fix: harden backend stability and test production utilities

backend/utils/datetime.js

@@ -0,0 +1,92 @@
+function parseDateTimeValue(value) {
+  if (!value || typeof value !== 'string') return null;
+
+  const directDate = new Date(value);
+  if (!Number.isNaN(directDate.getTime())) return directDate;
+
+  const normalizedDate = new Date(value.replace(' ', 'T'));
+  return Number.isNaN(normalizedDate.getTime()) ? null : normalizedDate;
+}
+
+function formatDateTimeForSqlite(date = new Date()) {
+  const target = date instanceof Date ? date : new Date(date);
+  const year = target.getFullYear();
+  const month = String(target.getMonth() + 1).padStart(2, '0');
+  const day = String(target.getDate()).padStart(2, '0');
+  const hours = String(target.getHours()).padStart(2, '0');
+  const minutes = String(target.getMinutes()).padStart(2, '0');
+  const seconds = String(target.getSeconds()).padStart(2, '0');
+  return `${year}-${month}-${day} ${hours}:${minutes}:${seconds}`;
+}
+
+function getDateKeyFromDate(date = new Date()) {
+  const target = date instanceof Date ? date : new Date(date);
+  if (Number.isNaN(target.getTime())) return null;
+  const year = target.getFullYear();
+  const month = String(target.getMonth() + 1).padStart(2, '0');
+  const day = String(target.getDate()).padStart(2, '0');
+  return `${year}-${month}-${day}`;
+}
+
+function getRecentDateKeys(days = 30, now = new Date()) {
+  const safeDays = Math.max(1, Math.floor(Number(days) || 30));
+  const keys = [];
+  for (let i = safeDays - 1; i >= 0; i -= 1) {
+    const date = new Date(now.getTime());
+    date.setDate(date.getDate() - i);
+    const key = getDateKeyFromDate(date);
+    if (key) keys.push(key);
+  }
+  return keys;
+}
+
+function getNextDownloadResetTime(lastResetAt, resetCycle) {
+  const baseDate = parseDateTimeValue(lastResetAt);
+  if (!baseDate) return null;
+
+  const next = new Date(baseDate.getTime());
+  if (resetCycle === 'daily') next.setDate(next.getDate() + 1);
+  else if (resetCycle === 'weekly') next.setDate(next.getDate() + 7);
+  else if (resetCycle === 'monthly') next.setMonth(next.getMonth() + 1);
+  else return null;
+  return next;
+}
+
+function normalizeTimeHHmm(value) {
+  if (typeof value !== 'string') return null;
+  const match = value.trim().match(/^(\d{2}):(\d{2})$/);
+  if (!match) return null;
+  const hours = Number(match[1]);
+  const minutes = Number(match[2]);
+  if (hours < 0 || hours > 23 || minutes < 0 || minutes > 59) return null;
+  return `${String(hours).padStart(2, '0')}:${String(minutes).padStart(2, '0')}`;
+}
+
+function toMinutesOfDay(hhmm) {
+  const normalized = normalizeTimeHHmm(hhmm);
+  if (!normalized) return null;
+  const [hours, minutes] = normalized.split(':').map(Number);
+  return hours * 60 + minutes;
+}
+
+function isCurrentTimeInWindow(startTime, endTime, now = new Date()) {
+  const start = toMinutesOfDay(startTime);
+  const end = toMinutesOfDay(endTime);
+  if (start === null || end === null) return true;
+
+  const nowMinutes = now.getHours() * 60 + now.getMinutes();
+  if (start === end) return true;
+  if (start < end) return nowMinutes >= start && nowMinutes < end;
+  return nowMinutes >= start || nowMinutes < end;
+}
+
+module.exports = {
+  parseDateTimeValue,
+  formatDateTimeForSqlite,
+  getDateKeyFromDate,
+  getRecentDateKeys,
+  getNextDownloadResetTime,
+  normalizeTimeHHmm,
+  toMinutesOfDay,
+  isCurrentTimeInWindow
+};