Calculate and display expected charge during 2PT review - Part 2

app/controllers/bill-runs.controller.js

@@ -10,6 +10,7 @@ const Boom = require('@hapi/boom')
 const AmendAdjustmentFactorService = require('../services/bill-runs/two-part-tariff/amend-adjustment-factor.service.js')
 const AmendAuthorisedVolumeService = require('../services/bill-runs/two-part-tariff/amend-authorised-volume.service.js')
 const AmendBillableReturnsService = require('../services/bill-runs/two-part-tariff/amend-billable-returns.service.js')
+const CalculateChargeService = require('../services/bill-runs/two-part-tariff/calculate-charge.service.js')
 const CancelBillRunService = require('../services/bill-runs/cancel-bill-run.service.js')
 const ChargeReferenceDetailsService = require('../services/bill-runs/two-part-tariff/charge-reference-details.service.js')
 const CreateBillRunValidator = require('../validators/create-bill-run.validator.js')
@@ -130,6 +131,14 @@ async function matchDetails (request, h) {
   })
 }
 
+async function previewCharge (request, h) {
+  const { id: billRunId, licenceId, reviewChargeReferenceId } = request.params
+
+  await CalculateChargeService.go(licenceId, reviewChargeReferenceId, request.yar)
+
+  return h.redirect(`/system/bill-runs/${billRunId}/review/${licenceId}/charge-reference-details/${reviewChargeReferenceId}`)
+}
+
 async function removeLicence (request, h) {
   const { id: billRunId, licenceId } = request.params
 
@@ -306,6 +315,7 @@ module.exports = {
   create,
   index,
   matchDetails,
+  previewCharge,
   removeLicence,
   review,
   reviewLicence,

app/presenters/base.presenter.js

@@ -211,6 +211,17 @@ function formatPounds (valueInPence) {
   return valueInPounds.toFixed(2)
 }
 
+/**
+ * Formats a date into a DD/MM/YYYY string, for example, '01/04/2022'
+ *
+ * @param {Date} date The date to be formatted
+ *
+ * @returns {string} The date formatted as a 'DD/MM/YYYY' string
+ */
+function formatShortDate (date) {
+  return date.toLocaleDateString('en-GB', { year: 'numeric', month: '2-digit', day: '2-digit' })
+}
+
 /**
  * Pads a number to a given length with leading zeroes and returns the result as a string
  *
@@ -274,6 +285,7 @@ module.exports = {
   formatLongDateTime,
   formatMoney,
   formatPounds,
+  formatShortDate,
   leftPadZeroes,
   sentenceCase,
   titleCase

app/routes/bill-runs.routes.js

@@ -253,6 +253,19 @@ const routes = [
       description: 'Submit the amended billable return volumes on a charge element'
     }
   },
+  {
+    method: 'GET',
+    path: '/bill-runs/{id}/review/{licenceId}/preview-charge/{reviewChargeReferenceId}',
+    handler: BillRunsController.previewCharge,
+    options: {
+      auth: {
+        access: {
+          scope: ['billing']
+        }
+      },
+      description: 'Sends a request to the Charging Module to calculate the charge for a charge reference'
+    }
+  },
   {
     method: 'GET',
     path: '/bill-runs/{id}/send',

app/services/bill-runs/two-part-tariff/calculate-charge.service.js

@@ -0,0 +1,125 @@
+'use strict'
+
+/**
+ * Calculates the charge for a charge reference to display in a banner to the user
+ * @module CalculateChargeService
+ */
+
+const { ref } = require('objection')
+
+const CalculateChargeRequest = require('../../../requests/charging-module/calculate-charge.request.js')
+const { formatMoney, formatShortDate } = require('../../../presenters/base.presenter.js')
+const LicenceModel = require('../../../models/licence.model.js')
+const ReviewChargeReferenceModel = require('../../../models/review-charge-reference.model.js')
+
+/**
+ * Calculates the charge for a charge reference to display in a banner to the user
+ *
+ * It does this by sending a transaction based on the selected charge reference to the charging module so that it can
+ * calculate the charge. The charge amount is then added to to a flash message which will be displayed to the user.
+ *
+ * @param {String} licenceId - The UUID of the licence related to the charge
+ * @param {String} reviewChargeReferenceId - The UUID of the charge reference review data to calculate the charge on
+ * @param {Object} yar - The Hapi `request.yar` session manager passed on by the controller
+ */
+async function go (licenceId, reviewChargeReferenceId, yar) {
+  const reviewChargeReference = await _fetchReviewChargeReference(reviewChargeReferenceId)
+  const waterUndertaker = await _fetchWaterUndertaker(licenceId)
+  const calculatedCharge = await _calculateCharge(reviewChargeReference, waterUndertaker)
+
+  if (calculatedCharge) {
+    yar.flash('charge', `Based on this information the example charge is ${formatMoney(calculatedCharge)}.`)
+  }
+}
+
+function _calculateActualVolume (reviewChargeElements) {
+  return reviewChargeElements.reduce((total, reviewChargeElement) => {
+    total += reviewChargeElement.amendedAllocated
+
+    return total
+  }, 0)
+}
+
+async function _calculateCharge (reviewChargeReference, waterUndertaker) {
+  const transaction = {
+    abatementFactor: reviewChargeReference.abatementAgreement,
+    actualVolume: _calculateActualVolume(reviewChargeReference.reviewChargeElements),
+    adjustmentFactor: reviewChargeReference.amendedChargeAdjustment,
+    aggregateProportion: reviewChargeReference.amendedAggregate,
+    authorisedDays: 0, // 2PT uses volumes in the calculations rather than days so this can be set to 0
+    authorisedVolume: reviewChargeReference.amendedAuthorisedVolume,
+    billableDays: 0, // 2PT uses volumes in the calculations rather than days so this can be set to 0
+    chargeCategoryCode: reviewChargeReference.chargeReference.chargeCategory.reference,
+    compensationCharge: false, // Always false for the two-part tariff annual
+    credit: false,
+    loss: reviewChargeReference.chargeReference.loss,
+    periodStart: formatShortDate(reviewChargeReference.reviewChargeVersion.chargePeriodStartDate),
+    periodEnd: formatShortDate(reviewChargeReference.reviewChargeVersion.chargePeriodEndDate),
+    ruleset: 'sroc',
+    section127Agreement: reviewChargeReference.chargeReference.section127Agreement,
+    section130Agreement: reviewChargeReference.chargeReference.section130Agreement,
+    supportedSource: reviewChargeReference.chargeReference.supportedSourceName !== null,
+    // If `supportedSource` is `true` then `supportedSourceName` must be present
+    supportedSourceName: reviewChargeReference.chargeReference.supportedSourceName,
+    // If `twoPartTariff` is `true` then `section127Agreement` must also be `true`
+    twoPartTariff: reviewChargeReference.twoPartTariffAgreement,
+    waterCompanyCharge: reviewChargeReference.chargeReference.waterCompanyCharge !== null,
+    waterUndertaker,
+    winterOnly: reviewChargeReference.winterDiscount
+  }
+
+  const calculatedCharge = await CalculateChargeRequest.send(transaction)
+
+  if (calculatedCharge.succeeded) {
+    return calculatedCharge.response.body.calculation.chargeValue
+  } else {
+    return null
+  }
+}
+
+async function _fetchReviewChargeReference (reviewChargeReferenceId) {
+  return ReviewChargeReferenceModel.query()
+    .findById(reviewChargeReferenceId)
+    .select(
+      'abatementAgreement',
+      'amendedAggregate',
+      'amendedAuthorisedVolume',
+      'amendedChargeAdjustment',
+      'twoPartTariffAgreement',
+      'winterDiscount'
+    )
+    .withGraphFetched('chargeReference')
+    .modifyGraph('chargeReference', (builder) => {
+      builder.select(
+        'loss',
+        'section127Agreement',
+        'section130Agreement',
+        ref('chargeReferences.additionalCharges:supportedSource.name').castText().as('supportedSourceName'),
+        ref('chargeReferences.additionalCharges:isSupplyPublicWater').castText().as('waterCompanyCharge')
+      )
+    })
+    .withGraphFetched('chargeReference.chargeCategory')
+    .modifyGraph('chargeReference.chargeCategory', (builder) => {
+      builder.select('reference')
+    })
+    .withGraphFetched('reviewChargeVersion')
+    .modifyGraph('reviewChargeVersion', (builder) => {
+      builder.select('chargePeriodStartDate', 'chargePeriodEndDate')
+    })
+    .withGraphFetched('reviewChargeElements')
+    .modifyGraph('reviewChargeElements', (builder) => {
+      builder.select('amendedAllocated')
+    })
+}
+
+async function _fetchWaterUndertaker (licenceId) {
+  const licence = await LicenceModel.query()
+    .findById(licenceId)
+    .select('waterUndertaker')
+
+  return licence.waterUndertaker
+}
+
+module.exports = {
+  go
+}

app/services/bill-runs/two-part-tariff/charge-reference-details.service.js

@@ -28,10 +28,12 @@ async function go (billRunId, licenceId, reviewChargeReferenceId, yar) {
   } = await FetchReviewChargeReferenceService.go(billRunId, reviewChargeReferenceId)
 
   const [bannerMessage] = yar.flash('banner')
+  const [chargeMessage] = yar.flash('charge')
   const pageData = ChargeReferenceDetailsPresenter.go(billRun, reviewChargeReference, licenceId)
 
   return {
     bannerMessage,
+    chargeMessage,
     ...pageData
   }
 }

app/views/bill-runs/charge-reference-details.njk

@@ -22,6 +22,14 @@
     }) }}
   {% endif %}
 
+  {# Charge preview banner #}
+  {% if chargeMessage %}
+    {{ govukNotificationBanner({
+      titleText: 'Information',
+      text: chargeMessage
+    }) }}
+  {% endif %}
+
 <div class="govuk-grid-row">
   <div class="govuk-grid-column-full">
       <h1 class="govuk-heading-l">
@@ -76,8 +84,9 @@
     <span class="inline">
       {{ govukButton({
         text: "Preview the charge",
+        classes: "govuk-button--secondary",
         preventDoubleClick: true,
-        classes: "govuk-button--secondary"
+        href: "../preview-charge/" + chargeReference.id
       }) }}
     </span>
   </div>

test/controllers/bill-runs.controller.test.js

@@ -13,6 +13,7 @@ const AmendAdjustmentFactorService = require('../../app/services/bill-runs/two-p
 const AmendAuthorisedVolumeService = require('../../app/services/bill-runs/two-part-tariff/amend-authorised-volume.service.js')
 const AmendBillableReturnsService = require('../../app/services/bill-runs/two-part-tariff/amend-billable-returns.service.js')
 const Boom = require('@hapi/boom')
+const CalculateCharge = require('../../app/services/bill-runs/two-part-tariff/calculate-charge.service.js')
 const CancelBillRunService = require('../../app/services/bill-runs/cancel-bill-run.service.js')
 const ChargeReferenceDetailsService = require('../../app/services/bill-runs/two-part-tariff/charge-reference-details.service.js')
 const IndexBillRunsService = require('../../app/services/bill-runs/index-bill-runs.service.js')
@@ -717,6 +718,32 @@ describe('Bill Runs controller', () => {
     })
   })
 
+  describe('/bill-runs/{id}/review/{licenceId}/preview-charge/{reviewChargeReferenceId}', () => {
+    describe('GET', () => {
+      const licenceId = '87cb11cf-1e5e-448d-8050-29f4e681b416'
+      const reviewChargeReferenceId = '7c09753d-f606-4deb-a929-4bc8aa7acb8d'
+
+      beforeEach(async () => {
+        options = _options('GET', `review/${licenceId}/preview-charge/${reviewChargeReferenceId}`)
+      })
+
+      describe('when a request is valid', () => {
+        beforeEach(() => {
+          Sinon.stub(CalculateCharge, 'go').resolves()
+        })
+
+        it('redirects to the review charge reference details page', async () => {
+          const response = await server.inject(options)
+
+          expect(response.statusCode).to.equal(302)
+          expect(response.headers.location).to.equal(
+            `/system/bill-runs/97db1a27-8308-4aba-b463-8a6af2558b28/review/${licenceId}/charge-reference-details/${reviewChargeReferenceId}`
+          )
+        })
+      })
+    })
+  })
+
   describe('/bill-runs/{id}/send', () => {
     describe('GET', () => {
       beforeEach(async () => {

test/presenters/base.presenter.test.js

@@ -261,6 +261,14 @@ describe('Base presenter', () => {
     })
   })
 
+  describe('#formatShortDate()', () => {
+    it('correctly formats the given date, for example, 12/09/2021', async () => {
+      const result = BasePresenter.formatShortDate(new Date('2021-09-12T14:41:10.511Z'))
+
+      expect(result).to.equal('12/09/2021')
+    })
+  })
+
   describe('#formatMoney()', () => {
     let valueInPence