Add initial implementation of the settler node for Node-RED

- Create package.json to define project metadata and dependencies
- Implement settler.html for the node's UI in Node-RED
- Add settler.js to register the settler node type and handle HTTP requests
- Introduce src/nodeClass.js for the settler node class functionality
- Define src/specificClass.js for settler-specific logic and utilities

package.json

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+{
+  "name": "settler",
+  "version": "0.0.1",
+  "description": "Sludge settler model for Node-Red",
+  "repository": {
+    "type": "git",
+    "url": "https://gitea.centraal.wbd-rd.nl/p.vanderwilt/settler.git"
+  },
+  "keywords": [
+    "settler",
+    "activated sludge",
+    "wastewater",
+    "node-red"
+  ],
+  "license": "SEE LICENSE",
+  "author": "P.R. van der Wilt",
+  "main": "settler.js",
+  "scripts": {
+    "test": "node settler.js"
+  },
+  "node-red": {
+    "nodes": {
+      "settler": "settler.js"
+    }
+  },
+  "dependencies": {
+    "generalFunctions": "git+https://gitea.centraal.wbd-rd.nl/RnD/generalFunctions.git",
+    "mathjs": "^14.5.2"
+  }
+}

settler.html

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+<script src="/reactor/menu.js"></script>
+
+<script type="text/javascript">
+    RED.nodes.registerType("settler", {
+        category: "WWTP",
+        color: "#e4a363",
+        defaults: {
+            name: { value: "" },
+            TS_set: { value: 0.1, required: true },
+            inlet: { value: 1, required: true }
+        },
+        inputs: 1,
+        outputs: 3,
+        outputLabels: ["process", "dbase", "parent"],
+        icon: "font-awesome/fa-random",
+        label: function() {
+            return this.name || "Settling basin";
+        },
+        oneditprepare: function() {
+            // wait for the menu scripts to load
+            const waitForMenuData = () => {
+                if (window.EVOLV?.nodes?.reactor?.initEditor) {
+                    window.EVOLV.nodes.reactor.initEditor(this);
+                } else {
+                    setTimeout(waitForMenuData, 50);
+                }
+            };
+            waitForMenuData();
+
+            $("#node-input-TS_set").typedInput({
+                type:"num",
+                types:["num"]
+            });
+            $("#node-input-inlet").typedInput({
+                type:"num",
+                types:["num"]
+            });
+        },
+        oneditsave: function() {
+            // save logger fields
+            if (window.EVOLV?.nodes?.reactor?.loggerMenu?.saveEditor) {
+                window.EVOLV.nodes.reactor.loggerMenu.saveEditor(this);
+            }
+
+            // save position field
+            if (window.EVOLV?.nodes?.measurement?.positionMenu?.saveEditor) {
+                window.EVOLV.nodes.rotatingMachine.positionMenu.saveEditor(this);
+            }
+
+            let TS_set = parseFloat($("#node-input-TS_set").typedInput("value"));
+            if (isNaN(TS_set) || TS_set < 0) {
+                RED.notify("TS is not set correctly", {type: "error"});
+            }
+            let inlet = parseInt($("#node-input-n_inlets").typedInput("value"));
+            if (inlet < 1) {
+                RED.notify("Number of inlets not set correctly", {type: "error"});
+            }
+        }
+    });
+</script>
+
+<script type="text/html" data-template-name="settler">
+    <div class="form-row">
+        <label for="node-input-name"><i class="fa fa-tag"></i> Name</label>
+        <input type="text" id="node-input-name" placeholder="Name">
+    </div>
+    <div class="form-row">
+        <label for="node-input-TS_set"><i class="fa fa-tag"></i> Total Solids set point [g m-3]</label>
+        <input type="text" id="node-input-TS_set" placeholder="">
+    </div>
+    <div class="form-row">
+        <label for="node-input-inlet"><i class="fa fa-tag"></i> Assigned inlet return line</label>
+        <input type="text" id="node-input-inlet" placeholder="#">
+    </div>
+
+    <!-- Logger fields injected here -->
+	<div id="logger-fields-placeholder"></div>
+
+    <!-- Position fields will be injected here -->
+    <div id="position-fields-placeholder"></div>
+
+</script>
+
+<script type="text/html" data-help-name="settler">
+    <p>Settling tank</p>
+</script>

settler.js

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+const nameOfNode = "settler"; // name of the node, should match file name and node type in Node-RED
+const nodeClass = require('./src/nodeClass.js'); // node class
+const { MenuManager } = require('generalFunctions');
+
+
+module.exports = function (RED) {
+    // Register the node type
+    RED.nodes.registerType(nameOfNode, function (config) {
+        // Initialize the Node-RED node first
+        RED.nodes.createNode(this, config);
+        // Then create your custom class and attach it
+        this.nodeClass = new nodeClass(config, RED, this, nameOfNode);
+    });
+
+    const menuMgr = new MenuManager();
+
+    // Serve /settler/menu.js
+    RED.httpAdmin.get(`/${nameOfNode}/menu.js`, (req, res) => {
+        try {
+            const script = menuMgr.createEndpoint(nameOfNode, ['logger', 'position']);
+            res.type('application/javascript').send(script);
+        } catch (err) {
+            res.status(500).send(`// Error generating menu: ${err.message}`);
+        }
+    });
+};

src/nodeClass.js

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+const { Settler } = require('./specificClass.js');
+
+
+class nodeClass {
+    /**
+    * Node-RED node class for settler.
+    * @param {object} uiConfig - Node-RED node configuration
+    * @param {object} RED - Node-RED runtime API
+    * @param {object} nodeInstance - Node-RED node instance
+    * @param {string} nameOfNode - Name of the node
+    */
+    constructor(uiConfig, RED, nodeInstance, nameOfNode) {
+        // Preserve RED reference for HTTP endpoints if needed
+        this.node = nodeInstance;
+        this.RED = RED;
+        this.name = nameOfNode;
+        this.source = null;
+
+        this._loadConfig(uiConfig)
+        this._setupClass();
+
+        this._attachInputHandler();
+        this._registerChild();
+        this._startTickLoop();
+        this._attachCloseHandler();
+    }
+
+    /**
+     * Handle node-red input messages
+     */
+    _attachInputHandler() {
+        this.node.on('input', (msg, send, done) => {
+
+            switch (msg.topic) {
+                case 'registerChild':
+                    // Register this node as a parent of the child node
+                    const childId = msg.payload;
+                    const childObj = this.RED.nodes.getNode(childId); 
+                    this.source.childRegistrationUtils.registerChild(childObj.source, msg.positionVsParent);
+                    break;
+                default:
+                    console.log("Unknown topic: " + msg.topic);
+            }
+
+            if (done) {
+                done();
+            }
+        });
+    }
+
+    /**
+     * Parse node configuration
+     * @param {object} uiConfig Config set in UI in node-red
+     */
+    _loadConfig(uiConfig) {
+        this.config = {
+            general: {
+                name: uiConfig.name || this.name,
+                id: this.node.id,
+                unit: null,
+                logging: {
+                    enabled: uiConfig.enableLog,
+                    logLevel: uiConfig.logLevel
+                }
+            },
+            functionality: {
+                positionVsParent: uiConfig.positionVsParent || 'atEquipment', // Default to 'atEquipment' if not specified
+                softwareType: "settler" // should be set in config manager
+            }
+        }
+    }
+
+    /**
+     * Register this node as a child upstream and downstream.
+     * Delayed to avoid Node-RED startup race conditions.
+     */
+    _registerChild() {
+        setTimeout(() => {
+        this.node.send([
+            null,
+            null,
+            { topic: 'registerChild', payload: this.node.id, positionVsParent: this.config?.functionality?.positionVsParent || 'atEquipment' }
+        ]);
+        }, 100);
+    }
+
+    /**
+     * Setup settler class
+     */
+    _setupClass() {
+
+        this.source = new Settler(this.config); // protect from reassignment
+        this.node.source = this.source;
+    }
+
+    _startTickLoop() {
+        setTimeout(() => {
+            this._tickInterval = setInterval(() => this._tick(), 1000);
+        }, 1000);
+    }
+
+    _tick(){
+        this.node.send([null, null, null]);
+    }
+
+    _attachCloseHandler() {
+        this.node.on('close', (done) => {
+            clearInterval(this._tickInterval);
+            done();
+        });
+    }
+}
+
+module.exports = nodeClass;

src/specificClass.js

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+const { childRegistrationUtils, logger, MeasurementContainer } = require('generalFunctions');
+const EventEmitter = require('events');
+
+class Settler {
+  constructor(config) {
+    this.config = config;
+    // EVOLV stuff
+    this.logger = new logger(this.config.general.logging.enabled, this.config.general.logging.logLevel, config.general.name);
+    this.emitter = new EventEmitter();
+    this.measurements = new MeasurementContainer();
+    this.childRegistrationUtils = new childRegistrationUtils(this); // Child registration utility
+  }
+}
+
+module.exports = { Settler };