wip: zen lite

1 files changed, 29 insertions, 0 deletions

diff --git a/packages/console/core/src/util/date.ts b/packages/console/core/src/util/date.ts
index 9c1ab12d2..dea9c390e 100644
--- a/packages/console/core/src/util/date.ts
+++ b/packages/console/core/src/util/date.ts
@@ -7,3 +7,32 @@ export function getWeekBounds(date: Date) {
   end.setUTCDate(start.getUTCDate() + 7)
   return { start, end }
 }
+
+export function getMonthlyBounds(now: Date, subscribed: Date) {
+  const day = subscribed.getUTCDate()
+  const hh = subscribed.getUTCHours()
+  const mm = subscribed.getUTCMinutes()
+  const ss = subscribed.getUTCSeconds()
+  const ms = subscribed.getUTCMilliseconds()
+
+  function anchor(year: number, month: number) {
+    const max = new Date(Date.UTC(year, month + 1, 0)).getUTCDate()
+    return new Date(Date.UTC(year, month, Math.min(day, max), hh, mm, ss, ms))
+  }
+
+  function shift(year: number, month: number, delta: number) {
+    const total = year * 12 + month + delta
+    return [Math.floor(total / 12), ((total % 12) + 12) % 12] as const
+  }
+
+  let y = now.getUTCFullYear()
+  let m = now.getUTCMonth()
+  let start = anchor(y, m)
+  if (start > now) {
+    ;[y, m] = shift(y, m, -1)
+    start = anchor(y, m)
+  }
+  const [ny, nm] = shift(y, m, 1)
+  const end = anchor(ny, nm)
+  return { start, end }
+}