src/pages/VisProgPage/VisProg.tsx

@@ -10,12 +10,13 @@ import '@xyflow/react/dist/style.css';
 import {useShallow} from 'zustand/react/shallow';
 
 import {
-  StartNode,
-  EndNode,
-  PhaseNode,
-  NormNode
+  StartNodeComponent,
+  EndNodeComponent,
+  PhaseNodeComponent,
+  NormNodeComponent
 } from './visualProgrammingUI/components/NodeDefinitions.tsx';
 import {DndToolbar} from './visualProgrammingUI/components/DragDropSidebar.tsx';
+import graphReducer from "./visualProgrammingUI/GraphReducer.ts";
 import useFlowStore from './visualProgrammingUI/VisProgStores.tsx';
 import type {FlowState} from './visualProgrammingUI/VisProgTypes.tsx';
 import styles from './VisProg.module.css'
@@ -26,10 +27,10 @@ import styles from './VisProg.module.css'
  * contains the types of all nodes that are available in the editor
  */
 const NODE_TYPES = {
-  start: StartNode,
-  end: EndNode,
-  phase: PhaseNode,
-  norm: NormNode
+  start: StartNodeComponent,
+  end: EndNodeComponent,
+  phase: PhaseNodeComponent,
+  norm: NormNodeComponent
 };
 
 /**
@@ -123,6 +124,12 @@ function VisualProgrammingUI() {
   );
 }
 
+// currently outputs the prepared program to the console
+function runProgram() {
+  const program = graphReducer();
+  console.log(program);
+}
+
 /**
  * houses the entire page, so also UI elements
  * that are not a part of the Visual Programming UI
@@ -132,6 +139,7 @@ function VisProgPage() {
   return (
     <>
       <VisualProgrammingUI/>
+      <button onClick={runProgram}>run program</button>
     </>
   )
 }

src/pages/VisProgPage/visualProgrammingUI/GraphReducer.ts

@@ -0,0 +1,188 @@
+import {
+  type Edge,
+  getIncomers,
+  getOutgoers
+} from '@xyflow/react';
+import useFlowStore from "./VisProgStores.tsx";
+import type {
+  BehaviorProgram,
+  GoalData,
+  GoalReducer,
+  GraphPreprocessor,
+  NormData,
+  NormReducer,
+  OrderedPhases,
+  Phase,
+  PhaseReducer,
+  PreparedGraph,
+  PreparedPhase
+} from "./GraphReducerTypes.ts";
+import type {
+  AppNode,
+  GoalNode,
+  NormNode,
+  PhaseNode
+} from "./VisProgTypes.tsx";
+
+/**
+ * Reduces the current graph inside the visual programming editor into a BehaviorProgram
+ *
+ * @param {GraphPreprocessor} graphPreprocessor
+ * @param {PhaseReducer} phaseReducer
+ * @param {NormReducer} normReducer
+ * @param {GoalReducer} goalReducer
+ * @returns {BehaviorProgram}
+ */
+export default function graphReducer(
+  graphPreprocessor: GraphPreprocessor = defaultGraphPreprocessor,
+  phaseReducer: PhaseReducer = defaultPhaseReducer,
+  normReducer: NormReducer = defaultNormReducer,
+  goalReducer: GoalReducer = defaultGoalReducer
+) : BehaviorProgram {
+  const nodes: AppNode[] = useFlowStore.getState().nodes;
+  const edges: Edge[] = useFlowStore.getState().edges;
+  const preparedGraph: PreparedGraph = graphPreprocessor(nodes, edges);
+
+  return preparedGraph.map((preparedPhase: PreparedPhase) : Phase =>
+    phaseReducer(
+      preparedPhase,
+      normReducer,
+      goalReducer
+    ));
+};
+
+/**
+ * reduces a single preparedPhase to a Phase object
+ * the Phase object describes a single phase in a BehaviorProgram
+ *
+ * @param {PreparedPhase} phase
+ * @param {NormReducer} normReducer
+ * @param {GoalReducer} goalReducer
+ * @returns {Phase}
+ */
+export function defaultPhaseReducer(
+  phase: PreparedPhase,
+  normReducer: NormReducer = defaultNormReducer,
+  goalReducer: GoalReducer = defaultGoalReducer
+) : Phase {
+  return {
+    id: phase.phaseNode.id,
+    name: phase.phaseNode.data.label,
+    nextPhaseId: phase.nextPhaseId,
+    phaseData: {
+      norms: phase.connectedNorms.map(normReducer),
+      goals: phase.connectedGoals.map(goalReducer)
+    }
+  }
+}
+
+/**
+ * the default implementation of the goalNode reducer function
+ *
+ * @param {GoalNode} node
+ * @returns {GoalData}
+ */
+function defaultGoalReducer(node: GoalNode) : GoalData {
+  return {
+    id: node.id,
+    name: node.data.label,
+    value: node.data.value
+  }
+}
+
+/**
+ * the default implementation of the normNode reducer function
+ *
+ * @param {NormNode} node
+ * @returns {NormData}
+ */
+function defaultNormReducer(node: NormNode) :NormData {
+  return {
+    id: node.id,
+    name: node.data.label,
+    value: node.data.value
+  }
+}
+
+// Graph preprocessing functions:
+
+/**
+ * Preprocesses the provide state of the behavior editor graph, preparing it for further processing in
+ * the graphReducer function
+ *
+ * @param {AppNode[]} nodes
+ * @param {Edge[]} edges
+ * @returns {PreparedGraph}
+ */
+export function defaultGraphPreprocessor(nodes: AppNode[], edges: Edge[]) : PreparedGraph {
+  const norms : NormNode[] = nodes.filter((node) => node.type === 'norm') as NormNode[];
+  const goals : GoalNode[] = nodes.filter((node) => node.type === 'goal') as GoalNode[];
+  const orderedPhases : OrderedPhases = orderPhases(nodes, edges);
+
+  return orderedPhases.phaseNodes.map((phase: PhaseNode) : PreparedPhase => {
+    const nextPhase = orderedPhases.connections.get(phase.id);
+      return {
+        phaseNode: phase,
+        nextPhaseId: nextPhase as string,
+        connectedNorms: getIncomers({id: phase.id}, norms,edges),
+        connectedGoals: getIncomers({id: phase.id}, goals,edges)
+      };
+    });
+}
+
+/**
+ * orderPhases takes the state of the graph created by the editor and turns it into an OrderedPhases object.
+ *
+ * @param {AppNode[]} nodes
+ * @param {Edge[]} edges
+ * @returns {OrderedPhases}
+ */
+export function orderPhases(nodes: AppNode[],edges: Edge[]) : OrderedPhases {
+  // find the first Phase node
+  const phaseNodes : PhaseNode[] = nodes.filter((node) => node.type === 'phase') as PhaseNode[];
+  const startNodeIndex = nodes.findIndex((node : AppNode):boolean  => {return (node.type === 'start');});
+  const firstPhaseNode = getOutgoers({ id: nodes[startNodeIndex].id },phaseNodes,edges);
+
+  // recursively adds the phase nodes to a list in the order they are connected in the graph
+  const nextPhase  = (
+    currentIndex: number,
+    { phaseNodes: phases, connections: connections} : OrderedPhases
+  ) : OrderedPhases => {
+    // get the current phase and the next phases;
+    const currentPhase = phases[currentIndex];
+    const nextPhaseNodes = getOutgoers(currentPhase,phaseNodes,edges);
+    const nextNodes = getOutgoers(currentPhase,nodes, edges);
+
+    // handles adding of the next phase to the chain, and error handle if an invalid state is received
+    if (nextPhaseNodes.length === 1 && nextNodes.length === 1) {
+      connections.set(currentPhase.id, nextPhaseNodes[0].id);
+      return nextPhase(phases.push(nextPhaseNodes[0] as PhaseNode) - 1, {phaseNodes: phases, connections: connections});
+    } else {
+      // handle erroneous states
+      if (nextNodes.length === 0){
+        throw new Error(`| INVALID PROGRAM | the source handle of "${currentPhase.id}" doesn't have any outgoing connections`);
+      } else {
+        if (nextNodes.length > 1) {
+          throw new Error(`| INVALID PROGRAM | the source handle of "${currentPhase.id}" connects to too many targets`);
+        } else {
+          if (nextNodes[0].type === "end"){
+            connections.set(currentPhase.id, "end");
+            // returns the final output of the function
+            return { phaseNodes: phases, connections: connections};
+          } else {
+            throw new Error(`| INVALID PROGRAM | the node "${nextNodes[0].id}" that "${currentPhase.id}" connects to is not a phase or end node`);
+          }
+        }
+      }
+    }
+  }
+  // initializes the Map describing the connections between phase nodes
+  // we need this Map to make sure we preserve this information,
+  // so we don't need to do checks on the entire set of edges in further stages of the reduction algorithm
+  const connections : Map<string, string> = new Map();
+
+  // returns an empty list if no phase nodes are present, otherwise returns an ordered list of phaseNodes
+  if (firstPhaseNode.length > 0) {
+      return nextPhase(0, {phaseNodes: [firstPhaseNode[0] as PhaseNode], connections: connections})
+  } else { return {phaseNodes: [], connections: connections} }
+}

src/pages/VisProgPage/visualProgrammingUI/GraphReducerTypes.ts

@@ -0,0 +1,106 @@
+import type {Edge} from "@xyflow/react";
+import type {AppNode, GoalNode, NormNode, PhaseNode} from "./VisProgTypes.tsx";
+
+
+/**
+ * defines how a norm is represented in the simplified behavior program
+  */
+export type NormData = {
+  id: string;
+  name: string;
+  value: string;
+};
+
+/**
+ * defines how a goal is represented in the simplified behavior program
+ */
+export type GoalData = {
+  id: string;
+  name: string;
+  value: string;
+};
+
+/**
+ * definition of a PhaseData object, it contains all phaseData that is relevant
+ * for further processing and execution of a phase.
+ */
+export type PhaseData = {
+  norms: NormData[];
+  goals: GoalData[];
+};
+
+/**
+ * Describes a single phase within the simplified representation of a behavior program,
+ *
+ * Contains:
+ * - the id of the described phase,
+ * - the name of the described phase,
+ * - the id of the next phase in the user defined behavior program
+ * - the data property of the described phase node
+ *
+ * @NOTE at the moment the type definitions do not support branching programs,
+ * if branching of phases is to be supported in the future, the type definition for Phase has to be updated
+ */
+export type Phase = {
+  id: string;
+  name: string;
+  nextPhaseId: string;
+  phaseData: PhaseData;
+};
+
+/**
+ * Describes a simplified behavior program as a list of Phase objects
+ */
+export type BehaviorProgram = Phase[];
+
+
+
+export type NormReducer = (node: NormNode) => NormData;
+export type GoalReducer = (node: GoalNode) => GoalData;
+export type PhaseReducer = (
+  preparedPhase: PreparedPhase,
+  normReducer: NormReducer,
+  goalReducer: GoalReducer
+) => Phase;
+
+/**
+ * contains:
+ *
+ * - list of phases, sorted based on position in chain between the start and end node
+ * - a dictionary containing all outgoing connections,
+ * to other phase or end nodes, for each phase node uses the id of the source node as key
+ * and the id of the target node as value
+ *
+ */
+export type OrderedPhases = {
+  phaseNodes: PhaseNode[];
+  connections: Map<string, string>;
+};
+
+/**
+ * A single prepared phase,
+ * contains:
+ * - the described phaseNode,
+ * - the id of the next phaseNode or "end" for the end node
+ * - a list of the normNodes that are connected to the described phase
+ * - a list of the goalNodes that are connected to the described phase
+ */
+export type PreparedPhase = {
+  phaseNode: PhaseNode;
+  nextPhaseId: string;
+  connectedNorms: NormNode[];
+  connectedGoals: GoalNode[];
+};
+
+/**
+ * a list of PreparedPhase objects,
+ * describes the preprocessed state of a program,
+ * before the contents of the node
+ */
+export type PreparedGraph = PreparedPhase[];
+
+export type GraphPreprocessor = (nodes: AppNode[], edges: Edge[]) => PreparedGraph;
+
+
+
+

src/pages/VisProgPage/visualProgrammingUI/VisProgStores.tsx

@@ -20,7 +20,7 @@ const initialNodes = [
     data: {label: 'start'}
   },
   {
-    id: 'genericPhase',
+    id: 'phase-1',
     type: 'phase',
     position: {x: 0, y: 150},
     data: {label: 'Generic Phase', number: 1},
@@ -38,9 +38,14 @@ const initialNodes = [
  */
 const initialEdges = [
   {
-    id: 'start-end',
+    id: 'start-phase-1',
     source: 'start',
-    target: 'end'
+    target: 'phase-1',
+  },
+  {
+    id: 'phase-1-end',
+    source: 'phase-1',
+    target: 'end',
   }
 ];
 

src/pages/VisProgPage/visualProgrammingUI/VisProgTypes.tsx

@@ -7,12 +7,24 @@ import {
   type OnReconnect,
 } from '@xyflow/react';
 
+
+type defaultNodeData = {
+  label: string;
+};
+
+export type StartNode = Node<defaultNodeData, 'start'>;
+export type EndNode = Node<defaultNodeData, 'end'>;
+export type GoalNode = Node<defaultNodeData & { value: string; }, 'goal'>;
+export type NormNode = Node<defaultNodeData & { value: string; }, 'norm'>;
+export type PhaseNode = Node<defaultNodeData & { number: number; }, 'phase'>;
+
+
 /**
  * a type meant to house different node types, currently not used
  * but will allow us to more clearly define nodeTypes when we implement
  * computation of the Graph inside the ReactFlow editor
  */
-export type AppNode = Node;
+export type AppNode = Node | StartNode | EndNode | NormNode | GoalNode | PhaseNode;
 
 
 /**

src/pages/VisProgPage/visualProgrammingUI/components/DragDropSidebar.tsx

@@ -11,6 +11,8 @@ import {
 } from 'react';
 import useFlowStore from "../VisProgStores.tsx";
 import styles from "../../VisProg.module.css"
+import type {AppNode, PhaseNode, NormNode} from "../VisProgTypes.tsx";
+
 
 
 /**
@@ -68,28 +70,45 @@ function DraggableNode({className, children, nodeType, onDrop}: DraggableNodePro
 // eslint-disable-next-line react-refresh/only-export-components
 export function addNode(nodeType: string, position: XYPosition) {
   const {setNodes} = useFlowStore.getState();
-  const nds = useFlowStore.getState().nodes;
+  const nds : AppNode[] = useFlowStore.getState().nodes;
   const newNode = () => {
     switch (nodeType) {
       case "phase":
       {
-        const phaseNumber = nds.filter((node) => node.type === 'phase').length;
-        return {
+        const phaseNodes= nds.filter((node) => node.type === 'phase');
+        let phaseNumber;
+        if (phaseNodes.length > 0) {
+          const finalPhaseId : number = +(phaseNodes[phaseNodes.length - 1].id.split('-')[1]);
+          phaseNumber = finalPhaseId + 1;
+        } else {
+          phaseNumber = 1;
+        }
+        const phaseNode : PhaseNode = {
           id: `phase-${phaseNumber}`,
           type: nodeType,
           position,
           data: {label: 'new', number: phaseNumber},
-        };
+        }
+        return phaseNode;
       }
       case "norm":
       {
-        const normNumber = nds.filter((node) => node.type === 'norm').length;
-        return {
+        const normNodes= nds.filter((node) => node.type === 'norm');
+        let normNumber
+        if (normNodes.length > 0) {
+          const finalNormId : number = +(normNodes[normNodes.length - 1].id.split('-')[1]);
+          normNumber = finalNormId + 1;
+        } else {
+          normNumber = 1;
+        }
+
+        const normNode : NormNode = {
           id: `norm-${normNumber}`,
           type: nodeType,
           position,
-          data: {label: `new norm node`},
-        };
+          data: {label: `new norm node`, value: "Pepper should be formal"},
+        }
+        return normNode;
       }
       default: {
         throw new Error(`Node ${nodeType} not found`);

src/pages/VisProgPage/visualProgrammingUI/components/NodeDefinitions.tsx

@@ -1,32 +1,32 @@
-import {Handle, NodeToolbar, Position} from '@xyflow/react';
+import {Handle, type NodeProps, NodeToolbar, Position} from '@xyflow/react';
 import '@xyflow/react/dist/style.css';
 import styles from '../../VisProg.module.css';
 import useFlowStore from "../VisProgStores.tsx";
+import type {
+  StartNode,
+  EndNode,
+  PhaseNode,
+  NormNode
+} from "../VisProgTypes.tsx";
 
-// Contains the datatypes for the data inside our NodeTypes
-// this has to be improved or adapted to suit our implementation for computing the graph
-// into a format that is useful for the Control Backend
-
-type defaultNodeData = {
-  label: string;
-};
-
-type startNodeData = defaultNodeData;
-type endNodeData = defaultNodeData;
-type normNodeData = defaultNodeData;
-type phaseNodeData = defaultNodeData & {
-  number: number;
-};
-
-export type nodeData = defaultNodeData | startNodeData | phaseNodeData | endNodeData;
-
-// Node Toolbar definition, contains node delete functionality
+//
 
 type ToolbarProps = {
   nodeId: string;
   allowDelete: boolean;
 };
 
+
+/**
+ * Node Toolbar definition:
+ * handles: node deleting functionality
+ * can be added to any custom node component as a React component
+ *
+ * @param {string} nodeId
+ * @param {boolean} allowDelete
+ * @returns {React.JSX.Element}
+ * @constructor
+ */
 export function Toolbar({nodeId, allowDelete}: ToolbarProps) {
   const {deleteNode} = useFlowStore();
 
@@ -42,14 +42,15 @@ export function Toolbar({nodeId, allowDelete}: ToolbarProps) {
 
 // Definitions of Nodes
 
-// Start Node definition:
-
-type StartNodeProps = {
-  id: string;
-  data: startNodeData;
-};
-
-export const StartNode = ({id, data}: StartNodeProps) => {
+/**
+ * Start Node definition:
+ *
+ * @param {string} id
+ * @param {defaultNodeData} data
+ * @returns {React.JSX.Element}
+ * @constructor
+ */
+export const StartNodeComponent = ({id, data}: NodeProps<StartNode>) => {
   return (
     <>
       <Toolbar nodeId={id} allowDelete={false}/>
@@ -62,14 +63,15 @@ export const StartNode = ({id, data}: StartNodeProps) => {
 };
 
 
-// End node definition:
-
-type EndNodeProps = {
-  id: string;
-  data: endNodeData;
-};
-
-export const EndNode = ({id, data}: EndNodeProps) => {
+/**
+ * End node definition:
+ *
+ * @param {string} id
+ * @param {defaultNodeData} data
+ * @returns {React.JSX.Element}
+ * @constructor
+ */
+export const EndNodeComponent = ({id, data}: NodeProps<EndNode>) => {
   return (
     <>
       <Toolbar nodeId={id} allowDelete={false}/>
@@ -82,14 +84,15 @@ export const EndNode = ({id, data}: EndNodeProps) => {
 };
 
 
-// Phase node definition:
-
-type PhaseNodeProps = {
-  id: string;
-  data: phaseNodeData;
-};
-
-export const PhaseNode = ({id, data}: PhaseNodeProps) => {
+/**
+ * Phase node definition:
+ *
+ * @param {string} id
+ * @param {defaultNodeData & {number: number}} data
+ * @returns {React.JSX.Element}
+ * @constructor
+ */
+export const PhaseNodeComponent = ({id, data}: NodeProps<PhaseNode>) => {
   return (
     <>
       <Toolbar nodeId={id} allowDelete={true}/>
@@ -104,14 +107,15 @@ export const PhaseNode = ({id, data}: PhaseNodeProps) => {
 };
 
 
-// Norm node definition:
-
-type NormNodeProps = {
-  id: string;
-  data: normNodeData;
-};
-
-export const NormNode = ({id, data}: NormNodeProps) => {
+/**
+ * Norm node definition:
+ *
+ * @param {string} id
+ * @param {defaultNodeData & {value: string}} data
+ * @returns {React.JSX.Element}
+ * @constructor
+ */
+export const NormNodeComponent = ({id, data}: NodeProps<NormNode>) => {
   return (
     <>
       <Toolbar nodeId={id} allowDelete={true}/>

test/pages/visProgPage/visualProgrammingUI/GraphReducer.test.ts

@@ -0,0 +1,986 @@
+import type {Edge} from "@xyflow/react";
+import graphReducer, {
+  defaultGraphPreprocessor, defaultPhaseReducer,
+  orderPhases
+} from "../../../../src/pages/VisProgPage/visualProgrammingUI/GraphReducer.ts";
+import type {PreparedPhase} from "../../../../src/pages/VisProgPage/visualProgrammingUI/GraphReducerTypes.ts";
+import useFlowStore from "../../../../src/pages/VisProgPage/visualProgrammingUI/VisProgStores.tsx";
+import type {AppNode} from "../../../../src/pages/VisProgPage/visualProgrammingUI/VisProgTypes.tsx";
+
+// sets of default values for nodes and edges to be used for test cases
+type FlowState = {
+  name: string;
+  nodes: AppNode[];
+  edges: Edge[];
+};
+
+// predefined graphs for testing:
+const onlyOnePhase : FlowState = {
+  name: "onlyOnePhase",
+  nodes: [
+    {
+      id: 'start',
+      type: 'start',
+      position: {x: 0, y: 0},
+      data: {label: 'start'}
+    },
+    {
+      id: 'phase-1',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 1},
+    },
+    {
+      id: 'end',
+      type: 'end',
+      position: {x: 0, y: 300},
+      data: {label: 'End'}
+    }
+  ],
+  edges:[
+    {
+      id: 'start-phase-1',
+      source: 'start',
+      target: 'phase-1',
+    },
+    {
+      id: 'phase-1-end',
+      source: 'phase-1',
+      target: 'end',
+    }
+  ]
+};
+const onlyThreePhases : FlowState = {
+  name: "onlyThreePhases",
+  nodes: [
+    {
+      id: 'start',
+      type: 'start',
+      position: {x: 0, y: 0},
+      data: {label: 'start'}
+    },
+    {
+      id: 'phase-1',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 1},
+    },
+    {
+      id: 'phase-3',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 3},
+    },
+    {
+      id: 'phase-2',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 2},
+    },
+    {
+      id: 'end',
+      type: 'end',
+      position: {x: 0, y: 300},
+      data: {label: 'End'}
+    }
+  ],
+  edges:[
+    {
+      id: 'start-phase-1',
+      source: 'start',
+      target: 'phase-1',
+    },
+    {
+      id: 'phase-1-phase-2',
+      source: 'phase-1',
+      target: 'phase-2',
+    },
+    {
+      id: 'phase-2-phase-3',
+      source: 'phase-2',
+      target: 'phase-3',
+    },
+    {
+      id: 'phase-3-end',
+      source: 'phase-3',
+      target: 'end',
+    }
+  ]
+};
+const onlySingleEdgeNorms : FlowState = {
+  name: "onlySingleEdgeNorms",
+  nodes: [
+    {
+      id: 'start',
+      type: 'start',
+      position: {x: 0, y: 0},
+      data: {label: 'start'}
+    },
+    {
+      id: 'phase-1',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 1},
+    },
+    {
+      id: 'norm-1',
+      type: 'norm',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Norm', value: "generic"},
+    },
+    {
+      id: 'norm-2',
+      type: 'norm',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Norm', value: "generic"},
+    },
+    {
+      id: 'phase-3',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 3},
+    },
+    {
+      id: 'phase-2',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 2},
+    },
+    {
+      id: 'end',
+      type: 'end',
+      position: {x: 0, y: 300},
+      data: {label: 'End'}
+    }
+  ],
+  edges:[
+    {
+      id: 'start-phase-1',
+      source: 'start',
+      target: 'phase-1',
+    },
+    {
+      id: 'norm-1-phase-2',
+      source: 'norm-1',
+      target: 'phase-2',
+    },
+    {
+      id: 'phase-1-phase-2',
+      source: 'phase-1',
+      target: 'phase-2',
+    },
+    {
+      id: 'phase-2-phase-3',
+      source: 'phase-2',
+      target: 'phase-3',
+    },
+    {
+      id: 'norm-2-phase-3',
+      source: 'norm-2',
+      target: 'phase-3',
+    },
+    {
+      id: 'phase-3-end',
+      source: 'phase-3',
+      target: 'end',
+    }
+  ]
+};
+const multiEdgeNorms : FlowState = {
+  name: "multiEdgeNorms",
+  nodes: [
+    {
+      id: 'start',
+      type: 'start',
+      position: {x: 0, y: 0},
+      data: {label: 'start'}
+    },
+    {
+      id: 'phase-1',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 1},
+    },
+    {
+      id: 'norm-1',
+      type: 'norm',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Norm', value: "generic"},
+    },
+    {
+      id: 'norm-2',
+      type: 'norm',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Norm', value: "generic"},
+    },
+    {
+      id: 'phase-3',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 3},
+    },
+    {
+      id: 'norm-3',
+      type: 'norm',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Norm', value: "generic"},
+    },
+    {
+      id: 'phase-2',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 2},
+    },
+    {
+      id: 'end',
+      type: 'end',
+      position: {x: 0, y: 300},
+      data: {label: 'End'}
+    }
+  ],
+  edges:[
+    {
+      id: 'start-phase-1',
+      source: 'start',
+      target: 'phase-1',
+    },
+    {
+      id: 'norm-1-phase-2',
+      source: 'norm-1',
+      target: 'phase-2',
+    },
+    {
+      id: 'norm-1-phase-3',
+      source: 'norm-1',
+      target: 'phase-3',
+    },
+    {
+      id: 'phase-1-phase-2',
+      source: 'phase-1',
+      target: 'phase-2',
+    },
+    {
+      id: 'norm-3-phase-1',
+      source: 'norm-3',
+      target: 'phase-1',
+    },
+    {
+      id: 'phase-2-phase-3',
+      source: 'phase-2',
+      target: 'phase-3',
+    },
+    {
+      id: 'norm-2-phase-3',
+      source: 'norm-2',
+      target: 'phase-3',
+    },
+    {
+      id: 'norm-2-phase-2',
+      source: 'norm-2',
+      target: 'phase-2',
+    },
+    {
+      id: 'phase-3-end',
+      source: 'phase-3',
+      target: 'end',
+    }
+  ]
+};
+const onlyStartEnd : FlowState = {
+  name: "onlyStartEnd",
+  nodes: [
+    {
+      id: 'start',
+      type: 'start',
+      position: {x: 0, y: 0},
+      data: {label: 'start'}
+    },
+    {
+      id: 'end',
+      type: 'end',
+      position: {x: 0, y: 300},
+      data: {label: 'End'}
+    }
+  ],
+  edges:[
+    {
+      id: 'start-end',
+      source: 'start',
+      target: 'end',
+    },
+  ]
+};
+
+// states that contain invalid programs for testing if correct errors are thrown:
+const phaseConnectsToInvalidNodeType : FlowState = {
+  name: "phaseConnectsToInvalidNodeType",
+  nodes: [
+    {
+      id: 'start',
+      type: 'start',
+      position: {x: 0, y: 0},
+      data: {label: 'start'}
+    },
+    {
+      id: 'phase-1',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 1},
+    },
+    {
+      id: 'default-1',
+      type: 'default',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Norm'},
+    },
+    {
+      id: 'end',
+      type: 'end',
+      position: {x: 0, y: 300},
+      data: {label: 'End'}
+    }
+  ],
+  edges:[
+    {
+      id: 'start-phase-1',
+      source: 'start',
+      target: 'phase-1',
+    },
+    {
+      id: 'phase-1-default-1',
+      source: 'phase-1',
+      target: 'default-1',
+    },
+  ]
+};
+const phaseHasNoOutgoingConnections : FlowState = {
+  name: "phaseHasNoOutgoingConnections",
+  nodes: [
+    {
+      id: 'start',
+      type: 'start',
+      position: {x: 0, y: 0},
+      data: {label: 'start'}
+    },
+    {
+      id: 'phase-1',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 1},
+    },
+    {
+      id: 'phase-2',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 2},
+    },
+    {
+      id: 'end',
+      type: 'end',
+      position: {x: 0, y: 300},
+      data: {label: 'End'}
+    }
+  ],
+  edges:[
+    {
+      id: 'start-phase-1',
+      source: 'start',
+      target: 'phase-1',
+    },
+  ]
+};
+const phaseHasTooManyOutgoingConnections : FlowState = {
+  name: "phaseHasTooManyOutgoingConnections",
+  nodes: [
+    {
+      id: 'start',
+      type: 'start',
+      position: {x: 0, y: 0},
+      data: {label: 'start'}
+    },
+    {
+      id: 'phase-1',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 1},
+    },
+    {
+      id: 'phase-2',
+      type: 'phase',
+      position: {x: 0, y: 150},
+      data: {label: 'Generic Phase', number: 2},
+    },
+    {
+      id: 'end',
+      type: 'end',
+      position: {x: 0, y: 300},
+      data: {label: 'End'}
+    }
+  ],
+  edges:[
+    {
+      id: 'start-phase-1',
+      source: 'start',
+      target: 'phase-1',
+    },
+    {
+      id: 'phase-1-phase-2',
+      source: 'phase-1',
+      target: 'phase-2',
+    },
+    {
+      id: 'phase-1-end',
+      source: 'phase-1',
+      target: 'end',
+    },
+    {
+      id: 'phase-2-end',
+      source: 'phase-2',
+      target: 'end',
+    },
+  ]
+};
+
+describe('Graph Reducer Tests', () => {
+  describe('defaultGraphPreprocessor', () => {
+    test.each([
+      {
+        state: onlyOnePhase,
+        expected: [
+          {
+            phaseNode: {
+              id: 'phase-1',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 1},
+            },
+            nextPhaseId: 'end',
+            connectedNorms: [],
+            connectedGoals: [],
+          }]
+      },
+      {
+        state: onlyThreePhases,
+        expected: [
+          {
+            phaseNode: {
+              id: 'phase-1',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 1},
+            },
+            nextPhaseId: 'phase-2',
+            connectedNorms: [],
+            connectedGoals: [],
+          },
+          {
+            phaseNode: {
+              id: 'phase-2',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 2},
+            },
+            nextPhaseId: 'phase-3',
+            connectedNorms: [],
+            connectedGoals: [],
+          },
+          {
+            phaseNode: {
+              id: 'phase-3',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 3},
+            },
+            nextPhaseId: 'end',
+            connectedNorms: [],
+            connectedGoals: [],
+          }]
+      },
+      {
+        state: onlySingleEdgeNorms,
+        expected: [
+          {
+            phaseNode: {
+              id: 'phase-1',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 1},
+            },
+            nextPhaseId: 'phase-2',
+            connectedNorms: [],
+            connectedGoals: [],
+          },
+          {
+            phaseNode: {
+              id: 'phase-2',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 2},
+            },
+            nextPhaseId: 'phase-3',
+            connectedNorms: [{
+              id: 'norm-1',
+              type: 'norm',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Norm', value: "generic"},
+            }],
+            connectedGoals: [],
+          },
+          {
+            phaseNode: {
+              id: 'phase-3',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 3},
+            },
+            nextPhaseId: 'end',
+            connectedNorms: [{
+              id: 'norm-2',
+              type: 'norm',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Norm', value: "generic"},
+            }],
+            connectedGoals: [],
+          }]
+      },
+      {
+        state: multiEdgeNorms,
+        expected: [
+          {
+            phaseNode: {
+              id: 'phase-1',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 1},
+            },
+            nextPhaseId: 'phase-2',
+            connectedNorms: [{
+              id: 'norm-3',
+              type: 'norm',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Norm', value: "generic"},
+            }],
+            connectedGoals: [],
+          },
+          {
+            phaseNode: {
+              id: 'phase-2',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 2},
+            },
+            nextPhaseId: 'phase-3',
+            connectedNorms: [{
+              id: 'norm-1',
+              type: 'norm',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Norm', value: "generic"},
+            },
+            {
+              id: 'norm-2',
+              type: 'norm',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Norm', value: "generic"},
+            }],
+            connectedGoals: [],
+          },
+          {
+            phaseNode: {
+              id: 'phase-3',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 3},
+            },
+            nextPhaseId: 'end',
+            connectedNorms: [{
+              id: 'norm-1',
+              type: 'norm',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Norm', value: "generic"},
+            },
+            {
+              id: 'norm-2',
+              type: 'norm',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Norm', value: "generic"},
+            }],
+            connectedGoals: [],
+          }]
+      },
+      {
+        state: onlyStartEnd,
+        expected: [],
+      }
+    ])(`tests state: $state.name`, ({state, expected}) => {
+      const output = defaultGraphPreprocessor(state.nodes, state.edges);
+      expect(output).toEqual(expected);
+    });
+  });
+  describe("orderPhases", () => {
+    test.each([
+      {
+        state: onlyOnePhase,
+        expected: {
+          phaseNodes: [{
+            id: 'phase-1',
+            type: 'phase',
+            position: {x: 0, y: 150},
+            data: {label: 'Generic Phase', number: 1},
+          }],
+          connections: new Map<string,string>([["phase-1","end"]])
+        }
+      },
+      {
+        state: onlyThreePhases,
+        expected: {
+          phaseNodes: [
+            {
+              id: 'phase-1',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 1},
+            },
+            {
+              id: 'phase-2',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 2},
+            },
+            {
+              id: 'phase-3',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 3},
+            }],
+          connections: new Map<string,string>([
+            ["phase-1","phase-2"],
+            ["phase-2","phase-3"],
+            ["phase-3","end"]
+          ])
+        }
+      },
+      {
+        state: onlySingleEdgeNorms,
+        expected: {
+          phaseNodes: [
+            {
+              id: 'phase-1',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 1},
+            },
+            {
+              id: 'phase-2',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 2},
+            },
+            {
+              id: 'phase-3',
+              type: 'phase',
+              position: {x: 0, y: 150},
+              data: {label: 'Generic Phase', number: 3},
+            }],
+          connections: new Map<string,string>([
+            ["phase-1","phase-2"],
+            ["phase-2","phase-3"],
+            ["phase-3","end"]
+          ])
+        }
+      },
+      {
+        state: onlyStartEnd,
+        expected: {
+          phaseNodes: [],
+          connections: new Map<string,string>()
+        }
+      }
+    ])(`tests state: $state.name`, ({state, expected}) => {
+      const output = orderPhases(state.nodes, state.edges);
+      expect(output.phaseNodes).toEqual(expected.phaseNodes);
+      expect(output.connections).toEqual(expected.connections);
+    });
+    test.each([
+      {
+        state: phaseConnectsToInvalidNodeType,
+        expected: new Error('| INVALID PROGRAM | the node "default-1" that "phase-1" connects to is not a phase or end node')
+      },
+      {
+        state: phaseHasNoOutgoingConnections,
+        expected: new Error('| INVALID PROGRAM | the source handle of "phase-1" doesn\'t have any outgoing connections')
+      },
+      {
+        state: phaseHasTooManyOutgoingConnections,
+        expected: new Error('| INVALID PROGRAM | the source handle of "phase-1" connects to too many targets')
+      }
+    ])(`tests erroneous state: $state.name`, ({state, expected}) => {
+      const testForError = () => {
+        orderPhases(state.nodes, state.edges);
+      };
+      expect(testForError).toThrow(expected);
+    })
+  })
+  describe("defaultPhaseReducer", () => {
+    test("phaseReducer handles empty norms and goals without failing", () => {
+      const input : PreparedPhase = {
+        phaseNode: {
+          id: 'phase-1',
+          type: 'phase',
+          position: {x: 0, y: 150},
+          data: {label: 'Generic Phase', number: 1},
+        },
+        nextPhaseId: 'end',
+        connectedNorms: [],
+        connectedGoals: [],
+      }
+      const output = defaultPhaseReducer(input);
+      expect(output).toEqual({
+        id: 'phase-1',
+        name: 'Generic Phase',
+        nextPhaseId: 'end',
+        phaseData: {
+          norms: [],
+          goals: []
+        }
+      });
+    });
+    test("defaultNormReducer reduces norms correctly", () => {
+      const input : PreparedPhase = {
+        phaseNode: {
+          id: 'phase-1',
+          type: 'phase',
+          position: {x: 0, y: 150},
+          data: {label: 'Generic Phase', number: 1},
+        },
+        nextPhaseId: 'end',
+        connectedNorms: [{
+          id: 'norm-1',
+          type: 'norm',
+          position: {x: 0, y: 150},
+          data: {label: 'Generic Norm', value: "generic"},
+        }],
+        connectedGoals: [],
+      }
+      const output = defaultPhaseReducer(input);
+      expect(output).toEqual({
+        id: 'phase-1',
+        name: 'Generic Phase',
+        nextPhaseId: 'end',
+        phaseData: {
+          norms: [{
+            id: 'norm-1',
+            name: 'Generic Norm',
+            value: "generic"
+          }],
+          goals: []
+        }
+      });
+    });
+    test("defaultGoalReducer reduces goals correctly", () => {
+      const input : PreparedPhase = {
+        phaseNode: {
+          id: 'phase-1',
+          type: 'phase',
+          position: {x: 0, y: 150},
+          data: {label: 'Generic Phase', number: 1},
+        },
+        nextPhaseId: 'end',
+        connectedNorms: [],
+        connectedGoals: [{
+          id: 'goal-1',
+          type: 'goal',
+          position: {x: 0, y: 150},
+          data: {label: 'Generic Goal', value: "generic"},
+        }],
+      }
+      const output = defaultPhaseReducer(input);
+      expect(output).toEqual({
+        id: 'phase-1',
+        name: 'Generic Phase',
+        nextPhaseId: 'end',
+        phaseData: {
+          norms: [],
+          goals: [{
+            id: 'goal-1',
+            name: 'Generic Goal',
+            value: "generic"
+          }]
+        }
+      });
+    });
+  })
+  describe("GraphReducer", () => {
+    test.each([
+      {
+        state: onlyOnePhase,
+        expected: [
+          {
+            id: 'phase-1',
+            name: 'Generic Phase',
+            nextPhaseId: 'end',
+            phaseData: {
+              norms: [],
+              goals: []
+            }
+          }]
+      },
+      {
+        state: onlyThreePhases,
+        expected: [
+          {
+            id: 'phase-1',
+            name: 'Generic Phase',
+            nextPhaseId: 'phase-2',
+            phaseData: {
+              norms: [],
+              goals: []
+            }
+          },
+          {
+            id: 'phase-2',
+            name: 'Generic Phase',
+            nextPhaseId: 'phase-3',
+            phaseData: {
+              norms: [],
+              goals: []
+            }
+          },
+          {
+            id: 'phase-3',
+            name: 'Generic Phase',
+            nextPhaseId: 'end',
+            phaseData: {
+              norms: [],
+              goals: []
+            }
+          }]
+      },
+      {
+        state: onlySingleEdgeNorms,
+        expected: [
+          {
+            id: 'phase-1',
+            name: 'Generic Phase',
+            nextPhaseId: 'phase-2',
+            phaseData: {
+              norms: [],
+              goals: []
+            }
+          },
+          {
+            id: 'phase-2',
+            name: 'Generic Phase',
+            nextPhaseId: 'phase-3',
+            phaseData: {
+              norms: [
+                {
+                  id: 'norm-1',
+                  name: 'Generic Norm',
+                  value: "generic"
+                }
+              ],
+              goals: []
+            }
+          },
+          {
+            id: 'phase-3',
+            name: 'Generic Phase',
+            nextPhaseId: 'end',
+            phaseData: {
+              norms: [{
+                id: 'norm-2',
+                name: 'Generic Norm',
+                value: "generic"
+              }],
+              goals: []
+            }
+          }]
+      },
+      {
+        state: multiEdgeNorms,
+        expected: [
+          {
+            id: 'phase-1',
+            name: 'Generic Phase',
+            nextPhaseId: 'phase-2',
+            phaseData: {
+              norms: [{
+                id: 'norm-3',
+                name: 'Generic Norm',
+                value: "generic"
+              }],
+              goals: []
+            }
+          },
+          {
+            id: 'phase-2',
+            name: 'Generic Phase',
+            nextPhaseId: 'phase-3',
+            phaseData: {
+              norms: [
+                {
+                  id: 'norm-1',
+                  name: 'Generic Norm',
+                  value: "generic"
+                },
+                {
+                  id: 'norm-2',
+                  name: 'Generic Norm',
+                  value: "generic"
+                }
+              ],
+              goals: []
+            }
+          },
+          {
+            id: 'phase-3',
+            name: 'Generic Phase',
+            nextPhaseId: 'end',
+            phaseData: {
+              norms: [{
+                id: 'norm-1',
+                name: 'Generic Norm',
+                value: "generic"
+              },
+              {
+                id: 'norm-2',
+                name: 'Generic Norm',
+                value: "generic"
+              }],
+              goals: []
+            }
+          }]
+      },
+      {
+        state: onlyStartEnd,
+        expected: [],
+      }
+    ])("`tests state: $state.name`", ({state, expected}) => {
+      useFlowStore.setState({nodes: state.nodes, edges: state.edges});
+      const output = graphReducer(); // uses default reducers
+      expect(output).toEqual(expected);
+    })
+    // we run the test for correct error handling for the entire graph reducer as well,
+    // to make sure no errors occur before we intend to handle the errors ourselves
+    test.each([
+      {
+        state: phaseConnectsToInvalidNodeType,
+        expected: new Error('| INVALID PROGRAM | the node "default-1" that "phase-1" connects to is not a phase or end node')
+      },
+      {
+        state: phaseHasNoOutgoingConnections,
+        expected: new Error('| INVALID PROGRAM | the source handle of "phase-1" doesn\'t have any outgoing connections')
+      },
+      {
+        state: phaseHasTooManyOutgoingConnections,
+        expected: new Error('| INVALID PROGRAM | the source handle of "phase-1" connects to too many targets')
+      }
+    ])(`tests erroneous state: $state.name`, ({state, expected}) => {
+      useFlowStore.setState({nodes: state.nodes, edges: state.edges});
+      const testForError = () => {
+        graphReducer();
+      };
+      expect(testForError).toThrow(expected);
+    })
+  })
+});

test/pages/visProgPage/visualProgrammingUI/components/DragDropSidebar.test.tsx

@@ -24,8 +24,8 @@ describe('Drag-and-Drop sidebar', () => {
     })
     const updatedState = useFlowStore.getState();
     expect(updatedState.nodes.length).toBe(2);
-    expect(updatedState.nodes[0].id).toBe(`${nodeType}-0`);
-    expect(updatedState.nodes[1].id).toBe(`${nodeType}-1`);
+    expect(updatedState.nodes[0].id).toBe(`${nodeType}-1`);
+    expect(updatedState.nodes[1].id).toBe(`${nodeType}-2`);
   });
   test('throws error on unexpected node type', () => {
       expect(() => addNode('I do not Exist', {x:100, y:100})).toThrow("Node I do not Exist not found");