1 files changed, 39 insertions, 0 deletions
diff --git a/src/tasks.ts b/src/tasks.ts
new file mode 100644
index 0000000..b370aad
--- /dev/null
+++ b/src/tasks.ts
@@ -0,0 +1,39 @@
+import { add, parse, format, startOfWeek, addWeeks, isWithinInterval, Duration } from "date-fns";
+import { RecurringTask } from "./db";
+import config from "./config";
+
+const INTERVAL_ABBREVS: Record<string, number> = {
+  pv: 1,
+  vk: 7,
+  kk: 30,
+  v: 365,
+};
+
+export const now = (): Date => {
+  return new Date(new Date().toLocaleString("en-US", { timeZone: config.tz }));
+};
+
+export const parseInterval = (intervalStr: string): Duration => {
+  const match = /^(\d+)(pv|vk|kk|v)$/.exec(intervalStr);
+  if (!match) throw new Error(`Virheellinen intervalli: "${intervalStr}"`);
+  const num = parseInt(match[1]);
+  const days = num * INTERVAL_ABBREVS[match[2]];
+  return { days };
+};
+
+export const getNextDate = (task: RecurringTask): Date => {
+  if (!task.last_done) return now();
+  const lastDate = parse(task.last_done, "yyyy-MM-dd", now());
+  return add(lastDate, parseInterval(task.interval));
+};
+
+export const isThisWeek = (task: RecurringTask): boolean => {
+  const nextDate = getNextDate(task);
+  const weekStart = startOfWeek(now(), { weekStartsOn: 1 });
+  const weekEnd = addWeeks(weekStart, 1);
+  return isWithinInterval(nextDate, { start: weekStart, end: weekEnd });
+};
+
+export const formatDate = (d: Date): string => format(d, "yyyy-MM-dd");
+
+export const today = (): string => format(now(), "yyyy-MM-dd");