const MeasurementBuilder = require('./MeasurementBuilder');
const EventEmitter = require('events');
const convertModule = require('../convert/index');
const { POSITIONS } = require('../constants/positions');

/* ============================================================================
 * MeasurementContainer — measurement storage with chainable type/variant/
 * position/child addressing.
 *
 * INTERNAL STORAGE SHAPE
 *   measurements[type][variant][position][childId] = Measurement instance
 *
 * The childId layer is ALWAYS present, even when the caller doesn't specify
 * one. _getOrCreateMeasurement defaults childId to 'default' when no
 * .child(...) is in the chain. So writing
 *
 *     mc.type('level').variant('measured').position('atequipment')
 *       .value(2.5, ts, 'm');
 *
 * stores the value at  measurements.level.measured.atequipment.default.
 *
 * READING — the chainable getters resolve the default child transparently,
 * so consumers usually don't see it:
 *
 *     mc.type('level').variant('measured').position('atequipment')
 *       .getCurrentValue('m');     // returns 2.5
 *
 * FLATTENED OUTPUT — getFlattenedOutput() emits ONE key per child, including
 * the implicit 'default' bucket:
 *
 *     {
 *       'level.measured.atequipment.default': 2.5,           // implicit child
 *       'flow.predicted.in.manual-qin':       0.05,          // explicit .child('manual-qin')
 *       'flow.predicted.in.from-pump-A':      0.03,
 *       …
 *     }
 *
 * ⚠ DASHBOARDS / DOWNSTREAM PARSERS MUST INCLUDE THE CHILD KEY
 *   The flat key format is `${type}.${variant}.${position}.${childId}`.
 *   When you have not used .child(), the childId is the literal string
 *   'default'. Use 'level.measured.atequipment.default', NOT
 *   'level.measured.atequipment'. This trips up new consumers — see the
 *   pumpingStation basic-dashboard parser for an example that gets it right.
 *
 * AGGREGATION — sum() folds all children of a position into one number:
 *
 *     mc.sum('flow', 'predicted', ['in'], 'm3/s');
 *     // = manual-qin + from-pump-A + … + (default if any)
 * ============================================================================
 */
class MeasurementContainer {
  constructor(options = {},logger) {
    this.logger = logger || null;
    this.emitter = new EventEmitter();
    this.measurements = {};
    this.windowSize = options.windowSize || 10; // Default window size
    
    // For chaining context
    this._currentChildId = null;
    this._currentType = null;
    this._currentVariant = null;
    this._currentPosition = null;
    this._currentDistance = null;
    this._unit = null;

    // Default units for each measurement type (ingress/preferred)
    this.defaultUnits = {
      pressure: 'mbar',
      flow: 'm3/h',
      power: 'kW',
      temperature: 'C',
      volume: 'm3',
      length: 'm',
      ...options.defaultUnits // Allow override
    };

    // Canonical storage unit map (single conversion anchor per measurement type)
    this.canonicalUnits = {
      pressure: 'Pa',
      atmPressure: 'Pa',
      flow: 'm3/s',
      power: 'W',
      hydraulicPower: 'W',
      temperature: 'K',
      volume: 'm3',
      length: 'm',
      mass: 'kg',
      energy: 'J',
      ...options.canonicalUnits,
    };
    
    // Auto-conversion settings
    this.autoConvert = options.autoConvert !== false; // Default to true
    this.preferredUnits = options.preferredUnits || {}; // Per-measurement overrides
    this.storeCanonical = options.storeCanonical === true;
    this.strictUnitValidation = options.strictUnitValidation === true;
    this.throwOnInvalidUnit = options.throwOnInvalidUnit === true;
    this.requireUnitForTypes = new Set(
      (options.requireUnitForTypes || []).map((t) => String(t).trim().toLowerCase())
    );

    // Map EVOLV measurement types to convert-module measure families
    this.measureMap = {
      pressure: 'pressure',
      atmpressure: 'pressure',
      flow: 'volumeFlowRate',
      power: 'power',
      hydraulicpower: 'power',
      reactivepower: 'reactivePower',
      apparentpower: 'apparentPower',
      temperature: 'temperature',
      volume: 'volume',
      length: 'length',
      mass: 'mass',
      energy: 'energy',
      reactiveenergy: 'reactiveEnergy',
    };
    
    // For chaining context
    this._currentType = null;
    this._currentVariant = null;
    this._currentPosition = null;
    this._unit = null;

    // NEW: Enhanced child identification
    this.childId = null;
    this.childName = null;
    this.parentRef = null;
    
  }

  // NEW: Methods to set child context
  setChildId(childId) {
      this.childId = childId;
      return this;
  }

  child(childId) {
    this._currentChildId = childId || 'default';
    return this;
  }

  setChildName(childName) {
      this.childName = childName;
      return this;
  }

  setParentRef(parent) {
      this.parentRef = parent;
      return this;
  }

  // New method to set preferred units
  setPreferredUnit(measurementType, unit) {
    this.preferredUnits[measurementType] = unit;
    return this;
  }

  setCanonicalUnit(measurementType, unit) {
    this.canonicalUnits[measurementType] = unit;
    return this;
  }

  // Get the target unit for a measurement type
  _getTargetUnit(measurementType) {
    return this.preferredUnits[measurementType] || 
           this.defaultUnits[measurementType] || 
           null;
  }

  _getCanonicalUnit(measurementType) {
    return this.canonicalUnits[measurementType] || null;
  }

  _normalizeType(measurementType) {
    return String(measurementType || '').trim().toLowerCase();
  }

  _describeUnit(unit) {
    if (typeof unit !== 'string' || unit.trim() === '') return null;
    try {
      return convertModule().describe(unit.trim());
    } catch (error) {
      return null;
    }
  }

  isUnitCompatible(measurementType, unit) {
    // Unknown type (not in measureMap): accept any unit. This lets user-
    // defined measurement types (e.g. 'humidity', 'co2', arbitrary IoT
    // channels in digital mode) pass through without being rejected just
    // because their unit string ('%', 'ppm', …) is not a known physical
    // unit to the convert module. Known types are still validated strictly.
    const normalizedType = this._normalizeType(measurementType);
    const expectedMeasure = this.measureMap[normalizedType];
    if (!expectedMeasure) return true;

    const desc = this._describeUnit(unit);
    if (!desc) return false;
    return desc.measure === expectedMeasure;
  }

  _handleUnitViolation(message) {
    if (this.throwOnInvalidUnit) {
      throw new Error(message);
    }
    if (this.logger) {
      this.logger.warn(message);
    }
  }

  _resolveUnitPolicy(measurementType, sourceUnit = null) {
    const normalizedType = this._normalizeType(measurementType);
    const rawSourceUnit = typeof sourceUnit === 'string' && sourceUnit.trim()
      ? sourceUnit.trim()
      : null;
    const fallbackIngressUnit = this._getTargetUnit(measurementType);
    const canonicalUnit = this._getCanonicalUnit(measurementType);
    const resolvedSourceUnit = rawSourceUnit || fallbackIngressUnit || canonicalUnit || null;

    if (this.requireUnitForTypes.has(normalizedType) && !rawSourceUnit) {
      this._handleUnitViolation(`Missing source unit for required measurement type '${measurementType}'.`);
      return { valid: false };
    }

    if (resolvedSourceUnit && !this.isUnitCompatible(measurementType, resolvedSourceUnit)) {
      this._handleUnitViolation(`Incompatible or unknown source unit '${resolvedSourceUnit}' for measurement type '${measurementType}'.`);
      return { valid: false };
    }

    const resolvedStorageUnit = this.storeCanonical
      ? (canonicalUnit || fallbackIngressUnit || resolvedSourceUnit)
      : (fallbackIngressUnit || canonicalUnit || resolvedSourceUnit);

    if (resolvedStorageUnit && !this.isUnitCompatible(measurementType, resolvedStorageUnit)) {
      this._handleUnitViolation(`Incompatible storage unit '${resolvedStorageUnit}' for measurement type '${measurementType}'.`);
      return { valid: false };
    }

    return {
      valid: true,
      sourceUnit: resolvedSourceUnit,
      storageUnit: resolvedStorageUnit || null,
      strictValidation: this.strictUnitValidation,
    };
  }

  getUnit(type) {
    if (!type) return null;
    if (this.preferredUnits && this.preferredUnits[type]) return this.preferredUnits[type];
    if (this.defaultUnits && this.defaultUnits[type]) return this.defaultUnits[type];
    return null;
  }

  // Chainable methods
  type(typeName) {
    this._currentType = typeName;
    this._currentVariant = null;
    this._currentPosition = null;
    this._currentChildId = null;
    return this;
  }

  variant(variantName) {
    if (!this._currentType) {
      if (this.logger) {
        this.logger.warn('variant() ignored: type must be specified before variant');
      }
      return this;
    }
    this._currentVariant = variantName;
    this._currentPosition = null;
    this._currentChildId = null;
    return this;
  }

  position(positionValue) {
    if (!this._currentVariant) {
      if (this.logger) {
        this.logger.warn('position() ignored: variant must be specified before position');
      }
      return this;
    }

    this._currentPosition = positionValue.toString().toLowerCase();
    
    return this;
  }

  distance(distance) {
    // If distance is not provided, derive from positionVsParent
    if(distance === null) {
      distance = this._convertPositionStr2Num(this._currentPosition);
    }

    this._currentDistance = distance;

    return this;
  }

  // ENHANCED: Update your existing value method
  value(val, timestamp = Date.now(), sourceUnit = null) {
      if (!this._ensureChainIsValid()) return this;

      const unitPolicy = this._resolveUnitPolicy(this._currentType, sourceUnit);
      if (!unitPolicy.valid) return this;

      const measurement = this._getOrCreateMeasurement();
      const targetUnit = unitPolicy.storageUnit;

      let convertedValue = val;
      let finalUnit = targetUnit || unitPolicy.sourceUnit;

      // Auto-convert if enabled and units are specified
      if (this.autoConvert && unitPolicy.sourceUnit && targetUnit && unitPolicy.sourceUnit !== targetUnit) {
        try {
          convertedValue = convertModule(val).from(unitPolicy.sourceUnit).to(targetUnit);
          finalUnit = targetUnit;
          
          if (this.logger) {
            this.logger.debug(`Auto-converted ${val} ${unitPolicy.sourceUnit} to ${convertedValue} ${targetUnit}`);
          }
        } catch (error) {
          const message = `Auto-conversion failed from ${unitPolicy.sourceUnit} to ${targetUnit}: ${error.message}`;
          if (this.strictUnitValidation) {
            this._handleUnitViolation(message);
            return this;
          }
          if (this.logger) this.logger.warn(message);
          convertedValue = val;
          finalUnit = unitPolicy.sourceUnit;
        }
      }

      measurement.setValue(convertedValue, timestamp);
      
      if (finalUnit) {
        measurement.setUnit(finalUnit);
      }

      // ENHANCED: Emit event with rich context
      const eventData = {
        value: convertedValue,
        originalValue: val,
        unit: finalUnit,
        sourceUnit: unitPolicy.sourceUnit,
        timestamp,
        position: this._currentPosition,
        distance: this._currentDistance,
        variant: this._currentVariant,
        type: this._currentType,
        // NEW: Enhanced context
        childId: this.childId,
        childName: this.childName,
        parentRef: this.parentRef,
      };

      // Emit the exact event your parent expects
      this.emitter.emit(`${this._currentType}.${this._currentVariant}.${this._currentPosition}`, eventData);
      //console.log(`Emitted event: ${this._currentType}.${this._currentVariant}.${this._currentPosition}`, eventData);

      return this;
  }

    /**
   * Check whether a measurement series exists.
   *
   * You can rely on the current chain (type/variant/position already set via
   * type().variant().position()), or pass them explicitly via the options.
   *
   * @param {object} options
   * @param {string} [options.type]      Override the current type
   * @param {string} [options.variant]   Override the current variant
   * @param {string} [options.position]  Override the current position
   * @param {boolean} [options.requireValues=false]
   *        When true, the series must contain at least one stored value.
   *
   * @returns {boolean}
   */
  exists({ type, variant, position, requireValues = false } = {}) {
    const typeKey = type ?? this._currentType;
    if (!typeKey) return false;

    const variantKey = variant ?? this._currentVariant;
    if (!variantKey) return false;

    const positionKey = position ?? this._currentPosition;

    const typeBucket = this.measurements[typeKey];
    if (!typeBucket) return false;

    const variantBucket = typeBucket[variantKey];
    if (!variantBucket) return false;

    if (!positionKey) {
      // No specific position requested – just check the variant bucket.
      return requireValues
        ? Object.values(variantBucket).some(m => m?.values?.length > 0)
        : Object.keys(variantBucket).length > 0;
    }

    const measurement = variantBucket[positionKey];
    if (!measurement) return false;

    return requireValues ? measurement.values?.length > 0 : true;
  }

  unit(unitName) {
    if (!this._ensureChainIsValid()) return this;
    
    const measurement = this._getOrCreateMeasurement();
    measurement.setUnit(unitName);
    this._unit = unitName;
    return this;
  }

  // Terminal operations - get data out
    get() {
      if (!this._ensureChainIsValid()) return null;
      const variantBucket = this.measurements[this._currentType]?.[this._currentVariant];
      if (!variantBucket) return null;
      const posBucket = variantBucket[this._currentPosition];
      if (!posBucket) return null;

      // Legacy single measurement
      if (posBucket?.getCurrentValue) return posBucket;

      // Child-aware: pick requested child, otherwise fall back to default, otherwise first available
      if (posBucket && typeof posBucket === 'object') {
        const requestedKey = this._currentChildId || this.childId;
        const keys = Object.keys(posBucket);
        if (!keys.length) return null;
        const measurement =
          (requestedKey && posBucket[requestedKey]) ||
          posBucket.default ||
          posBucket[keys[0]];
        return measurement || null;
      }

      return null;
    }



  getCurrentValue(requestedUnit = null) {
    const measurement = this.get();
    if (!measurement) return null;
    const value = measurement.getCurrentValue();
    if (value === null) return null;
    if (!requestedUnit || !measurement.unit || requestedUnit === measurement.unit) {
      return value;
    }
    try {
      return convertModule(value).from(measurement.unit).to(requestedUnit);
    } catch (error) {
      if (this.logger) this.logger.error(`Unit conversion failed: ${error.message}`);
      return value;
    }
  }

  getAverage(requestedUnit = null) {
    const measurement = this.get();
    if (!measurement) return null;
    
    const avgValue = measurement.getAverage();
    if (avgValue === null) return null;

    if (!requestedUnit || !measurement.unit || requestedUnit === measurement.unit) {
      return avgValue;
    }

    try {
      return convertModule(avgValue).from(measurement.unit).to(requestedUnit);
    } catch (error) {
      if (this.logger) {
        this.logger.error(`Unit conversion failed: ${error.message}`);
      }
      return avgValue;
    }
  }

  getMin() {
    const measurement = this.get();
    return measurement ? measurement.getMin() : null;
  }

  getMax() {
    const measurement = this.get();
    return measurement ? measurement.getMax() : null;
  }

  getAllValues() {
    const measurement = this.get();
    return measurement ? measurement.getAllValues() : null;
  }

  getLaggedValue(lag = 1,requestedUnit = null ){
    const measurement = this.get();
    if (!measurement) return null;
    
    let sample = measurement.getLaggedSample(lag);
    if (sample === null) return null;
    const value = sample.value;

    // Return as-is if no unit conversion requested
    if (!requestedUnit) {
      return value;
    }

    // Convert if needed
    if (measurement.unit && requestedUnit !== measurement.unit) {
      try {
        const convertedValue = convertModule(sample.value).from(measurement.unit).to(requestedUnit);
        //replace old value in sample and return obj
        sample.value = convertedValue ;
        sample.unit = requestedUnit;
        return sample;

      } catch (error) {
        if (this.logger) {
          this.logger.error(`Unit conversion failed: ${error.message}`);
        }
        return sample; // Return original value if conversion fails
      }
    }

    return value;
  }

  getLaggedSample(lag = 1,requestedUnit = null ){
    const measurement = this.get();
    if (!measurement) return null;

    let sample = measurement.getLaggedSample(lag);
    if (sample === null) return null;

    // Return as-is if no unit conversion requested
    if (!requestedUnit) {
      return sample;
    }

    // Convert if needed
    if (measurement.unit && requestedUnit !== measurement.unit) {
      try {
        const convertedValue = convertModule(sample.value).from(measurement.unit).to(requestedUnit);
        //replace old value in sample and return obj
        sample.value = convertedValue ;
        sample.unit = requestedUnit;
        return sample;

      } catch (error) {
        if (this.logger) {
          this.logger.error(`Unit conversion failed: ${error.message}`);
        }
        return sample; // Return original value if conversion fails
      }
    }

    return sample;
  }

  sum(type, variant, positions = [], targetUnit = null) {
    const bucket = this.measurements?.[type]?.[variant];
    if (!bucket) return 0;
    return positions
      .map((pos) => {
        const posBucket = bucket[pos];
        if (!posBucket) return 0;
        return Object.values(posBucket)
          .map((m) => {
            if (!m?.getCurrentValue) return 0;
            const val = m.getCurrentValue();
            if (val == null) return 0;
            const fromUnit = m.unit || targetUnit;
            if (!targetUnit || !fromUnit || fromUnit === targetUnit) return val;
            try { return convertModule(val).from(fromUnit).to(targetUnit); } catch { return val; }
          })
          .reduce((acc, v) => acc + (Number.isFinite(v) ? v : 0), 0);
      })
      .reduce((acc, v) => acc + v, 0);
  }

    /**
     * Flatten the entire container to a key→value map, suitable for
     * dashboards / InfluxDB / debug dumps.
     *
     * KEY FORMAT — child-bucketed series (the common case):
     *   `${type}.${variant}.${position}.${childId}`
     *
     * Even measurements written without an explicit `.child(...)` end up
     * here under `childId === 'default'` (see _getOrCreateMeasurement).
     * Examples:
     *   level.measured.atequipment.default     // implicit child
     *   flow.predicted.in.manual-qin           // explicit child
     *   flow.predicted.in.from-pump-A          // explicit child
     *
     * Consumers (Node-RED dashboards, parsers) MUST include the trailing
     * `.default` when reading default-bucket measurements. Stripping it
     * silently misses the value. This is the #1 footgun for new code that
     * uses MeasurementContainer.
     *
     * The "Legacy single series" branch below catches a pre-v2 storage
     * shape where a position held a Measurement directly (no child layer);
     * new code never produces that shape but old serialized state may.
     */
    getFlattenedOutput(options = {}) {
      const requestedUnits = options.requestedUnits || (options.usePreferredUnits ? this.preferredUnits : null);
      const out = {};
      Object.entries(this.measurements).forEach(([type, variants]) => {
        Object.entries(variants).forEach(([variant, positions]) => {
          Object.entries(positions).forEach(([position, entry]) => {
            // Legacy single series (no childId layer)
            if (entry?.getCurrentValue) {
              out[`${type}.${variant}.${position}`] = this._resolveOutputValue(type, entry, requestedUnits);
              return;
            }
            // Child-bucketed series — ALWAYS the case for new writes,
            // including the implicit 'default' bucket when no .child() is
            // used. The flat key carries the childId.
            if (entry && typeof entry === 'object') {
              Object.entries(entry).forEach(([childId, m]) => {
                if (m?.getCurrentValue) {
                  out[`${type}.${variant}.${position}.${childId}`] = this._resolveOutputValue(type, m, requestedUnits);
                }
              });
            }
          });
        });
      });
      return out;
  }

  // Difference calculations between positions
  difference({ from = POSITIONS.DOWNSTREAM, to = POSITIONS.UPSTREAM, unit: requestedUnit } = {}) {
    if (!this._currentType || !this._currentVariant) {
      if (this.logger) {
        this.logger.warn('difference() ignored: type and variant must be specified');
      }
      return null;
    }

    const get = pos => {
      const bucket = this.measurements?.[this._currentType]?.[this._currentVariant]?.[pos];
      if (!bucket) return null;
      // child-aware bucket: pick current childId/default or first available
      if (bucket && typeof bucket === 'object' && !bucket.getCurrentValue) {
        const childKey = this._currentChildId || this.childId || Object.keys(bucket)[0];
        return bucket?.[childKey] || null;
      }
      // legacy single measurement
      return bucket;
    };

    const a = get(from);
    const b = get(to);
    if (!a || !b || !a.values || !b.values || a.values.length === 0 || b.values.length === 0) {
      return null;
    }

    const targetUnit = requestedUnit || a.unit || b.unit;
    const aVal = this._convertValueToUnit(a.getCurrentValue(), a.unit, targetUnit);
    const bVal = this._convertValueToUnit(b.getCurrentValue(), b.unit, targetUnit);

    const aAvg = this._convertValueToUnit(a.getAverage(), a.unit, targetUnit);
    const bAvg = this._convertValueToUnit(b.getAverage(), b.unit, targetUnit);

    return { value: aVal - bVal, avgDiff: aAvg - bAvg, unit: targetUnit, from, to };
  }

  // Helper methods
  _ensureChainIsValid() {
    if (!this._currentType || !this._currentVariant || !this._currentPosition) {
      if (this.logger) {
        this.logger.error('Incomplete measurement chain, required: type, variant, and position');
      }
      return false;
    }
    return true;
  }

  _getOrCreateMeasurement() {
    // Initialize nested structure if needed
    if (!this.measurements[this._currentType]) {
      this.measurements[this._currentType] = {};
    }
    
    if (!this.measurements[this._currentType][this._currentVariant]) {
      this.measurements[this._currentType][this._currentVariant] = {};
    }
    
    const positionKey = this._currentPosition;
    const childKey = this._currentChildId || this.childId || 'default';

    if (!this.measurements[this._currentType][this._currentVariant][positionKey]) {
      this.measurements[this._currentType][this._currentVariant][positionKey] = {};
    }

    const bucket = this.measurements[this._currentType][this._currentVariant][positionKey];

    if (!bucket[childKey]) {
      bucket[childKey] = new MeasurementBuilder()
        .setType(this._currentType)
        .setVariant(this._currentVariant)
        .setPosition(positionKey)
        .setWindowSize(this.windowSize)
        .setDistance(this._currentDistance)
        .build();
    }

    return bucket[childKey];
  }

  // Additional utility methods
  getTypes() {
    return Object.keys(this.measurements);
  }

  getVariants() {
    if (!this._currentType) {
      if (this.logger) {
        this.logger.warn('getVariants() ignored: type must be specified first');
      }
      return [];
    }
    return this.measurements[this._currentType] ? 
      Object.keys(this.measurements[this._currentType]) : [];
  }

  _resolveOutputValue(type, measurement, requestedUnits = null) {
    const value = measurement.getCurrentValue();
    if (!requestedUnits || value === null || typeof value === 'undefined') {
      return value;
    }
    const targetUnit = requestedUnits[type];
    if (!targetUnit) {
      return value;
    }
    return this._convertValueToUnit(value, measurement.unit, targetUnit);
  }

  getPositions() {
    if (!this._currentType || !this._currentVariant) {
      if (this.logger) {
        this.logger.warn('getPositions() ignored: type and variant must be specified first');
      }
      return [];
    }
    
    if (!this.measurements[this._currentType] || 
        !this.measurements[this._currentType][this._currentVariant]) {
      return [];
    }

    return Object.keys(this.measurements[this._currentType][this._currentVariant]);
  }

  clear() {
    this.measurements = {};
    this._currentType = null;
    this._currentVariant = null;
    this._currentPosition = null;
    this._currentDistance = null;
    this._unit = null;
  }

  // Helper method for value conversion
  _convertValueToUnit(value, fromUnit, toUnit) {
    if ((value === null || typeof value === 'undefined') || !fromUnit || !toUnit || fromUnit === toUnit) {
      return value;
    }

    try {
      return convertModule(value).from(fromUnit).to(toUnit);
    } catch (error) {
      if (this.logger) {
        this.logger.warn(`Conversion failed from ${fromUnit} to ${toUnit}: ${error.message}`);
      }
      return value;
    }
  }

  // Get available units for a measurement type
  getAvailableUnits(measurementType = null) {
    const type = measurementType || this._currentType;
    if (!type) return [];

    const convertMeasure = this.measureMap[this._normalizeType(type)];
    if (!convertMeasure) return [];

    try {
      return convertModule().possibilities(convertMeasure);
    } catch (error) {
      return [];
    }
  }

  // Get best unit for current value
  getBestUnit(excludeUnits = []) {
    const measurement = this.get();
    if (!measurement || !measurement.unit) return null;

    const currentValue = measurement.getCurrentValue();
    if (currentValue === null) return null;

    try {
      const best = convertModule(currentValue)
        .from(measurement.unit)
        .toBest({ exclude: excludeUnits });
      
      return best;
    } catch (error) {
      if (this.logger) {
        this.logger.error(`getBestUnit failed: ${error.message}`);
      }
      return null;
    }
  }

  _convertPositionStr2Num(positionString) {
    switch(positionString) {
      case POSITIONS.AT_EQUIPMENT:
        return 0;
      case POSITIONS.UPSTREAM:
        return Number.POSITIVE_INFINITY;
      case POSITIONS.DOWNSTREAM:
        return Number.NEGATIVE_INFINITY;
      
      default:
        if (this.logger) {
          this.logger.error(`Invalid positionVsParent provided: ${positionString}`);
        }
        return;
    }
  }

  _convertPositionNum2Str(positionValue) {
    if (positionValue === 0) {
      return POSITIONS.AT_EQUIPMENT;
    }
    if (positionValue < 0) {
      return POSITIONS.UPSTREAM;
    }
    if (positionValue > 0) {
      return POSITIONS.DOWNSTREAM;
    }
    if (this.logger) {
      this.logger.warn(`Invalid position provided: ${positionValue}`);
    }
    return null;
  }

}

module.exports = MeasurementContainer;