!timezone: add fuzzy matching for timezone name; add reset

backend/src/utils/parseFuzzyTimezone.ts

@@ -0,0 +1,32 @@
+import moment from "moment-timezone";
+import escapeStringRegexp from "escape-string-regexp";
+
+const normalizeTzName = str => str.replace(/[^a-zA-Z0-9+\-]/g, "").toLowerCase();
+
+const validTimezones = moment.tz.names();
+const normalizedTimezoneMap = validTimezones.reduce((map, tz) => {
+  map.set(normalizeTzName(tz), tz);
+  return map;
+}, new Map());
+const normalizedTimezones = Array.from(normalizedTimezoneMap.keys());
+
+export function parseFuzzyTimezone(input: string) {
+  const normalizedInput = normalizeTzName(input);
+
+  if (normalizedTimezoneMap.has(normalizedInput)) {
+    return normalizedTimezoneMap.get(normalizedInput);
+  }
+
+  const searchRegex = new RegExp(`.*${escapeStringRegexp(normalizedInput)}.*`);
+  for (const tz of normalizedTimezones) {
+    if (searchRegex.test(tz)) {
+      const result = normalizedTimezoneMap.get(tz);
+      // Ignore Etc/GMT timezones unless explicitly specified, as they have confusing functionality
+      // with the inverted +/- sign
+      if (result.startsWith("Etc/GMT")) continue;
+      return result;
+    }
+  }
+
+  return null;
+}