uid: rules_tools:meter
label: Meter Reading
description: Keeps a sum from a counting meter Item that can randomly be reset back to zero.
configDescriptions:
  - name: meter
    type: TEXT
    context: item
    filterCriteria:
      - name: type
        value: Number
    label: Meter Item
    required: true
    description: Item that holds the meter readings.
  - name: total
    type: TEXT
    context: item
    filterCriteria:
      - name: type
        value: Number
    label: Total Item
    required: true
    description: Item that holds the running total.
triggers:
  - id: "2"
    configuration:
      itemName: "{{meter}}"
    type: core.ItemStateChangeTrigger    
conditions:
  - inputs: {}
    id: "3"
    configuration:
      type: application/javascript
      script: >-
        var meterType = items['{{meter}}'].type;

        var totalType = items['{{total}}'].type;

        if(!meterType.startsWith('Number') || !totalType.startsWith('Number')) {
          console.error('The counting rule template only works with Number Items: {{meter}}=' + meterType + ' {{total}}=' + totalType);
          false;
        }

        else {
          (event.itemState.toString() != 'NULL' && event.itemState.toString() != 'UNDEF');
        }
    type: script.ScriptCondition  
actions:
  - inputs: {}
    id: "1"
    configuration:
      type: application/javascript
      script: >-
        // Version 1.1
        
        var totalItem = items.getItem('{{total}}');

        var meterItem = items.getItem('{{meter}}');

        var rawReading = event.itemState;

        var rawLastReading = (event.oldItemState.toString() == 'NULL' ||
        event.oldItemState.toString() == 'UNDEF') ? rawReading :
        event.oldItemState;


        var total = 'UNDEF';


        // Quantity Types

        if(meterItem.type.includes(':')){
          const unit = Quantity(rawReading).toString().split(' ')[1];
          const currTotal = (totalItem.isUninitialized) ? Quantity('0 ' + unit) : totalItem.quantityState;
          const reading = Quantity(rawReading.toString());
          const lastReading = Quantity(rawLastReading.toString());
          const delta = (reading.lessThanOrEqual(lastReading)) ? reading : (reading.subtract(lastReading));
          total = currTotal.add(delta);
        }


        // Plain Numbers

        else {
          const currTotal = (totalItem.isUnitialized) ? 0 : totalItem.numericState;
          const reading = rawReading.floatValue();
          const lastReading = rawLastReading.floatValue();
          const delta = (reading <= lastReading) ? reading : (reading - lastReading);
          total = currTotal + delta;
        }


        totalItem.postUpdate(total);
    type: script.ScriptAction