1 files changed, 55 insertions, 0 deletions
diff --git a/mobile/android/geckoview/src/main/java/org/mozilla/gecko/util/DateUtil.java b/mobile/android/geckoview/src/main/java/org/mozilla/gecko/util/DateUtil.java
new file mode 100644
index 000000000..9d34a0fe8
--- /dev/null
+++ b/mobile/android/geckoview/src/main/java/org/mozilla/gecko/util/DateUtil.java
@@ -0,0 +1,55 @@
+/*
+ * 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/.
+ */
+
+package org.mozilla.gecko.util;
+
+import android.support.annotation.NonNull;
+
+import java.text.DateFormat;
+import java.text.SimpleDateFormat;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.Locale;
+import java.util.TimeZone;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Utilities to help with manipulating Java's dates and calendars.
+ */
+public class DateUtil {
+    private DateUtil() {}
+
+    /**
+     * @param date the date to convert to HTTP format
+     * @return the date as specified in rfc 1123, e.g. "Tue, 01 Feb 2011 14:00:00 GMT"
+     */
+    public static String getDateInHTTPFormat(@NonNull final Date date) {
+        final DateFormat df = new SimpleDateFormat("E, dd MMM yyyy HH:mm:ss z", Locale.US);
+        df.setTimeZone(TimeZone.getTimeZone("GMT"));
+        return df.format(date);
+    }
+
+    /**
+     * Returns the timezone offset for the current date in minutes. See
+     * {@link #getTimezoneOffsetInMinutesForGivenDate(Calendar)} for more details.
+     */
+    public static int getTimezoneOffsetInMinutes(@NonNull final TimeZone timezone) {
+        return getTimezoneOffsetInMinutesForGivenDate(Calendar.getInstance(timezone));
+    }
+
+    /**
+     * Returns the time zone offset for the given date in minutes. The date makes a difference due to daylight
+     * savings time in some regions. We return minutes because we can accurately represent time zones that are
+     * offset by non-integer hour values, e.g. parts of New Zealand at UTC+12:45.
+     *
+     * @param calendar A calendar with the appropriate time zone & date already set.
+     */
+    public static int getTimezoneOffsetInMinutesForGivenDate(@NonNull final Calendar calendar) {
+        // via Date.getTimezoneOffset deprecated docs (note: it had incorrect order of operations).
+        // Also, we cast to int because we should never overflow here - the max should be GMT+14 = 840.
+        return (int) TimeUnit.MILLISECONDS.toMinutes(calendar.get(Calendar.ZONE_OFFSET) + calendar.get(Calendar.DST_OFFSET));
+    }
+}