Optimize data fetching

backend/controllers/getCongestion.js

@@ -1,52 +1,22 @@
-const axios = require("axios");
-const API_URL = "https://route.ls.hereapi.com/routing/7.2/calculateroute.json";
+const getColorForPercentage = require("../utils/getColorForPercentage");
 
-async function getCongestionData(route, results, departureTime) {
-  let promises = [];
-  for (let i = 0; i < route.length; i++) {
-    let p = axios.get(API_URL, {
-      params: {
-        waypoint0: `${route[i].begin.lat},${route[i].begin.lng}`,
-        waypoint1: `${route[i].end.lat},${route[i].end.lng}`,
-        mode: "fastest;car;traffic:enabled",
-        apiKey: process.env.here_api_key,
-        departure: departureTime,
-      },
-    });
-    promises.push(p);
-  }
-  try {
-    let responses = await Promise.all(promises);
-    let result = [];
-    for (let i = 0; i < route.length; i++) {
-      let { baseTime, travelTime } = responses[
-        i
-      ].data.response.route[0].summary;
-      let congestionValue = travelTime / baseTime;
-      let congestionColor =
-        route[i].transport.mode === "pedestrian"
-          ? "green"
-          : getCongestionColor(congestionValue);
-
-      result = [...result, { ...route[i], congestionColor }];
-    }
-    results.push(result);
-  } catch (err) {
-    console.log(err);
-  }
-}
-async function calculateCongestion(routes, departureTime) {
-  let results = [];
-  for (let i = 0; i < routes.length; i++) {
-    await getCongestionData(routes[i], results, departureTime);
-  }
-  return results;
+async function calculateCongestion(congestionParams) {
+  const congestionData =
+    congestionParams && congestionParams.length
+      ? congestionParams.map((param, index) => {
+          const { baseDuration, duration } = param
+            ? param
+            : { baseDuration: 1, duration: 1 };
+          const congestionValue =
+            duration / baseDuration < 1 ? 1 : duration / baseDuration;
+          const normalizedCongestion = Math.min(congestionValue - 1, 1);
+          return {
+            congestionValue,
+            congestionColor: getColorForPercentage(normalizedCongestion),
+          };
+        })
+      : [];
+  return congestionData;
 }
 
-function getCongestionColor(congestionValue) {
-  if (congestionValue < 1.25) return "green";
-  else if (congestionValue >= 1.25 && congestionValue < 1.5) return "blue";
-  else if (congestionValue >= 1.5 && congestionValue < 2) return "orange";
-  else if (congestionValue >= 2) return "red";
-}
 module.exports = calculateCongestion;

backend/controllers/getPM2_5.js

@@ -10,7 +10,7 @@ exports.updateDatabase = async () => {
     let lat1 = 28.08652,
       lat2 = 28.921631,
       long1 = 76.730347,
-      long2 = 77.631226;
+      long2 = 77.631226; // bouding coordinates for delhi region
     const api_url = `https://api.waqi.info/map/bounds/?latlng=${lat1},${long1},${lat2},${long2}&token=${process.env.waqi_api_key}`;
     await axios
       .get(api_url)
@@ -41,7 +41,7 @@ exports.updateDatabase = async () => {
   // console.log(database);
 };
 
-exports.getPM2_5 = (lat, lng) => {
+exports.getPM2_5 = (lat, lng, currentDatabase) => {
   const x1 = lat;
   const y1 = lng;
 
@@ -58,7 +58,6 @@ exports.getPM2_5 = (lat, lng) => {
 
     return 12742 * Math.asin(Math.sqrt(a)); // 2 * R; R = 6371 km
   }
-  const currentDatabase = [...database]; // use contant value for a particular calculation as database is updated every 10 seconds
   for (let i = 0; i < currentDatabase.length; i++) {
     const x2 = currentDatabase[i].latitude;
     const y2 = currentDatabase[i].longitude;
@@ -84,19 +83,45 @@ exports.getPMColor = (routes = [], minPm, maxPm) => {
   routes.forEach((route) => {
     colorizedPmRoutes = [
       ...colorizedPmRoutes,
-      route && route.length > 0
-        ? route.map((section) => {
-            const normalizedPm =
-              maxPm > minPm ? (section.pmValue - minPm) / (maxPm - minPm) : -1;
-            return {
-              ...section,
-              normalizedPm,
-              pmColor: getColorForPercentage(normalizedPm),
-            };
-          })
-        : {},
+      {
+        ...route,
+        sections:
+          route.sections && route.sections.length > 0
+            ? route.sections.map((section) => {
+                const newSpans = section.spans.map((span) => {
+                  const normalizedPm =
+                    maxPm > minPm
+                      ? (span.pmValue - minPm) / (maxPm - minPm)
+                      : -1;
+                  return {
+                    ...span,
+                    pmColor: getColorForPercentage(normalizedPm),
+                  };
+                });
+                return {
+                  ...section,
+                  spans: newSpans,
+                };
+              })
+            : [],
+      },
     ];
   });
   // console.log(colorizedPmRoutes)
   return colorizedPmRoutes;
 };
+
+exports.calculatePmValuesList = async (locationsList) => {
+  const currentDatabase = [...database]; // use contant value for a particular calculation as database is updated every 10 seconds
+  const promises = locationsList.map((location) => {
+    return new Promise((resolve, reject) =>
+      resolve(this.getPM2_5(location.lat, location.lng, currentDatabase))
+    );
+  });
+  try {
+    const responses = await Promise.all(promises);
+    return responses;
+  } catch (err) {
+    console.log(err);
+  }
+};