1// Copyright (c) 2010 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "chrome/browser/chromeos/low_battery_observer.h"
6
7#include "base/utf_string_conversions.h"
8#include "chrome/common/time_format.h"
9#include "grit/generated_resources.h"
10#include "grit/theme_resources.h"
11#include "ui/base/l10n/l10n_util.h"
12
13namespace chromeos {
14
15LowBatteryObserver::LowBatteryObserver(Profile* profile)
16  : notification_(profile, "battery.chromeos",
17                  IDR_NOTIFICATION_LOW_BATTERY,
18                  l10n_util::GetStringUTF16(IDS_LOW_BATTERY_TITLE)),
19    remaining_(0) {}
20
21LowBatteryObserver::~LowBatteryObserver() {
22  Hide();
23}
24
25void LowBatteryObserver::PowerChanged(PowerLibrary* object) {
26  const int limit_min = 15;   // Notification will show when remaining number
27                              // of minutes is <= limit.
28  const int limit_max = 30;   // Notification will hid when remaining number
29                              // of minutes is > limit_max.
30  const int critical = 5;  // Notification will be forced visible if hidden
31                           // by user when time remaining <= critical.
32
33  base::TimeDelta remaining = object->battery_time_to_empty();
34  int remaining_minutes = remaining.InMinutes();
35
36  // To simplify the logic - we handle the case of calculating the remaining
37  // time as if we were on line power.
38  // remaining time of zero means still calculating, this is denoted by
39  // base::TimeDelta().
40  bool line_power = object->line_power_on() || remaining == base::TimeDelta();
41
42  // The urgent flag is used to re-notify the user if the power level
43  // goes critical. We only want to do this once even if the time remaining
44  // goes back up (so long as it doesn't go above limit_max.
45  bool urgent = !line_power &&
46      (notification_.urgent() || remaining_minutes <= critical);
47
48  // This is a simple state machine with two states and three edges:
49  // States: visible_, !visible_
50  // Edges: hide: is visible_ to !visible_ triggered if we transition
51  //          to line_power, we're calculating our time remaining,
52  //          or our time remaining has climbed higher than
53  //          limit_max (either by reduced user an undetected transition
54  //          to/from line_power).
55  //        update: is visible_ to _visible triggered when we didn't hide
56  //          and the minutes remaining changed from what's shown.
57  //        show: is !visible_ to visible_ triggered when we're on battery,
58  //          we know the remaining time, and that time is less than limit.
59
60  if (notification_.visible()) {
61    if (line_power || remaining_minutes > limit_max) {
62      Hide();
63    } else if (remaining_minutes != remaining_) {
64      Show(remaining, urgent);
65    }
66  } else {
67    if (!line_power && remaining_minutes <= limit_min) {
68      Show(remaining, urgent);
69    }
70  }
71}
72
73void LowBatteryObserver::Show(base::TimeDelta remaining, bool urgent) {
74  notification_.Show(l10n_util::GetStringFUTF16(IDS_LOW_BATTERY_MESSAGE,
75      TimeFormat::TimeRemaining(remaining)), urgent, true);
76  remaining_ = remaining.InMinutes();
77}
78
79void LowBatteryObserver::Hide() {
80  notification_.Hide();
81}
82
83}  // namespace chromeos
84