Adding a periods overlap helper

app/lib/general.lib.js

@@ -27,6 +27,30 @@ function generateUUID () {
   return randomUUID({ disableEntropyCache: true })
 }
 
+/**
+ * Checks if any of the periods in checkPeriods overlap with any period in referencePeriods
+ * @param {*} referencePeriods Array of objects representing periods with startDate and endDate properties
+ * @param {*} checkPeriods Array of objects representing periods to check with startDate and endDate properties
+ * @returns Returns true if there is an overlap, otherwise false
+ */
+function periodsOverlap (referencePeriods, checkPeriods) {
+  for (const referencePeriod of referencePeriods) {
+    const overLappingPeriods = checkPeriods.filter((checkPeriod) => {
+      if (checkPeriod.startDate > referencePeriod.endDate || referencePeriod.startDate > checkPeriod.endDate) {
+        return false
+      }
+
+      return true
+    })
+
+    if (overLappingPeriods.length) {
+      return true
+    }
+  }
+
+  return false
+}
+
 /**
  * Returns the current date and time as an ISO string
  *
@@ -44,5 +68,6 @@ function timestampForPostgres () {
 
 module.exports = {
   generateUUID,
+  periodsOverlap,
   timestampForPostgres
 }

test/lib/general.lib.test.js

@@ -48,4 +48,49 @@ describe('RequestLib', () => {
       expect(result).to.equal('2015-10-21T20:31:57.000Z')
     })
   })
+
+  describe('#periodsOverlap', () => {
+    let referencePeriod
+    let checkPeriod
+
+    describe('when given dates that do not overlap', () => {
+      beforeEach(() => {
+        referencePeriod = [{
+          startDate: new Date('2023-02-01'),
+          endDate: new Date('2023-02-02')
+        }]
+
+        checkPeriod = [{
+          startDate: new Date('2023-01-01'),
+          endDate: new Date('2023-01-31')
+        }]
+      })
+
+      it('returns false', () => {
+        const result = GeneralLib.periodsOverlap(referencePeriod, checkPeriod)
+
+        expect(result).to.equal(false)
+      })
+    })
+
+    describe('when given dates that do overlap', () => {
+      beforeEach(() => {
+        referencePeriod = [{
+          startDate: new Date('2023-01-01'),
+          endDate: new Date('2023-01-02')
+        }]
+
+        checkPeriod = [{
+          startDate: new Date('2023-01-01'),
+          endDate: new Date('2023-01-31')
+        }]
+      })
+
+      it('returns true', () => {
+        const result = GeneralLib.periodsOverlap(referencePeriod, checkPeriod)
+
+        expect(result).to.equal(true)
+      })
+    })
+  })
 })