Fix bad hourly start timestamp on chart data (#75)

* Fix bad date string/timezone combo to AE query

* Remove formatDateTime and use dayjs#format instead

app/analytics/query.ts

@@ -42,30 +42,6 @@ function accumulateCountsFromRowResult(
  counts.views += Number(row.count);
 }
 
-/**
- * Convert a Date object to YY-MM-DD HH:MM:SS
- */
-function formatDateString(d: Date) {
- function pad(n: number) {
- return n < 10 ? "0" + n : n;
- }
- const dash = "-";
- const colon = ":";
- return (
- d.getFullYear() +
- dash +
- pad(d.getMonth() + 1) +
- dash +
- pad(d.getDate()) +
- " " +
- pad(d.getHours()) +
- colon +
- pad(d.getMinutes()) +
- colon +
- pad(d.getSeconds())
- );
-}
-
 function intervalToSql(interval: string, tz?: string) {
  let intervalSql = "";
  switch (interval) {
@@ -176,8 +152,8 @@ export class AnalyticsEngineAPI {
  async getViewsGroupedByInterval(
  siteId: string,
  intervalType: "DAY" | "HOUR",
- startDateTime: Date,
- tz?: string,
+ startDateTime: Date, // start date/time in local timezone
+ tz?: string, // local timezone
  ) {
  let intervalCount = 1;
 
@@ -206,24 +182,22 @@ export class AnalyticsEngineAPI {
  // to generate empty buckets in JS (generateEmptyRowsOverInterval)
  // and merge them with the results.
 
+ const utcStartDateTime = dayjs(startDateTime).tz(tz).utc();
+
  const query = `
  SELECT SUM(_sample_interval) as count,
 
  /* interval start needs local timezone, e.g. 00:00 in America/New York means start of day in NYC */
- toStartOfInterval(timestamp, INTERVAL '${intervalCount}' ${intervalType}, '${tz}') as _bucket,
-
- /* format output date as UTC (otherwise will be users local TZ) */
- toDateTime(_bucket, 'Etc/UTC') as bucket
+ toStartOfInterval(timestamp, INTERVAL '${intervalCount}' ${intervalType}) as bucket
 
  FROM metricsDataset
- WHERE timestamp > toDateTime('${formatDateString(startDateTime)}', '${tz}')
+ WHERE timestamp > toDateTime('${utcStartDateTime.format("YYYY-MM-DD HH:mm:ss")}')
  AND ${ColumnMappings.siteId} = '${siteId}'
- GROUP BY _bucket
- ORDER BY _bucket ASC`;
+ GROUP BY bucket
+ ORDER BY bucket ASC`;
 
  type SelectionSet = {
  count: number;
- _bucket: string;
  bucket: string;
  };
 
@@ -245,7 +219,9 @@ export class AnalyticsEngineAPI {
  const rowsByDateTime = responseData.data.reduce(
  (accum, row) => {
  const utcDateTime = new Date(row["bucket"]);
- const key = formatDateString(utcDateTime);
+ const key = dayjs(utcDateTime).format(
+ "YYYY-MM-DD HH:mm:ss",
+ );
  accum[key] = Number(row["count"]);
  return accum;
  },