Moves out chart (data modelling) helpers to a separate file

components/chart/y-axis.js

@@ -2,8 +2,7 @@ import React from 'react'
 import PropTypes from 'prop-types'
 import { View } from 'react-native'
 
-import config from '../../config'
-import { scaleObservable, unitObservable } from '../../local-storage'
+import { getTickPositions } from '../helpers/chart'
 
 import SymptomIcon from './symptom-icon'
 import TickList from './tick-list'
@@ -11,44 +10,6 @@ import ChartLegend from './chart-legend'
 
 import styles from './styles'
 
-export function getTickList(columnHeight) {
-
-  const units = unitObservable.value
-  const scaleMax = scaleObservable.value.max
-
-  return getTickPositions(columnHeight).map((tickPosition, i) => {
-
-    const tick = scaleMax - i * units
-    let isBold, label, shouldShowLabel
-
-    if (Number.isInteger(tick)) {
-      isBold = true
-      label = tick.toString() + '.0'
-    } else {
-      isBold = false
-      label = tick.toString()
-    }
-
-    // when temp range <= 3, units === 0.1 we show temp values with step 0.2
-    // when temp range > 3, units === 0.5 we show temp values with step 0.5
-
-    if (units === 0.1) {
-      // show label with step 0.2
-      shouldShowLabel = !(tick * 10 % 2)
-    } else {
-      // show label with step 0.5
-      shouldShowLabel = !(tick * 10 % 5)
-    }
-
-    return {
-      position: tickPosition,
-      label,
-      isBold,
-      shouldShowLabel,
-    }
-  })
-}
-
 export function makeHorizontalGrid(columnHeight, symptomRowHeight) {
   return getTickPositions(columnHeight).map(tick => {
     return (
@@ -61,33 +22,6 @@ export function makeHorizontalGrid(columnHeight, symptomRowHeight) {
   })
 }
 
-function getTickPositions(columnHeight) {
-  const units = unitObservable.value
-  const scaleMin = scaleObservable.value.min
-  const scaleMax = scaleObservable.value.max
-  const numberOfTicks = (scaleMax - scaleMin) * (1 / units) + 1
-  const tickDistance = 1 / (numberOfTicks - 1)
-  const tickPositions = []
-  for (let i = 0; i < numberOfTicks; i++) {
-    const position = getAbsoluteValue(tickDistance * i, columnHeight)
-    tickPositions.push(position)
-  }
-  return tickPositions
-}
-
-export function normalizeToScale(temp, columnHeight) {
-  const scale = scaleObservable.value
-  const valueRelativeToScale = (scale.max - temp) / (scale.max - scale.min)
-  return getAbsoluteValue(valueRelativeToScale, columnHeight)
-}
-
-function getAbsoluteValue(relative, columnHeight) {
-  // we add some height to have some breathing room
-  const verticalPadding = columnHeight * config.temperatureScale.verticalPadding
-  const scaleHeight = columnHeight - 2 * verticalPadding
-  return scaleHeight * relative + verticalPadding
-}
-
 const YAxis = ({ height, symptomsToDisplay, symptomsSectionHeight }) => {
   const symptomIconHeight = symptomsSectionHeight / symptomsToDisplay.length
   return (