Add logic 2 determine billable abstraction periods

app/services/supplementary-billing/abstraction-billing-period.service.js

@@ -0,0 +1,81 @@
+'use strict'
+
+/**
+ * Calculates billing periods needed when generating a supplementary bill run
+ * @module AbstractionBillingPeriodService
+ */
+
+function go (billingPeriod, chargePurpose) {
+  const abstractionPeriods = _abstractionPeriods(billingPeriod, chargePurpose)
+
+  _flagPeriodsForConsideration(billingPeriod, abstractionPeriods)
+
+  _calculateBillableDays(abstractionPeriods)
+
+  return abstractionPeriods
+}
+
+function _abstractionPeriods (billingPeriod, chargePurpose) {
+  const billingPeriodStartYear = billingPeriod.startDate.getFullYear()
+  const billingPeriodEndYear = billingPeriod.endDate.getFullYear()
+  const {
+    abstractionPeriodStartDay: startDay,
+    abstractionPeriodStartMonth: startMonth,
+    abstractionPeriodEndDay: endDay,
+    abstractionPeriodEndMonth: endMonth
+  } = chargePurpose
+  const firstPeriod = {}
+
+  if (endMonth === startMonth) {
+    if (endDay >= startDay) {
+      firstPeriod.startDate = new Date(billingPeriodEndYear, startMonth - 1, startDay)
+      firstPeriod.endDate = new Date(billingPeriodEndYear, endMonth - 1, endDay)
+    } else {
+      firstPeriod.startDate = new Date(billingPeriodStartYear, startMonth - 1, startDay)
+      firstPeriod.endDate = new Date(billingPeriodEndYear, endMonth - 1, endDay)
+    }
+  } else if (endMonth >= startMonth) {
+    firstPeriod.startDate = new Date(billingPeriodEndYear, startMonth - 1, startDay)
+    firstPeriod.endDate = new Date(billingPeriodEndYear, endMonth - 1, endDay)
+  } else {
+    firstPeriod.startDate = new Date(billingPeriodStartYear, startMonth - 1, startDay)
+    firstPeriod.endDate = new Date(billingPeriodEndYear, endMonth - 1, endDay)
+  }
+
+  const previousPeriod = {
+    startDate: _subtractOneYear(firstPeriod.startDate),
+    endDate: _subtractOneYear(firstPeriod.endDate)
+  }
+
+  return [previousPeriod, firstPeriod]
+}
+
+function _calculateBillableDays (abstractionPeriods) {
+  let difference
+  let billableDays
+  for (const abstractionPeriod of abstractionPeriods) {
+    difference = abstractionPeriod.endDate.getTime() - abstractionPeriod.startDate.getTime() // difference in msecs
+    billableDays = Math.ceil(difference / (1000 * 3600 * 24)) + 1 // (1000 msecs * (60 secs * 60 mins) * 24 hrs)
+    abstractionPeriod.billableDays = billableDays
+  }
+}
+
+function _flagPeriodsForConsideration (billingPeriod, abstractionPeriods) {
+  for (const abstractionPeriod of abstractionPeriods) {
+    if (abstractionPeriod.startDate > billingPeriod.endDate) {
+      abstractionPeriod.consider = false
+    } else if (abstractionPeriod.endDate < billingPeriod.startDate) {
+      abstractionPeriod.consider = false
+    } else {
+      abstractionPeriod.consider = true
+    }
+  }
+}
+
+function _subtractOneYear (date) {
+  return new Date(date.getFullYear() - 1, date.getMonth(), date.getDate())
+}
+
+module.exports = {
+  go
+}