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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Visual Programming Language</title>
  <style>
    body { margin: 0; font-family: Arial, sans-serif; }
    #canvas {
      width: 100vw;
      height: 100vh;
      background: #f0f0f0;
      position: relative;
      overflow: auto;
    }
    .node {
      position: absolute;
      width: 250px;
      background: #fff;
      border: 2px solid #333;
      border-radius: 5px;
      padding: 10px;
      cursor: move;
      user-select: none;
      box-sizing: border-box;
      transition: box-shadow 0.1s ease;
    }
    .node.executing { border: 3px solid orange; }
    .node.error { border-color: red; }
    .node-header {
      font-weight: bold;
      margin-bottom: 5px;
      position: relative;
    }
    .remove-node {
      position: absolute;
      right: 0;
      top: 0;
      cursor: pointer;
      color: red;
      font-weight: bold;
      padding: 0 4px;
      user-select: none;
    }
    .port {
      width: 10px;
      height: 10px;
      background: #666;
      border-radius: 50%;
      position: absolute;
      cursor: pointer;
    }
    .port-input { left: -15px; top: 50%; transform: translateY(-50%); }
    .port-output { right: -15px; top: 50%; transform: translateY(-50%); }
    .port-output-true { right: -15px; top: 30%; }
    .port-output-false { right: -15px; top: 70%; }
    #toolbar {
      position: fixed;
      top: 10px;
      left: 10px;
      background: #ddd;
      padding: 10px;
      border-radius: 5px;
      z-index: 1000;
    }
    button { margin: 2px; }
    #connections {
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      pointer-events: none;
      z-index: 0;
    }
    input { width: 80%; margin: 5px 0; }
    .case-container { margin: 5px 0; display: flex; align-items: center; }
    .label { font-size: 12px; color: #555; position: absolute; right: -50px; }
    .arg-container { margin: 5px 0; }
    .elements-container input { width: 70%; margin: 3px 0; }
  </style>
</head>
<body>
  <div id="toolbar">
    <!-- Existing Nodes -->
    <button onclick="addNode('Variable')">Variable</button>
    <button onclick="addNode('Assign')">Assign</button>
    <button onclick="addNode('Print')">Print</button>
    <button onclick="addNode('Function')">Function</button>
    <button onclick="addNode('Return')">Return</button>
    <button onclick="addNode('Call')">Call</button>
    <button onclick="addNode('If')">If</button>
    <button onclick="addNode('WhileLoop')">While Loop</button>
    <button onclick="addNode('Switch')">Switch</button>
    <button onclick="addNode('Break')">Break</button>
    <button onclick="addNode('Continue')">Continue</button>
    <button onclick="addNode('Add')">Add</button>
    <button onclick="addNode('Subtract')">Subtract</button>
    <button onclick="addNode('Multiply')">Multiply</button>
    <button onclick="addNode('Divide')">Divide</button>
    <button onclick="addNode('Array')">Array</button>
    <button onclick="addNode('Library')">Import Library</button>
    <!-- New Nodes -->
    <button onclick="addNode('Comment')">Comment</button>
    <button onclick="addNode('ForLoop')">For Loop</button>
    <br>
    <button onclick="runWorkflow()">Run Workflow</button>
    <button onclick="startStepExecution()">Start Step Execution</button>
    <button onclick="stepExecution()">Step Execution</button>
    <button onclick="saveWorkflow()">Save Workflow</button>
    <button onclick="loadWorkflow()">Load Workflow</button>
    <button onclick="groupSimilarNodes()">Group Similar Nodes</button>
    <button onclick="exportCode()">Export Code</button>
  </div>
  <div id="canvas">
    <svg id="connections"></svg>
  </div>

  <script>
    // Global variables
    const canvas = document.getElementById('canvas');
    const connectionsSvg = document.getElementById('connections');
    let nodes = [];
    let connections = [];
    let draggingNode = null;
    let draggingPort = null;
    let tempLine = null;
    let offsetX, offsetY;
    let variables = {};
    let functionReturns = {};
    let nodeIdCounter = 0;
    const gridSize = 20;
    let zoomFactor = 1.0;
    let workflowOutput = "";
    let executionQueue = [];
    const controlNodes = ["If", "WhileLoop", "Switch", "Break", "Continue", "Function", "Return"];
    let highestZ = 100;

    // ----------------------------
    // Node creation and UI helpers
    // ----------------------------
    function addNode(type, options = {}) {
      const node = document.createElement('div');
      node.className = 'node';
      node.dataset.type = type;
      node.dataset.id = nodeIdCounter++;
      const left = options.left || Math.round((Math.random() * 300 + 50) / gridSize) * gridSize;
      const top = options.top || Math.round((Math.random() * 300 + 50) / gridSize) * gridSize;
      node.style.left = `${left}px`;
      node.style.top = `${top}px`;
      highestZ++;
      node.style.zIndex = highestZ;
      
      let html = `<div class="node-header">${type}<span class="remove-node" onclick="removeNode(this)">×</span></div>`;
      if (type === 'Variable') {
        html += `
          <input type="text" class="var-name" placeholder="Variable Name">
          <input type="text" class="var-value" placeholder="Value">
          <div class="port port-output" data-type="output"></div>
        `;
      } else if (type === 'Assign') {
        html += `
          <input type="text" class="assign-expr" placeholder="Assignment (e.g., i = i + 1)">
          <div class="port port-input" data-type="input"></div>
          <div class="port port-output" data-type="output"></div>
        `;
      } else if (type === 'Print') {
        html += `
          <input type="text" class="print-value" placeholder='Expression to print (e.g., "Hello " + x)'>
          <div class="port port-input" data-type="input"></div>
        `;
      } else if (type === 'Function') {
        html += `
          <input type="text" class="func-name" placeholder="Function Name">
          <div class="arg-container">
            <input type="text" class="arg-name" placeholder="Arg Name (e.g., a)">
          </div>
          <button onclick="addArg(this.parentElement)">Add Arg</button>
          <div class="port port-input" data-type="input"></div>
          <div class="port port-output" data-type="output"></div>
        `;
      } else if (type === 'Return') {
        html += `
          <input type="text" class="return-value" placeholder="Return Value (e.g., x + 1)">
          <div class="port port-input" data-type="input"></div>
        `;
      } else if (type === 'Call') {
        html += `
          <input type="text" class="call-name" placeholder="Function Name (e.g., add)">
          <div class="arg-container">
            <input type="text" class="call-arg" placeholder="Arg Value (e.g., 3)">
          </div>
          <button onclick="addCallArg(this.parentElement)">Add Arg</button>
          <input type="text" class="call-result" placeholder="Result Var (e.g., z)">
          <div class="port port-input" data-type="input"></div>
          <div class="port port-output" data-type="output"></div>
        `;
      } else if (type === 'If') {
        html += `
          <input type="text" class="condition" placeholder="Condition (e.g., x > 5)">
          <div class="port port-input" data-type="input"></div>
          <div class="port port-output-true" data-type="output" data-branch="true">
            <span class="label">True</span>
          </div>
          <div class="port port-output-false" data-type="output" data-branch="false">
            <span class="label">False</span>
          </div>
        `;
      } else if (type === 'WhileLoop') {
        html += `
          <input type="text" class="condition" placeholder="Condition (e.g., i < 5)">
          <input type="text" class="update" placeholder="Update (e.g., i = i + 1)">
          <div class="port port-input" data-type="input"></div>
          <div class="port port-output" data-type="output"></div>
        `;
      } else if (type === 'Switch') {
        html += `
          <input type="text" class="switch-var" placeholder="Variable to Switch">
          <div class="case-container">
            <input type="text" class="case-value" placeholder="Case Value (e.g., 1)">
            <input type="checkbox" class="case-break" title="Break after this case">
            <div class="port port-output" data-type="output" data-case="0"></div>
          </div>
          <button onclick="addCase(this.parentElement)">Add Case</button>
          <div class="port port-input" data-type="input"></div>
        `;
      } else if (type === 'Break' || type === 'Continue') {
        html += `<div class="port port-input" data-type="input"></div>`;
      } else if (type === 'Add' || type === 'Subtract' ||
                 type === 'Multiply' || type === 'Divide') {
        html += `
          <input type="text" class="operand1" placeholder="Operand 1">
          <input type="text" class="operand2" placeholder="Operand 2">
          <input type="text" class="result-var" placeholder="Result Var">
          <div class="port port-output" data-type="output"></div>
        `;
      } else if (type === 'Array') {
        html += `
          <input type="text" class="array-name" placeholder="Array Name">
          <div class="elements-container"></div>
          <button onclick="addArrayElement(this.parentElement)">Add Element</button>
          <div class="port port-output" data-type="output"></div>
        `;
      }
      // New: Library Node
      else if (type === 'Library') {
        html += `
          <input type="text" class="lib-url" placeholder="Library (e.g., os)">
          <div class="port port-output" data-type="output"></div>
        `;
      }
      // New: Comment Node
      else if (type === 'Comment') {
        html += `
          <input type="text" class="comment-text" placeholder="Enter comment">
          <div class="port port-output" data-type="output"></div>
        `;
      }
      // New: For Loop Node
      else if (type === 'ForLoop') {
        html += `
          <input type="text" class="init" placeholder="Initialization (e.g., let i = 0)">
          <input type="text" class="condition" placeholder="Condition (e.g., i < 10)">
          <input type="text" class="update" placeholder="Update (e.g., i++)">
          <div class="port port-input" data-type="input"></div>
          <div class="port port-output" data-type="output"></div>
        `;
      }
      node.innerHTML = html;
      canvas.appendChild(node);
      nodes.push(node);
      if (options.inputs) {
        Object.keys(options.inputs).forEach(className => {
          const input = node.querySelector(`.${className}`);
          if (input) input.value = options.inputs[className];
        });
      }
      // Bring node to front on mousedown
      node.addEventListener('mousedown', (e) => {
        if (!e.target.classList.contains('port') &&
            e.target.tagName !== 'INPUT' &&
            e.target.tagName !== 'BUTTON') {
          highestZ++;
          node.style.zIndex = highestZ;
          draggingNode = node;
          const rect = node.getBoundingClientRect();
          offsetX = e.clientX - rect.left;
          offsetY = e.clientY - rect.top;
        }
      });
      const ports = node.querySelectorAll('.port');
      ports.forEach(port => {
        port.addEventListener('mousedown', (e) => {
          e.stopPropagation();
          draggingPort = port;
        });
      });
    }

    // ----------------------------
    // Remove Node
    // ----------------------------
    function removeNode(removeButton) {
      const node = removeButton.parentElement.parentElement;
      connections = connections.filter(conn => conn.from.parentElement !== node && conn.to.parentElement !== node);
      node.remove();
      nodes = nodes.filter(n => n !== node);
      updateConnections();
    }

    // ----------------------------
    // Additional helper functions for node inputs
    // ----------------------------
    function addArg(funcNode) {
      const argCount = funcNode.querySelectorAll('.arg-container').length;
      const argDiv = document.createElement('div');
      argDiv.className = 'arg-container';
      argDiv.innerHTML = `<input type="text" class="arg-name" placeholder="Arg Name (e.g., arg${argCount + 1})">`;
      funcNode.insertBefore(argDiv, funcNode.querySelector('button'));
    }
    function addCallArg(callNode) {
      const argCount = callNode.querySelectorAll('.arg-container').length;
      const argDiv = document.createElement('div');
      argDiv.className = 'arg-container';
      argDiv.innerHTML = `<input type="text" class="call-arg" placeholder="Arg Value (e.g., ${argCount + 1})">`;
      callNode.insertBefore(argDiv, callNode.querySelector('button'));
    }
    function addCase(switchNode) {
      const caseCount = switchNode.querySelectorAll('.case-container').length;
      const caseDiv = document.createElement('div');
      caseDiv.className = 'case-container';
      caseDiv.innerHTML = `
        <input type="text" class="case-value" placeholder="Case Value (e.g., ${caseCount + 1})">
        <input type="checkbox" class="case-break" title="Break after this case">
        <div class="port port-output" data-type="output" data-case="${caseCount}"></div>
      `;
      switchNode.insertBefore(caseDiv, switchNode.querySelector('button'));
      const newPort = caseDiv.querySelector('.port');
      newPort.addEventListener('mousedown', (e) => {
        e.stopPropagation();
        draggingPort = newPort;
      });
    }
    function addArrayElement(arrayNode) {
      const container = arrayNode.querySelector('.elements-container');
      const input = document.createElement('input');
      input.type = 'text';
      input.className = 'element-value';
      input.placeholder = 'Element value';
      container.appendChild(input);
    }

    // ----------------------------
    // Dragging and Connection Handling
    // ----------------------------
    document.addEventListener('mousemove', (e) => {
      if (draggingNode) {
        requestAnimationFrame(() => {
          const canvasRect = canvas.getBoundingClientRect();
          let x = e.clientX - offsetX - canvasRect.left;
          let y = e.clientY - offsetY - canvasRect.top;
          x = Math.round(x / gridSize) * gridSize;
          y = Math.round(y / gridSize) * gridSize;
          draggingNode.style.left = `${x}px`;
          draggingNode.style.top = `${y}px`;
          updateConnections();
        });
      }
      if (draggingPort) {
        requestAnimationFrame(() => {
          if (!tempLine) {
            tempLine = document.createElementNS('http://www.w3.org/2000/svg', 'line');
            tempLine.setAttribute('stroke', 'green');
            tempLine.setAttribute('stroke-width', '2');
            connectionsSvg.appendChild(tempLine);
          }
          const canvasRect = canvas.getBoundingClientRect();
          const fromRect = draggingPort.getBoundingClientRect();
          const x1 = fromRect.left + fromRect.width / 2 - canvasRect.left;
          const y1 = fromRect.top + fromRect.height / 2 - canvasRect.top;
          const x2 = e.clientX - canvasRect.left;
          const y2 = e.clientY - canvasRect.top;
          tempLine.setAttribute('x1', x1);
          tempLine.setAttribute('y1', y1);
          tempLine.setAttribute('x2', x2);
          tempLine.setAttribute('y2', y2);
        });
      } else {
        if (tempLine) {
          tempLine.remove();
          tempLine = null;
        }
      }
    });
    document.addEventListener('mouseup', (e) => {
      if (draggingNode) draggingNode = null;
      if (draggingPort) {
        const targetPort = e.target.closest('.port');
        if (targetPort &&
            targetPort !== draggingPort &&
            draggingPort.dataset.type === "output" &&
            targetPort.dataset.type === "input") {
          connections.push({ from: draggingPort, to: targetPort });
          updateConnections();
        }
        draggingPort = null;
        if (tempLine) {
          tempLine.remove();
          tempLine = null;
        }
      }
    });
    function updateConnections() {
      connectionsSvg.innerHTML = '';
      const canvasRect = canvas.getBoundingClientRect();
      connections.forEach(conn => {
        const fromRect = conn.from.getBoundingClientRect();
        const toRect = conn.to.getBoundingClientRect();
        const line = document.createElementNS('http://www.w3.org/2000/svg', 'line');
        line.setAttribute('x1', fromRect.left + fromRect.width / 2 - canvasRect.left);
        line.setAttribute('y1', fromRect.top + fromRect.height / 2 - canvasRect.top);
        line.setAttribute('x2', toRect.left + toRect.width / 2 - canvasRect.left);
        line.setAttribute('y2', toRect.top + toRect.height / 2 - canvasRect.top);
        const fromNodeType = conn.from.parentElement.dataset.type;
        line.setAttribute('stroke', controlNodes.includes(fromNodeType) ? 'red' : 'blue');
        line.setAttribute('stroke-width', '2');
        connectionsSvg.appendChild(line);
      });
    }

    // ----------------------------
    // Expression Evaluation (with string support)
    // ----------------------------
    function evaluateExpression(expr) {
      if (!expr) return null;
      try {
        let evalExpr = expr;
        // Replace variable names with their values. If a variable is a non-numeric string, wrap in quotes.
        for (const [varName, varValue] of Object.entries(variables)) {
          let replacement = varValue;
          if (typeof varValue === "string" || isNaN(varValue)) {
            replacement = `"${varValue}"`;
          }
          evalExpr = evalExpr.replace(new RegExp(`\\b${varName}\\b`, 'g'), replacement);
        }
        if (evalExpr.includes('=')) {
          const [varName, value] = evalExpr.split('=').map(s => s.trim());
          variables[varName] = eval(value);
          return null;
        }
        return eval(evalExpr);
      } catch (e) {
        return `Error in expression: ${e.message}`;
      }
    }

    function markError(node, message) {
      node.classList.add('error');
      node.title = message;
    }

    // ----------------------------
    // Export Workflow to Code (DFS-based, with proper indentation)
    // ----------------------------
    function getChild(node, portSelector) {
      const port = node.querySelector(portSelector);
      if (!port) return null;
      const conn = connections.find(c => c.from === port);
      return conn ? conn.to.parentElement : null;
    }
    function exportWorkflowToLanguage(language) {
      let visited = new Set();
      let code = "";
      function exportNode(node, indentLevel) {
        let indent = "    ".repeat(indentLevel);
        if (visited.has(node.dataset.id)) return "";
        visited.add(node.dataset.id);
        let nodeCode = "";
        let inputs = {};
        node.querySelectorAll('input').forEach(input => {
          inputs[input.className.split(' ')[0]] = input.value;
        });
        switch(node.dataset.type) {
          case "Variable":
            if (language === "JavaScript") {
              nodeCode += indent + `let ${inputs["var-name"]} = ${inputs["var-value"]};\n`;
            } else if (language === "Python") {
              nodeCode += indent + `${inputs["var-name"]} = ${inputs["var-value"]}\n`;
            } else if (language === "C") {
              nodeCode += indent + `int ${inputs["var-name"]} = ${inputs["var-value"]};\n`;
            }
            break;
          case "Assign":
            nodeCode += indent + inputs["assign-expr"] + (language === "Python" ? "\n" : ";\n");
            break;
          case "Print":
            if (language === "JavaScript") {
              nodeCode += indent + `console.log(${inputs["print-value"]});\n`;
            } else if (language === "Python") {
              nodeCode += indent + `print(${inputs["print-value"]})\n`;
            } else if (language === "C") {
              nodeCode += indent + `printf("%d", ${inputs["print-value"]});\n`;
            }
            break;
          case "Function":
            if (language === "JavaScript") {
              nodeCode += indent + `function ${inputs["func-name"]}(${inputs["arg-name"] || ""}) {\n  // function body\n}\n`;
            } else if (language === "Python") {
              nodeCode += indent + `def ${inputs["func-name"]}(${inputs["arg-name"] || ""}):\n    # function body\n\n`;
            } else if (language === "C") {
              nodeCode += indent + `void ${inputs["func-name"]}(${inputs["arg-name"] || "void"}) {\n  // function body\n}\n`;
            }
            break;
          case "Return":
            nodeCode += indent + (language === "Python" ? "return " : "return ") + inputs["return-value"] + (language === "Python" ? "\n" : ";\n");
            break;
          case "Call":
            if (inputs["call-result"]) {
              if (language === "JavaScript") {
                nodeCode += indent + `let ${inputs["call-result"]} = ${inputs["call-name"]}(${inputs["call-arg"] || ""});\n`;
              } else if (language === "Python") {
                nodeCode += indent + `${inputs["call-result"]} = ${inputs["call-name"]}(${inputs["call-arg"] || ""})\n`;
              } else if (language === "C") {
                nodeCode += indent + `${inputs["call-name"]}(${inputs["call-arg"] || ""}); // assign result to ${inputs["call-result"]}\n`;
              }
            } else {
              nodeCode += indent + `${inputs["call-name"]}(${inputs["call-arg"] || ""});\n`;
            }
            break;
          case "If":
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `if (${inputs["condition"]}) {\n`;
            } else if (language === "Python") {
              nodeCode += indent + `if ${inputs["condition"]}:\n`;
            }
            let trueChild = getChild(node, '.port-output-true');
            if (trueChild) {
              nodeCode += exportNode(trueChild, indentLevel + 1);
            }
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `} else {\n`;
            } else if (language === "Python") {
              nodeCode += indent + `else:\n`;
            }
            let falseChild = getChild(node, '.port-output-false');
            if (falseChild) {
              nodeCode += exportNode(falseChild, indentLevel + 1);
            }
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `}\n`;
            }
            break;
          case "WhileLoop":
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `while (${inputs["condition"]}) {\n  ${inputs["update"]};\n`;
            } else if (language === "Python") {
              nodeCode += indent + `while ${inputs["condition"]}:\n    ${inputs["update"]}\n`;
            }
            let whileChild = getChild(node, '.port-output');
            if (whileChild) {
              nodeCode += exportNode(whileChild, indentLevel + 1);
            }
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `}\n`;
            }
            break;
          case "ForLoop":
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `for (${inputs["init"]}; ${inputs["condition"]}; ${inputs["update"]}) {\n`;
            } else if (language === "Python") {
              nodeCode += indent + `# For loop converted to while:\n${inputs["init"]}\nwhile ${inputs["condition"]}:\n`;
            }
            let forChild = getChild(node, '.port-output');
            if (forChild) {
              nodeCode += exportNode(forChild, indentLevel + 1);
            }
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `}\n`;
            }
            break;
          case "Comment":
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `// ${inputs["comment-text"]}\n`;
            } else if (language === "Python") {
              nodeCode += indent + `# ${inputs["comment-text"]}\n`;
            }
            break;
          case "Library":
            if (language === "JavaScript") {
              nodeCode += indent + `import * as lib from '${inputs["lib-url"]}';\n`;
            } else if (language === "Python") {
              nodeCode += indent + `import ${inputs["lib-url"]}\n`;
            } else if (language === "C") {
              nodeCode += indent + `#include <${inputs["lib-url"]}>\n`;
            }
            break;
          default:
            nodeCode += indent + `// Unhandled node type: ${node.dataset.type}\n`;
        }
        // For non-control nodes, append the next connected node (if any)
        if (node.dataset.type !== "If" && node.dataset.type !== "WhileLoop" && node.dataset.type !== "ForLoop") {
          let child = getChild(node, '.port-output');
          if (child) {
            nodeCode += exportNode(child, indentLevel);
          }
        }
        return nodeCode;
      }
      let startNodes = nodes.filter(n => !connections.some(c => c.to.parentElement === n));
      startNodes.forEach(node => {
        code += exportNode(node, 0);
      });
      return code;
    }

    function exportCode() {
      const language = prompt("Enter target language (JavaScript, Python, or C):", "JavaScript");
      if (!language) return;
      const code = exportWorkflowToLanguage(language);
      const codeWindow = window.open("", "Exported Code", "width=600,height=400");
      if (codeWindow) {
        codeWindow.document.write("<pre>" + code + "</pre>");
      } else {
        alert("Exported Code:\n" + code);
      }
    }

    // ----------------------------
    // Group Similar Nodes
    // ----------------------------
    function groupSimilarNodes() {
      const groups = {};
      nodes.forEach(node => {
        const type = node.dataset.type;
        if (!groups[type]) {
          groups[type] = [];
        }
        groups[type].push(node);
      });
      let xOffset = 20;
      const yStart = 20;
      const xGap = 280;
      for (const type in groups) {
        let yOffset = yStart;
        groups[type].forEach(node => {
          node.style.left = `${xOffset}px`;
          node.style.top = `${yOffset}px`;
          yOffset += node.offsetHeight + 20;
        });
        xOffset += xGap;
      }
      updateConnections();
    }

    // ----------------------------
    // Workflow Persistence (Save/Load)
    // ----------------------------
    function getPortIdentifier(port) {
      return Array.from(port.classList).find(cls => cls.startsWith("port-"));
    }
    function saveWorkflow() {
      const workflow = {
        nodes: nodes.map(n => {
          const inputs = {};
          n.querySelectorAll('input').forEach(input => {
            inputs[input.className.split(' ')[0]] = input.value;
          });
          return {
            id: n.dataset.id,
            type: n.dataset.type,
            left: n.style.left,
            top: n.style.top,
            inputs: inputs
          };
        }),
        connections: connections.map(c => {
          return {
            fromNodeId: c.from.parentElement.dataset.id,
            fromPortClass: getPortIdentifier(c.from),
            toNodeId: c.to.parentElement.dataset.id,
            toPortClass: getPortIdentifier(c.to)
          };
        })
      };
      prompt("Copy your workflow JSON:", JSON.stringify(workflow));
    }
    function loadWorkflow() {
      const data = prompt("Paste your workflow JSON:");
      if (!data) return;
      try {
        const workflow = JSON.parse(data);
        nodes = [];
        connections = [];
        canvas.querySelectorAll('.node').forEach(n => n.remove());
        workflow.nodes.forEach(nData => {
          addNode(nData.type, { left: parseInt(nData.left), top: parseInt(nData.top), inputs: nData.inputs });
        });
        workflow.connections.forEach(conn => {
          const fromNode = nodes.find(n => n.dataset.id === conn.fromNodeId);
          const toNode = nodes.find(n => n.dataset.id === conn.toNodeId);
          if (fromNode && toNode) {
            const fromPort = Array.from(fromNode.querySelectorAll('.port')).find(p => p.classList.contains(conn.fromPortClass));
            const toPort = Array.from(toNode.querySelectorAll('.port')).find(p => p.classList.contains(conn.toPortClass));
            if (fromPort && toPort) {
              connections.push({ from: fromPort, to: toPort });
            }
          }
        });
        updateConnections();
      } catch (e) {
        alert("Invalid JSON data.");
      }
    }

    // ----------------------------
    // Workflow Execution Functions
    // ----------------------------
    function executeNext(node, branch, loopControl, funcContext) {
      let portClass;
      if (node.dataset.type === 'Switch') {
        portClass = `.port-output[data-case="${branch}"]`;
      } else {
        portClass = branch === 'true' ? '.port-output-true' :
                    branch === 'false' ? '.port-output-false' : '.port-output';
      }
      const nextConn = connections.find(c => c.from === node.querySelector(portClass));
      if (nextConn && (!funcContext || !funcContext.returned)) {
        const nextNode = nextConn.to.parentElement;
        executeNode(nextNode, loopControl, funcContext);
      }
    }
    function executeNode(node, loopControl = { break: false, continue: false }, funcContext = null) {
      if (node.dataset.executed || loopControl.break) return;
      node.dataset.executed = true;
      const type = node.dataset.type;
      if (type === 'Variable') {
        const name = node.querySelector('.var-name').value;
        const value = node.querySelector('.var-value').value;
        variables[name] = isNaN(value) ? value : Number(value);
        executeNext(node, 'output', loopControl, funcContext);
      } else if (type === 'Assign') {
        const expr = node.querySelector('.assign-expr').value;
        const error = evaluateExpression(expr);
        if (typeof error === 'string' && error.startsWith('Error')) markError(node, error);
        executeNext(node, 'output', loopControl, funcContext);
      } else if (type === 'Print') {
        const expr = node.querySelector('.print-value').value;
        const result = evaluateExpression(expr);
        workflowOutput += (result !== null ? result : "") + "\n";
      } else if (type === 'Function') {
        const funcName = node.querySelector('.func-name').value;
        const args = Array.from(node.querySelectorAll('.arg-name')).map(input => input.value);
        const prevVars = { ...variables };
        funcContext = { name: funcName, args: {}, returned: false };
        executeNext(node, 'output', loopControl, funcContext);
        variables = prevVars;
        if (!funcContext.returned) functionReturns[funcName] = undefined;
      } else if (type === 'Return') {
        if (funcContext) {
          const returnValue = node.querySelector('.return-value').value;
          const result = evaluateExpression(returnValue);
          if (result && !result.startsWith('Error')) {
            functionReturns[funcContext.name] = result;
          } else if (result) {
            workflowOutput += `${result}\n`;
          }
          funcContext.returned = true;
        }
      } else if (type === 'Call') {
        const callName = node.querySelector('.call-name').value;
        const callArgs = Array.from(node.querySelectorAll('.call-arg')).map(input => evaluateExpression(input.value) || input.value);
        const resultVar = node.querySelector('.call-result').value;
        const targetFunc = nodes.find(n => n.dataset.type === 'Function' && n.querySelector('.func-name').value === callName);
        if (targetFunc) {
          const funcArgs = Array.from(targetFunc.querySelectorAll('.arg-name')).map(input => input.value);
          const prevVars = { ...variables };
          funcArgs.forEach((argName, index) => {
            variables[argName] = callArgs[index] !== undefined ? callArgs[index] : undefined;
          });
          const funcContext = { name: callName, args: {}, returned: false };
          executeNode(targetFunc, { break: false, continue: false }, funcContext);
          variables = prevVars;
          if (resultVar && functionReturns[callName] !== undefined) {
            variables[resultVar] = functionReturns[callName];
          }
        } else {
          workflowOutput += `Function ${callName} not found!\n`;
        }
        executeNext(node, 'output', loopControl, funcContext);
      }
      else if (type === 'Library') {
        const libUrl = node.querySelector('.lib-url').value;
        if (libUrl) {
          let script = document.createElement('script');
          script.src = libUrl;
          script.onload = () => {
            workflowOutput += `Library loaded: ${libUrl}\n`;
            executeNext(node, 'output', loopControl, funcContext);
          };
          script.onerror = () => {
            markError(node, `Failed to load library: ${libUrl}`);
            workflowOutput += `Failed to load library: ${libUrl}\n`;
            executeNext(node, 'output', loopControl, funcContext);
          };
          document.head.appendChild(script);
          return;
        } else {
          executeNext(node, 'output', loopControl, funcContext);
        }
      }
      else if (type === 'Comment') {
        executeNext(node, 'output', loopControl, funcContext);
      }
      else if (type === 'ForLoop') {
        const init = node.querySelector('.init').value;
        const condition = node.querySelector('.condition').value;
        const update = node.querySelector('.update').value;
        evaluateExpression(init);
        let result = true;
        while (result && !loopControl.break) {
          try {
            let evalCondition = condition;
            for (const [varName, varValue] of Object.entries(variables)) {
              evalCondition = evalCondition.replace(new RegExp(`\\b${varName}\\b`, 'g'), varValue);
            }
            result = eval(evalCondition);
            if (result) {
              let innerControl = { break: false, continue: false };
              executeNext(node, 'output', innerControl, funcContext);
              if (innerControl.continue) { evaluateExpression(update); continue; }
              if (innerControl.break) break;
              const error = evaluateExpression(update);
              if (error) workflowOutput += `${error}\n`;
            }
          } catch (e) {
            workflowOutput += `Error in ForLoop condition: ${e.message}\n`;
            break;
          }
        }
        executeNext(node, 'output', loopControl, funcContext);
      }
      else if (type === 'If') {
        const condition = node.querySelector('.condition').value;
        let result = false;
        try {
          let evalCondition = condition;
          for (const [varName, varValue] of Object.entries(variables)) {
            evalCondition = evalCondition.replace(new RegExp(`\\b${varName}\\b`, 'g'), varValue);
          }
          result = eval(evalCondition);
        } catch (e) {
          workflowOutput += `Error in If condition: ${e.message}\n`;
        }
        executeNext(node, result ? 'true' : 'false', loopControl, funcContext);
      } else if (type === 'WhileLoop') {
        const condition = node.querySelector('.condition').value;
        const update = node.querySelector('.update').value;
        let result = true;
        while (result && !loopControl.break) {
          try {
            let evalCondition = condition;
            for (const [varName, varValue] of Object.entries(variables)) {
              evalCondition = evalCondition.replace(new RegExp(`\\b${varName}\\b`, 'g'), varValue);
            }
            result = eval(evalCondition);
            if (result) {
              let innerControl = { break: false, continue: false };
              executeNext(node, 'output', innerControl, funcContext);
              if (innerControl.continue) continue;
              if (innerControl.break) break;
              const error = evaluateExpression(update);
              if (error) workflowOutput += `${error}\n`;
            }
          } catch (e) {
            workflowOutput += `Error in WhileLoop condition: ${e.message}\n`;
            break;
          }
        }
      } else if (type === 'Switch') {
        const switchVar = node.querySelector('.switch-var').value;
        const caseInputs = node.querySelectorAll('.case-container');
        const value = variables[switchVar];
        let matched = false;
        for (let [index, container] of caseInputs.entries()) {
          const caseValue = container.querySelector('.case-value').value;
          const shouldBreak = container.querySelector('.case-break').checked;
          if (caseValue == value || matched) {
            matched = true;
            executeNext(node, index.toString(), loopControl, funcContext);
            if (shouldBreak) break;
          }
        }
        if (!matched) workflowOutput += `No matching case for ${switchVar}=${value}\n`;
      } else if (type === 'Break') {
        loopControl.break = true;
      } else if (type === 'Continue') {
        loopControl.continue = true;
      } else if (type === 'Add') {
        const op1 = evaluateExpression(node.querySelector('.operand1').value);
        const op2 = evaluateExpression(node.querySelector('.operand2').value);
        const resultVar = node.querySelector('.result-var').value;
        variables[resultVar] = Number(op1) + Number(op2);
        executeNext(node, 'output', loopControl, funcContext);
      } else if (type === 'Subtract') {
        const op1 = evaluateExpression(node.querySelector('.operand1').value);
        const op2 = evaluateExpression(node.querySelector('.operand2').value);
        const resultVar = node.querySelector('.result-var').value;
        variables[resultVar] = Number(op1) - Number(op2);
        executeNext(node, 'output', loopControl, funcContext);
      } else if (type === 'Multiply') {
        const op1 = evaluateExpression(node.querySelector('.operand1').value);
        const op2 = evaluateExpression(node.querySelector('.operand2').value);
        const resultVar = node.querySelector('.result-var').value;
        variables[resultVar] = Number(op1) * Number(op2);
        executeNext(node, 'output', loopControl, funcContext);
      } else if (type === 'Divide') {
        const op1 = evaluateExpression(node.querySelector('.operand1').value);
        const op2 = evaluateExpression(node.querySelector('.operand2').value);
        const resultVar = node.querySelector('.result-var').value;
        if (Number(op2) === 0) {
          workflowOutput += "Division by zero error\n";
          markError(node, "Division by zero");
        } else {
          variables[resultVar] = Number(op1) / Number(op2);
        }
        executeNext(node, 'output', loopControl, funcContext);
      } else if (type === 'Array') {
        const arrayName = node.querySelector('.array-name').value;
        const elements = Array.from(node.querySelectorAll('.element-value')).map(input => evaluateExpression(input.value));
        variables[arrayName] = elements;
        executeNext(node, 'output', loopControl, funcContext);
      }
    }
    function runWorkflow() {
      workflowOutput = "";
      variables = {};
      functionReturns = {};
      nodes.forEach(n => delete n.dataset.executed);
      let startNodes = nodes.filter(n => !connections.some(c => c.to.parentElement === n));
      if (startNodes.length === 0) startNodes = nodes;
      startNodes.forEach(node => executeNode(node));
      alert(workflowOutput || 'No output generated! Check your connections and node settings.');
    }
    // ----------------------------
    // Step-by-step execution
    // ----------------------------
    function startStepExecution() {
      executionQueue = [];
      nodes.forEach(n => delete n.dataset.executedStep);
      let startNodes = nodes.filter(n => !connections.some(c => c.to.parentElement === n));
      if (startNodes.length === 0) startNodes = nodes;
      executionQueue.push(...startNodes);
      alert("Step execution started. Click 'Step Execution' to execute the next node. Check the console for output.");
    }
    function stepExecution() {
      if (executionQueue.length === 0) {
        alert("Execution finished.");
        return;
      }
      const node = executionQueue.shift();
      node.classList.add('executing');
      const nextNodes = executeNodeStep(node);
      executionQueue.push(...nextNodes.filter(n => n));
      setTimeout(() => { node.classList.remove('executing'); }, 500);
    }
    function executeNodeStep(node) {
      let nextNodes = [];
      const type = node.dataset.type;
      if (type === 'Variable') {
        const name = node.querySelector('.var-name').value;
        const value = node.querySelector('.var-value').value;
        variables[name] = isNaN(value) ? value : Number(value);
        nextNodes.push(getNextNode(node));
      } else if (type === 'Assign') {
        const expr = node.querySelector('.assign-expr').value;
        const error = evaluateExpression(expr);
        if (typeof error === 'string' && error.startsWith('Error')) markError(node, error);
        nextNodes.push(getNextNode(node));
      } else if (type === 'Print') {
        const expr = node.querySelector('.print-value').value;
        const result = evaluateExpression(expr);
        console.log(result);
      } else if (type === 'Add') {
        const op1 = evaluateExpression(node.querySelector('.operand1').value);
        const op2 = evaluateExpression(node.querySelector('.operand2').value);
        const resultVar = node.querySelector('.result-var').value;
        variables[resultVar] = Number(op1) + Number(op2);
        nextNodes.push(getNextNode(node));
      } else if (type === 'Subtract') {
        const op1 = evaluateExpression(node.querySelector('.operand1').value);
        const op2 = evaluateExpression(node.querySelector('.operand2').value);
        const resultVar = node.querySelector('.result-var').value;
        variables[resultVar] = Number(op1) - Number(op2);
        nextNodes.push(getNextNode(node));
      } else if (type === 'Multiply') {
        const op1 = evaluateExpression(node.querySelector('.operand1').value);
        const op2 = evaluateExpression(node.querySelector('.operand2').value);
        const resultVar = node.querySelector('.result-var').value;
        variables[resultVar] = Number(op1) * Number(op2);
        nextNodes.push(getNextNode(node));
      } else if (type === 'Divide') {
        const op1 = evaluateExpression(node.querySelector('.operand1').value);
        const op2 = evaluateExpression(node.querySelector('.operand2').value);
        const resultVar = node.querySelector('.result-var').value;
        if (Number(op2) === 0) {
          markError(node, "Division by zero");
        } else {
          variables[resultVar] = Number(op1) / Number(op2);
        }
        nextNodes.push(getNextNode(node));
      } else if (type === 'Array') {
        const arrayName = node.querySelector('.array-name').value;
        const elements = Array.from(node.querySelectorAll('.element-value')).map(input => evaluateExpression(input.value));
        variables[arrayName] = elements;
        nextNodes.push(getNextNode(node));
      } else {
        nextNodes.push(getNextNode(node));
      }
      return nextNodes.filter(n => n);
    }
    function getNextNode(node) {
      const port = node.querySelector('.port.port-output');
      const conn = connections.find(c => c.from === port);
      return conn ? conn.to.parentElement : null;
    }
    // ----------------------------
    // Workflow Persistence (Save/Load)
    // ----------------------------
    function getPortIdentifier(port) {
      return Array.from(port.classList).find(cls => cls.startsWith("port-"));
    }
    function saveWorkflow() {
      const workflow = {
        nodes: nodes.map(n => {
          const inputs = {};
          n.querySelectorAll('input').forEach(input => {
            inputs[input.className.split(' ')[0]] = input.value;
          });
          return {
            id: n.dataset.id,
            type: n.dataset.type,
            left: n.style.left,
            top: n.style.top,
            inputs: inputs
          };
        }),
        connections: connections.map(c => {
          return {
            fromNodeId: c.from.parentElement.dataset.id,
            fromPortClass: getPortIdentifier(c.from),
            toNodeId: c.to.parentElement.dataset.id,
            toPortClass: getPortIdentifier(c.to)
          };
        })
      };
      prompt("Copy your workflow JSON:", JSON.stringify(workflow));
    }
    function loadWorkflow() {
      const data = prompt("Paste your workflow JSON:");
      if (!data) return;
      try {
        const workflow = JSON.parse(data);
        nodes = [];
        connections = [];
        canvas.querySelectorAll('.node').forEach(n => n.remove());
        workflow.nodes.forEach(nData => {
          addNode(nData.type, { left: parseInt(nData.left), top: parseInt(nData.top), inputs: nData.inputs });
        });
        workflow.connections.forEach(conn => {
          const fromNode = nodes.find(n => n.dataset.id === conn.fromNodeId);
          const toNode = nodes.find(n => n.dataset.id === conn.toNodeId);
          if (fromNode && toNode) {
            const fromPort = Array.from(fromNode.querySelectorAll('.port')).find(p => p.classList.contains(conn.fromPortClass));
            const toPort = Array.from(toNode.querySelectorAll('.port')).find(p => p.classList.contains(conn.toPortClass));
            if (fromPort && toPort) {
              connections.push({ from: fromPort, to: toPort });
            }
          }
        });
        updateConnections();
      } catch (e) {
        alert("Invalid JSON data.");
      }
    }
    // ----------------------------
    // Export Workflow to Code
    // ----------------------------
    function exportWorkflowToLanguage(language) {
      let visited = new Set();
      let code = "";
      function exportNode(node, indentLevel) {
        let indent = "    ".repeat(indentLevel);
        if (visited.has(node.dataset.id)) return "";
        visited.add(node.dataset.id);
        let nodeCode = "";
        let inputs = {};
        node.querySelectorAll('input').forEach(input => {
          inputs[input.className.split(' ')[0]] = input.value;
        });
        switch(node.dataset.type) {
          case "Variable":
            if (language === "JavaScript") {
              nodeCode += indent + `let ${inputs["var-name"]} = ${inputs["var-value"]};\n`;
            } else if (language === "Python") {
              nodeCode += indent + `${inputs["var-name"]} = ${inputs["var-value"]}\n`;
            } else if (language === "C") {
              nodeCode += indent + `int ${inputs["var-name"]} = ${inputs["var-value"]};\n`;
            }
            break;
          case "Assign":
            nodeCode += indent + inputs["assign-expr"] + (language === "Python" ? "\n" : ";\n");
            break;
          case "Print":
            if (language === "JavaScript") {
              nodeCode += indent + `console.log(${inputs["print-value"]});\n`;
            } else if (language === "Python") {
              nodeCode += indent + `print(${inputs["print-value"]})\n`;
            } else if (language === "C") {
              nodeCode += indent + `printf("%d", ${inputs["print-value"]});\n`;
            }
            break;
          case "Function":
            if (language === "JavaScript") {
              nodeCode += indent + `function ${inputs["func-name"]}(${inputs["arg-name"] || ""}) {\n  // function body\n}\n`;
            } else if (language === "Python") {
              nodeCode += indent + `def ${inputs["func-name"]}(${inputs["arg-name"] || ""}):\n    # function body\n\n`;
            } else if (language === "C") {
              nodeCode += indent + `void ${inputs["func-name"]}(${inputs["arg-name"] || "void"}) {\n  // function body\n}\n`;
            }
            break;
          case "Return":
            nodeCode += indent + (language === "Python" ? "return " : "return ") + inputs["return-value"] + (language === "Python" ? "\n" : ";\n");
            break;
          case "Call":
            if (inputs["call-result"]) {
              if (language === "JavaScript") {
                nodeCode += indent + `let ${inputs["call-result"]} = ${inputs["call-name"]}(${inputs["call-arg"] || ""});\n`;
              } else if (language === "Python") {
                nodeCode += indent + `${inputs["call-result"]} = ${inputs["call-name"]}(${inputs["call-arg"] || ""})\n`;
              } else if (language === "C") {
                nodeCode += indent + `${inputs["call-name"]}(${inputs["call-arg"] || ""}); // assign result to ${inputs["call-result"]}\n`;
              }
            } else {
              nodeCode += indent + `${inputs["call-name"]}(${inputs["call-arg"] || ""});\n`;
            }
            break;
          case "If":
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `if (${inputs["condition"]}) {\n`;
            } else if (language === "Python") {
              nodeCode += indent + `if ${inputs["condition"]}:\n`;
            }
            let trueChild = getChild(node, '.port-output-true');
            if (trueChild) {
              nodeCode += exportNode(trueChild, indentLevel + 1);
            }
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `} else {\n`;
            } else if (language === "Python") {
              nodeCode += indent + `else:\n`;
            }
            let falseChild = getChild(node, '.port-output-false');
            if (falseChild) {
              nodeCode += exportNode(falseChild, indentLevel + 1);
            }
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `}\n`;
            }
            break;
          case "WhileLoop":
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `while (${inputs["condition"]}) {\n  ${inputs["update"]};\n`;
            } else if (language === "Python") {
              nodeCode += indent + `while ${inputs["condition"]}:\n    ${inputs["update"]}\n`;
            }
            let whileChild = getChild(node, '.port-output');
            if (whileChild) {
              nodeCode += exportNode(whileChild, indentLevel + 1);
            }
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `}\n`;
            }
            break;
          case "ForLoop":
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `for (${inputs["init"]}; ${inputs["condition"]}; ${inputs["update"]}) {\n`;
            } else if (language === "Python") {
              nodeCode += indent + `# For loop converted to while:\n${inputs["init"]}\nwhile ${inputs["condition"]}:\n`;
            }
            let forChild = getChild(node, '.port-output');
            if (forChild) {
              nodeCode += exportNode(forChild, indentLevel + 1);
            }
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `}\n`;
            }
            break;
          case "Comment":
            if (language === "JavaScript" || language === "C") {
              nodeCode += indent + `// ${inputs["comment-text"]}\n`;
            } else if (language === "Python") {
              nodeCode += indent + `# ${inputs["comment-text"]}\n`;
            }
            break;
          case "Library":
            if (language === "JavaScript") {
              nodeCode += indent + `import * as lib from '${inputs["lib-url"]}';\n`;
            } else if (language === "Python") {
              nodeCode += indent + `import ${inputs["lib-url"]}\n`;
            } else if (language === "C") {
              nodeCode += indent + `#include <${inputs["lib-url"]}>\n`;
            }
            break;
          default:
            nodeCode += indent + `// Unhandled node type: ${node.dataset.type}\n`;
        }
        // For non-control nodes, add the next connected node
        if (node.dataset.type !== "If" && node.dataset.type !== "WhileLoop" && node.dataset.type !== "ForLoop") {
          let child = getChild(node, '.port-output');
          if (child) {
            nodeCode += exportNode(child, indentLevel);
          }
        }
        return nodeCode;
      }
      let startNodes = nodes.filter(n => !connections.some(c => c.to.parentElement === n));
      startNodes.forEach(node => {
        code += exportNode(node, 0);
      });
      return code;
    }

    function exportCode() {
      const language = prompt("Enter target language (JavaScript, Python, or C):", "JavaScript");
      if (!language) return;
      const code = exportWorkflowToLanguage(language);
      const codeWindow = window.open("", "Exported Code", "width=600,height=400");
      if (codeWindow) {
        codeWindow.document.write("<pre>" + code + "</pre>");
      } else {
        alert("Exported Code:\n" + code);
      }
    }

    // ----------------------------
    // Group Similar Nodes
    // ----------------------------
    function groupSimilarNodes() {
      const groups = {};
      nodes.forEach(node => {
        const type = node.dataset.type;
        if (!groups[type]) {
          groups[type] = [];
        }
        groups[type].push(node);
      });
      let xOffset = 20;
      const yStart = 20;
      const xGap = 280;
      for (const type in groups) {
        let yOffset = yStart;
        groups[type].forEach(node => {
          node.style.left = `${xOffset}px`;
          node.style.top = `${yOffset}px`;
          yOffset += node.offsetHeight + 20;
        });
        xOffset += xGap;
      }
      updateConnections();
    }

    // ----------------------------
    // Workflow Persistence (Save/Load)
    // ----------------------------
    function getPortIdentifier(port) {
      return Array.from(port.classList).find(cls => cls.startsWith("port-"));
    }
    function saveWorkflow() {
      const workflow = {
        nodes: nodes.map(n => {
          const inputs = {};
          n.querySelectorAll('input').forEach(input => {
            inputs[input.className.split(' ')[0]] = input.value;
          });
          return {
            id: n.dataset.id,
            type: n.dataset.type,
            left: n.style.left,
            top: n.style.top,
            inputs: inputs
          };
        }),
        connections: connections.map(c => {
          return {
            fromNodeId: c.from.parentElement.dataset.id,
            fromPortClass: getPortIdentifier(c.from),
            toNodeId: c.to.parentElement.dataset.id,
            toPortClass: getPortIdentifier(c.to)
          };
        })
      };
      prompt("Copy your workflow JSON:", JSON.stringify(workflow));
    }
    function loadWorkflow() {
      const data = prompt("Paste your workflow JSON:");
      if (!data) return;
      try {
        const workflow = JSON.parse(data);
        nodes = [];
        connections = [];
        canvas.querySelectorAll('.node').forEach(n => n.remove());
        workflow.nodes.forEach(nData => {
          addNode(nData.type, { left: parseInt(nData.left), top: parseInt(nData.top), inputs: nData.inputs });
        });
        workflow.connections.forEach(conn => {
          const fromNode = nodes.find(n => n.dataset.id === conn.fromNodeId);
          const toNode = nodes.find(n => n.dataset.id === conn.toNodeId);
          if (fromNode && toNode) {
            const fromPort = Array.from(fromNode.querySelectorAll('.port')).find(p => p.classList.contains(conn.fromPortClass));
            const toPort = Array.from(toNode.querySelectorAll('.port')).find(p => p.classList.contains(conn.toPortClass));
            if (fromPort && toPort) {
              connections.push({ from: fromPort, to: toPort });
            }
          }
        });
        updateConnections();
      } catch (e) {
        alert("Invalid JSON data.");
      }
    }

    // ----------------------------
    // Zooming Support
    // ----------------------------
    // canvas.addEventListener('wheel', (e) => {
    //   e.preventDefault();
    //   if (e.deltaY < 0) {
    //     zoomFactor *= 1.1;
    //   } else {
    //     zoomFactor /= 1.1;
    //   }
    //   canvas.style.transform = `scale(${zoomFactor})`;
    // });
  </script>
</body>
</html>