chart.js

import React, { Component } from 'react'
import { View, FlatList, Text } from 'react-native'
import range from 'date-range'
import { LocalDate } from 'js-joda'
import { makeYAxisLabels, normalizeToScale, makeHorizontalGrid } from './y-axis'
import nfpLines from './nfp-lines'
import DayColumn from './day-column'
import { getCycleDay, cycleDaysSortedByDate, getAmountOfCycleDays } from '../../db'
import styles from './styles'
import { scaleObservable } from '../../local-storage'

export default class CycleChart extends Component {
  constructor(props) {
    super(props)
    this.state = {}
    this.renderColumn = ({item, index}) => {
      return (
        <DayColumn
          {...item}
          index={index}
          navigate={this.props.navigate}
          chartHeight={this.state.chartHeight}
        />
      )
    }
  }

  onLayout = ({ nativeEvent }) => {
    if (this.state.chartHeight) return

    const height = nativeEvent.layout.height
    this.setState({ chartHeight: height })
    this.reCalculateChartInfo = () => {
      this.setState({ columns: this.makeColumnInfo(nfpLines(height)) })
    }

    cycleDaysSortedByDate.addListener(this.reCalculateChartInfo)
    this.removeObvListener = scaleObservable(this.reCalculateChartInfo, false)
  }

  componentWillUnmount() {
    cycleDaysSortedByDate.removeListener(this.reCalculateChartInfo)
    this.removeObvListener()
  }

  makeColumnInfo(getFhmAndLtlInfo) {
    let amountOfCycleDays = getAmountOfCycleDays()
    // if there's not much data yet, we want to show at least 30 days on the chart
    if (amountOfCycleDays < 30) {
      amountOfCycleDays = 30
    } else {
      // we don't want the chart to end abruptly before the first data day
      amountOfCycleDays += 5
    }
    const jsDates = getTodayAndPreviousDays(amountOfCycleDays)
    const xAxisDates = jsDates.map(jsDate => {
      return LocalDate.of(
        jsDate.getFullYear(),
        jsDate.getMonth() + 1,
        jsDate.getDate()
      ).toString()
    })

    const columns = xAxisDates.map(dateString => {
      const cycleDay = getCycleDay(dateString)
      const symptoms = ['temperature', 'mucus', 'bleeding'].reduce((acc, symptom) => {
        acc[symptom] = cycleDay && cycleDay[symptom] && cycleDay[symptom].value
        acc[`${symptom}Exclude`] = cycleDay && cycleDay[symptom] && cycleDay[symptom].exclude
        return acc
      }, {})

      const temp = symptoms.temperature
      return {
        dateString,
        y: temp ? normalizeToScale(temp, this.state.chartHeight) : null,
        ...symptoms,
        ...getFhmAndLtlInfo(dateString, temp)
      }
    })

    return columns.map((col, i) => {
      const info = getInfoForNeighborColumns(i, columns)
      return Object.assign(col, info)
    })
  }

  render() {
    return (
      <View
        onLayout={this.onLayout}
        style={{ flexDirection: 'row', flex: 1 }}
      >
        {!this.state.chartHeight && <Text>Loading...</Text>}
        {this.state.chartHeight &&
          <View
            style={[styles.yAxis, {height: this.state.chartHeight}]}
          >
            {makeYAxisLabels(this.state.chartHeight)}
          </View>}

        {this.state.chartHeight && makeHorizontalGrid(this.state.chartHeight)}

        {this.state.chartHeight &&
          <FlatList
            horizontal={true}
            inverted={true}
            showsHorizontalScrollIndicator={false}
            data={this.state.columns}
            renderItem={this.renderColumn}
            keyExtractor={item => item.dateString}
            initialNumToRender={15}
            maxToRenderPerBatch={5}
          >
          </FlatList>
        }
      </View>
    )
  }
}


function getTodayAndPreviousDays(n) {
  const today = new Date()
  today.setHours(0)
  today.setMinutes(0)
  today.setSeconds(0)
  today.setMilliseconds(0)
  const earlierDate = new Date(today - (range.DAY * n))

  return range(earlierDate, today).reverse()
}

function getInfoForNeighborColumns(index, cols) {
  const ret = {
    rightY: null,
    rightTemperatureExclude: null,
    leftY: null,
    leftTemperatureExclude: null
  }
  const right = index > 0 ? cols[index - 1] : undefined
  const left = index < cols.length - 1 ? cols[index + 1] : undefined
  if (right && right.y) {
    ret.rightY = right.y
    ret.rightTemperatureExclude = right.temperatureExclude
  }
  if (left && left.y) {
    ret.leftY = left.y
    ret.leftTemperatureExclude = left.temperatureExclude
  }
  return ret
}