Merge branch '109-display-stats-about-period-length' into 'master'

Resolve "add stats button on home screen and show stats about period length"

Closes #109

See merge request bloodyhealth/drip!41

app.js

@@ -5,6 +5,7 @@ import Calendar from './components/calendar'
 import CycleDay from './components/cycle-day'
 import Chart from './components/chart/chart'
 import Settings from './components/settings'
+import Stats from './components/stats'
 
 // this is until react native fixes this bugg, see
 // https://github.com/facebook/react-native/issues/18868#issuecomment-382671739
@@ -16,5 +17,6 @@ export default createStackNavigator({
   calendar: { screen: Calendar },
   cycleDay: { screen: CycleDay },
   chart: { screen: Chart },
-  settings: { screen: Settings }
+  settings: { screen: Settings },
+  stats: { screen: Stats}
 })

components/home.js

@@ -87,6 +87,12 @@ export default class Home extends Component {
               title="delete everything">
             </Button>
           </View>
+          <View style={styles.homeButton}>
+            <Button
+              onPress={() => navigate('stats')}
+              title="Go to stats">
+            </Button>
+          </View>
         </View>
       </ScrollView>
     )

components/stats.js

@@ -0,0 +1,51 @@
+import React, { Component } from 'react'
+import {
+  Text,
+  View,
+  ScrollView
+} from 'react-native'
+import { LocalDate, ChronoUnit } from 'js-joda'
+import styles from '../styles/index'
+import cycleModule from '../lib/cycle'
+import getCycleInfo from '../lib/cycle-length'
+
+export default class Stats extends Component {
+  render() {
+    const allMensesStarts = cycleModule().getAllMensesStarts()
+    const statsText = determineStatsText(allMensesStarts)
+    return (
+      <ScrollView>
+        <View>
+          <Text style={styles.stats}>{statsText}</Text>
+        </View>
+      </ScrollView>
+    )
+  }
+}
+
+function getCycleLength(cycleStartDates) {
+  const cycleLengths = []
+  for (let i = 0; i < cycleStartDates.length - 1; i++) {
+    const nextCycleStart = LocalDate.parse(cycleStartDates[i])
+    const cycleStart = LocalDate.parse(cycleStartDates[i + 1])
+    cycleLengths.push(cycleStart.until(nextCycleStart, ChronoUnit.DAYS))
+  }
+  return cycleLengths
+}
+
+function determineStatsText(allMensesStarts) {
+  const emptyStats = 'At least one completed cycle is needed to present you with stats here.'
+  if (allMensesStarts.length < 2) {
+    return emptyStats
+  } else {
+    const cycleLengths = getCycleLength(allMensesStarts)
+    const numberOfCycles = cycleLengths.length
+    if (numberOfCycles === 1) {
+      return `You have documented one cycle of ${cycleLengths[0]} days.`
+    }
+    const cycleInfo = getCycleInfo(cycleLengths)
+    const statsText = `Stats are based on ${numberOfCycles} completed cycles.\n\n\
+    Average cycle length: ${cycleInfo.mean} days\n\nShortest cycle: ${cycleInfo.minimum} days\nLongest cycle: ${cycleInfo.maximum} days\nMedian length (meaning 50% of cycles are of this length or shorter): ${cycleInfo.median} days\nStandard deviation: ${cycleInfo.stdDeviation}`
+    return statsText
+  }
+}

lib/cycle-length.js

@@ -1,38 +1,38 @@
 import assert from 'assert'
 
-export default function getPeriodLengthStats(cycleLengths) {
+export default function getCycleLengthStats(cycleLengths) {
   throwIfArgsAreNotInRequiredFormat(cycleLengths)
-  const periodLengthStats = {}
+  const cycleLengthStats = {}
   const sortedCycleLengths = cycleLengths.sort((a, b) => {
     return a - b
   })
-  periodLengthStats.minimum = sortedCycleLengths[0]
-  periodLengthStats.maximum = sortedCycleLengths[cycleLengths.length - 1]
-  periodLengthStats.mean = Math.round(
+  cycleLengthStats.minimum = sortedCycleLengths[0]
+  cycleLengthStats.maximum = sortedCycleLengths[cycleLengths.length - 1]
+  cycleLengthStats.mean = Math.round(
     cycleLengths.reduce(getSum) / cycleLengths.length * 100
   ) / 100
   // median
   if (cycleLengths.length % 2 == 1) {
-    periodLengthStats.median = sortedCycleLengths[
+    cycleLengthStats.median = sortedCycleLengths[
       (cycleLengths.length + 1) / 2 - 1
     ]
   } else {
     const middle = cycleLengths.length / 2
-    periodLengthStats.median = (sortedCycleLengths[middle - 1] +
+    cycleLengthStats.median = (sortedCycleLengths[middle - 1] +
        sortedCycleLengths[middle]) / 2
   }
   // corrected standard deviation (based on unbiased sample variance)
   if (cycleLengths.length > 1) {
     const sumOfSquares = cycleLengths.map(cycleLength => {
-      return Math.pow(cycleLength - periodLengthStats.mean, 2)
+      return Math.pow(cycleLength - cycleLengthStats.mean, 2)
     }).reduce(getSum)
-    periodLengthStats.stdDeviation = Math.round(
+    cycleLengthStats.stdDeviation = Math.round(
       Math.sqrt(sumOfSquares / (cycleLengths.length - 1 )) * 100
     ) / 100
   } else {
-    periodLengthStats.stdDeviation = null
+    cycleLengthStats.stdDeviation = null
   }
-  return periodLengthStats
+  return cycleLengthStats
 }
 
 function getSum(total, num) {

lib/cycle.js

@@ -130,10 +130,24 @@ export default function config(opts) {
     }
   }
 
+  function getAllMensesStarts(day, collectedDates) {
+    day = day || LocalDate.now().toString()
+    collectedDates = collectedDates || []
+    const lastStart = getLastMensesStart(day)
+    if (!lastStart) {
+      return collectedDates
+    } else {
+      const newDay = LocalDate.parse(lastStart.date).minusDays(1).toString()
+      collectedDates.push(lastStart.date)
+      return getAllMensesStarts(newDay, collectedDates)
+    }
+  }
+
   return {
     getCycleDayNumber,
     getCycleForDay,
     getPreviousCycle,
-    getCyclesBefore
+    getCyclesBefore,
+    getAllMensesStarts
   }
 }

styles/index.js

@@ -82,5 +82,11 @@ export default StyleSheet.create({
     marginTop: 15,
     marginLeft: 'auto',
     marginRight: 'auto'
+  },
+  stats: {
+    fontSize: 18,
+    margin: 30,
+    textAlign: 'left',
+    textAlignVertical: 'center'
   }
 })

test/cycle-length.spec.js

@@ -1,14 +1,14 @@
 import chai from 'chai'
 import { AssertionError } from 'assert'
 
-import periodInfo from '../lib/period-length'
+import cycleInfo from '../lib/cycle-length'
 
 const expect = chai.expect
 
-describe('getPeriodLengthStats', () => {
+describe('getCycleLengthStats', () => {
   it('works for a simple odd-numbered array', () => {
-    const periodLengths = [99, 5, 1, 2, 100]
-    const result = periodInfo(periodLengths)
+    const cycleLengths = [99, 5, 1, 2, 100]
+    const result = cycleInfo(cycleLengths)
     const expectedResult = {
       minimum: 1,
       maximum: 100,
@@ -20,8 +20,8 @@ describe('getPeriodLengthStats', () => {
   })
 
   it('works for a simple even-numbered array', () => {
-    const periodLengths = [4, 1, 15, 2, 20, 5]
-    const result = periodInfo(periodLengths)
+    const cycleLengths = [4, 1, 15, 2, 20, 5]
+    const result = cycleInfo(cycleLengths)
     const expectedResult = {
       minimum: 1,
       maximum: 20,
@@ -32,8 +32,8 @@ describe('getPeriodLengthStats', () => {
     expect(result).to.eql(expectedResult)
   })
   it('works for an one-element array', () => {
-    const periodLengths = [42]
-    const result = periodInfo(periodLengths)
+    const cycleLengths = [42]
+    const result = cycleInfo(cycleLengths)
     const expectedResult = {
       minimum: 42,
       maximum: 42,
@@ -45,20 +45,20 @@ describe('getPeriodLengthStats', () => {
   })
   describe('when args are wrong', () => {
     it('throws when arg object is an empty array', () => {
-      const periodLengths = []
-      expect(() => periodInfo(periodLengths).to.throw(AssertionError))
+      const cycleLengths = []
+      expect(() => cycleInfo(cycleLengths).to.throw(AssertionError))
     })
     it('throws when arg object is not in right format', () => {
       const wrongObject = { hello: 'world' }
-      expect(() => periodInfo(wrongObject).to.throw(AssertionError))
+      expect(() => cycleInfo(wrongObject).to.throw(AssertionError))
     })
     it('throws when arg array contains a string', () => {
       const wrongElement = [4, 1, 15, '2', 20, 5]
-      expect(() => periodInfo(wrongElement).to.throw(AssertionError))
+      expect(() => cycleInfo(wrongElement).to.throw(AssertionError))
     })
     it('throws when arg array contains a NaN', () => {
       const wrongElement = [4, 1, 15, NaN, 20, 5]
-      expect(() => periodInfo(wrongElement).to.throw(AssertionError))
+      expect(() => cycleInfo(wrongElement).to.throw(AssertionError))
     })
   })
 })