const MeasurementBuilder = require('./MeasurementBuilder');
const EventEmitter = require('events');
const convertModule = require('../convert/index');

class MeasurementContainer {
  constructor(options = {},logger) {
    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
    this.defaultUnits = {
      pressure: 'mbar',
      flow: 'm3/h',
      power: 'kW',
      temperature: 'C',
      volume: 'm3',
      length: 'm',
      ...options.defaultUnits // Allow override
    };
    
    // Auto-conversion settings
    this.autoConvert = options.autoConvert !== false; // Default to true
    this.preferredUnits = options.preferredUnits || {}; // Per-measurement overrides
    
    // 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;
  }

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

  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) {
      throw new Error('Type must be specified before variant');
    }
    this._currentVariant = variantName;
    this._currentPosition = null;
    this._currentChildId = null;
    return this;
  }

  position(positionValue) {
    if (!this._currentVariant) {
      throw new Error('Variant must be specified before position');
    }

    
    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 measurement = this._getOrCreateMeasurement();
      const targetUnit = this._getTargetUnit(this._currentType);
      
      let convertedValue = val;
      let finalUnit = sourceUnit || targetUnit;

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

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

      // ENHANCED: Emit event with rich context
      const eventData = {
        value: convertedValue,
        originalValue: val,
        unit: finalUnit,
        sourceUnit: 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(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(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);
  }

    getFlattenedOutput() {
      const out = {};
      Object.entries(this.measurements).forEach(([type, variants]) => {
        Object.entries(variants).forEach(([variant, positions]) => {
          Object.entries(positions).forEach(([position, entry]) => {
            // Legacy single series
            if (entry?.getCurrentValue) {
              out[`${type}.${variant}.${position}`] = entry.getCurrentValue();
              return;
            }
            // Child-bucketed series
            if (entry && typeof entry === 'object') {
              Object.entries(entry).forEach(([childId, m]) => {
                if (m?.getCurrentValue) {
                  out[`${type}.${variant}.${position}.${childId}`] = m.getCurrentValue();
                }
              });
            }
          });
        });
      });
      return out;
  }

  // Difference calculations between positions
  difference({ from = "downstream", to = "upstream", unit: requestedUnit } = {}) {
    if (!this._currentType || !this._currentVariant) {
      throw new Error("Type and variant must be specified for difference calculation");
    }

    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) {
      throw new Error('Type must be specified before listing variants');
    }
    return this.measurements[this._currentType] ? 
      Object.keys(this.measurements[this._currentType]) : [];
  }

  getPositions() {
    if (!this._currentType || !this._currentVariant) {
      throw new Error('Type and variant must be specified before listing positions');
    }
    
    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;
  }

  // Helper method for value conversion
  _convertValueToUnit(value, fromUnit, toUnit) {
    if (!value || !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 [];

    // Map measurement types to convert module measures
    const measureMap = {
      pressure: 'pressure',
      flow: 'volumeFlowRate',
      power: 'power',
      temperature: 'temperature',
      volume: 'volume',
      length: 'length',
      mass: 'mass',
      energy: 'energy'
    };

    const convertMeasure = measureMap[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 "atEquipment":
        return 0;
      case "upstream":
        return Number.POSITIVE_INFINITY;
      case "downstream":
        return Number.NEGATIVE_INFINITY;
      
      default:
        if (this.logger) {
          this.logger.error(`Invalid positionVsParent provided: ${positionString}`);
        }
        return;
    }
  }

  _convertPositionNum2Str(positionValue) {
    switch (positionValue) {
    case 0:
      return "atEquipment";
    case (positionValue < 0):
      return "upstream";
    case (positionValue > 0):
      return "downstream";
    default:
      console.log(`Invalid position provided: ${positionValue}`);
    }
  }

}

module.exports = MeasurementContainer;
