const EventEmitter = require('events');
const {loadCurve,gravity,logger,configUtils,configManager,state, nrmse, MeasurementContainer, predict, interpolation , childRegistrationUtils,coolprop, convert, POSITIONS} = require('generalFunctions');

const CANONICAL_UNITS = Object.freeze({
  pressure: 'Pa',
  atmPressure: 'Pa',
  flow: 'm3/s',
  power: 'W',
  temperature: 'K',
});

const DEFAULT_IO_UNITS = Object.freeze({
  pressure: 'mbar',
  flow: 'm3/h',
  power: 'kW',
  temperature: 'C',
});

const DEFAULT_CURVE_UNITS = Object.freeze({
  pressure: 'mbar',
  flow: 'm3/h',
  power: 'kW',
  control: '%',
});

/**
 * Rotating machine domain model.
 * Combines machine curves, state transitions and measurement reconciliation
 * to produce flow/power/efficiency behavior for pumps and similar assets.
 */
class Machine {

  /*-------------------               Construct and set vars               -------------------*/
  constructor(machineConfig = {}, stateConfig = {}, errorMetricsConfig = {}) {

    //basic setup
    this.emitter = new EventEmitter();  // Own EventEmitter
    
    this.logger = new logger(machineConfig.general.logging.enabled,machineConfig.general.logging.logLevel, machineConfig.general.name);
    this.configManager = new configManager(); 
    this.defaultConfig = this.configManager.getConfig('rotatingMachine'); // Load default config for rotating machine ( use software type name ? )
    this.configUtils = new configUtils(this.defaultConfig);

    // Load a specific curve
    this.model = machineConfig.asset.model; // Get the model from the machineConfig
    this.rawCurve = this.model ? loadCurve(this.model) : null;
    this.curve = null;

    //Init config and check if it is valid
    this.config = this.configUtils.initConfig(machineConfig);
    
    //add unique name for this node.
    this.config = this.configUtils.updateConfig(this.config, {general:{name: this.config.functionality?.softwareType + "_" + machineConfig.general.id}}); // add unique name if not present
    this.unitPolicy = this._buildUnitPolicy(this.config);
    this.config = this.configUtils.updateConfig(this.config, {
      general: { unit: this.unitPolicy.output.flow },
      asset: {
        ...this.config.asset,
        unit: this.unitPolicy.output.flow,
        curveUnits: this.unitPolicy.curve,
      },
    });

    if (!this.model || !this.rawCurve) {
      this.logger.error(`${!this.model ? 'Model not specified' : 'Curve not found for model ' + this.model} in machineConfig. Cannot make predictions.`);
      // Set prediction objects to null to prevent method calls
      this.predictFlow = null;
      this.predictPower = null;
      this.predictCtrl = null;
      this.hasCurve = false;
    }
    else{
      try {
        this.hasCurve = true;
        this.curve = this._normalizeMachineCurve(this.rawCurve);
        this.config = this.configUtils.updateConfig(this.config, { asset: { ...this.config.asset, machineCurve: this.curve } }); 
        //machineConfig = { ...machineConfig, asset: { ...machineConfig.asset, machineCurve: this.curve } }; // Merge curve into machineConfig
        this.predictFlow = new predict({ curve: this.config.asset.machineCurve.nq });     // load nq (x : ctrl , y : flow relationship) 
        this.predictPower = new predict({ curve: this.config.asset.machineCurve.np });     // load np (x : ctrl , y : power relationship)
        this.predictCtrl = new predict({ curve: this.reverseCurve(this.config.asset.machineCurve.nq) }); // load reversed nq (x: flow, y: ctrl relationship)
      } catch (error) {
        this.logger.error(`Curve normalization failed for model '${this.model}': ${error.message}`);
        this.predictFlow = null;
        this.predictPower = null;
        this.predictCtrl = null;
        this.hasCurve = false;
      }
    }

    this.state = new state(stateConfig, this.logger); // Init State manager and pass logger
    this.errorMetrics = new nrmse(errorMetricsConfig, this.logger);

    // Initialize measurements
    this.measurements = new MeasurementContainer({
      autoConvert: true,
      windowSize: 50,
      defaultUnits: {
        pressure: this.unitPolicy.output.pressure,
        flow: this.unitPolicy.output.flow,
        power: this.unitPolicy.output.power,
        temperature: this.unitPolicy.output.temperature,
        atmPressure: 'Pa',
      },
      preferredUnits: {
        pressure: this.unitPolicy.output.pressure,
        flow: this.unitPolicy.output.flow,
        power: this.unitPolicy.output.power,
        temperature: this.unitPolicy.output.temperature,
        atmPressure: 'Pa',
      },
      canonicalUnits: this.unitPolicy.canonical,
      storeCanonical: true,
      strictUnitValidation: true,
      throwOnInvalidUnit: true,
      requireUnitForTypes: ['pressure', 'flow', 'power', 'temperature', 'atmPressure'],
    }, this.logger);

    this.interpolation = new interpolation();

    this.flowDrift = null;
    this.powerDrift = null;
    this.pressureDrift = { level: 0, flags: ["nominal"], source: null };
    this.driftProfiles = {
      flow: {
        windowSize: 30,
        minSamplesForLongTerm: 10,
        ewmaAlpha: 0.15,
        alignmentToleranceMs: 2500,
        strictValidation: true,
      },
      power: {
        windowSize: 30,
        minSamplesForLongTerm: 10,
        ewmaAlpha: 0.15,
        alignmentToleranceMs: 2500,
        strictValidation: true,
      },
    };
    this.errorMetrics.registerMetric("flow", this.driftProfiles.flow);
    this.errorMetrics.registerMetric("power", this.driftProfiles.power);
    this.predictionHealth = {
      quality: "invalid",
      confidence: 0,
      pressureSource: null,
      flags: ["not_initialized"],
    };

    this.currentMode = this.config.mode.current;
    this.currentEfficiencyCurve = {};
    this.cog = 0;
    this.NCog = 0;
    this.cogIndex = 0;
    this.minEfficiency = 0;
    this.absDistFromPeak = 0;
    this.relDistFromPeak = 0;

    // When position state changes, update position
    this.state.emitter.on("positionChange", (data) => {
      this.logger.debug(`Position change detected: ${data}`);
      this.updatePosition();
    });

    //When state changes look if we need to do other updates
    this.state.emitter.on("stateChange", (newState) => {
      this.logger.debug(`State change detected: ${newState}`);
      this._updateState();
    });


    //perform init for certain values
    this._init();

    this.child = {}; // object to hold child information so we know on what to subscribe
    this.childRegistrationUtils = new childRegistrationUtils(this); // Child registration utility
    this.virtualPressureChildIds = {
      upstream: "dashboard-sim-upstream",
      downstream: "dashboard-sim-downstream",
    };
    this.virtualPressureChildren = {};
    this.realPressureChildIds = {
      upstream: new Set(),
      downstream: new Set(),
    };
    this.childMeasurementListeners = new Map();
    this._initVirtualPressureChildren();


  }

  _initVirtualPressureChildren() {
    const createVirtualChild = (position) => {
      const id = this.virtualPressureChildIds[position];
      const name = `dashboard-sim-${position}`;
      const measurements = new MeasurementContainer({
        autoConvert: true,
        defaultUnits: {
          pressure: this.unitPolicy.output.pressure,
          flow: this.unitPolicy.output.flow,
          power: this.unitPolicy.output.power,
          temperature: this.unitPolicy.output.temperature,
        },
        preferredUnits: {
          pressure: this.unitPolicy.output.pressure,
          flow: this.unitPolicy.output.flow,
          power: this.unitPolicy.output.power,
          temperature: this.unitPolicy.output.temperature,
        },
        canonicalUnits: this.unitPolicy.canonical,
        storeCanonical: true,
        strictUnitValidation: true,
        throwOnInvalidUnit: true,
        requireUnitForTypes: ['pressure'],
      }, this.logger);

      measurements.setChildId(id);
      measurements.setChildName(name);
      measurements.setParentRef(this);

      return {
        config: {
          general: { id, name },
          functionality: {
            softwareType: "measurement",
            positionVsParent: position,
          },
          asset: {
            type: "pressure",
            unit: this.unitPolicy.output.pressure,
          },
        },
        measurements,
      };
    };

    const upstreamChild = createVirtualChild("upstream");
    const downstreamChild = createVirtualChild("downstream");
    this.virtualPressureChildren.upstream = upstreamChild;
    this.virtualPressureChildren.downstream = downstreamChild;

    this.registerChild(upstreamChild, "measurement");
    this.registerChild(downstreamChild, "measurement");
  }

  _init(){
    //assume standard temperature is 20degrees
    this.measurements.type('temperature').variant('measured').position('atEquipment').value(15, Date.now(), this.unitPolicy.output.temperature);
    //assume standard atm pressure is at sea level
    this.measurements.type('atmPressure').variant('measured').position('atEquipment').value(101325, Date.now(), 'Pa');
    //populate min and max when curve data is available
    const flowunit = this.unitPolicy.canonical.flow;
    if (this.predictFlow) {
      this.measurements.type('flow').variant('predicted').position('max').value(this.predictFlow.currentFxyYMax, Date.now() , flowunit);
      this.measurements.type('flow').variant('predicted').position('min').value(this.predictFlow.currentFxyYMin, Date.now(), flowunit);
    } else {
      this.measurements.type('flow').variant('predicted').position('max').value(0, Date.now(), flowunit);
      this.measurements.type('flow').variant('predicted').position('min').value(0, Date.now(), flowunit);
    }
  }

  _updateState(){
    const isOperational = this._isOperationalState();
    if(!isOperational){
      //overrule the last prediction this should be 0 now
      this.measurements.type("flow").variant("predicted").position("downstream").value(0,Date.now(),this.unitPolicy.canonical.flow);
      this.measurements.type("flow").variant("predicted").position("atEquipment").value(0,Date.now(),this.unitPolicy.canonical.flow);
      this.measurements.type("power").variant("predicted").position("atEquipment").value(0,Date.now(),this.unitPolicy.canonical.power);
    }
    this._updatePredictionHealth();
  }

  /*-------------------               Register child events               -------------------*/
  registerChild(child, softwareType) {
    const resolvedSoftwareType = softwareType || child?.config?.functionality?.softwareType || "measurement";
    this.logger.debug('Setting up child event for softwaretype ' + resolvedSoftwareType);

    if(resolvedSoftwareType === "measurement"){
          const position = String(child.config.functionality.positionVsParent || "atEquipment").toLowerCase();
          const measurementType = child.config.asset.type;
          const childId = child.config?.general?.id || `${measurementType}-${position}-unknown`;
          const isVirtualPressureChild = Object.values(this.virtualPressureChildIds).includes(childId);

          if (measurementType === "pressure" && !isVirtualPressureChild) {
            this.realPressureChildIds[position]?.add(childId);
          }

          //rebuild to measurementype.variant no position and then switch based on values not strings or names.
          const eventName = `${measurementType}.measured.${position}`;
          const listenerKey = `${childId}:${eventName}`;
          const existingListener = this.childMeasurementListeners.get(listenerKey);
          if (existingListener) {
            if (typeof existingListener.emitter.off === "function") {
              existingListener.emitter.off(existingListener.eventName, existingListener.handler);
            } else if (typeof existingListener.emitter.removeListener === "function") {
              existingListener.emitter.removeListener(existingListener.eventName, existingListener.handler);
            }
          }

          this.logger.debug(`Setting up listener for ${eventName} from child ${child.config.general.name}`);
          // Register event listener for measurement updates
          const listener = (eventData) => {
          this.logger.debug(`🔄 ${position} ${measurementType} from ${eventData.childName}: ${eventData.value} ${eventData.unit}`);
      

          this.logger.debug(` Emitting... ${eventName} with data:`);
          // Route through centralized handlers so unit validation/conversion is applied once.
          this._callMeasurementHandler(measurementType, eventData.value, position, eventData);
      };
      child.measurements.emitter.on(eventName, listener);
      this.childMeasurementListeners.set(listenerKey, {
        emitter: child.measurements.emitter,
        eventName,
        handler: listener,
      });
    }
  }

// Centralized handler dispatcher
_callMeasurementHandler(measurementType, value, position, context) {
  switch (measurementType) {
    case 'pressure':
      this.updateMeasuredPressure(value, position, context);
      break;
      
    case 'flow':
      this.updateMeasuredFlow(value, position, context);
      break;

    case 'power':
      this.updateMeasuredPower(value, position, context);
      break;
      
    case 'temperature':
      this.updateMeasuredTemperature(value, position, context);
      break;
      
    default:
      this.logger.warn(`No handler for measurement type: ${measurementType}`);
      // Generic handler - just update position
      this.updatePosition();
      break;
  }
}

//---------------- END child stuff -------------//

  _buildUnitPolicy(config) {
    const flowOutputUnit = this._resolveUnitOrFallback(
      config?.general?.unit,
      'volumeFlowRate',
      DEFAULT_IO_UNITS.flow,
      'general.flow'
    );
    const pressureOutputUnit = this._resolveUnitOrFallback(
      config?.asset?.pressureUnit,
      'pressure',
      DEFAULT_IO_UNITS.pressure,
      'asset.pressure'
    );
    const powerOutputUnit = this._resolveUnitOrFallback(
      config?.asset?.powerUnit,
      'power',
      DEFAULT_IO_UNITS.power,
      'asset.power'
    );
    const temperatureOutputUnit = this._resolveUnitOrFallback(
      config?.asset?.temperatureUnit,
      'temperature',
      DEFAULT_IO_UNITS.temperature,
      'asset.temperature'
    );
    const curveUnits = this._resolveCurveUnits(config?.asset?.curveUnits || {}, flowOutputUnit);

    return {
      canonical: { ...CANONICAL_UNITS },
      output: {
        pressure: pressureOutputUnit,
        flow: flowOutputUnit,
        power: powerOutputUnit,
        temperature: temperatureOutputUnit,
        atmPressure: 'Pa',
      },
      curve: curveUnits,
    };
  }

  _resolveCurveUnits(curveUnits = {}, fallbackFlowUnit = DEFAULT_CURVE_UNITS.flow) {
    const pressure = this._resolveUnitOrFallback(
      curveUnits.pressure,
      'pressure',
      DEFAULT_CURVE_UNITS.pressure,
      'asset.curveUnits.pressure'
    );
    const flow = this._resolveUnitOrFallback(
      curveUnits.flow,
      'volumeFlowRate',
      fallbackFlowUnit || DEFAULT_CURVE_UNITS.flow,
      'asset.curveUnits.flow'
    );
    const power = this._resolveUnitOrFallback(
      curveUnits.power,
      'power',
      DEFAULT_CURVE_UNITS.power,
      'asset.curveUnits.power'
    );
    const control = typeof curveUnits.control === 'string' && curveUnits.control.trim()
      ? curveUnits.control.trim()
      : DEFAULT_CURVE_UNITS.control;

    return { pressure, flow, power, control };
  }

  _resolveUnitOrFallback(candidate, expectedMeasure, fallbackUnit, label) {
    const fallback = String(fallbackUnit || '').trim();
    const raw = typeof candidate === 'string' ? candidate.trim() : '';
    if (!raw) return fallback;
    try {
      const desc = convert().describe(raw);
      if (expectedMeasure && desc.measure !== expectedMeasure) {
        throw new Error(`expected ${expectedMeasure} but got ${desc.measure}`);
      }
      return raw;
    } catch (error) {
      this.logger.warn(`Invalid ${label} unit '${raw}' (${error.message}). Falling back to '${fallback}'.`);
      return fallback;
    }
  }

  _convertUnitValue(value, fromUnit, toUnit, contextLabel = 'unit conversion') {
    const numeric = Number(value);
    if (!Number.isFinite(numeric)) {
      throw new Error(`${contextLabel}: value '${value}' is not finite`);
    }
    if (!fromUnit || !toUnit || fromUnit === toUnit) {
      return numeric;
    }
    return convert(numeric).from(fromUnit).to(toUnit);
  }

  _normalizeCurveSection(section, fromYUnit, toYUnit, fromPressureUnit, toPressureUnit, sectionName) {
    const normalized = {};
    for (const [pressureKey, pair] of Object.entries(section || {})) {
      const canonicalPressure = this._convertUnitValue(
        Number(pressureKey),
        fromPressureUnit,
        toPressureUnit,
        `${sectionName} pressure axis`
      );
      const xArray = Array.isArray(pair?.x) ? pair.x.map(Number) : [];
      const yArray = Array.isArray(pair?.y) ? pair.y.map((v) => this._convertUnitValue(v, fromYUnit, toYUnit, `${sectionName} output`)) : [];
      if (!xArray.length || !yArray.length || xArray.length !== yArray.length) {
        throw new Error(`Invalid ${sectionName} section at pressure '${pressureKey}'.`);
      }
      normalized[String(canonicalPressure)] = {
        x: xArray,
        y: yArray,
      };
    }
    return normalized;
  }

  _normalizeMachineCurve(rawCurve, curveUnits = this.unitPolicy.curve) {
    if (!rawCurve || typeof rawCurve !== 'object' || !rawCurve.nq || !rawCurve.np) {
      throw new Error('Machine curve is missing required nq/np sections.');
    }
    return {
      nq: this._normalizeCurveSection(
        rawCurve.nq,
        curveUnits.flow,
        this.unitPolicy.canonical.flow,
        curveUnits.pressure,
        this.unitPolicy.canonical.pressure,
        'nq'
      ),
      np: this._normalizeCurveSection(
        rawCurve.np,
        curveUnits.power,
        this.unitPolicy.canonical.power,
        curveUnits.pressure,
        this.unitPolicy.canonical.pressure,
        'np'
      ),
    };
  }

  isUnitValidForType(type, unit) {
    return this.measurements?.isUnitCompatible?.(type, unit) === true;
  }

  _resolveMeasurementUnit(type, providedUnit) {
    const unit = typeof providedUnit === 'string' ? providedUnit.trim() : '';
    if (!unit) {
      throw new Error(`Missing unit for ${type} measurement.`);
    }
    if (!this.isUnitValidForType(type, unit)) {
      throw new Error(`Unsupported unit '${unit}' for ${type} measurement.`);
    }
    return unit;
  }

  _measurementPositionForMetric(metricId) {
    if (metricId === "power") return "atEquipment";
    return "downstream";
  }

  _resolveProcessRangeForMetric(metricId, predictedValue, measuredValue) {
    let processMin = NaN;
    let processMax = NaN;

    if (metricId === "flow") {
      processMin = Number(this.predictFlow?.currentFxyYMin);
      processMax = Number(this.predictFlow?.currentFxyYMax);
    } else if (metricId === "power") {
      processMin = Number(this.predictPower?.currentFxyYMin);
      processMax = Number(this.predictPower?.currentFxyYMax);
    }

    if (!Number.isFinite(processMin) || !Number.isFinite(processMax) || processMax <= processMin) {
      const p = Number(predictedValue);
      const m = Number(measuredValue);
      const localMin = Math.min(p, m);
      const localMax = Math.max(p, m);
      processMin = Number.isFinite(localMin) ? localMin : 0;
      processMax = Number.isFinite(localMax) && localMax > processMin ? localMax : processMin + 1;
    }

    return { processMin, processMax };
  }

  _updateMetricDrift(metricId, measuredValue, context = {}) {
    const position = this._measurementPositionForMetric(metricId);
    const predictedValue = Number(
      this.measurements
        .type(metricId)
        .variant("predicted")
        .position(position)
        .getCurrentValue()
    );
    const measured = Number(measuredValue);
    if (!Number.isFinite(predictedValue) || !Number.isFinite(measured)) return null;

    const { processMin, processMax } = this._resolveProcessRangeForMetric(metricId, predictedValue, measured);
    const timestamp = Number(context.timestamp || Date.now());
    const profile = this.driftProfiles[metricId] || {};

    try {
      const drift = this.errorMetrics.assessPoint(metricId, predictedValue, measured, {
        ...profile,
        processMin,
        processMax,
        predictedTimestamp: timestamp,
        measuredTimestamp: timestamp,
      });

      if (drift && drift.valid) {
        if (metricId === "flow") this.flowDrift = drift;
        if (metricId === "power") this.powerDrift = drift;
      }

      return drift;
    } catch (error) {
      this.logger.warn(`Drift update failed for metric '${metricId}': ${error.message}`);
      return null;
    }
  }

  _updatePressureDriftStatus() {
    const status = this.getPressureInitializationStatus();
    const flags = [];
    let level = 0;

    if (!status.initialized) {
      level = 2;
      flags.push("no_pressure_input");
    } else if (!status.hasDifferential) {
      level = 1;
      flags.push("single_side_pressure");
    }

    if (status.hasDifferential) {
      const upstream = this._getPreferredPressureValue("upstream");
      const downstream = this._getPreferredPressureValue("downstream");
      const diff = Number(downstream) - Number(upstream);
      if (Number.isFinite(diff) && diff < 0) {
        level = Math.max(level, 3);
        flags.push("negative_pressure_differential");
      }
    }

    this.pressureDrift = {
      level,
      source: status.source,
      flags: flags.length ? flags : ["nominal"],
    };

    return this.pressureDrift;
  }

  assessDrift(measurement, processMin, processMax) {
    const metricId = String(measurement || "").toLowerCase();
    const position = this._measurementPositionForMetric(metricId);
    const predictedMeasurement = this.measurements.type(metricId).variant("predicted").position(position).getAllValues();
    const measuredMeasurement = this.measurements.type(metricId).variant("measured").position(position).getAllValues();

    if (!predictedMeasurement?.values || !measuredMeasurement?.values) return null;

    return this.errorMetrics.assessDrift(
      predictedMeasurement.values,
      measuredMeasurement.values,
      processMin,
      processMax,
      {
        metricId,
        predictedTimestamps: predictedMeasurement.timestamps,
        measuredTimestamps: measuredMeasurement.timestamps,
        ...(this.driftProfiles[metricId] || {}),
      }
    );
  }

  _applyDriftPenalty(drift, confidence, flags, prefix) {
    if (!drift || !drift.valid || !Number.isFinite(drift.nrmse)) return confidence;
    if (drift.immediateLevel >= 3) {
      confidence -= 0.3;
      flags.push(`${prefix}_high_immediate_drift`);
    } else if (drift.immediateLevel === 2) {
      confidence -= 0.2;
      flags.push(`${prefix}_medium_immediate_drift`);
    } else if (drift.immediateLevel === 1) {
      confidence -= 0.1;
      flags.push(`${prefix}_low_immediate_drift`);
    }
    if (drift.longTermLevel >= 2) {
      confidence -= 0.1;
      flags.push(`${prefix}_long_term_drift`);
    }
    return confidence;
  }

  _updatePredictionHealth() {
    const status = this.getPressureInitializationStatus();
    const pressureDrift = this._updatePressureDriftStatus();
    const flags = [...pressureDrift.flags];
    let confidence = 0;

    const pressureSource = status.source;
    if (pressureSource === "differential") {
      confidence = 0.9;
    } else if (pressureSource === "upstream" || pressureSource === "downstream") {
      confidence = 0.55;
    } else {
      confidence = 0.2;
    }

    if (!this._isOperationalState()) {
      confidence = 0;
      flags.push("not_operational");
    }

    if (pressureDrift.level >= 3) confidence -= 0.35;
    else if (pressureDrift.level === 2) confidence -= 0.2;
    else if (pressureDrift.level === 1) confidence -= 0.1;

    const currentPosition = Number(this.state?.getCurrentPosition?.());
    const { min, max } = this._resolveSetpointBounds();
    if (Number.isFinite(currentPosition) && Number.isFinite(min) && Number.isFinite(max) && max > min) {
      const span = max - min;
      const edgeDistance = Math.min(Math.abs(currentPosition - min), Math.abs(max - currentPosition));
      if (edgeDistance < span * 0.05) {
        confidence -= 0.1;
        flags.push("near_curve_edge");
      }
    }

    confidence = this._applyDriftPenalty(this.flowDrift, confidence, flags, "flow");
    confidence = this._applyDriftPenalty(this.powerDrift, confidence, flags, "power");

    confidence = Math.max(0, Math.min(1, confidence));
    let quality = "invalid";
    if (confidence >= 0.8) quality = "high";
    else if (confidence >= 0.55) quality = "medium";
    else if (confidence >= 0.3) quality = "low";

    this.predictionHealth = {
      quality,
      confidence,
      pressureSource,
      flags: flags.length ? Array.from(new Set(flags)) : ["nominal"],
    };

    return this.predictionHealth;
  }

  reverseCurve(curve) {
    const reversedCurve = {};
    for (const [pressure, values] of Object.entries(curve)) {
      reversedCurve[pressure] = {
        x: [...values.y], // Previous y becomes new x
        y: [...values.x]  // Previous x becomes new y
      };
    }
    return reversedCurve;
  }

  // -------- Config -------- //
  updateConfig(newConfig) {
    this.config = this.configUtils.updateConfig(this.config, newConfig);
  }

  // -------- Mode and Input Management -------- //
  isValidSourceForMode(source, mode) {
    const allowedSourcesSet = this.config.mode.allowedSources[mode] || [];
    const allowed = allowedSourcesSet.has(source);
    allowed? 
    this.logger.debug(`source is allowed proceeding with ${source} for mode ${mode}`) : 
    this.logger.warn(`${source} is not allowed in mode ${mode}`);

    return allowed;
  }

  isValidActionForMode(action, mode) {
    const allowedActionsSet = this.config.mode.allowedActions[mode] || [];
    const allowed = allowedActionsSet.has(action);
    allowed ? 
    this.logger.debug(`Action is allowed proceeding with ${action} for mode ${mode}`) : 
    this.logger.warn(`${action} is not allowed in mode ${mode}`);

    return allowed;
  }

  async handleInput(source, action, parameter) {

    //sanitize input
    if( typeof action !== 'string'){this.logger.error(`Action must be string`); return;}
    //convert to lower case to avoid to many mistakes in commands
    action = action.toLowerCase();

    // check for validity of the request
    if(!this.isValidActionForMode(action,this.currentMode)){return ;}
    if (!this.isValidSourceForMode(source, this.currentMode)) {return ;}
    
    this.logger.info(`Handling input from source '${source}' with action '${action}' in mode '${this.currentMode}'.`);
    
    try {
      switch (action) {

        case "execsequence":
          return await this.executeSequence(parameter);

        case "execmovement":
          return await this.setpoint(parameter);

        case "entermaintenance":
           
          return await this.executeSequence(parameter);

        
        case "exitmaintenance":
          return await this.executeSequence(parameter);

        case "flowmovement":
          // External flow setpoint is interpreted in configured output flow unit.
          const canonicalFlowSetpoint = this._convertUnitValue(
            parameter,
            this.unitPolicy.output.flow,
            this.unitPolicy.canonical.flow,
            'flowmovement setpoint'
          );
          // Calculate the control value for a desired flow
          const pos = this.calcCtrl(canonicalFlowSetpoint);
          // Move to the desired setpoint
          return await this.setpoint(pos);

        case "emergencystop":
          this.logger.warn(`Emergency stop activated by '${source}'.`);
          return await this.executeSequence("emergencyStop");

        case "statuscheck":
          this.logger.info(`Status Check: Mode = '${this.currentMode}', Source = '${source}'.`);
          break;

        default:
          this.logger.warn(`Action '${action}' is not implemented.`);
          break;
      }
      this.logger.debug(`Action '${action}' successfully executed`);
      return {status : true , feedback: `Action '${action}' successfully executed.`};
    } catch (error) {
      this.logger.error(`Error handling input: ${error}`);
    }

  }

  abortMovement(reason = "group override") {
    if (this.state?.abortCurrentMovement) {
      this.state.abortCurrentMovement(reason);
    }
  }

  setMode(newMode) {
    const availableModes = this.defaultConfig.mode.current.rules.values.map(v => v.value);
    if (!availableModes.includes(newMode)) {
      this.logger.warn(`Invalid mode '${newMode}'. Allowed modes are: ${availableModes.join(', ')}`);
      return;
    }

    this.currentMode = newMode;
    this.logger.info(`Mode successfully changed to '${newMode}'.`);
  }

  // -------- Sequence Handlers -------- //
  async executeSequence(sequenceName) {

    const sequence = this.config.sequences[sequenceName];

    if (!sequence || sequence.size === 0) {
      this.logger.warn(`Sequence '${sequenceName}' not defined.`);
      return;
    }

    if (this.state.getCurrentState() == "operational" && sequenceName == "shutdown") {
      this.logger.info(`Machine will ramp down to position 0 before performing ${sequenceName} sequence`);
      await this.setpoint(0);
    }

    this.logger.info(` --------- Executing sequence: ${sequenceName} -------------`);

    for (const state of sequence) {
      try {
        await this.state.transitionToState(state);
        // Update measurements after state change

      } catch (error) {
        this.logger.error(`Error during sequence '${sequenceName}': ${error}`);
        break; // Exit sequence execution on error
      }
    }

    //recalc flow and power
    this.updatePosition();
  }

  async setpoint(setpoint) {

    try {
      // Validate and normalize setpoint
      if (!Number.isFinite(setpoint)) {
        this.logger.error("Invalid setpoint: Setpoint must be a finite number.");
        return;
      }
      const { min, max } = this._resolveSetpointBounds();
      const constrainedSetpoint = Math.min(Math.max(setpoint, min), max);
      if (constrainedSetpoint !== setpoint) {
        this.logger.warn(`Requested setpoint ${setpoint} constrained to ${constrainedSetpoint} (min=${min}, max=${max})`);
      }

      this.logger.info(`Setting setpoint to ${constrainedSetpoint}. Current position: ${this.state.getCurrentPosition()}`);

      // Move to the desired setpoint
      await this.state.moveTo(constrainedSetpoint);

    } catch (error) {
      this.logger.error(`Error setting setpoint: ${error}`);
    }
  }

  _resolveSetpointBounds() {
    const stateMin = Number(this.state?.movementManager?.minPosition);
    const stateMax = Number(this.state?.movementManager?.maxPosition);
    const curveMin = Number(this.predictFlow?.currentFxyXMin);
    const curveMax = Number(this.predictFlow?.currentFxyXMax);

    const minCandidates = [stateMin, curveMin].filter(Number.isFinite);
    const maxCandidates = [stateMax, curveMax].filter(Number.isFinite);

    const fallbackMin = Number.isFinite(stateMin) ? stateMin : 0;
    const fallbackMax = Number.isFinite(stateMax) ? stateMax : 100;

    let min = minCandidates.length ? Math.max(...minCandidates) : fallbackMin;
    let max = maxCandidates.length ? Math.min(...maxCandidates) : fallbackMax;

    if (min > max) {
      this.logger.warn(`Invalid setpoint bounds detected (min=${min}, max=${max}). Falling back to movement bounds.`);
      min = fallbackMin;
      max = fallbackMax;
    }

    return { min, max };
  }

  // Calculate flow based on current pressure and position
  calcFlow(x) {
    if(this.hasCurve) {
      if (!this._isOperationalState()) {
        this.measurements.type("flow").variant("predicted").position("downstream").value(0,Date.now(),this.unitPolicy.canonical.flow);
        this.measurements.type("flow").variant("predicted").position("atEquipment").value(0,Date.now(),this.unitPolicy.canonical.flow);
        this.logger.debug(`Machine is not operational. Setting predicted flow to 0.`);
        return 0;
      }

      const cFlow = this.predictFlow.y(x);
      this.measurements.type("flow").variant("predicted").position("downstream").value(cFlow,Date.now(),this.unitPolicy.canonical.flow);
      this.measurements.type("flow").variant("predicted").position("atEquipment").value(cFlow,Date.now(),this.unitPolicy.canonical.flow);
      //this.logger.debug(`Calculated flow: ${cFlow} for pressure: ${this.getMeasuredPressure()} and position: ${x}`);
      return cFlow;
    }

    // If no curve data is available, log a warning and return 0
    this.logger.warn(`No curve data available for flow calculation. Returning 0.`);
    this.measurements.type("flow").variant("predicted").position("downstream").value(0, Date.now(),this.unitPolicy.canonical.flow);
    this.measurements.type("flow").variant("predicted").position("atEquipment").value(0, Date.now(),this.unitPolicy.canonical.flow);
    return 0;
    
  }

  // Calculate power based on current pressure and position
  calcPower(x) {
    if(this.hasCurve) {
      if (!this._isOperationalState()) {
        this.measurements.type("power").variant("predicted").position('atEquipment').value(0, Date.now(), this.unitPolicy.canonical.power);
        this.logger.debug(`Machine is not operational. Setting predicted power to 0.`);
        return 0;
      }
    
      //this.predictPower.currentX = x; Decrepated
      const cPower = this.predictPower.y(x);
      this.measurements.type("power").variant("predicted").position('atEquipment').value(cPower, Date.now(), this.unitPolicy.canonical.power);
      //this.logger.debug(`Calculated power: ${cPower} for pressure: ${this.getMeasuredPressure()} and position: ${x}`);
      return cPower;
    }
    // If no curve data is available, log a warning and return 0
    this.logger.warn(`No curve data available for power calculation. Returning 0.`);
    this.measurements.type("power").variant("predicted").position('atEquipment').value(0, Date.now(), this.unitPolicy.canonical.power);
    return 0;

  }

  // calculate the power consumption using only flow and pressure
  inputFlowCalcPower(flow) {
    if(this.hasCurve) {

      this.predictCtrl.currentX = flow;
      const cCtrl = this.predictCtrl.y(flow);
      this.predictPower.currentX = cCtrl;
      const cPower = this.predictPower.y(cCtrl);
      return cPower;
    }
    
    // If no curve data is available, log a warning and return 0
    this.logger.warn(`No curve data available for power calculation. Returning 0.`);
    this.measurements.type("power").variant("predicted").position('atEquipment').value(0, Date.now(), this.unitPolicy.canonical.power);
    return 0;

  }

  // Function to predict control value for a desired flow
  calcCtrl(x) {
    if(this.hasCurve) {
      this.predictCtrl.currentX = x;
      const cCtrl = this.predictCtrl.y(x);
      this.measurements.type("ctrl").variant("predicted").position('atEquipment').value(cCtrl);
      //this.logger.debug(`Calculated ctrl: ${cCtrl} for pressure: ${this.getMeasuredPressure()} and position: ${x}`);
      return cCtrl;
    }
    
    // If no curve data is available, log a warning and return 0
    this.logger.warn(`No curve data available for control calculation. Returning 0.`);
    this.measurements.type("ctrl").variant("predicted").position('atEquipment').value(0, Date.now());
    return 0;

  }

  // returns the best available pressure measurement to use in the prediction calculation
  // this will be either the differential pressure, downstream or upstream pressure
  getMeasuredPressure() {
    if(this.hasCurve === false){
      this.logger.error(`No valid curve available to calculate prediction using last known pressure`);
      return 0;
    }
    
    const upstreamPressure = this._getPreferredPressureValue("upstream");
    const downstreamPressure = this._getPreferredPressureValue("downstream");

    // Both upstream & downstream => differential
    if (upstreamPressure != null && downstreamPressure != null) {
      const pressureDiffValue = downstreamPressure - upstreamPressure;
      this.logger.debug(`Pressure differential: ${pressureDiffValue}`);
      this.predictFlow.fDimension = pressureDiffValue;
      this.predictPower.fDimension = pressureDiffValue;
      this.predictCtrl.fDimension = pressureDiffValue;
      //update the cog
      const { cog, minEfficiency } = this.calcCog();
      // calc efficiency
      const efficiency = this.calcEfficiency(this.predictPower.outputY, this.predictFlow.outputY, "predicted");
      //update the distance from peak
      this.calcDistanceBEP(efficiency,cog,minEfficiency);

      return pressureDiffValue;
    }

    // Only downstream => use it, warn that it's partial
    if (downstreamPressure != null) {
      this.logger.warn(`Using downstream pressure only for prediction: ${downstreamPressure} This is less acurate!!`);
      this.predictFlow.fDimension = downstreamPressure;
      this.predictPower.fDimension = downstreamPressure;
      this.predictCtrl.fDimension = downstreamPressure;
            //update the cog
            const { cog, minEfficiency } = this.calcCog();
            // calc efficiency
            const efficiency = this.calcEfficiency(this.predictPower.outputY, this.predictFlow.outputY, "predicted");
            //update the distance from peak
            this.calcDistanceBEP(efficiency,cog,minEfficiency);
      return downstreamPressure;
    }

    // Only upstream => use it, warn that it's partial
    if (upstreamPressure != null) {
      this.logger.warn(`Using upstream pressure only for prediction: ${upstreamPressure} This is less acurate!!`);
      this.predictFlow.fDimension = upstreamPressure;
      this.predictPower.fDimension = upstreamPressure;
      this.predictCtrl.fDimension = upstreamPressure;
            //update the cog
            const { cog, minEfficiency } = this.calcCog();
            // calc efficiency
            const efficiency = this.calcEfficiency(this.predictPower.outputY, this.predictFlow.outputY, "predicted");
            //update the distance from peak
            this.calcDistanceBEP(efficiency,cog,minEfficiency);
      return upstreamPressure;
    }

    this.logger.error(`No valid pressure measurements available to calculate prediction using last known pressure`);

    //set default at 0 => lowest pressure possible
    this.predictFlow.fDimension = 0;
    this.predictPower.fDimension = 0;
    this.predictCtrl.fDimension = 0;
          //update the cog
          const { cog, minEfficiency } = this.calcCog();
          // calc efficiency
          const efficiency = this.calcEfficiency(this.predictPower.outputY, this.predictFlow.outputY, "predicted");
          //update the distance from peak
          this.calcDistanceBEP(efficiency,cog,minEfficiency);
          //place min and max flow capabilities in containerthis.predictFlow.currentFxyYMax - this.predictFlow.currentFxyYMin
          this.measurements.type('flow').variant('predicted').position('max').value(this.predictFlow.currentFxyYMax, Date.now(), this.unitPolicy.canonical.flow);
          this.measurements.type('flow').variant('predicted').position('min').value(this.predictFlow.currentFxyYMin, Date.now(), this.unitPolicy.canonical.flow);
    return 0;
  }

  _getPreferredPressureValue(position) {
    const realIds = Array.from(this.realPressureChildIds[position] || []);
    for (const childId of realIds) {
      const value = this.measurements
        .type("pressure")
        .variant("measured")
        .position(position)
        .child(childId)
        .getCurrentValue();
      if (value != null) return value;
    }

    const virtualId = this.virtualPressureChildIds[position];
    if (virtualId) {
      const simulatedValue = this.measurements
        .type("pressure")
        .variant("measured")
        .position(position)
        .child(virtualId)
        .getCurrentValue();
      if (simulatedValue != null) return simulatedValue;
    }

    return this.measurements
      .type("pressure")
      .variant("measured")
      .position(position)
      .getCurrentValue();
  }

  getPressureInitializationStatus() {
    const upstreamPressure = this._getPreferredPressureValue("upstream");
    const downstreamPressure = this._getPreferredPressureValue("downstream");

    const hasUpstream = upstreamPressure != null;
    const hasDownstream = downstreamPressure != null;
    const hasDifferential = hasUpstream && hasDownstream;

    return {
      hasUpstream,
      hasDownstream,
      hasDifferential,
      initialized: hasUpstream || hasDownstream || hasDifferential,
      source: hasDifferential ? 'differential' : hasDownstream ? 'downstream' : hasUpstream ? 'upstream' : null,
    };
  }

  updateSimulatedMeasurement(type, position, value, context = {}) {
    const normalizedType = String(type || "").toLowerCase();
    const normalizedPosition = String(position || "atEquipment").toLowerCase();

    if (normalizedType !== "pressure") {
      this._callMeasurementHandler(normalizedType, value, normalizedPosition, context);
      return;
    }

    if (!this.virtualPressureChildIds[normalizedPosition]) {
      this.logger.warn(`Unsupported simulated pressure position '${normalizedPosition}'`);
      return;
    }

    const child = this.virtualPressureChildren[normalizedPosition];
    if (!child?.measurements) {
      this.logger.error(`Virtual pressure child '${normalizedPosition}' is missing`);
      return;
    }

    let measurementUnit;
    try {
      measurementUnit = this._resolveMeasurementUnit('pressure', context.unit);
    } catch (error) {
      this.logger.warn(`Rejected simulated pressure measurement: ${error.message}`);
      return;
    }

    child.measurements
      .type("pressure")
      .variant("measured")
      .position(normalizedPosition)
      .value(value, context.timestamp || Date.now(), measurementUnit);
  }

  handleMeasuredFlow() {
    const flowDiff = this.measurements.type('flow').variant('measured').difference();

    // If both are present
    if (flowDiff != null) {
      // In theory, mass flow in = mass flow out, so they should match or be close.
      if (flowDiff.value < 0.001) {
        // flows match within tolerance
        this.logger.debug(`Flow match: ${flowDiff.value}`);
        return flowDiff.value;
      } else {
        // Mismatch => decide how to handle. Maybe take the average?
        // Or bail out with an error. Example: we bail out here.
        this.logger.error(`Something wrong with down or upstream flow measurement. Bailing out!`);
        return null;
      }
    }

    // get
    const upstreamFlow = this.measurements.type('flow').variant('measured').position('upstream').getCurrentValue();

    // Only upstream => might still accept it, but warn
    if (upstreamFlow != null) {
      this.logger.warn(`Only upstream flow is present. Using it but results may be incomplete!`);
      return upstreamFlow;
    }

    // get
    const downstreamFlow = this.measurements.type('flow').variant('measured').position('downstream').getCurrentValue();

    // Only downstream => might still accept it, but warn
    if (downstreamFlow != null) {
      this.logger.warn(`Only downstream flow is present. Using it but results may be incomplete!`);
      return downstreamFlow;
    }

    // Neither => error
    this.logger.error(`No upstream or downstream flow measurement. Bailing out!`);
    return null;
  }

  handleMeasuredPower() {
    const power = this.measurements.type("power").variant("measured").position("atEquipment").getCurrentValue();
    // If your system calls it "upstream" or just a single "value", adjust accordingly

    if (power != null) {
      this.logger.debug(`Measured power: ${power}`);
      return power;
    } else {
      this.logger.error(`No measured power found. Bailing out!`);
      return null;
    }
  }

  updateMeasuredTemperature(value, position, context = {}) {
    this.logger.debug(`Temperature update: ${value} at ${position} from ${context.childName || 'child'} (${context.childId || 'unknown-id'})`);
    let measurementUnit;
    try {
      measurementUnit = this._resolveMeasurementUnit('temperature', context.unit);
    } catch (error) {
      this.logger.warn(`Rejected temperature update: ${error.message}`);
      return;
    }
    this.measurements.type("temperature").variant("measured").position(position || 'atEquipment').child(context.childId).value(value, context.timestamp, measurementUnit);
  }
  
  // context handler for pressure updates
  updateMeasuredPressure(value, position, context = {}) {
   
    this.logger.debug(`Pressure update: ${value} at ${position} from ${context.childName || 'child'} (${context.childId || 'unknown-id'})`);
    let measurementUnit;
    try {
      measurementUnit = this._resolveMeasurementUnit('pressure', context.unit);
    } catch (error) {
      this.logger.warn(`Rejected pressure update: ${error.message}`);
      return;
    }
    
    //  Store in parent's measurement container 
    this.measurements.type("pressure").variant("measured").position(position).child(context.childId).value(value, context.timestamp, measurementUnit);

    // Determine what kind of value to use as pressure (upstream , downstream or difference)
    const pressure = this.getMeasuredPressure();
    this.updatePosition();
    this._updatePressureDriftStatus();
    this._updatePredictionHealth();
    
    this.logger.debug(`Using pressure: ${pressure} for calculations`);
  }

  // NEW: Flow handler
  updateMeasuredFlow(value, position, context = {}) {
    if (!this._isOperationalState()) {
      this.logger.warn(`Machine not operational, skipping flow update from ${context.childName || 'unknown'}`);
      return;
    }

    this.logger.debug(`Flow update: ${value} at ${position} from ${context.childName || 'child'}`);
    let measurementUnit;
    try {
      measurementUnit = this._resolveMeasurementUnit('flow', context.unit);
    } catch (error) {
      this.logger.warn(`Rejected flow update: ${error.message}`);
      return;
    }
    
    // Store in parent's measurement container
    this.measurements.type("flow").variant("measured").position(position).child(context.childId).value(value, context.timestamp, measurementUnit);
    
    // Update predicted flow if you have prediction capability
    if (this.predictFlow) {
      this.measurements.type("flow").variant("predicted").position("downstream").value(this.predictFlow.outputY || 0, Date.now(), this.unitPolicy.canonical.flow);
      this.measurements.type("flow").variant("predicted").position("atEquipment").value(this.predictFlow.outputY || 0, Date.now(), this.unitPolicy.canonical.flow);
    }

    const measuredCanonical = this.measurements
      .type("flow")
      .variant("measured")
      .position(position)
      .getCurrentValue(this.unitPolicy.canonical.flow);

    this._updateMetricDrift("flow", measuredCanonical, context);
    this._updatePredictionHealth();
  }

  updateMeasuredPower(value, position, context = {}) {
    if (!this._isOperationalState()) {
      this.logger.warn(`Machine not operational, skipping power update from ${context.childName || 'unknown'}`);
      return;
    }

    this.logger.debug(`Power update: ${value} at ${position} from ${context.childName || 'child'}`);
    let measurementUnit;
    try {
      measurementUnit = this._resolveMeasurementUnit('power', context.unit);
    } catch (error) {
      this.logger.warn(`Rejected power update: ${error.message}`);
      return;
    }
    this.measurements.type("power").variant("measured").position(position).child(context.childId).value(value, context.timestamp, measurementUnit);

    if (this.predictPower) {
      this.measurements.type("power").variant("predicted").position("atEquipment").value(this.predictPower.outputY || 0, Date.now(), this.unitPolicy.canonical.power);
    }

    const measuredCanonical = this.measurements
      .type("power")
      .variant("measured")
      .position(position)
      .getCurrentValue(this.unitPolicy.canonical.power);

    this._updateMetricDrift("power", measuredCanonical, context);
    this._updatePredictionHealth();
  }

  // Helper method for operational state check
  _isOperationalState() {
    const state = this.state.getCurrentState();
    const activeStates = ["operational", "warmingup", "accelerating", "decelerating"];
    this.logger.debug(`Checking operational state ${this.state.getCurrentState()} ? ${activeStates.includes(state)}`);
    return activeStates.includes(state);
  }

  //what is the internal functions that need updating when something changes that has influence on this.
  updatePosition() {
    
    if (this._isOperationalState()) {

      const currentPosition = this.state.getCurrentPosition();

      // Update the predicted values based on the new position
      const { cPower, cFlow } = this.calcFlowPower(currentPosition);

      // Calc predicted efficiency
      const efficiency = this.calcEfficiency(cPower, cFlow, "predicted");

      //update the cog
      const { cog, minEfficiency } = this.calcCog();

      //update the distance from peak
      this.calcDistanceBEP(efficiency,cog,minEfficiency);

    }

    this._updatePredictionHealth();

  }

  calcDistanceFromPeak(currentEfficiency,peakEfficiency){
    return Math.abs(currentEfficiency - peakEfficiency);
  }

  calcRelativeDistanceFromPeak(currentEfficiency,maxEfficiency,minEfficiency){
    let distance = 1;
    if(currentEfficiency != null){
      distance = this.interpolation.interpolate_lin_single_point(currentEfficiency,maxEfficiency, minEfficiency, 0, 1);
    }
    return distance;
  }

  showWorkingCurves() {
    // Show the current curves for debugging
    const { powerCurve, flowCurve } = this.getCurrentCurves();
    return {
      powerCurve: powerCurve, 
      flowCurve: flowCurve,
      cog: this.cog,
      cogIndex: this.cogIndex,
      NCog: this.NCog,
      minEfficiency: this.minEfficiency,
      currentEfficiencyCurve: this.currentEfficiencyCurve,
      absDistFromPeak: this.absDistFromPeak,
      relDistFromPeak: this.relDistFromPeak
    };
  }

   // Calculate the center of gravity for current pressure
  calcCog() {

    //fetch current curve data for power and flow
    const { powerCurve, flowCurve }  = this.getCurrentCurves();

    const {efficiencyCurve, peak, peakIndex, minEfficiency } = this.calcEfficiencyCurve(powerCurve, flowCurve);

    // Calculate the normalized center of gravity
    const NCog = (flowCurve.y[peakIndex] - this.predictFlow.currentFxyYMin) / (this.predictFlow.currentFxyYMax - this.predictFlow.currentFxyYMin); //

    //store in object for later retrieval
    this.currentEfficiencyCurve = efficiencyCurve;
    this.cog = peak;
    this.cogIndex = peakIndex;
    this.NCog = NCog;
    this.minEfficiency = minEfficiency;

    return { cog: peak, cogIndex: peakIndex, NCog: NCog, minEfficiency: minEfficiency };

  }

  calcEfficiencyCurve(powerCurve, flowCurve) {

    const efficiencyCurve = [];
    let peak = 0;
    let peakIndex = 0;
    let minEfficiency = 0;

    // Calculate efficiency curve based on power and flow curves
    powerCurve.y.forEach((power, index) => {

      // Get flow for the current power
      const flow = flowCurve.y[index];

      // higher efficiency is better
      efficiencyCurve.push( Math.round( ( flow / power ) * 100 ) / 100);

      // Keep track of peak efficiency
      peak = Math.max(peak, efficiencyCurve[index]);
      peakIndex = peak == efficiencyCurve[index] ? index : peakIndex;
      minEfficiency = Math.min(...efficiencyCurve);

    });

    return { efficiencyCurve, peak, peakIndex, minEfficiency };

  }

  //calc flow power based on pressure and current position
  calcFlowPower(x) {

    // Calculate flow and power
    const cFlow = this.calcFlow(x);
    const cPower = this.calcPower(x);

    return { cPower, cFlow };
  }

  calcEfficiency(power,flow,variant) {

    // Request a pressure differential explicitly in Pascal for hydraulic efficiency.
    const pressureDiff = this.measurements
      .type('pressure')
      .variant('measured')
      .difference({ unit: 'Pa' });
    const g = gravity.getStandardGravity();
    const temp = this.measurements.type('temperature').variant('measured').position('atEquipment').getCurrentValue('K');
    const atmPressure = this.measurements.type('atmPressure').variant('measured').position('atEquipment').getCurrentValue('Pa');  
    
    let rho = null;
    try {
      rho = coolprop.PropsSI('D', 'T', temp, 'P', atmPressure, 'WasteWater');
    } catch (error) {
      // coolprop can throw transient initialization errors; keep machine calculations running.
      this.logger.warn(`CoolProp density lookup failed: ${error.message}. Using fallback density.`);
      rho = 1000; // kg/m3 fallback for water-like fluids
    }
    

    this.logger.debug(`temp: ${temp} atmPressure : ${atmPressure} rho : ${rho} pressureDiff: ${pressureDiff?.value || 0}`);
    const flowM3s = this.measurements.type('flow').variant('predicted').position('atEquipment').getCurrentValue('m3/s');
    const powerWatt = this.measurements.type('power').variant('predicted').position('atEquipment').getCurrentValue('W');
    this.logger.debug(`Flow : ${flowM3s} power: ${powerWatt}`);

    if (power != 0 && flow != 0) {
      const specificFlow = flow / power;
      const specificEnergyConsumption = power / flow;

      this.measurements.type("efficiency").variant(variant).position('atEquipment').value(specificFlow);
      this.measurements.type("specificEnergyConsumption").variant(variant).position('atEquipment').value(specificEnergyConsumption);
    
      if (pressureDiff?.value != null && Number.isFinite(flowM3s) && Number.isFinite(powerWatt) && powerWatt > 0) {
        // Engineering references: P_h = Q * Δp = ρ g Q H, η_h = P_h / P_in
        const pressureDiffPa = Number(pressureDiff.value);
        const headMeters = (Number.isFinite(rho) && rho > 0) ? pressureDiffPa / (rho * g) : null;
        const hydraulicPowerW = pressureDiffPa * flowM3s;
        const nHydraulicEfficiency = hydraulicPowerW / powerWatt;

        if (Number.isFinite(headMeters)) {
          this.measurements.type("pumpHead").variant(variant).position('atEquipment').value(headMeters, Date.now(), 'm');
        }
        this.measurements.type("hydraulicPower").variant(variant).position('atEquipment').value(hydraulicPowerW, Date.now(), 'W');
        this.measurements.type("nHydraulicEfficiency").variant(variant).position('atEquipment').value(nHydraulicEfficiency);
      }
    
    } 

    //change this to nhydrefficiency ? 
    return this.measurements.type("efficiency").variant(variant).position('atEquipment').getCurrentValue();

  }

  updateCurve(newCurve) {
    this.logger.info(`Updating machine curve`);
    const normalizedCurve = this._normalizeMachineCurve(newCurve);
    const newConfig = {
      asset: {
        machineCurve: normalizedCurve,
        curveUnits: this.unitPolicy.curve,
      },
    };

    //validate input of new curve fed to the machine
    this.config = this.configUtils.updateConfig(this.config, newConfig);

    //After we passed validation load the curves into their predictors
    this.predictFlow.updateCurve(this.config.asset.machineCurve.nq);
    this.predictPower.updateCurve(this.config.asset.machineCurve.np);
    this.predictCtrl.updateCurve(this.reverseCurve(this.config.asset.machineCurve.nq));
  }

  getCompleteCurve() {
    const powerCurve = this.predictPower.inputCurveData;
    const flowCurve = this.predictFlow.inputCurveData;
    return { powerCurve, flowCurve };
  }

  getCurrentCurves() {
    const powerCurve = this.predictPower.currentFxyCurve[this.predictPower.currentF];
    const flowCurve = this.predictFlow.currentFxyCurve[this.predictFlow.currentF];

    return { powerCurve, flowCurve };

  }

  calcDistanceBEP(efficiency,maxEfficiency,minEfficiency) {

    const absDistFromPeak = this.calcDistanceFromPeak(efficiency,maxEfficiency);
    const relDistFromPeak = this.calcRelativeDistanceFromPeak(efficiency,maxEfficiency,minEfficiency);

    //store internally
    this.absDistFromPeak = absDistFromPeak ;
    this.relDistFromPeak = relDistFromPeak;

    return { absDistFromPeak: absDistFromPeak, relDistFromPeak: relDistFromPeak };
  }

  getOutput() {

    // Improved output object generation

    const output = this.measurements.getFlattenedOutput({
      requestedUnits: this.unitPolicy.output,
    });

    //fill in the rest of the output object
    output["state"] = this.state.getCurrentState();
    output["runtime"] = this.state.getRunTimeHours();
    output["ctrl"] = this.state.getCurrentPosition();
    output["moveTimeleft"] = this.state.getMoveTimeLeft();
    output["mode"] = this.currentMode;
    output["cog"] = this.cog; // flow / power efficiency
    output["NCog"] = this.NCog; // normalized cog
    output["NCogPercent"] = Math.round(this.NCog * 100 * 100) / 100 ;
    output["maintenanceTime"] = this.state.getMaintenanceTimeHours();

    if(this.flowDrift != null){
      const flowDrift = this.flowDrift;
      output["flowNrmse"] = flowDrift.nrmse;
      output["flowLongterNRMSD"] = flowDrift.longTermNRMSD;
      output["flowLongTermNRMSD"] = flowDrift.longTermNRMSD;
      output["flowImmediateLevel"] = flowDrift.immediateLevel;
      output["flowLongTermLevel"] = flowDrift.longTermLevel;
      output["flowDriftValid"] = flowDrift.valid;
    }

    if(this.powerDrift != null){
      const powerDrift = this.powerDrift;
      output["powerNrmse"] = powerDrift.nrmse;
      output["powerLongTermNRMSD"] = powerDrift.longTermNRMSD;
      output["powerImmediateLevel"] = powerDrift.immediateLevel;
      output["powerLongTermLevel"] = powerDrift.longTermLevel;
      output["powerDriftValid"] = powerDrift.valid;
    }

    output["pressureDriftLevel"] = this.pressureDrift.level;
    output["pressureDriftSource"] = this.pressureDrift.source;
    output["pressureDriftFlags"] = this.pressureDrift.flags;

    output["predictionQuality"] = this.predictionHealth.quality;
    output["predictionConfidence"] = Math.round(this.predictionHealth.confidence * 1000) / 1000;
    output["predictionPressureSource"] = this.predictionHealth.pressureSource;
    output["predictionFlags"] = this.predictionHealth.flags;

    //should this all go in the container of measurements?
    output["effDistFromPeak"] = this.absDistFromPeak;
    output["effRelDistFromPeak"] = this.relDistFromPeak;
    //this.logger.debug(`Output: ${JSON.stringify(output)}`);

    return output;
  }


} // end of class

module.exports = Machine;