perf: use cache to fetch historical velocity aggregation data

Author: NoamGaash

src/pages/velocityHeatmap/index.tsx

@@ -25,7 +25,7 @@ const VelocityHeatmapPage: React.FC = () => {
   const [max, setMax] = useState(1)
 
   const handleTimestampChange = (time: dayjs.Dayjs | null) => {
-    setSearch((current) => ({ ...current, timestamp: time?.valueOf() ?? Date.now() }))
+    setSearch((current) => ({ ...current, timestamp: time?.valueOf() ?? +new Date('2026-01-01') }))
   }
 
   return (

src/pages/velocityHeatmap/useVelocityAggregationData.ts

@@ -1,3 +1,4 @@
+import { SiriVelocityAggregationPydanticModel } from '@hasadna/open-bus-api-client'
 import { useQuery } from '@tanstack/react-query'
 import { SIRI_API } from 'src/api/apiConfig'
 import dayjs from 'src/dayjs'
@@ -9,31 +10,15 @@ export interface VelocityAggregationBounds {
   maxLon: number
 }
 
+const cacheDomain = 'https://docbuvbfdq5r6.cloudfront.net/'
+
 export function useVelocityAggregationData(
   bounds: VelocityAggregationBounds,
   timestamp: dayjs.Dayjs,
   zoom: number,
 ) {
   const { data, isLoading, error } = useQuery({
-    queryFn: async () => {
-      const data =
-        await SIRI_API.velocityAggregationSiriVelocityAggregationSiriVelocityAggregationGet({
-          recordedFrom: timestamp.toDate(),
-          lonMin: bounds.minLon,
-          lonMax: bounds.maxLon,
-          latMin: bounds.minLat,
-          latMax: bounds.maxLat,
-          roundingPrecision: zoom,
-        }).then((data) => data.filter((p) => p.totalSampleCount > 4))
-
-      if (data.length === 0) {
-        throw new Error(
-          'No data points with more than 4 samples found in the specified area. Try expanding the area.',
-        )
-      }
-
-      return data
-    },
+    queryFn: queryFn.bind(null, bounds, timestamp, zoom),
     queryKey: [
       'velocity_aggregation',
       bounds.minLon,
@@ -42,8 +27,66 @@ export function useVelocityAggregationData(
       bounds.maxLat,
       zoom,
       timestamp.toString(),
+      'v2',
     ],
   })
 
   return { data, loading: isLoading, error, currZoom: zoom }
 }
+
+function snakeToCamel(o: SiriVelocityAggregationPydanticModel) {
+  return Object.fromEntries(
+    Object.entries(o).map(([k, v]) => {
+      const newKey = k.replace(/(_\w)/g, (m) => m[1].toUpperCase())
+      return [newKey, v]
+    }),
+  )
+}
+
+async function loadFromCache(
+  bounds: VelocityAggregationBounds,
+  timestamp: dayjs.Dayjs,
+  zoom: number,
+) {
+  const dataFromCache = await fetch(
+    `${cacheDomain}siri_velocity_aggregation/siri_velocity_aggregation?recorded_from=${encodeURIComponent(
+      timestamp.toISOString(),
+    )}&lon_min=${bounds.minLon}&lon_max=${bounds.maxLon}&lat_min=${bounds.minLat}&lat_max=${bounds.maxLat}&rounding_precision=${zoom}`,
+  )
+    .then(async (res) => {
+      if (!res.ok) {
+        throw new Error('No cached data found')
+      }
+      const rawResult = (await res.json()) as SiriVelocityAggregationPydanticModel[]
+      return rawResult.map(snakeToCamel)
+    })
+    .catch(() => null)
+
+  return dataFromCache
+}
+
+async function queryFn(bounds: VelocityAggregationBounds, timestamp: dayjs.Dayjs, zoom: number) {
+  // only try cached data if date is in the past
+  if (timestamp.isBefore(dayjs('yesterday'))) {
+    const cachedData = await loadFromCache(bounds, timestamp, zoom)
+    if (cachedData) {
+      return cachedData
+    }
+  }
+  const data = await SIRI_API.velocityAggregationSiriVelocityAggregationSiriVelocityAggregationGet({
+    recordedFrom: timestamp.toDate(),
+    lonMin: bounds.minLon,
+    lonMax: bounds.maxLon,
+    latMin: bounds.minLat,
+    latMax: bounds.maxLat,
+    roundingPrecision: zoom,
+  }).then((data) => data.filter((p) => p.totalSampleCount > 4))
+
+  if (data.length === 0) {
+    throw new Error(
+      'No data points with more than 4 samples found in the specified area. Try expanding the area.',
+    )
+  }
+
+  return data
+}