1 files changed, 148 insertions, 0 deletions
diff --git a/browser/components/urlbar/unitconverters/UnitConverterTimezone.sys.mjs b/browser/components/urlbar/unitconverters/UnitConverterTimezone.sys.mjs
new file mode 100644
index 0000000000..50ba924bed
--- /dev/null
+++ b/browser/components/urlbar/unitconverters/UnitConverterTimezone.sys.mjs
@@ -0,0 +1,148 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const TIMEZONES = {
+  IDLW: -12,
+  NT: -11,
+  HST: -10,
+  AKST: -9,
+  PST: -8,
+  AKDT: -8,
+  MST: -7,
+  PDT: -7,
+  CST: -6,
+  MDT: -6,
+  EST: -5,
+  CDT: -5,
+  EDT: -4,
+  AST: -4,
+  GUY: -3,
+  ADT: -3,
+  AT: -2,
+  UTC: 0,
+  GMT: 0,
+  Z: 0,
+  WET: 0,
+  WEST: 1,
+  CET: 1,
+  BST: 1,
+  IST: 1,
+  CEST: 2,
+  EET: 2,
+  EEST: 3,
+  MSK: 3,
+  MSD: 4,
+  ZP4: 4,
+  ZP5: 5,
+  ZP6: 6,
+  WAST: 7,
+  AWST: 8,
+  WST: 8,
+  JST: 9,
+  ACST: 9.5,
+  ACDT: 10.5,
+  AEST: 10,
+  AEDT: 11,
+  NZST: 12,
+  IDLE: 12,
+  NZD: 13,
+};
+
+const TIME_REGEX = "([0-2]?[0-9])(:([0-5][0-9]))?\\s*([ap]m)?";
+const TIMEZONE_REGEX = "\\w+";
+
+// NOTE: This regex need to be localized upon supporting multi locales
+//       since it supports en-US input format only.
+const QUERY_REGEX = new RegExp(
+  `^(${TIME_REGEX}|now)\\s*(${TIMEZONE_REGEX})?(?:\\s+in\\s+|\\s+to\\s+|\\s*=\\s*)(${TIMEZONE_REGEX}|here)`,
+  "i"
+);
+
+const KEYWORD_HERE = "HERE";
+const KEYWORD_NOW = "NOW";
+
+/**
+ * This module converts timezone.
+ */
+export class UnitConverterTimezone {
+  /**
+   * Convert the given search string.
+   *
+   * @param {string} searchString
+   *   The string to be converted
+   * @returns {string} conversion result.
+   */
+  convert(searchString) {
+    const regexResult = QUERY_REGEX.exec(searchString);
+    if (!regexResult) {
+      return null;
+    }
+
+    const inputTime = regexResult[1].toUpperCase();
+    const inputTimezone = regexResult[6]?.toUpperCase();
+    let outputTimezone = regexResult[7].toUpperCase();
+
+    if (
+      (inputTimezone &&
+        inputTimezone !== KEYWORD_NOW &&
+        !(inputTimezone in TIMEZONES)) ||
+      (outputTimezone !== KEYWORD_HERE && !(outputTimezone in TIMEZONES))
+    ) {
+      return null;
+    }
+
+    const inputDate = new Date();
+    let isMeridiemNeeded = false;
+    if (inputTime === KEYWORD_NOW) {
+      inputDate.setUTCHours(inputDate.getHours());
+      inputDate.setUTCMinutes(inputDate.getMinutes());
+    } else {
+      // If the input was given as AM/PM, we need to convert it to 24h.
+      // 12AM is converted to 00, and for PM times we add 12 to the hour value except for 12PM.
+      // If the input is for example 23PM, we use 23 as the hour - we don't add 12 as this would result in a date increment.
+      const inputAMPM = regexResult[5]?.toLowerCase() || "";
+      const inputHours =
+        regexResult[2] === "12" && inputAMPM === "am"
+          ? 0
+          : Number(regexResult[2]);
+      const inputMinutes = regexResult[4] ? Number(regexResult[4]) : 0;
+      const inputMeridianHourShift =
+        inputAMPM === "pm" && inputHours < 12 ? 12 : 0;
+      inputDate.setUTCHours(inputHours + inputMeridianHourShift);
+      inputDate.setUTCMinutes(inputMinutes);
+      isMeridiemNeeded = !!inputAMPM;
+    }
+
+    const inputOffset = inputTimezone
+      ? TIMEZONES[inputTimezone] * 60
+      : -inputDate.getTimezoneOffset();
+    let outputOffset;
+    if (outputTimezone === KEYWORD_HERE) {
+      outputOffset = -inputDate.getTimezoneOffset();
+      const sign = -inputDate.getTimezoneOffset() > 0 ? "+" : "-";
+      const hours = parseInt(Math.abs(outputOffset) / 60);
+      const minutes = formatMinutes((outputOffset % 60) * 60);
+      outputTimezone = `UTC${sign}${hours}${minutes}`;
+    } else {
+      outputOffset = TIMEZONES[outputTimezone] * 60;
+    }
+
+    const outputDate = new Date(inputDate.getTime());
+    outputDate.setUTCMinutes(
+      outputDate.getUTCMinutes() - inputOffset + outputOffset
+    );
+
+    const time = new Intl.DateTimeFormat("en-US", {
+      timeStyle: "short",
+      hour12: isMeridiemNeeded,
+      timeZone: "UTC",
+    }).format(outputDate);
+
+    return `${time} ${outputTimezone}`;
+  }
+}
+
+function formatMinutes(minutes) {
+  return minutes.toString().padStart(2, "0");
+}