Add new data formatters to base presenter (#350)

https://eaflood.atlassian.net/browse/WATER-4070
https://eaflood.atlassian.net/browse/WATER-4073

Whilst working on [Create endpoint to generate fake data](#347) we added a number of formatters. These take DB data and re-format it to match how the UI displays the values.

We will need these formatters in future changes we'll be making, the first of which is a re-designed bill run page.

So, to help prepare for that we are adding those formatters to our `BasePresenter` so they are available to any future presenters we add.

app/presenters/base.presenter.js

@@ -1,13 +1,60 @@
 'use strict'
 
 /**
- * Converts a date into the format required by output files, eg 25/03/2021 becomes 25-MAR-2021
+ * Converts a number which represents pence into pounds by dividing it by 100
  *
- * @param {Date} date The date value to format to a string
+ * This is such a simply calculation it could be done in place. But by having it as a named method we make it clear
+ * what we are doing rather than those that follow having to derive the intent.
+ *
+ * @param {Number} value
+ *
+ * @returns {Number} the value divided by 100
+ */
+function convertPenceToPounds (value) {
+  return value / 100
+}
+
+/**
+ * Formats an abstraction day and month into its string variant, for example, 1 and 4 becomes '1 April'
+ *
+ * @param {Number} abstractionDay
+ * @param {Number} abstractionMonth Note: the index starts at 1, for example, 4 would be April
+ *
+ * @returns {string} The abstraction date formatted as a 'DD MMMM' string
+ */
+function formatAbstractionDate (abstractionDay, abstractionMonth) {
+  // NOTE: Because of the unique qualities of Javascript, Year and Day are literal values, month is an index! So,
+  // January is actually 0, February is 1 etc. This is why we are always deducting 1 from the months.
+  const abstractionDate = new Date(1970, abstractionMonth - 1, abstractionDay)
+
+  return abstractionDate.toLocaleDateString('en-GB', { day: 'numeric', month: 'long' })
+}
+
+/**
+ * Formats an abstraction period into its string variant, for example, '1 April to 31 October'
+ *
+ * @param {Number} startDay
+ * @param {Number} startMonth
+ * @param {Number} endDay
+ * @param {Number} endMonth
+ *
+ * @returns {string} The abstraction period formatted as a 'DD MMMM to DD MMMM' string
+ */
+function formatAbstractionPeriod (startDay, startMonth, endDay, endMonth) {
+  const startDate = formatAbstractionDate(startDay, startMonth)
+  const endDate = formatAbstractionDate(endDay, endMonth)
+
+  return `${startDate} to ${endDate}`
+}
+
+/**
+ * Converts a date into the format required by the Charging Module, eg 25/03/2021 becomes 25-MAR-2021
+ *
+ * @param {Date} date The date to be formatted
  *
  * @returns {string} The date formatted as a 'DD-MMM-YYYY' string
  */
-function formatDate (date) {
+function formatChargingModuleDate (date) {
   // The output date format of methods such as toLocaleString() are based on the Unicode CLDR which is subject to
   // change and cannot be relied on to be consistent: https://github.com/nodejs/node/issues/42030. We therefore
   // generate the formatted date ourselves.
@@ -22,6 +69,31 @@ function formatDate (date) {
   return `${day}-${month}-${year}`
 }
 
+/**
+ * Formats a date into a human readable day, month and year string, for example, '12 September 2021'
+ *
+ * @param {Date} date The date to be formatted
+ *
+ * @returns {string} The date formatted as a 'DD MMMM YYYY' string
+ */
+function formatLongDate (date) {
+  return date.toLocaleDateString('en-GB', { year: 'numeric', month: 'long', day: 'numeric' })
+}
+
+/**
+ * Formats a number which represents a value in pounds as a money string, for example, 1149 as '1149.00'
+ *
+ * @param {Number} value The value to display as currency. Assumed to be in pounds
+ * @param {Boolean} includeSymbol Whether to add the £ symbol to the start of the returned string
+ *
+ * @returns {string} The value formatted as a money string with optional currency symbol
+ */
+function formatNumberAsMoney (value, includeSymbol = false) {
+  const symbol = includeSymbol ? '£' : ''
+
+  return `${symbol}${value.toFixed(2)}`
+}
+
 /**
  * Pads a number to a given length with leading zeroes and returns the result as a string
  *
@@ -37,6 +109,11 @@ function leftPadZeroes (number, length) {
 }
 
 module.exports = {
-  formatDate,
+  convertPenceToPounds,
+  formatAbstractionDate,
+  formatAbstractionPeriod,
+  formatChargingModuleDate,
+  formatLongDate,
+  formatNumberAsMoney,
   leftPadZeroes
 }

app/presenters/charging-module/create-transaction.presenter.js

@@ -1,6 +1,6 @@
 'use strict'
 
-const { formatDate } = require('../base.presenter.js')
+const { formatChargingModuleDate } = require('../base.presenter.js')
 
 /**
  * Formats a transaction object, generated by `FormatSrocTransactionLineService`, as a Charging Module API transaction
@@ -15,8 +15,8 @@ const { formatDate } = require('../base.presenter.js')
  * @returns {Object} an object that can be directly used as the body in a charging module POST transaction request
  */
 function go (transaction, billingPeriod, invoiceAccountNumber, licence) {
-  const periodStart = formatDate(billingPeriod.startDate)
-  const periodEnd = formatDate(billingPeriod.endDate)
+  const periodStart = formatChargingModuleDate(billingPeriod.startDate)
+  const periodEnd = formatChargingModuleDate(billingPeriod.endDate)
 
   return {
     clientId: transaction.billingTransactionId,

test/presenters/base.presenter.test.js

@@ -4,15 +4,67 @@
 const Lab = require('@hapi/lab')
 const Code = require('@hapi/code')
 
-const { describe, it } = exports.lab = Lab.script()
+const { describe, it, beforeEach } = exports.lab = Lab.script()
 const { expect } = Code
 
 // Thing under test
 const BasePresenter = require('../../app/presenters/base.presenter.js')
 
 describe('Base presenter', () => {
-  describe('#formatDate()', () => {
-    it('correctly formats dates', async () => {
+  describe('#convertPenceToPounds()', () => {
+    let valueInPence
+
+    describe('when the value divides evenly', () => {
+      beforeEach(() => {
+        valueInPence = 114900
+      })
+
+      it('correctly returns the value in pounds, for example, 1149', async () => {
+        const result = BasePresenter.convertPenceToPounds(valueInPence)
+
+        expect(result).to.equal(1149)
+      })
+    })
+
+    describe('when the value does not divide evenly', () => {
+      beforeEach(() => {
+        valueInPence = 114901
+      })
+
+      it('correctly returns the value in pounds, for example, 1149.01', async () => {
+        const result = BasePresenter.convertPenceToPounds(valueInPence)
+
+        expect(result).to.equal(1149.01)
+      })
+    })
+  })
+
+  describe('#formatAbstractionDate()', () => {
+    const day = 12
+    const month = 9
+
+    it('correctly formats the given date, for example, 12 September', async () => {
+      const result = BasePresenter.formatAbstractionDate(day, month)
+
+      expect(result).to.equal('12 September')
+    })
+  })
+
+  describe('#formatAbstractionPeriod()', () => {
+    const startDay = 1
+    const startMonth = 4
+    const endDay = 12
+    const endMonth = 9
+
+    it('correctly formats the given period, for example, 1 April to 12 September', async () => {
+      const result = BasePresenter.formatAbstractionPeriod(startDay, startMonth, endDay, endMonth)
+
+      expect(result).to.equal('1 April to 12 September')
+    })
+  })
+
+  describe('#formatChargingModuleDate()', () => {
+    it('correctly formats the given date, for example, 12-SEP-2021', async () => {
       // We check an array of dates, one for each month, to ensure that every month is formatted correctly
       const results = [
         new Date('2021-01-01T14:41:10.511Z'),
@@ -27,7 +79,7 @@ describe('Base presenter', () => {
         new Date('2021-10-12T14:41:10.511Z'),
         new Date('2021-11-12T14:41:10.511Z'),
         new Date('2021-12-12T14:41:10.511Z')
-      ].map(date => BasePresenter.formatDate(date))
+      ].map(date => BasePresenter.formatChargingModuleDate(date))
 
       expect(results).to.equal([
         '01-JAN-2021',
@@ -46,6 +98,34 @@ describe('Base presenter', () => {
     })
   })
 
+  describe('#formatLongDate()', () => {
+    it('correctly formats the given date, for example, 12 September 2021', async () => {
+      const result = BasePresenter.formatLongDate(new Date('2021-09-12T14:41:10.511Z'))
+
+      expect(result).to.equal('12 September 2021')
+    })
+  })
+
+  describe('#formatNumberAsMoney()', () => {
+    const valueInPence = 1149.5
+
+    describe('when no £ symbol is requested', () => {
+      it('correctly returns the value as a money string with no symbol, for example, 1149.50', async () => {
+        const result = BasePresenter.formatNumberAsMoney(valueInPence)
+
+        expect(result).to.equal('1149.50')
+      })
+    })
+
+    describe('when the £ symbol is requested', () => {
+      it('correctly returns the value as a money string with a symbol, for example, £1149.50', async () => {
+        const result = BasePresenter.formatNumberAsMoney(valueInPence, true)
+
+        expect(result).to.equal('£1149.50')
+      })
+    })
+  })
+
   describe('#leftPadZeroes()', () => {
     it('correctly pads numbers', async () => {
       const number = 123