Make getCycleLenghts filter for max cycle length

lib/cycle.js

@@ -1,5 +1,5 @@
 import * as joda from 'js-joda'
-import {getCycleLengthStats} from './cycle-length'
+import { getCycleLengthStats } from './cycle-length'
 const LocalDate = joda.LocalDate
 const DAYS = joda.ChronoUnit.DAYS
 
@@ -142,24 +142,19 @@ export default function config(opts) {
   function getAllCycleLengths() {
     return cycleStartsSortedByDate
       .map(day => LocalDate.parse(day.date))
-      .reduce((lengths, cycleStart, i, startsAsLocalDates) => {
-        if (i === startsAsLocalDates.length - 1) return lengths
+      .map((cycleStart, i, startsAsLocalDates) => {
+        if (i === cycleStartsSortedByDate.length - 1) return null
         const prevCycleStart = startsAsLocalDates[i + 1]
-        const cycleLength = prevCycleStart.until(cycleStart, DAYS)
-        if (cycleLength <= maxCycleLength) { lengths.push(cycleLength) }
-        return lengths
-      }, [])
+        return prevCycleStart.until(cycleStart, DAYS)
+      })
+      .filter(length => length && length <= maxCycleLength)
   }
 
   function getPredictedMenses() {
-    const allMensesStarts = cycleStartsSortedByDate
-    const atLeastOneCycle = allMensesStarts.length > 1
-    if (!atLeastOneCycle ||
-      allMensesStarts.length < minCyclesForPrediction
-    ) {
+    const cycleLengths = getAllCycleLengths()
+    if (cycleLengths.length < minCyclesForPrediction) {
       return []
     }
-    const cycleLengths = getAllCycleLengths()
     const cycleInfo = getCycleLengthStats(cycleLengths)
     const periodDistance = Math.round(cycleInfo.mean)
     let periodStartVariation
@@ -173,6 +168,7 @@ export default function config(opts) {
     if (periodDistance - 5 < periodStartVariation) { // otherwise predictions overlap
       return []
     }
+    const allMensesStarts = cycleStartsSortedByDate
     let lastStart = LocalDate.parse(allMensesStarts[0].date)
     const predictedMenses = []
     for (let i = 0; i < 3; i++) {