConnectionValue(outputPin.Connection, std::move(value));
+	}
+}
+
+void WorkflowEvaluationContext::Run() {
+	std::queue<size_t> candidates; // Stores index to nodes
+	int evaluatedCount = 0;
+	int erroredCount = 0;
+
+	// Evaluate all the input nodes first
+	for (size_t i = 0; i < mRuntimeNodes.size(); ++i) {
+		if (mWorkflow->mNodes[i]->GetType() == WorkflowNode::InputType) {
+			candidates.push(i);
+		}
+	}
+
+	auto AddOutputsToCandidates = [&](size_t idx) {
+		auto& node = *mWorkflow->mNodes[idx];
+		auto& rNode = mRuntimeNodes[idx];
+		for (auto& pin : node.mOutputs) {
+			if (!pin.IsConnected()) continue;
+			// TODO support the other variant
+			if (pin.GetSupportedDirection() != WorkflowConnection::OneToMany) continue;
+
+			auto& rConn = mRuntimeConnections[pin.Connection];
+			auto& conn = mWorkflow->mConnections[pin.Connection];
+			if (rConn.IsAvailableValue()) {
+				for (WorkflowConnection::ConnectionPoint& cp : conn.MultiConnections) {
+					if (rNode.Status != EvaluationStatus::Unevaluated) {
+						candidates.push(cp.Node);
+					}
+				}
+			}
+		}
+	};
+	auto FindCandidates = [&]() {
+		for (size_t i = 0; i < mWorkflow->mNodes.size(); ++i) {
+			auto& node = mWorkflow->mNodes[i];
+			auto& rNode = mRuntimeNodes[i];
+
+			if (rNode.Status != EvaluationStatus::Unevaluated) {
+				continue;
+			}
+
+			for (auto& pin : node->mInputs) {
+				if (!pin.IsConnected()) continue;
+
+				auto& rConn = mRuntimeConnections[pin.Connection];
+				if (!rConn.IsAvailableValue()) {
+					goto skip;
+				}
+			}
+
+			candidates.push(i);
+
+		skip:
+			continue;
+		}
+	};
+
+	while (true) {
+		while (!candidates.empty()) {
+			auto idx = candidates.front();
+			auto& node = *mWorkflow->mNodes[idx];
+			auto& rNode = mRuntimeNodes[idx];
+			candidates.pop();
+
+			int preEvalErrors = mErrors.size();
+			node.Evaluate(*this);
+			if (preEvalErrors != mErrors.size()) {
+				erroredCount++;
+			} else {
+				evaluatedCount++;
+				AddOutputsToCandidates(idx);
+			}
+		}
+
+		if (evaluatedCount + erroredCount >= mRuntimeNodes.size()) {
+			break;
+		}
+
+		// Candidates empty, but there are still possibly-evaluable nodes
+		FindCandidates();
+	}
+
+	for (size_t i = 0; i < mRuntimeNodes.size(); ++i) {
+		if (mWorkflow->mNodes[i]->GetType() == WorkflowNode::OutputType) {
+			// TODO
+		}
+	}
+}
+
+void WorkflowEvaluationContext::ReportError(std::string message, const WorkflowNode& node, int pinId, bool inputPin) {
+	mErrors.push_back(WorkflowEvaluationError{
+		.Message = std::move(message),
+		.NodeId = node.GetId(),
+		.PinId = pinId,
+		.PinType = inputPin ? WorkflowEvaluationError::InputPin : WorkflowEvaluationError::OutputPin,
+		.Type = WorkflowEvaluationError::Error,
+	});
+}
+
+void WorkflowEvaluationContext::ReportError(std::string message, const WorkflowNode& node) {
+	mErrors.push_back(WorkflowEvaluationError{
+		.Message = std::move(message),
+		.NodeId = node.GetId(),
+		.PinId = -1,
+		.PinType = WorkflowEvaluationError::NoPin,
+		.Type = WorkflowEvaluationError::Error,
+	});
+}
+
+void WorkflowEvaluationContext::ReportWarning(std::string message, const WorkflowNode& node, int pinId, bool inputPin) {
+	mErrors.push_back(WorkflowEvaluationError{
+		.Message = std::move(message),
+		.NodeId = node.GetId(),
+		.PinId = pinId,
+		.PinType = inputPin ? WorkflowEvaluationError::InputPin : WorkflowEvaluationError::OutputPin,
+		.Type = WorkflowEvaluationError::Warning,
+	});
+}
+
+void WorkflowEvaluationContext::ReportWarning(std::string message, const WorkflowNode& node) {
+	mErrors.push_back(WorkflowEvaluationError{
+		.Message = std::move(message),
+		.NodeId = node.GetId(),
+		.PinId = -1,
+		.PinType = WorkflowEvaluationError::NoPin,
+		.Type = WorkflowEvaluationError::Warning,
+	});
+}
diff --git a/core/src/Model/Workflow/Evaluation.hpp b/core/src/Model/Workflow/Evaluation.hpp
new file mode 100644
index 0000000..be2e862
--- /dev/null
+++ b/core/src/Model/Workflow/Evaluation.hpp
@@ -0,0 +1,57 @@
+#pragma once
+
+#include "Model/Workflow/Workflow.hpp"
+
+#include <cstddef>
+#include <cstdint>
+#include <string>
+#include <vector>
+
+class WorkflowEvaluationError {
+public:
+	enum MessageType : int16_t {
+		Error,
+		Warning,
+	};
+
+	enum PinType : int16_t {
+		NoPin,
+		InputPin,
+		OutputPin,
+	};
+
+public:
+	std::string Message;
+	size_t NodeId;
+	int PinId;
+	PinType PinType;
+	MessageType Type;
+};
+
+class WorkflowEvaluationContext {
+private:
+	struct RuntimeNode;
+	struct RuntimeConnection;
+
+	Workflow* mWorkflow;
+	std::vector<RuntimeNode> mRuntimeNodes;
+	std::vector<RuntimeConnection> mRuntimeConnections;
+	std::vector<WorkflowEvaluationError> mErrors;
+	std::vector<WorkflowEvaluationError> mWarnings;
+
+public:
+	WorkflowEvaluationContext(Workflow& workflow);
+
+	BaseValue* GetConnectionValue(size_t id, bool constant);
+	BaseValue* GetConnectionValue(const WorkflowNode::InputPin& inputPin);
+	void SetConnectionValue(size_t id, std::unique_ptr<BaseValue> value);
+	void SetConnectionValue(const WorkflowNode::OutputPin& outputPin, std::unique_ptr<BaseValue> value);
+
+	void ReportError(std::string message, const WorkflowNode& node, int pinId, bool inputPin);
+	void ReportError(std::string message, const WorkflowNode& node);
+	void ReportWarning(std::string message, const WorkflowNode& node, int pinId, bool inputPin);
+	void ReportWarning(std::string message, const WorkflowNode& node);
+
+	/// Run until all possible paths have been evaluated.
+	void Run();
+};
diff --git a/core/src/Model/Workflow/Nodes/DocumentNodes.cpp b/core/src/Model/Workflow/Nodes/DocumentNodes.cpp
new file mode 100644
index 0000000..66d2eae
--- /dev/null
+++ b/core/src/Model/Workflow/Nodes/DocumentNodes.cpp
@@ -0,0 +1,15 @@
+#include "DocumentNodes.hpp"
+
+#include "Model/Workflow/Evaluation.hpp"
+#include "Model/Workflow/Values/BasicValues.hpp"
+
+bool DocumentTemplateExpansionNode::IsInstance(const WorkflowNode* node) {
+	return node->GetKind() == KD_DocumentTemplateExpansion;
+}
+
+DocumentTemplateExpansionNode::DocumentTemplateExpansionNode()
+	: WorkflowNode(TransformType, KD_DocumentTemplateExpansion) {
+}
+
+void DocumentTemplateExpansionNode::Evaluate(WorkflowEvaluationContext& ctx) {
+}
diff --git a/core/src/Model/Workflow/Nodes/DocumentNodes.hpp b/core/src/Model/Workflow/Nodes/DocumentNodes.hpp
new file mode 100644
index 0000000..3b775ec
--- /dev/null
+++ b/core/src/Model/Workflow/Nodes/DocumentNodes.hpp
@@ -0,0 +1,12 @@
+#pragma once
+
+#include "Model/Workflow/Workflow.hpp"
+
+class DocumentTemplateExpansionNode : public WorkflowNode {
+public:
+	static bool IsInstance(const WorkflowNode* node);
+	DocumentTemplateExpansionNode();
+
+	// TODO
+	virtual void Evaluate(WorkflowEvaluationContext& ctx) override;
+};
diff --git a/core/src/Model/Workflow/Nodes/NumericNodes.cpp b/core/src/Model/Workflow/Nodes/NumericNodes.cpp
new file mode 100644
index 0000000..1722224
--- /dev/null
+++ b/core/src/Model/Workflow/Nodes/NumericNodes.cpp
@@ -0,0 +1,86 @@
+#include "NumericNodes.hpp"
+
+#include "Model/Workflow/Evaluation.hpp"
+#include "Model/Workflow/Values/BasicValues.hpp"
+#include "Utils/Macros.hpp"
+#include "Utils/RTTI.hpp"
+
+#include <cassert>
+#include <utility>
+
+WorkflowNode::Kind NumericOperationNode::OperationTypeToNodeKind(OperationType type) {
+	switch (type) {
+		case Addition: return KD_NumericAddition;
+		case Subtraction: return KD_NumericSubtraction;
+		case Multiplication: return KD_NumericMultiplication;
+		case Division: return KD_NumericDivision;
+		default: UNREACHABLE;
+	}
+}
+
+NumericOperationNode::OperationType NumericOperationNode::NodeKindToOperationType(Kind kind) {
+	switch (kind) {
+		case KD_NumericAddition: return Addition;
+		case KD_NumericSubtraction: return Subtraction;
+		case KD_NumericMultiplication: return Multiplication;
+		case KD_NumericDivision: return Division;
+		default: UNREACHABLE;
+	}
+}
+
+bool NumericOperationNode::IsInstance(const WorkflowNode* node) {
+	return node->GetKind() >= KD_NumericAddition && node->GetKind() <= KD_NumericDivision;
+}
+
+NumericOperationNode::NumericOperationNode(OperationType type)
+	: WorkflowNode(TransformType, OperationTypeToNodeKind(type))
+	, mType{ type } {
+	mInputs.resize(2);
+	mInputs[0].MatchingType = BaseValue::KD_Numeric;
+	mInputs[1].MatchingType = BaseValue::KD_Numeric;
+
+	mOutputs.resize(1);
+	mOutputs[0].MatchingType = BaseValue::KD_Numeric;
+}
+
+void NumericOperationNode::Evaluate(WorkflowEvaluationContext& ctx) {
+	auto lhsVal = dyn_cast<NumericValue>(ctx.GetConnectionValue(mInputs[0]));
+	if (!lhsVal) return;
+	double lhs = lhsVal->GetValue();
+
+	auto rhsVal = dyn_cast<NumericValue>(ctx.GetConnectionValue(mInputs[1]));
+	if (!rhsVal) return;
+	double rhs = rhsVal->GetValue();
+
+	double res;
+	switch (mType) {
+		case Addition: res = lhs + rhs; break;
+		case Subtraction: res = lhs - rhs; break;
+		case Multiplication: res = lhs * rhs; break;
+		case Division: {
+			if (rhs == 0.0) {
+				// TODO localize
+				ctx.ReportError("Error: division by 0", *this);
+				return;
+			}
+			res = lhs / rhs;
+		} break;
+
+		default: return;
+	}
+
+	auto value = std::make_unique<NumericValue>();
+	value->SetValue(res);
+	ctx.SetConnectionValue(mOutputs[0], std::move(value));
+}
+
+bool NumericExpressionNode::IsInstance(const WorkflowNode* node) {
+	return node->GetKind() == KD_NumericExpression;
+}
+
+NumericExpressionNode::NumericExpressionNode()
+	: WorkflowNode(TransformType, KD_NumericExpression) {
+}
+
+void NumericExpressionNode::Evaluate(WorkflowEvaluationContext& ctx) {
+}
diff --git a/core/src/Model/Workflow/Nodes/NumericNodes.hpp b/core/src/Model/Workflow/Nodes/NumericNodes.hpp
new file mode 100644
index 0000000..32610f6
--- /dev/null
+++ b/core/src/Model/Workflow/Nodes/NumericNodes.hpp
@@ -0,0 +1,41 @@
+#pragma once
+
+#include "Model/Workflow/Workflow.hpp"
+
+#include <cstddef>
+#include <memory>
+#include <variant>
+#include <vector>
+
+class NumericOperationNode : public WorkflowNode {
+public:
+	enum OperationType {
+		Addition,
+		Subtraction,
+		Multiplication,
+		Division,
+
+		InvalidType,
+		TypeCount = InvalidType,
+	};
+
+private:
+	OperationType mType;
+
+public:
+	static Kind OperationTypeToNodeKind(OperationType type);
+	static OperationType NodeKindToOperationType(Kind kind);
+	static bool IsInstance(const WorkflowNode* node);
+	NumericOperationNode(OperationType type);
+
+	virtual void Evaluate(WorkflowEvaluationContext& ctx) override;
+};
+
+class NumericExpressionNode : public WorkflowNode {
+public:
+	static bool IsInstance(const WorkflowNode* node);
+	NumericExpressionNode();
+
+	// TODO
+	virtual void Evaluate(WorkflowEvaluationContext& ctx) override;
+};
\ No newline at end of file
diff --git a/core/src/Model/WorkflowNodes.cpp b/core/src/Model/Workflow/Nodes/TextNodes.cpp
index f58c8bb..3852c66 100644
--- a/core/src/Model/WorkflowNodes.cpp
+++ b/core/src/Model/Workflow/Nodes/TextNodes.cpp
@@ -1,5 +1,7 @@
-#include "WorkflowNodes.hpp"
+#include "TextNodes.hpp"
 
+#include "Model/Workflow/Evaluation.hpp"
+#include "Model/Workflow/Values/BasicValues.hpp"
 #include "Utils/Macros.hpp"
 #include "Utils/RTTI.hpp"
 #include "Utils/Variant.hpp"
@@ -7,85 +9,10 @@
 #include <cassert>
 #include <utility>
 #include <variant>
+#include <vector>
 
-WorkflowNode::Kind NumericOperationNode::OperationTypeToNodeKind(OperationType type) {
-	switch (type) {
-		case Addition: return KD_NumericAddition;
-		case Subtraction: return KD_NumericSubtraction;
-		case Multiplication: return KD_NumericMultiplication;
-		case Division: return KD_NumericDivision;
-		default: UNREACHABLE;
-	}
-}
-
-NumericOperationNode::OperationType NumericOperationNode::NodeKindToOperationType(Kind kind) {
-	switch (kind) {
-		case KD_NumericAddition: return Addition;
-		case KD_NumericSubtraction: return Subtraction;
-		case KD_NumericMultiplication: return Multiplication;
-		case KD_NumericDivision: return Division;
-		default: UNREACHABLE;
-	}
-}
-
-bool NumericOperationNode::IsInstance(const WorkflowNode* node) {
-	return node->GetKind() >= KD_NumericAddition && node->GetKind() <= KD_NumericDivision;
-}
-
-NumericOperationNode::NumericOperationNode(OperationType type)
-	: WorkflowNode(TransformType, OperationTypeToNodeKind(type))
-	, mType{ type } {
-	mInputs.resize(2);
-	mInputs[0].MatchingType = BaseValue::KD_Numeric;
-	mInputs[1].MatchingType = BaseValue::KD_Numeric;
-
-	mOutputs.resize(1);
-	mOutputs[0].MatchingType = BaseValue::KD_Numeric;
-}
-
-void NumericOperationNode::Evaluate(WorkflowEvaluationContext& ctx) {
-	auto lhsVal = dyn_cast<NumericValue>(ctx.GetConnectionValue(mInputs[0]));
-	if (!lhsVal) return;
-	double lhs = lhsVal->GetValue();
-
-	auto rhsVal = dyn_cast<NumericValue>(ctx.GetConnectionValue(mInputs[1]));
-	if (!rhsVal) return;
-	double rhs = rhsVal->GetValue();
-
-	double res;
-	switch (mType) {
-		case Addition: res = lhs + rhs; break;
-		case Subtraction: res = lhs - rhs; break;
-		case Multiplication: res = lhs * rhs; break;
-		case Division: {
-			if (rhs == 0.0) {
-				// TODO localize
-				ctx.ReportError("Error: division by 0", *this);
-				return;
-			}
-			res = lhs / rhs;
-		} break;
-
-		default: return;
-	}
-
-	auto value = std::make_unique<NumericValue>();
-	value->SetValue(res);
-	ctx.SetConnectionValue(mOutputs[0], std::move(value));
-}
-
-bool NumericExpressionNode::IsInstance(const WorkflowNode* node) {
-	return node->GetKind() == KD_NumericExpression;
-}
-
-NumericExpressionNode::NumericExpressionNode()
-	: WorkflowNode(TransformType, KD_NumericExpression) {
-}
-
-struct TextFormatterNode::Argument {
-	ArgumentType ArgumentType;
-	int PinIdx;
-
+class TextFormatterNode::Impl {
+public:
 	template <class TFunction>
 	static void ForArguments(std::vector<Element>::iterator begin, std::vector<Element>::iterator end, const TFunction& func) {
 		for (auto it = begin; it != end; ++it) {
@@ -157,7 +84,7 @@ void TextFormatterNode::SetElement(int idx, ArgumentType argument) {
 
 				mElements[idx] = Argument{
 					.ArgumentType = argument,
-					.PinIdx = Argument::FindPinForElement(mElements, idx),
+					.PinIdx = Impl::FindPinForElement(mElements, idx),
 				};
 				/* `original` is invalid from this point */
 			},
@@ -191,7 +118,7 @@ void TextFormatterNode::InsertElement(int idx, ArgumentType argument) {
 	assert(idx >= 0);
 	if (idx >= mElements.size()) AppendElement(argument);
 
-	int pinIdx = Argument::FindPinForElement(mElements, idx);
+	int pinIdx = Impl::FindPinForElement(mElements, idx);
 
 	// Create pin
 	auto& pin = InsertInputPin(pinIdx);
@@ -278,35 +205,11 @@ void TextFormatterNode::PreRemoveElement(int idx) {
 	auto& elm = mElements[idx];
 	if (auto arg = std::get_if<Argument>(&elm)) {
 		RemoveInputPin(arg->PinIdx);
-		Argument::ForArguments(
+		Impl::ForArguments(
 			mElements.begin() + idx + 1,
 			mElements.end(),
 			[&](Argument& arg) {
 				arg.PinIdx--;
 			});
 	}
-}
-
-bool DocumentTemplateExpansionNode::IsInstance(const WorkflowNode* node) {
-	return node->GetKind() == KD_DocumentTemplateExpansion;
-}
-
-DocumentTemplateExpansionNode::DocumentTemplateExpansionNode()
-	: WorkflowNode(TransformType, KD_DocumentTemplateExpansion) {
-}
-
-bool FormInputNode::IsInstance(const WorkflowNode* node) {
-	return node->GetKind() == KD_FormInput;
-}
-
-FormInputNode::FormInputNode()
-	: WorkflowNode(InputType, KD_FormInput) {
-}
-
-bool DatabaseRowsInputNode::IsInstance(const WorkflowNode* node) {
-	return node->GetKind() == KD_DatabaseRowsInput;
-}
-
-DatabaseRowsInputNode::DatabaseRowsInputNode()
-	: WorkflowNode(InputType, KD_DatabaseRowsInput) {
-}
+}
\ No newline at end of file
diff --git a/core/src/Model/Workflow/Nodes/TextNodes.hpp b/core/src/Model/Workflow/Nodes/TextNodes.hpp
new file mode 100644
index 0000000..278db32
--- /dev/null
+++ b/core/src/Model/Workflow/Nodes/TextNodes.hpp
@@ -0,0 +1,50 @@
+#pragma once
+
+#include "Model/Workflow/Workflow.hpp"
+
+#include <cstddef>
+#include <memory>
+#include <variant>
+#include <vector>
+
+class TextFormatterNode : public WorkflowNode {
+public:
+	enum ArgumentType {
+		NumericArgument,
+		TextArgument,
+		DateTimeArgument,
+	};
+
+private:
+	class Impl;
+
+	struct Argument {
+		ArgumentType ArgumentType;
+		int PinIdx;
+	};
+	using Element = std::variant<std::string, Argument>;
+
+	std::vector<Element> mElements;
+	int mMinOutputChars;
+
+public:
+	static BaseValue::Kind ArgumentTypeToValueKind(ArgumentType arg);
+	static bool IsInstance(const WorkflowNode* node);
+	TextFormatterNode();
+
+	int GetElementCount() const;
+	const Element& GetElement(int idx) const;
+
+	void SetElement(int idx, std::string text);
+	void SetElement(int idx, ArgumentType argument);
+	void InsertElement(int idx, std::string text);
+	void InsertElement(int idx, ArgumentType argument);
+	void AppendElement(std::string text);
+	void AppendElement(ArgumentType argument);
+	void RemoveElement(int idx);
+
+	virtual void Evaluate(WorkflowEvaluationContext& ctx) override;
+
+private:
+	void PreRemoveElement(int idx);
+};
\ No newline at end of file
diff --git a/core/src/Model/Workflow/Nodes/UserInputNodes.cpp b/core/src/Model/Workflow/Nodes/UserInputNodes.cpp
new file mode 100644
index 0000000..f59226a
--- /dev/null
+++ b/core/src/Model/Workflow/Nodes/UserInputNodes.cpp
@@ -0,0 +1,26 @@
+#include "UserInputNodes.hpp"
+
+#include "Model/Workflow/Evaluation.hpp"
+#include "Model/Workflow/Values/BasicValues.hpp"
+
+bool FormInputNode::IsInstance(const WorkflowNode* node) {
+	return node->GetKind() == KD_FormInput;
+}
+
+FormInputNode::FormInputNode()
+	: WorkflowNode(InputType, KD_FormInput) {
+}
+
+void FormInputNode::Evaluate(WorkflowEvaluationContext& ctx) {
+}
+
+bool DatabaseRowsInputNode::IsInstance(const WorkflowNode* node) {
+	return node->GetKind() == KD_DatabaseRowsInput;
+}
+
+DatabaseRowsInputNode::DatabaseRowsInputNode()
+	: WorkflowNode(InputType, KD_DatabaseRowsInput) {
+}
+
+void DatabaseRowsInputNode::Evaluate(WorkflowEvaluationContext& ctx) {
+}
diff --git a/core/src/Model/Workflow/Nodes/UserInputNodes.hpp b/core/src/Model/Workflow/Nodes/UserInputNodes.hpp
new file mode 100644
index 0000000..fe66cb4
--- /dev/null
+++ b/core/src/Model/Workflow/Nodes/UserInputNodes.hpp
@@ -0,0 +1,21 @@
+#pragma once
+
+#include "Model/Workflow/Workflow.hpp"
+
+class FormInputNode : public WorkflowNode {
+public:
+	static bool IsInstance(const WorkflowNode* node);
+	FormInputNode();
+
+	// TODO
+	virtual void Evaluate(WorkflowEvaluationContext& ctx) override;
+};
+
+class DatabaseRowsInputNode : public WorkflowNode {
+public:
+	static bool IsInstance(const WorkflowNode* node);
+	DatabaseRowsInputNode();
+
+	// TODO
+	virtual void Evaluate(WorkflowEvaluationContext& ctx) override;
+};
diff --git a/core/src/Model/Workflow/Nodes/fwd.hpp b/core/src/Model/Workflow/Nodes/fwd.hpp
new file mode 100644
index 0000000..4153825
--- /dev/null
+++ b/core/src/Model/Workflow/Nodes/fwd.hpp
@@ -0,0 +1,15 @@
+#pragma once
+
+// DocumentNodes.hpp
+class DocumentTemplateExpansionNode;
+
+// InputNodes.hpp
+class FormInputNode;
+class DatabaseRowsInputNode;
+
+// NumericNodes.hpp
+class NumericOperationNode;
+class NumericExpressionNode;
+
+// TextNodes.hpp
+class TextFormatterNode;
diff --git a/core/src/Model/Workflow/Value.cpp b/core/src/Model/Workflow/Value.cpp
new file mode 100644
index 0000000..7e5aabf
--- /dev/null
+++ b/core/src/Model/Workflow/Value.cpp
@@ -0,0 +1,9 @@
+#include "Value.hpp"
+
+BaseValue::BaseValue(Kind kind)
+	: mKind{ kind } {
+}
+
+BaseValue::Kind BaseValue::GetKind() const {
+	return mKind;
+}
diff --git a/core/src/Model/Workflow/Value.hpp b/core/src/Model/Workflow/Value.hpp
new file mode 100644
index 0000000..eb99c14
--- /dev/null
+++ b/core/src/Model/Workflow/Value.hpp
@@ -0,0 +1,28 @@
+#pragma once
+
+class BaseValue {
+public:
+	enum Kind {
+		KD_Numeric,
+		KD_Text,
+		KD_DateTime,
+
+		/// An unspecified type, otherwise known as "any" in some contexts.
+		KindInvalid,
+		KindCount = KindInvalid,
+	};
+
+private:
+	Kind mKind;
+
+public:
+	BaseValue(Kind kind);
+	virtual ~BaseValue() = default;
+
+	BaseValue(const BaseValue&) = delete;
+	BaseValue& operator=(const BaseValue&) = delete;
+	BaseValue(BaseValue&&) = default;
+	BaseValue& operator=(BaseValue&&) = default;
+
+	Kind GetKind() const;
+};
diff --git a/core/src/Model/EvaluatedValue.cpp b/core/src/Model/Workflow/Values/BasicValues.cpp
index 685d50f..fd70acd 100644
--- a/core/src/Model/EvaluatedValue.cpp
+++ b/core/src/Model/Workflow/Values/BasicValues.cpp
@@ -1,15 +1,7 @@
-#include "EvaluatedValue.hpp"
+#include "BasicValues.hpp"
 
 #include <charconv>
 
-BaseValue::BaseValue(Kind kind)
-	: mKind{ kind } {
-}
-
-BaseValue::Kind BaseValue::GetKind() const {
-	return mKind;
-}
-
 bool NumericValue::IsInstance(const BaseValue* value) {
 	return value->GetKind() == KD_Numeric;
 }
diff --git a/core/src/Model/EvaluatedValue.hpp b/core/src/Model/Workflow/Values/BasicValues.hpp
index 880fd3e..a116c8c 100644
--- a/core/src/Model/EvaluatedValue.hpp
+++ b/core/src/Model/Workflow/Values/BasicValues.hpp
@@ -1,36 +1,11 @@
 #pragma once
 
+#include "Model/Workflow/Value.hpp"
+
 #include <chrono>
 #include <cstdint>
 #include <string>
 
-class BaseValue {
-public:
-	enum Kind {
-		KD_Numeric,
-		KD_Text,
-		KD_DateTime,
-
-		/// An unspecified type, otherwise known as "any" in some contexts.
-		KindInvalid,
-		KindCount = KindInvalid,
-	};
-
-private:
-	Kind mKind;
-
-public:
-	BaseValue(Kind kind);
-	virtual ~BaseValue() = default;
-
-	BaseValue(const BaseValue&) = delete;
-	BaseValue& operator=(const BaseValue&) = delete;
-	BaseValue(BaseValue&&) = default;
-	BaseValue& operator=(BaseValue&&) = default;
-
-	Kind GetKind() const;
-};
-
 class NumericValue : public BaseValue {
 private:
 	double mValue;
diff --git a/core/src/Model/Workflow/Values/fwd.hpp b/core/src/Model/Workflow/Values/fwd.hpp
new file mode 100644
index 0000000..24f8119
--- /dev/null
+++ b/core/src/Model/Workflow/Values/fwd.hpp
@@ -0,0 +1,6 @@
+#pragma once
+
+// BasicValues.hpp
+class NumericValue;
+class TextValue;
+class DateTimeValue;
diff --git a/core/src/Model/Workflow.cpp b/core/src/Model/Workflow/Workflow.cpp
index 7ca1b9e..a32149e 100644
--- a/core/src/Model/Workflow.cpp
+++ b/core/src/Model/Workflow/Workflow.cpp
@@ -394,183 +394,3 @@ std::pair<std::unique_ptr<WorkflowNode>&, size_t> Workflow::AllocWorkflowStep()
 	auto id = mNodes.size();
 	return { mNodes.emplace_back(std::unique_ptr<WorkflowNode>()), id };
 }
-
-namespace {
-enum class EvaluationStatus {
-	Unevaluated,
-	Success,
-	Failed,
-};
-} // namespace
-
-struct WorkflowEvaluationContext::RuntimeNode {
-	EvaluationStatus Status = EvaluationStatus::Unevaluated;
-};
-
-struct WorkflowEvaluationContext::RuntimeConnection {
-	std::unique_ptr<BaseValue> Value;
-
-	bool IsAvailableValue() const {
-		return Value != nullptr;
-	}
-};
-
-WorkflowEvaluationContext::WorkflowEvaluationContext(Workflow& workflow)
-	: mWorkflow{ &workflow } {
-	mRuntimeNodes.resize(workflow.mNodes.size());
-	mRuntimeConnections.resize(workflow.mConnections.size());
-}
-
-BaseValue* WorkflowEvaluationContext::GetConnectionValue(size_t id, bool constant) {
-	if (constant) {
-		return mWorkflow->GetConstantById(id);
-	} else {
-		return mRuntimeConnections[id].Value.get();
-	}
-}
-
-BaseValue* WorkflowEvaluationContext::GetConnectionValue(const WorkflowNode::InputPin& inputPin) {
-	if (inputPin.IsConnected()) {
-		return GetConnectionValue(inputPin.Connection, inputPin.IsConstantConnection());
-	} else {
-		return nullptr;
-	}
-}
-
-void WorkflowEvaluationContext::SetConnectionValue(size_t id, std::unique_ptr<BaseValue> value) {
-	mRuntimeConnections[id].Value = std::move(value);
-}
-
-void WorkflowEvaluationContext::SetConnectionValue(const WorkflowNode::OutputPin& outputPin, std::unique_ptr<BaseValue> value) {
-	if (outputPin.IsConnected()) {
-		SetConnectionValue(outputPin.Connection, std::move(value));
-	}
-}
-
-void WorkflowEvaluationContext::Run() {
-	std::queue<size_t> candidates; // Stores index to nodes
-	int evaluatedCount = 0;
-	int erroredCount = 0;
-
-	// Evaluate all the input nodes first
-	for (size_t i = 0; i < mRuntimeNodes.size(); ++i) {
-		if (mWorkflow->mNodes[i]->GetType() == WorkflowNode::InputType) {
-			candidates.push(i);
-		}
-	}
-
-	auto AddOutputsToCandidates = [&](size_t idx) {
-		auto& node = *mWorkflow->mNodes[idx];
-		auto& rNode = mRuntimeNodes[idx];
-		for (auto& pin : node.mOutputs) {
-			if (!pin.IsConnected()) continue;
-			// TODO support the other variant
-			if (pin.GetSupportedDirection() != WorkflowConnection::OneToMany) continue;
-
-			auto& rConn = mRuntimeConnections[pin.Connection];
-			auto& conn = mWorkflow->mConnections[pin.Connection];
-			if (rConn.IsAvailableValue()) {
-				for (WorkflowConnection::ConnectionPoint& cp : conn.MultiConnections) {
-					if (rNode.Status != EvaluationStatus::Unevaluated) {
-						candidates.push(cp.Node);
-					}
-				}
-			}
-		}
-	};
-	auto FindCandidates = [&]() {
-		for (size_t i = 0; i < mWorkflow->mNodes.size(); ++i) {
-			auto& node = mWorkflow->mNodes[i];
-			auto& rNode = mRuntimeNodes[i];
-
-			if (rNode.Status != EvaluationStatus::Unevaluated) {
-				continue;
-			}
-
-			for (auto& pin : node->mInputs) {
-				if (!pin.IsConnected()) continue;
-
-				auto& rConn = mRuntimeConnections[pin.Connection];
-				if (!rConn.IsAvailableValue()) {
-					goto skip;
-				}
-			}
-
-			candidates.push(i);
-
-		skip:
-			continue;
-		}
-	};
-
-	while (true) {
-		while (!candidates.empty()) {
-			auto idx = candidates.front();
-			auto& node = *mWorkflow->mNodes[idx];
-			auto& rNode = mRuntimeNodes[idx];
-			candidates.pop();
-
-			int preEvalErrors = mErrors.size();
-			node.Evaluate(*this);
-			if (preEvalErrors != mErrors.size()) {
-				erroredCount++;
-			} else {
-				evaluatedCount++;
-				AddOutputsToCandidates(idx);
-			}
-		}
-
-		if (evaluatedCount + erroredCount >= mRuntimeNodes.size()) {
-			break;
-		}
-
-		// Candidates empty, but there are still possibly-evaluable nodes
-		FindCandidates();
-	}
-
-	for (size_t i = 0; i < mRuntimeNodes.size(); ++i) {
-		if (mWorkflow->mNodes[i]->GetType() == WorkflowNode::OutputType) {
-			// TODO
-		}
-	}
-}
-
-void WorkflowEvaluationContext::ReportError(std::string message, const WorkflowNode& node, int pinId, bool inputPin) {
-	mErrors.push_back(WorkflowEvaluationError{
-		.Message = std::move(message),
-		.NodeId = node.GetId(),
-		.PinId = pinId,
-		.PinType = inputPin ? WorkflowEvaluationError::InputPin : WorkflowEvaluationError::OutputPin,
-		.Type = WorkflowEvaluationError::Error,
-	});
-}
-
-void WorkflowEvaluationContext::ReportError(std::string message, const WorkflowNode& node) {
-	mErrors.push_back(WorkflowEvaluationError{
-		.Message = std::move(message),
-		.NodeId = node.GetId(),
-		.PinId = -1,
-		.PinType = WorkflowEvaluationError::NoPin,
-		.Type = WorkflowEvaluationError::Error,
-	});
-}
-
-void WorkflowEvaluationContext::ReportWarning(std::string message, const WorkflowNode& node, int pinId, bool inputPin) {
-	mErrors.push_back(WorkflowEvaluationError{
-		.Message = std::move(message),
-		.NodeId = node.GetId(),
-		.PinId = pinId,
-		.PinType = inputPin ? WorkflowEvaluationError::InputPin : WorkflowEvaluationError::OutputPin,
-		.Type = WorkflowEvaluationError::Warning,
-	});
-}
-
-void WorkflowEvaluationContext::ReportWarning(std::string message, const WorkflowNode& node) {
-	mErrors.push_back(WorkflowEvaluationError{
-		.Message = std::move(message),
-		.NodeId = node.GetId(),
-		.PinId = -1,
-		.PinType = WorkflowEvaluationError::NoPin,
-		.Type = WorkflowEvaluationError::Warning,
-	});
-}
diff --git a/core/src/Model/Workflow.hpp b/core/src/Model/Workflow/Workflow.hpp
index f1459ba..a7b2c31 100644
--- a/core/src/Model/Workflow.hpp
+++ b/core/src/Model/Workflow/Workflow.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "Model/EvaluatedValue.hpp"
+#include "Value.hpp"
 #include "cplt_fwd.hpp"
 
 #include <cstddef>
@@ -8,6 +8,7 @@
 #include <limits>
 #include <memory>
 #include <span>
+#include <string>
 #include <vector>
 
 class WorkflowConnection {
@@ -160,52 +161,3 @@ private:
 	std::pair<WorkflowConnection&, size_t> AllocWorkflowConnection();
 	std::pair<std::unique_ptr<WorkflowNode>&, size_t> AllocWorkflowStep();
 };
-
-class WorkflowEvaluationError {
-public:
-	enum MessageType : int16_t {
-		Error,
-		Warning,
-	};
-
-	enum PinType : int16_t {
-		NoPin,
-		InputPin,
-		OutputPin,
-	};
-
-public:
-	std::string Message;
-	size_t NodeId;
-	int PinId;
-	PinType PinType;
-	MessageType Type;
-};
-
-class WorkflowEvaluationContext {
-private:
-	struct RuntimeNode;
-	struct RuntimeConnection;
-
-	Workflow* mWorkflow;
-	std::vector<RuntimeNode> mRuntimeNodes;
-	std::vector<RuntimeConnection> mRuntimeConnections;
-	std::vector<WorkflowEvaluationError> mErrors;
-	std::vector<WorkflowEvaluationError> mWarnings;
-
-public:
-	WorkflowEvaluationContext(Workflow& workflow);
-
-	BaseValue* GetConnectionValue(size_t id, bool constant);
-	BaseValue* GetConnectionValue(const WorkflowNode::InputPin& inputPin);
-	void SetConnectionValue(size_t id, std::unique_ptr<BaseValue> value);
-	void SetConnectionValue(const WorkflowNode::OutputPin& outputPin, std::unique_ptr<BaseValue> value);
-
-	void ReportError(std::string message, const WorkflowNode& node, int pinId, bool inputPin);
-	void ReportError(std::string message, const WorkflowNode& node);
-	void ReportWarning(std::string message, const WorkflowNode& node, int pinId, bool inputPin);
-	void ReportWarning(std::string message, const WorkflowNode& node);
-
-	/// Run until all possible paths have been evaluated.
-	void Run();
-};
diff --git a/core/src/Model/Workflow/fwd.hpp b/core/src/Model/Workflow/fwd.hpp
new file mode 100644
index 0000000..2323a91
--- /dev/null
+++ b/core/src/Model/Workflow/fwd.hpp
@@ -0,0 +1,14 @@
+#pragma once
+
+#include "Model/Workflow/Nodes/fwd.hpp"
+#include "Model/Workflow/Values/fwd.hpp"
+
+// Value.hpp
+class BaseValue;
+
+// Workflow.hpp
+class WorkflowConnection;
+class WorkflowNode;
+class Workflow;
+class WorkflowEvaluationError;
+class WorkflowEvaluationContext;
diff --git a/core/src/Model/WorkflowNodes.hpp b/core/src/Model/WorkflowNodes.hpp
deleted file mode 100644
index 677158c..0000000
--- a/core/src/Model/WorkflowNodes.hpp
+++ /dev/null
@@ -1,101 +0,0 @@
-#pragma once
-
-#include "Model/Workflow.hpp"
-
-#include <cstddef>
-#include <memory>
-#include <variant>
-#include <vector>
-
-class NumericOperationNode : public WorkflowNode {
-public:
-	enum OperationType {
-		Addition,
-		Subtraction,
-		Multiplication,
-		Division,
-
-		InvalidType,
-		TypeCount = InvalidType,
-	};
-
-private:
-	OperationType mType;
-
-public:
-	static Kind OperationTypeToNodeKind(OperationType type);
-	static OperationType NodeKindToOperationType(Kind kind);
-	static bool IsInstance(const WorkflowNode* node);
-	NumericOperationNode(OperationType type);
-
-	virtual void Evaluate(WorkflowEvaluationContext& ctx) override;
-};
-
-class NumericExpressionNode : public WorkflowNode {
-public:
-	static bool IsInstance(const WorkflowNode* node);
-	NumericExpressionNode();
-
-	// TODO
-};
-
-class TextFormatterNode : public WorkflowNode {
-public:
-	enum ArgumentType {
-		NumericArgument,
-		TextArgument,
-		DateTimeArgument,
-	};
-
-private:
-	struct Argument;
-	using Element = std::variant<std::string, Argument>;
-
-	std::vector<Element> mElements;
-	int mMinOutputChars;
-
-public:
-	static BaseValue::Kind ArgumentTypeToValueKind(ArgumentType arg);
-	static bool IsInstance(const WorkflowNode* node);
-	TextFormatterNode();
-
-	int GetElementCount() const;
-	const Element& GetElement(int idx) const;
-
-	void SetElement(int idx, std::string text);
-	void SetElement(int idx, ArgumentType argument);
-	void InsertElement(int idx, std::string text);
-	void InsertElement(int idx, ArgumentType argument);
-	void AppendElement(std::string text);
-	void AppendElement(ArgumentType argument);
-	void RemoveElement(int idx);
-
-	virtual void Evaluate(WorkflowEvaluationContext& ctx) override;
-
-private:
-	void PreRemoveElement(int idx);
-};
-
-class DocumentTemplateExpansionNode : public WorkflowNode {
-public:
-	static bool IsInstance(const WorkflowNode* node);
-	DocumentTemplateExpansionNode();
-
-	// TODO
-};
-
-class FormInputNode : public WorkflowNode {
-public:
-	static bool IsInstance(const WorkflowNode* node);
-	FormInputNode();
-
-	// TODO
-};
-
-class DatabaseRowsInputNode : public WorkflowNode {
-public:
-	static bool IsInstance(const WorkflowNode* node);
-	DatabaseRowsInputNode();
-
-	// TODO
-};
diff --git a/core/src/Model/fwd.hpp b/core/src/Model/fwd.hpp
index 5a75394..594599c 100644
--- a/core/src/Model/fwd.hpp
+++ b/core/src/Model/fwd.hpp
@@ -1,10 +1,6 @@
 #pragma once
 
-// EvaluatedValue.hpp
-class BaseValue;
-class NumericValue;
-class TextValue;
-class DateTimeValue;
+#include "Model/Workflow/fwd.hpp"
 
 // Filter.hpp
 class TableRowsFilter;
@@ -29,18 +25,3 @@ class SalesTable;
 class PurchasesTable;
 class DeliveryTable;
 class TransactionModel;
-
-// Workflow.hpp
-class WorkflowConnection;
-class WorkflowNode;
-class Workflow;
-class WorkflowEvaluationError;
-class WorkflowEvaluationContext;
-
-// WorkflowSteps.hpp
-class NumericOperationNode;
-class NumericExpressionNode;
-class TextFormatterNode;
-class DocumentTemplateExpansionNode;
-class FormInputNode;
-class DatabaseRowsInputNode;
diff --git a/core/src/UI/UI_Workflows.cpp b/core/src/UI/UI_Workflows.cpp
index 101fa7b..0adfdc2 100644
--- a/core/src/UI/UI_Workflows.cpp
+++ b/core/src/UI/UI_Workflows.cpp
@@ -1,11 +1,16 @@
 #include "UI.hpp"
 
-#include "Model/Workflow.hpp"
-#include "Model/WorkflowNodes.hpp"
+#include "Model/Workflow/Nodes/DocumentNodes.hpp"
+#include "Model/Workflow/Nodes/NumericNodes.hpp"
+#include "Model/Workflow/Nodes/TextNodes.hpp"
+#include "Model/Workflow/Nodes/UserInputNodes.hpp"
+#include "Model/Workflow/Workflow.hpp"
 #include "UI/Localization.hpp"
+#include "Utils/Macros.hpp"
 
 #include <imgui.h>
 #include <memory>
+#include <span>
 #include <vector>
 
 namespace {
@@ -13,12 +18,41 @@ class WorkflowCreationMenu {
 private:
 	using WorkflowNodeConstructor = std::unique_ptr<WorkflowNode> (*)();
 
+	enum Category {
+		NumericCategory,
+		TextCategory,
+		DocumentsCategory,
+		UserInputCategory,
+		SystemInputCategory,
+		OutputCategory,
+	};
+
 	struct Candidate {
 		WorkflowNodeConstructor Constructor;
+		std::string Name;
+		Category Category;
 	};
 
 	std::vector<Candidate> mCandidates;
 
+#define SUB_RANGE_ACCESS(Type, AccessorName, storage, begin, nextBegin) \
+	std::span<Type> AccessorName() { return { &storage[begin], (size_t)(nextBegin - begin) }; }
+
+	int mTextOffset;
+	int mDocumentOffset;
+	int mUserInputOffset;
+	int mSystemInputNodes;
+	int mOutputOffset;
+
+	SUB_RANGE_ACCESS(Candidate, GetNumericNodes, mCandidates, 0, mTextOffset);
+	SUB_RANGE_ACCESS(Candidate, GetTextNodes, mCandidates, mTextOffset, mDocumentOffset);
+	SUB_RANGE_ACCESS(Candidate, GetDocumentNodes, mCandidates, mDocumentOffset, mUserInputOffset);
+	SUB_RANGE_ACCESS(Candidate, GetUserInputNodes, mCandidates, mUserInputOffset, mSystemInputNodes);
+	SUB_RANGE_ACCESS(Candidate, GetSystemInputNodes, mCandidates, mSystemInputNodes, mOutputOffset);
+	SUB_RANGE_ACCESS(Candidate, GetOutputNodes, mCandidates, mOutputOffset, mCandidates.size());
+
+#undef SUB_RANGE_ACCESS
+
 public:
 	WorkflowCreationMenu() {
 		SetupCandidates();
@@ -26,41 +60,67 @@ public:
 
 private:
 	void SetupCandidates() {
+		// Numeric nodes offset start at 0
 		mCandidates.push_back(Candidate{
 			.Constructor = []() -> std::unique_ptr<WorkflowNode> { return std::make_unique<NumericOperationNode>(NumericOperationNode::Addition); },
+			.Name = "Add",
+			.Category = NumericCategory,
 		});
-
 		mCandidates.push_back(Candidate{
 			.Constructor = []() -> std::unique_ptr<WorkflowNode> { return std::make_unique<NumericOperationNode>(NumericOperationNode::Subtraction); },
+			.Name = "Subtract",
+			.Category = NumericCategory,
 		});
-
 		mCandidates.push_back(Candidate{
 			.Constructor = []() -> std::unique_ptr<WorkflowNode> { return std::make_unique<NumericOperationNode>(NumericOperationNode::Multiplication); },
+			.Name = "Multiply",
+			.Category = NumericCategory,
 		});
-
 		mCandidates.push_back(Candidate{
 			.Constructor = []() -> std::unique_ptr<WorkflowNode> { return std::make_unique<NumericOperationNode>(NumericOperationNode::Division); },
+			.Name = "Divide",
+			.Category = NumericCategory,
+		});
+		mCandidates.push_back(Candidate{
+			.Constructor = []() -> std::unique_ptr<WorkflowNode> { return std::make_unique<NumericExpressionNode>(); },
+			.Name = "Evaluate expression",
+			.Category = NumericCategory,
 		});
 
-//		mCandidates.push_back(Candidate{
-//			.Constructor = []() -> std::unique_ptr<WorkflowNode> { return std::make_unique<NumericExpressionNode>(); },
-//		});
-
+		mTextOffset = mCandidates.size();
 		mCandidates.push_back(Candidate{
 			.Constructor = []() -> std::unique_ptr<WorkflowNode> { return std::make_unique<TextFormatterNode>(); },
+			.Name = "Fill template text",
+			.Category = TextCategory,
+		});
+
+		mDocumentOffset = mCandidates.size();
+		mCandidates.push_back(Candidate{
+			.Constructor = []() -> std::unique_ptr<WorkflowNode> { return std::make_unique<DocumentTemplateExpansionNode>(); },
+			.Name = "Document template",
+			.Category = Category::DocumentsCategory,
+		});
+
+		/* Inputs */
+
+		mUserInputOffset = mCandidates.size();
+		mCandidates.push_back(Candidate{
+			.Constructor = []() -> std::unique_ptr<WorkflowNode> { return std::make_unique<FormInputNode>(); },
+			.Name = "Input: form",
+			.Category = Category::UserInputCategory,
+		});
+
+		mCandidates.push_back(Candidate{
+			.Constructor = []() -> std::unique_ptr<WorkflowNode> { return std::make_unique<DatabaseRowsInputNode>(); },
+			.Name = "Input: database rows",
+			.Category = Category::UserInputCategory,
 		});
 
-//		mCandidates.push_back(Candidate{
-//			.Constructor = []() -> std::unique_ptr<WorkflowNode> { return std::make_unique<DocumentTemplateExpansionNode>(); },
-//		});
+		mSystemInputNodes = mCandidates.size();
 
-//		mCandidates.push_back(Candidate{
-//			.Constructor = []() -> std::unique_ptr<WorkflowNode> { return std::make_unique<FormInputNode>(); },
-//		});
+		/* Outputs */
 
-//		mCandidates.push_back(Candidate{
-//			.Constructor = []() -> std::unique_ptr<WorkflowNode> { return std::make_unique<DatabaseRowsInputNode>(); },
-//		});
+		mOutputOffset = mCandidates.size();
 	}
 };