first exploration of place of feature and how to access data

lib/sympto-occurance.js

@@ -0,0 +1,44 @@
+import * as joda from '@js-joda/core'
+const LocalDate = joda.LocalDate
+// const DAYS = joda.ChronoUnit.DAYS
+
+export default function config(opts) {
+  let cycleStartsSortedByDate
+
+  if (!opts) {
+    // we only want to require (and run) the db module
+    // when not running the tests
+    cycleStartsSortedByDate = require('../db').getCycleStartsSortedByDate()
+    // maxCycleLength = 45
+  } else {
+    cycleStartsSortedByDate = opts.cycleStartsSortedByDate || []
+    // maxCycleLength = opts.maxCycleLength || 99
+  }
+
+  function getCycleStartsOfLastYear() {
+    const today = LocalDate.parse(new Date().toISOString().slice(0, 10))
+    const firstRelevantCycleStart = today.minusYears(1)
+    const relevantCycles = cycleStartsSortedByDate.filter(({ date }) =>
+      LocalDate.parse(date).isAfter(firstRelevantCycleStart)
+    )
+    return relevantCycles.map(({ date }) => date)
+  }
+
+  function getTodayDate() {
+    return new Date().toISOString().slice(0, 10)
+  }
+
+  const getStats = () =>
+    cycleStartsSortedByDate.map((day, i) => {
+      const today = getTodayDate()
+      return {
+        date: today,
+        k: i,
+      }
+    })
+
+  return {
+    getCycleStartsOfLastYear,
+    getStats,
+  }
+}