Download counts: add computations for weekly downloads

app/lib/fake/backend/fake_download_counts.dart

@@ -5,7 +5,7 @@
 import 'dart:io';
 
 import 'package:gcloud/storage.dart';
-import 'package:pub_dev/service/download_counts/compute_30_days_total_counts.dart';
+import 'package:pub_dev/service/download_counts/computations.dart';
 import 'package:pub_dev/shared/configuration.dart';
 import 'package:pub_dev/shared/utils.dart';
 

app/lib/service/download_counts/backend.dart

@@ -7,7 +7,7 @@ import 'dart:convert';
 import 'package:gcloud/service_scope.dart' as ss;
 import 'package:gcloud/storage.dart';
 import 'package:googleapis/storage/v1.dart';
-import 'package:pub_dev/service/download_counts/compute_30_days_total_counts.dart';
+import 'package:pub_dev/service/download_counts/computations.dart';
 import 'package:pub_dev/service/download_counts/download_counts.dart';
 import 'package:pub_dev/service/download_counts/models.dart';
 import 'package:pub_dev/service/entrypoint/analyzer.dart';

app/lib/service/download_counts/compute_30_days_total_counts.dart → app/lib/service/download_counts/computations.dart

@@ -42,3 +42,32 @@ Future<void> upload30DaysTotal(Map<String, int> counts) async {
   await uploadBytesWithRetry(reportsBucket, downloadCounts30DaysTotalsFileName,
       jsonUtf8Encoder.convert(counts));
 }
+
+/// Computes `weeklyDownloads` starting from `newestDate` for [package].
+///
+/// Each number in `weeklyDownloads` is the total number of downloads for
+/// a given 7 day period starting from the newest date with download counts
+/// data available.
+Future<({List<int> weeklyDownloads, DateTime? newestDate})>
+    computeWeeklyDownloads(String package) async {
+  final weeklyDownloads = List.filled(52, 0);
+  final countData =
+      await downloadCountsBackend.lookupDownloadCountData(package);
+  if (countData == null) {
+    return (weeklyDownloads: <int>[], newestDate: null);
+  }
+
+  final totals = countData.totalCounts;
+
+  for (int w = 0; w < 52; w++) {
+    var sum = 0;
+    for (int d = 0; d < 7; d++) {
+      if (totals[w * 7 + d] > 0) {
+        sum += totals[w * 7 + d];
+      }
+    }
+    weeklyDownloads[w] = sum;
+  }
+
+  return (weeklyDownloads: weeklyDownloads, newestDate: countData.newestDate!);
+}

app/lib/tool/neat_task/pub_dev_tasks.dart

@@ -8,7 +8,7 @@ import 'dart:io';
 import 'package:gcloud/service_scope.dart' as ss;
 import 'package:logging/logging.dart';
 import 'package:neat_periodic_task/neat_periodic_task.dart';
-import 'package:pub_dev/service/download_counts/compute_30_days_total_counts.dart';
+import 'package:pub_dev/service/download_counts/computations.dart';
 
 import '../../account/backend.dart';
 import '../../account/consent_backend.dart';

app/test/service/download_counts/compute_total_download_counts_test.dart → app/test/service/download_counts/computations_test.dart

@@ -7,7 +7,7 @@ import 'package:basics/basics.dart';
 import 'package:gcloud/storage.dart';
 import 'package:pub_dev/fake/backend/fake_download_counts.dart';
 import 'package:pub_dev/service/download_counts/backend.dart';
-import 'package:pub_dev/service/download_counts/compute_30_days_total_counts.dart';
+import 'package:pub_dev/service/download_counts/computations.dart';
 import 'package:pub_dev/shared/configuration.dart';
 import 'package:test/test.dart';
 
@@ -119,5 +119,49 @@ void main() {
       expect(downloadCountsBackend.lookup30DaysTotalCounts('baz'), 150);
       expect(downloadCountsBackend.lookup30DaysTotalCounts('bax'), isNull);
     });
+
+    testWithProfile('compute weekly', fn: () async {
+      final pkg = 'foo';
+      final date = DateTime.parse('1986-02-16');
+      final versionsCounts = {
+        '1.0.1': 2,
+        '2.0.0-alpha': 2,
+        '2.0.0': 2,
+        '2.1.0': 2,
+        '3.1.0': 2,
+        '4.0.0-0': 2,
+        '6.1.0': 2,
+      };
+      final versionsCounts2 = {
+        '1.0.1': 3,
+        '2.0.0-alpha': 3,
+        '2.0.0': 3,
+        '2.1.0': 3,
+        '3.1.0': 3,
+        '4.0.0-0': 3,
+        '6.1.0': 3,
+      };
+
+      for (var i = 0; i <= 7 * 20; i++) {
+        await downloadCountsBackend.updateDownloadCounts(
+            pkg, versionsCounts, date.addCalendarDays(i));
+      }
+
+      for (var i = 7 * 20 + 1; i <= 7 * 40; i++) {
+        await downloadCountsBackend.updateDownloadCounts(
+            pkg, versionsCounts2, date.addCalendarDays(i));
+      }
+
+      final res = await computeWeeklyDownloads(pkg);
+
+      final expectedList = List.from(List.filled(20, 147))
+        ..addAll(List.filled(20, 98))
+        ..add(14)
+        ..addAll(List.filled(11, 0));
+      final expectedNewstDate = date.addCalendarDays(7 * 40);
+
+      expect(res.weeklyDownloads, expectedList);
+      expect(res.newestDate, expectedNewstDate);
+    });
   });
 }