// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

library fuchsia.timezone;

// TODO(US-384): Update protocol for more stuctured data: timezone names,
// standard timezone codenames, and DST start/end information
// (see go/garnet-time).
//
// For more information on the ICU timezone ID format, see:
// http://userguide.icu-project.org/datetime
[Discoverable]
protocol Timezone {
    // Returns local timezone offset (in minutes from UTC. Can be negative) for
    // the supplied number of milliseconds since the Unix epoch. Returns a
    // non-zero DST offset when appropriate.
    GetTimezoneOffsetMinutes(int64 milliseconds_since_epoch)
        -> (int32 local_offset_minutes, int32 dst_offset_minutes);

    // Sets the timezone for the machine based on an ICU ID.
    SetTimezone(string timezone_id) -> (bool status);

    // Gets the timezone ID string.
    GetTimezoneId() -> (string timezone_id);

    // Watches for updates to the timezone ID.
    Watch(TimezoneWatcher watcher);
};

protocol TimezoneWatcher {
    // When the timezone changes, returns the new timezone ID.
    OnTimezoneOffsetChange(string timezone_id);
};