From 441f059f32c05892031cfdffb5c0017a98072229 Mon Sep 17 00:00:00 2001
From: Erik Escoffier <me@erik.nz>
Date: Mon, 25 Sep 2023 16:25:35 +0200
Subject: [PATCH] Return the guessed number of items based on collection
 metadata

---
 .../define/use-stac-collection-search.ts      | 50 +++++++++++++++++--
 .../analysis/results/timeseries-data.ts       |  2 +-
 2 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/app/scripts/components/analysis/define/use-stac-collection-search.ts b/app/scripts/components/analysis/define/use-stac-collection-search.ts
index 2fed3097f..975172783 100644
--- a/app/scripts/components/analysis/define/use-stac-collection-search.ts
+++ b/app/scripts/components/analysis/define/use-stac-collection-search.ts
@@ -4,8 +4,9 @@ import axios from 'axios';
 import { useQuery } from '@tanstack/react-query';
 import booleanIntersects from '@turf/boolean-intersects';
 import bboxPolygon from '@turf/bbox-polygon';
-import { areIntervalsOverlapping } from 'date-fns';
+import { areIntervalsOverlapping, eachDayOfInterval, eachMonthOfInterval, eachYearOfInterval } from 'date-fns';
 
+import { TimeseriesDataResult } from '../results/timeseries-data';
 import { allAvailableDatasetsLayers } from '.';
 
 import { utcString2userTzDate } from '$utils/date';
@@ -16,6 +17,12 @@ interface UseStacSearchProps {
   aoi?: FeatureCollection<Polygon> | null;
 }
 
+const DATE_INTERVAL_FN = {
+  day: eachDayOfInterval,
+  month: eachMonthOfInterval,
+  year: eachYearOfInterval
+};
+
 const collectionUrl = `${process.env.API_STAC_ENDPOINT}/collections`;
 
 export function useStacCollectionSearch({
@@ -47,13 +54,36 @@ export function useStacCollectionSearch({
     }
   }, [result.data, aoi, start, end]);
 
+  const selectableDatasetLayersWithNumberOfItems = selectableDatasetLayers.map(
+    (l) => {
+      const numberOfItems = getNumberOfItemsWithinTimeRange(
+        start,
+        end,
+        l
+      );
+      return { ...l, numberOfItems };
+    }
+  );
+
   return {
-    selectableDatasetLayers: selectableDatasetLayers,
+    selectableDatasetLayers: selectableDatasetLayersWithNumberOfItems,
     stacSearchStatus: result.status,
     readyToLoadDatasets
   };
 }
 
+function getNumberOfItemsWithinTimeRange(start, end, collection) {
+  const {isPeriodic, timeDensity, domain, timeseries} = collection;
+  if (!isPeriodic) {
+    return timeseries.length; // Check in with back-end team
+  }
+  const eachOf = DATE_INTERVAL_FN[timeDensity];
+  const statStart = +(new Date(domain[0])) > +(new Date(start))? new Date(domain[0]): new Date(start);
+  const statEnd = +(new Date(domain[1])) < +(new Date(end))? new Date(domain[1]): new Date(end);
+
+  return eachOf({start: statStart, end: statEnd}).length;
+}
+
 function getInTemporalAndSpatialExtent(collectionData, aoi, timeRange) {
   const matchingCollectionIds = collectionData.reduce((acc, col) => {
     const id = col.id;
@@ -95,7 +125,21 @@ function getInTemporalAndSpatialExtent(collectionData, aoi, timeRange) {
     }
   }, []);
 
-  return allAvailableDatasetsLayers.filter((l) =>
+  const filteredDatasets = allAvailableDatasetsLayers.filter((l) =>
     matchingCollectionIds.includes(l.stacCol)
   );
+
+  const filteredDatasetsWithCollections: TimeseriesDataResult[] =
+    filteredDatasets.map((l) => {
+      const collection = collectionData.find((c) => c.id === l.stacCol);
+      return {
+        ...l,
+        isPeriodic: collection['dashboard:is_periodic'],
+        timeDensity: collection['dashboard:time_density'],
+        domain: collection.extent.temporal.interval[0],
+        timeseries: collection.summaries.datetime
+      };
+    });
+
+  return filteredDatasetsWithCollections;
 }
diff --git a/app/scripts/components/analysis/results/timeseries-data.ts b/app/scripts/components/analysis/results/timeseries-data.ts
index 8fc621d32..628c7e4b4 100644
--- a/app/scripts/components/analysis/results/timeseries-data.ts
+++ b/app/scripts/components/analysis/results/timeseries-data.ts
@@ -30,7 +30,7 @@ export interface TimeseriesDataUnit {
   percentile_98: number;
 }
 
-interface TimeseriesDataResult {
+export interface TimeseriesDataResult {
   isPeriodic: boolean;
   timeDensity: TimeDensity;
   domain: string[];