refactor: price chart utility functions (#7266)

* refactor: price chart utility functions

* fix: snapshot

* fix: combine useMemos

* fix: pr nits

src/components/Charts/PriceChart/utils.ts

-import { timeDay, timeHour, TimeInterval, timeMinute, timeMonth } from 'd3'
-import { TimePeriod } from 'graphql/data/util'
+import { bisector, ScaleLinear, timeDay, timeHour, TimeInterval, timeMinute, timeMonth } from 'd3'
+import { PricePoint, TimePeriod } from 'graphql/data/util'
+
+/**
+ * Returns the minimum and maximum values in the given array of PricePoints.
+ */
+export function getPriceBounds(prices: PricePoint[]): { min: number; max: number } {
+  if (!prices.length) return { min: 0, max: 0 }
+
+  let min = prices[0].value
+  let max = prices[0].value
+
+  for (const pricePoint of prices) {
+    if (pricePoint.value < min) {
+      min = pricePoint.value
+    }
+    if (pricePoint.value > max) {
+      max = pricePoint.value
+    }
+  }
+
+  return { min, max }
+}
+
+/**
+ * Cleans an array of PricePoints by removing zero values and marking gaps in data as blanks.
+ *
+ * @param prices - The original array of PricePoints
+ * @returns An object containing two arrays: fixedChart and blanks
+ */
+export function cleanPricePoints(prices: PricePoint[]) {
+  const validPrices: PricePoint[] = [] // PricePoint array with 0 values removed
+  const blanks: [PricePoint, PricePoint][] = [] // PricePoint pairs that represent blank spaces in the chart
+  let lastValidPrice: PricePoint | undefined
+
+  prices.forEach((pricePoint, index) => {
+    if (pricePoint.value !== 0) {
+      const isFirstValidPrice = validPrices.length === 0
+
+      if (isFirstValidPrice && index !== 0) {
+        const blankStart = { timestamp: prices[0].timestamp, value: pricePoint.value }
+        blanks.push([blankStart, pricePoint])
+      }
+
+      lastValidPrice = pricePoint
+      validPrices.push(pricePoint)
+    }
+  })
+
+  if (lastValidPrice) {
+    const isLastPriceInvalid = lastValidPrice !== prices[prices.length - 1]
+
+    if (isLastPriceInvalid) {
+      const blankEnd = { timestamp: prices[prices.length - 1].timestamp, value: lastValidPrice.value }
+      blanks.push([lastValidPrice, blankEnd])
+    }
+  }
+
+  return { prices: validPrices, blanks, lastValidPrice }
+}
+
+/**
+ * Retrieves the nearest PricePoint to a given x-coordinate based on a linear time scale.
+ *
+ * @param x - The x-coordinate to find the nearest PricePoint for.
+ * @param prices - An array of PricePoints, assumed to be sorted by timestamp.
+ * @param timeScale - A D3 ScaleLinear instance for time scaling.
+ * @returns The nearest PricePoint to the given x-coordinate.
+ */
+export function getNearestPricePoint(
+  x: number,
+  prices: PricePoint[],
+  timeScale: ScaleLinear<number, number, never>
+): PricePoint | undefined {
+  // Convert the x-coordinate back to a timestamp
+  const targetTimestamp = timeScale.invert(x)
+
+  // Use bisector for O(log N) complexity, assumes prices are sorted by timestamp
+  const bisect = bisector((d: PricePoint) => d.timestamp).left
+  const index = bisect(prices, targetTimestamp, 1)
+
+  // Get potential nearest PricePoints
+  const previousPoint = prices[index - 1]
+  const nextPoint = prices[index]
+
+  // Default to the previous point if next point doesn't exist
+  if (!nextPoint) {
+    return previousPoint
+  }
+
+  // Calculate temporal distances to target timestamp
+  const distanceToPrevious = Math.abs(targetTimestamp.valueOf() - previousPoint.timestamp.valueOf())
+  const distanceToNext = Math.abs(nextPoint.timestamp.valueOf() - targetTimestamp.valueOf())
+
+  // Return the PricePoint with the smallest temporal distance to targetTimestamp
+  return distanceToPrevious < distanceToNext ? previousPoint : nextPoint
+}
 
 const fiveMinutes = timeMinute.every(5)
 const TIME_PERIOD_INTERVAL_TABLE: Record<TimePeriod, { interval: TimeInterval; step: number }> = {

src/components/Charts/SparklineChart.tsx

@@ -5,8 +5,8 @@ import { PricePoint } from 'graphql/data/util'
 import { memo } from 'react'
 import styled, { useTheme } from 'styled-components'
 
-import { getPriceBounds } from '../Tokens/TokenDetails/PriceChart'
 import LineChart from './LineChart'
+import { getPriceBounds } from './PriceChart/utils'
 
 const LoadingContainer = styled.div`
   height: 100%;
@@ -48,7 +48,9 @@ function _SparklineChart({ width, height, tokenData, pricePercentChange, sparkli
       // the range of possible output values that the inputs should be transformed to (see https://www.d3indepth.com/scales/ for details)
       [0, 110]
     )
-  const rdScale = scaleLinear().domain(getPriceBounds(pricePoints)).range([30, 0])
+
+  const { min, max } = getPriceBounds(pricePoints)
+  const rdScale = scaleLinear().domain([min, max]).range([30, 0])
   const curveTension = 0.9
 
   return (

src/components/Tokens/TokenDetails/PriceChart.tsx

@@ -7,9 +7,9 @@ import { Line } from '@visx/shape'
 import AnimatedInLineChart from 'components/Charts/AnimatedInLineChart'
 import FadedInLineChart from 'components/Charts/FadeInLineChart'
 import { getTimestampFormatter, TimestampFormatterType } from 'components/Charts/PriceChart/format'
-import { getTicks } from 'components/Charts/PriceChart/utils'
+import { cleanPricePoints, getNearestPricePoint, getPriceBounds, getTicks } from 'components/Charts/PriceChart/utils'
 import { MouseoverTooltip } from 'components/Tooltip'
-import { bisect, curveCardinal, scaleLinear } from 'd3'
+import { curveCardinal, scaleLinear } from 'd3'
 import { PricePoint, TimePeriod } from 'graphql/data/util'
 import { useActiveLocale } from 'hooks/useActiveLocale'
 import { ReactNode, useCallback, useEffect, useMemo, useState } from 'react'
@@ -23,13 +23,6 @@ import { calculateDelta, DeltaArrow, formatDelta } from './Delta'
 
 const DATA_EMPTY = { value: 0, timestamp: 0 }
 
-export function getPriceBounds(pricePoints: PricePoint[]): [number, number] {
-  const prices = pricePoints.map((x) => x.value)
-  const min = Math.min(...prices)
-  const max = Math.max(...prices)
-  return [min, max]
-}
-
 const ChartHeader = styled.div`
   position: absolute;
   ${textFadeIn};
@@ -65,29 +58,6 @@ const OutdatedPriceContainer = styled.div`
   line-height: 44px;
 `
 
-function fixChart(prices: PricePoint[] | undefined | null) {
-  if (!prices) return { prices: null, blanks: [] }
-
-  const fixedChart: PricePoint[] = []
-  const blanks: PricePoint[][] = []
-  let lastValue: PricePoint | undefined = undefined
-  for (let i = 0; i < prices.length; i++) {
-    if (prices[i].value !== 0) {
-      if (fixedChart.length === 0 && i !== 0) {
-        blanks.push([{ ...prices[0], value: prices[i].value }, prices[i]])
-      }
-      lastValue = prices[i]
-      fixedChart.push(prices[i])
-    }
-  }
-
-  if (lastValue && lastValue !== prices[prices.length - 1]) {
-    blanks.push([lastValue, { ...prices[prices.length - 1], value: lastValue.value }])
-  }
-
-  return { prices: fixedChart, blanks }
-}
-
 const margin = { top: 100, bottom: 48, crosshair: 72 }
 const timeOptionsHeight = 44
 
@@ -119,7 +89,8 @@ export function PriceChart({ width, height, prices: originalPrices, timePeriod }
   const theme = useTheme()
 
   const { prices, blanks } = useMemo(
-    () => (originalPrices && originalPrices.length > 0 ? fixChart(originalPrices) : { prices: null, blanks: [] }),
+    () =>
+      originalPrices && originalPrices.length > 0 ? cleanPricePoints(originalPrices) : { prices: null, blanks: [] },
     [originalPrices]
   )
 
@@ -180,34 +151,17 @@ export function PriceChart({ width, height, prices: originalPrices, timePeriod }
     [startingPrice, endingPrice, width]
   )
   // y scale
-  const rdScale = useMemo(
-    () =>
-      scaleLinear()
-        .domain(getPriceBounds(originalPrices ?? []))
-        .range([graphInnerHeight, 0]),
-    [originalPrices, graphInnerHeight]
-  )
+  const rdScale = useMemo(() => {
+    const { min, max } = getPriceBounds(originalPrices ?? [])
+    return scaleLinear().domain([min, max]).range([graphInnerHeight, 0])
+  }, [originalPrices, graphInnerHeight])
 
   const handleHover = useCallback(
     (event: Element | EventType) => {
       if (!prices) return
 
       const { x } = localPoint(event) || { x: 0 }
-      const x0 = timeScale.invert(x) // get timestamp from the scalexw
-      const index = bisect(
-        prices.map((x) => x.timestamp),
-        x0,
-        1
-      )
-
-      const d0 = prices[index - 1]
-      const d1 = prices[index]
-      let pricePoint = d0
-
-      const hasPreviousData = d1 && d1.timestamp
-      if (hasPreviousData) {
-        pricePoint = x0.valueOf() - d0.timestamp.valueOf() > d1.timestamp.valueOf() - x0.valueOf() ? d1 : d0
-      }
+      const pricePoint = getNearestPricePoint(x, prices, timeScale)
 
       if (pricePoint) {
         setCrosshair(timeScale(pricePoint.timestamp))

src/components/Tokens/TokenTable/__snapshots__/TokenRow.test.tsx.snap

@@ -2,15 +2,7 @@
 
 exports[`LoadedRow.tsx renders a row 1`] = `
 <DocumentFragment>
-  .c18 {
-  color: #40B66B;
-}
-
-.c19 {
-  color: #40B66B;
-}
-
-.c9 {
+  .c9 {
   opacity: 0;
   -webkit-transition: opacity 250ms ease-in;
   transition: opacity 250ms ease-in;
@@ -50,6 +42,14 @@ exports[`LoadedRow.tsx renders a row 1`] = `
   display: none;
 }
 
+.c18 {
+  color: #40B66B;
+}
+
+.c19 {
+  color: #40B66B;
+}
+
 .c2 {
   display: -webkit-box;
   display: -webkit-flex;