refactor

frontend/src/utils/date.js

@@ -0,0 +1,57 @@
+const ensureDate = (value) => {
+  if (!value) {
+    return null;
+  }
+  const date = value instanceof Date ? new Date(value.getTime()) : new Date(value);
+  return Number.isNaN(date.getTime()) ? null : date;
+};
+
+export const formatDate = (value, { fallback = '—', locale, options } = {}) => {
+  const date = ensureDate(value);
+  if (!date) {
+    return fallback;
+  }
+  return date.toLocaleDateString(locale, options);
+};
+
+export const formatDateTime = (value, { fallback = '—', locale, options } = {}) => {
+  const date = ensureDate(value);
+  if (!date) {
+    return fallback;
+  }
+  return date.toLocaleString(locale, options);
+};
+
+export const toDateInputValue = (value) => {
+  const date = ensureDate(value);
+  if (!date) {
+    return '';
+  }
+  const timezoneOffset = date.getTimezoneOffset();
+  const localDate = new Date(date.getTime() - timezoneOffset * 60000);
+  return localDate.toISOString().slice(0, 10);
+};
+
+export const toIssuedTimestamp = (dateString, fallback) => {
+  if (!dateString) {
+    return null;
+  }
+  const base = ensureDate(fallback) || new Date();
+  const [year, month, day] = dateString.split('-').map((part) => Number.parseInt(part, 10));
+  if (!year || !month || !day) {
+    return null;
+  }
+  const candidate = new Date(base);
+  candidate.setUTCFullYear(year, month - 1, day);
+  return Number.isNaN(candidate.getTime()) ? null : candidate.toISOString();
+};
+
+export const parseDateValue = (value) => ensureDate(value);
+
+export default {
+  formatDate,
+  formatDateTime,
+  toDateInputValue,
+  toIssuedTimestamp,
+  parseDateValue,
+};

frontend/src/utils/math.js

@@ -0,0 +1,13 @@
+export const clamp = (value, min, max) => {
+  if (value < min) {
+    return min;
+  }
+  if (value > max) {
+    return max;
+  }
+  return value;
+};
+
+export default {
+  clamp,
+};