Allocate returns volumes to charge elements

app/services/check/allocate-returns-volumes.service.js

@@ -0,0 +1,54 @@
+'use strict'
+
+/**
+ * Used to allocate the abstraction volumes to the charge elements
+ * @module AllocateReturnsVolumes
+ */
+
+function go (chargeReference) {
+  let returnVolumeInMegalitres
+  // Loop through each return
+  chargeReference.returns.forEach((returnData) => {
+    // The volumes on the return are in Cubic Metres so we convert to Megalitres to match the charge version data
+    returnVolumeInMegalitres = returnData.volumes.total / 1000
+    // Loop through each charge element
+    chargeReference.chargeElements.forEach((chargeElement) => {
+      // Check the chargeElement is not already fully allocated
+      if (chargeElement.billableAnnualQuantity < chargeElement.authorisedAnnualQuantity) {
+        // Check if the return's purpose and abstraction period match the charge element
+        if (_matchReturnToElement(returnData.metadata, chargeElement)) {
+          // Calculate how much is left to allocated to the ChargeElement from the return
+          let volumeLeftToAllocate = chargeElement.authorisedAnnualQuantity - chargeElement.billableAnnualQuantity
+          // Check for the case that the return does not cover the full allocation
+          if (returnVolumeInMegalitres < volumeLeftToAllocate) {
+            volumeLeftToAllocate = returnVolumeInMegalitres
+          }
+
+          chargeElement.billableAnnualQuantity += volumeLeftToAllocate
+          returnVolumeInMegalitres -= volumeLeftToAllocate
+        }
+      }
+    })
+
+    if (returnVolumeInMegalitres > 0) {
+      // Convert any remaining volume back to Cubic Metres and add it to the volumes object
+      returnData.volumes.unallocated = returnVolumeInMegalitres * 1000
+    } else {
+      returnData.volumes.unallocated = 0
+    }
+  })
+}
+
+function _matchReturnToElement (returnMetadata, chargeElement) {
+  return (
+    returnMetadata.purposes[0].tertiary.code === chargeElement.purpose.legacyId &&
+    returnMetadata.nald.periodStartDay === chargeElement.abstractionPeriodStartDay.toString() &&
+    returnMetadata.nald.periodStartMonth === chargeElement.abstractionPeriodStartMonth.toString() &&
+    returnMetadata.nald.periodEndDay === chargeElement.abstractionPeriodEndDay.toString() &&
+    returnMetadata.nald.periodEndMonth === chargeElement.abstractionPeriodEndMonth.toString()
+  )
+}
+
+module.exports = {
+  go
+}

app/services/check/calculate-returns-volumes.service.js

@@ -38,9 +38,14 @@ function _calculateReturnLinesVolumes (lines, billableAbstractionPeriods) {
     }
   })
 
+  const inPeriod = _totalLineQuantities(inPeriodLines)
+  const outsidePeriod = _totalLineQuantities(outsidePeriodLines)
+  const total = inPeriod + outsidePeriod
+
   return {
-    inPeriod: _totalLineQuantities(inPeriodLines),
-    outsidePeriod: _totalLineQuantities(outsidePeriodLines)
+    inPeriod,
+    outsidePeriod,
+    total
   }
 }
 

app/services/check/friendly-response.service.js

@@ -108,6 +108,7 @@ function _formatFriendlyChargeElements (friendlyChargeElements, chargeElements)
   chargeElements.forEach((chargeElement) => {
     const {
       authorisedAnnualQuantity,
+      billableAnnualQuantity,
       chargePurposeId,
       description,
       isSection127AgreementEnabled,
@@ -124,7 +125,8 @@ function _formatFriendlyChargeElements (friendlyChargeElements, chargeElements)
       id: chargePurposeId,
       description,
       abstractionPeriod: formatAbstractionPeriod(startDay, startMonth, endDay, endMonth),
-      annualQuantities: authorisedAnnualQuantity,
+      authorisedAnnualQuantity,
+      billableAnnualQuantity,
       timeLimit: _formatTimeLimit(timeLimitedStartDate, timeLimitedEndDate),
       loss
     }

app/services/check/two-part.service.js

@@ -7,6 +7,7 @@
 
 const { ref } = require('objection')
 
+const AllocateReturnsVolumes = require('./allocate-returns-volumes.service.js')
 const CalculateReturnsVolumes = require('./calculate-returns-volumes.service.js')
 const ChargeReferenceModel = require('../../models/water/charge-reference.model.js')
 const ChargeVersionModel = require('../../models/water/charge-version.model.js')
@@ -126,6 +127,7 @@ async function _fetchAndApplyReturns (billingPeriod, chargeVersion) {
       })
 
     CalculateReturnsVolumes.go(billingPeriod, chargeReference.returns)
+    AllocateReturnsVolumes.go(chargeReference)
 
     const chargeReferenceReturnsStatuses = chargeReference.returns.map((matchedReturn) => {
       if (matchedReturn.underQuery) {