local Device = require("device")

-- If a device can power off or go into standby, it can also suspend ;).
if not Device:canSuspend() then
    return { disabled = true, }
end

local Event = require("ui/event")
local NetworkMgr = require("ui/network/manager")
local PluginShare = require("pluginshare")
local UIManager = require("ui/uimanager")
local WidgetContainer = require("ui/widget/container/widgetcontainer")
local logger = require("logger")
local util = require("util")
local time = require("ui/time")
local _ = require("gettext")
local Math = require("optmath")
local T = require("ffi/util").template

local default_autoshutdown_timeout_seconds = 3*24*60*60 -- three days
local default_auto_suspend_timeout_seconds = 15*60 -- 15 minutes
local default_auto_standby_timeout_seconds = 4 -- 4 seconds; should be safe on Kobo/Sage

local AutoSuspend = WidgetContainer:extend{
    name = "autosuspend",
    is_doc_only = false,
    autoshutdown_timeout_seconds = default_autoshutdown_timeout_seconds,
    auto_suspend_timeout_seconds = default_auto_suspend_timeout_seconds,
    auto_standby_timeout_seconds = default_auto_standby_timeout_seconds,
    last_action_time = 0,
    is_standby_scheduled = nil,
    task = nil,
    standby_task = nil,
    leave_standby_task = nil,
    wrapped_leave_standby_task = nil,
    going_to_suspend = nil,
}

function AutoSuspend:_enabledStandby()
    return Device:canStandby() and self.auto_standby_timeout_seconds > 0
end

function AutoSuspend:_enabled()
    -- NOTE: Plugin is only enabled if Device:canSuspend(), so we can elide the check here
    return self.auto_suspend_timeout_seconds > 0
end

function AutoSuspend:_enabledShutdown()
    return Device:canPowerOff() and self.autoshutdown_timeout_seconds > 0
end

function AutoSuspend:_schedule(shutdown_only)
    if not self:_enabled() and not self:_enabledShutdown() then
        logger.dbg("AutoSuspend: suspend/shutdown timer is disabled")
        return
    end

    local suspend_delay_seconds, shutdown_delay_seconds
    local is_charging
    -- On devices with an auxiliary battery, we only care about the auxiliary battery being charged...
    local powerd = Device:getPowerDevice()
    if Device:hasAuxBattery() and powerd:isAuxBatteryConnected() then
        is_charging = powerd:isAuxCharging() and not powerd:isAuxCharged()
    else
        is_charging = powerd:isCharging() and not powerd:isCharged()
    end
    -- We *do* want to make sure we attempt to go into suspend/shutdown again while *fully* charged, though.
    if PluginShare.pause_auto_suspend or is_charging then
        suspend_delay_seconds = self.auto_suspend_timeout_seconds
        shutdown_delay_seconds = self.autoshutdown_timeout_seconds
    else
        local now = UIManager:getElapsedTimeSinceBoot()
        suspend_delay_seconds = self.auto_suspend_timeout_seconds - time.to_number(now - self.last_action_time)
        shutdown_delay_seconds = self.autoshutdown_timeout_seconds - time.to_number(now - self.last_action_time)
    end

    -- Try to shutdown first, as we may have been woken up from suspend just for the sole purpose of doing that.
    if self:_enabledShutdown() and shutdown_delay_seconds <= 0 then
        logger.dbg("AutoSuspend: initiating shutdown")
        UIManager:poweroff_action()
    elseif self:_enabled() and suspend_delay_seconds <= 0 and not shutdown_only then
        logger.dbg("AutoSuspend: will suspend the device")
        UIManager:suspend()
    else
        if self:_enabled() and not shutdown_only then
            logger.dbg("AutoSuspend: scheduling next suspend check in", suspend_delay_seconds)
            UIManager:scheduleIn(suspend_delay_seconds, self.task)
        end
        if self:_enabledShutdown() then
            logger.dbg("AutoSuspend: scheduling next shutdown check in", shutdown_delay_seconds)
            UIManager:scheduleIn(shutdown_delay_seconds, self.task)
        end
    end
end

function AutoSuspend:_unschedule()
    if self.task then
        logger.dbg("AutoSuspend: unschedule suspend/shutdown timer")
        UIManager:unschedule(self.task)
    end
end

function AutoSuspend:_start()
    if self:_enabled() or self:_enabledShutdown() then
        logger.dbg("AutoSuspend: start suspend/shutdown timer at", time.format_time(self.last_action_time))
        self:_schedule()
    end
end

function AutoSuspend:_start_standby()
    if self:_enabledStandby() then
        logger.dbg("AutoSuspend: start standby timer at", time.format_time(self.last_action_time))
        self:_schedule_standby()
    end
end

-- Variant that only re-engages the shutdown timer for onUnexpectedWakeupLimit
function AutoSuspend:_restart()
    if self:_enabledShutdown() then
        logger.dbg("AutoSuspend: restart shutdown timer at", time.format_time(self.last_action_time))
        self:_schedule(true)
    end
end

function AutoSuspend:init()
    logger.dbg("AutoSuspend: init")
    self.autoshutdown_timeout_seconds = G_reader_settings:readSetting("autoshutdown_timeout_seconds",
        default_autoshutdown_timeout_seconds)
    self.auto_suspend_timeout_seconds = G_reader_settings:readSetting("auto_suspend_timeout_seconds",
        default_auto_suspend_timeout_seconds)
    -- Disabled, until the user opts in.
    self.auto_standby_timeout_seconds = G_reader_settings:readSetting("auto_standby_timeout_seconds", -1)

    -- We only want those to exist as *instance* members
    self.is_standby_scheduled = false
    self.going_to_suspend = false

    UIManager.event_hook:registerWidget("InputEvent", self)
    -- We need an instance-specific function reference to schedule, because in some rare cases,
    -- we may instantiate a new plugin instance *before* tearing down the old one.
    -- If we only cared about accessing the right instance members,
    -- we could use scheduleIn(t, self.function, self),
    -- but we also care about unscheduling the task from *this* instance only:
    -- unschedule(self.function) would unschedule that function for *every* instance,
    -- as self.function == AutoSuspend.function ;).
    self.task = function(shutdown_only)
        self:_schedule(shutdown_only)
    end
    self.standby_task = function()
        self:_schedule_standby()
    end
    self.leave_standby_task = function()
        -- Only if we're not already entering suspend...
        if self.going_to_suspend then
            return
        end

        UIManager:broadcastEvent(Event:new("LeaveStandby"))
    end

    -- Make sure we only have an AllowStandby handler when we actually want one...
    self:toggleStandbyHandler(self:_enabledStandby())

    self.last_action_time = UIManager:getElapsedTimeSinceBoot()
    self:_start()
    self:_start_standby()

    -- self.ui is nil in the testsuite
    if not self.ui or not self.ui.menu then return end
    self.ui.menu:registerToMainMenu(self)
end

-- NOTE: event_hook takes care of overloading this to unregister the hook, too.
function AutoSuspend:onCloseWidget()
    logger.dbg("AutoSuspend: onCloseWidget")

    self:_unschedule()
    self.task = nil

    self:_unschedule_standby()
    self.standby_task = nil
    self.leave_standby_task = nil
end

function AutoSuspend:onInputEvent()
    logger.dbg("AutoSuspend: onInputEvent")
    self.last_action_time = UIManager:getElapsedTimeSinceBoot()
end

function AutoSuspend:_unschedule_standby()
    if self.is_standby_scheduled and self.standby_task then
        logger.dbg("AutoSuspend: unschedule standby timer")
        UIManager:unschedule(self.standby_task)
        -- Restore the UIManager balance, as we run preventStandby right after scheduling this task.
        UIManager:allowStandby()

        self.is_standby_scheduled = false
    end

    -- Make sure we don't trigger a ghost LeaveStandby event...
    if self.leave_standby_task then
        logger.dbg("AutoSuspend: unschedule leave standby task")
        UIManager:unschedule(self.leave_standby_task)
    end
end

function AutoSuspend:_schedule_standby()
    -- Start the long list of conditions in which we do *NOT* want to go into standby ;).
    if not Device:canStandby() then
        return
    end

    -- Don't even schedule standby if we haven't set a proper timeout yet.
    -- NOTE: We've essentially split the _enabledStandby check in two branches,
    --       simply to avoid logging noise on devices that can't even standby ;).
    if self.auto_standby_timeout_seconds <= 0 then
        logger.dbg("AutoSuspend: No timeout set, no standby")
        return
    end

    -- When we're in a state where entering suspend is undesirable, we simply postpone the check by the full delay.
    local standby_delay_seconds
    -- NOTE: As this may fire repeatedly, we don't want to poke the actual Device implementation every few seconds,
    --       instead, we rely on NetworkMgr's last known status. (i.e., this *should* match NetworkMgr:isWifiOn).
    if NetworkMgr:getWifiState() then
        -- Don't enter standby if wifi is on, as this will break in fun and interesting ways (from Wi-Fi issues to kernel deadlocks).
        --logger.dbg("AutoSuspend: WiFi is on, delaying standby")
        standby_delay_seconds = self.auto_standby_timeout_seconds
    elseif Device.powerd:isCharging() and not Device:canPowerSaveWhileCharging() then
        -- Don't enter standby when charging on devices where charging *may* prevent entering low power states.
        -- (*May*, because depending on the USB controller, it might depend on what it's plugged to, and how it's setup:
        -- e.g., generally, on those devices, USBNet being enabled is guaranteed to prevent PM).
        -- NOTE: Minor simplification here, we currently don't do the hasAuxBattery dance like in _schedule,
        --       because all the hasAuxBattery devices can currently enter PM states while charging ;).
        --logger.dbg("AutoSuspend: charging, delaying standby")
        standby_delay_seconds = self.auto_standby_timeout_seconds
    else
        local now = UIManager:getElapsedTimeSinceBoot()
        standby_delay_seconds = self.auto_standby_timeout_seconds - time.to_number(now - self.last_action_time)

        -- If we blow past the deadline on the first call of a scheduling cycle,
        -- make sure we don't go straight to allowStandby, as we haven't called preventStandby yet...
        if not self.is_standby_scheduled and standby_delay_seconds <= 0 then
            -- If this happens, it means we hit LeaveStandby or Resume *before* consuming new input events,
            -- e.g., if there weren't any input events at all (woken up by an alarm),
            -- or if the only input events we consumed did not trigger an InputEvent event (woken up by gyro events),
            -- meaning self.last_action_time is further in the past than it ought to.
            -- Delay by the full amount to avoid further bad scheduling interactions.
            standby_delay_seconds = self.auto_standby_timeout_seconds
        end
    end

    if standby_delay_seconds <= 0 then
        -- We blew the deadline, tell UIManager we're ready to enter standby
        self:allowStandby()
    else
        -- Reschedule standby for the full or remaining delay
        -- NOTE: This is fairly chatty, given the low delays, but really helpful nonetheless... :/
        logger.dbg("AutoSuspend: scheduling next standby check in", standby_delay_seconds)
        UIManager:scheduleIn(standby_delay_seconds, self.standby_task)

        -- Prevent standby until we actually blow the deadline
        if not self.is_standby_scheduled then
            self:preventStandby()
        end

        self.is_standby_scheduled = true
    end
end

function AutoSuspend:preventStandby()
    logger.dbg("AutoSuspend: preventStandby")
    -- Tell UIManager that we want to prevent standby until our allowStandby scheduled task runs.
    UIManager:preventStandby()
end

-- NOTE: This is what our scheduled task runs to trip the UIManager state to standby
function AutoSuspend:allowStandby()
    logger.dbg("AutoSuspend: allowStandby")
    -- Tell UIManager that we now allow standby.
    UIManager:allowStandby()

    -- We've just run our course.
    self.is_standby_scheduled = false
end

function AutoSuspend:onSuspend()
    logger.dbg("AutoSuspend: onSuspend")
    -- We do not want auto suspend procedure to waste battery during suspend. So let's unschedule it
    -- when suspending and restart it after resume.
    self:_unschedule()
    self:_unschedule_standby()
    if self:_enabledShutdown() and Device.wakeup_mgr then
        Device.wakeup_mgr:addTask(self.autoshutdown_timeout_seconds, UIManager.poweroff_action)
    end

    -- Make sure we won't attempt to standby during suspend
    -- (because _unschedule_standby calls allowStandby,
    -- so we may trip UIManager's _standbyTransition and end up in AutoSuspend:onAllowStandby)...
    -- NOTE: We only want to do this *once*, because we might get a series of Suspend events before actually getting a Resume!
    --       (e.g., Power (button) -> Charging (USB plug) -> SleepCover).
    if self:_enabledStandby() and not self.going_to_suspend then
        UIManager:preventStandby()
    end

    -- And make sure onLeaveStandby, which will come *after* us if we suspended *during* standby,
    -- won't re-schedule stuff right before entering suspend...
    self.going_to_suspend = true
end

function AutoSuspend:onResume()
    logger.dbg("AutoSuspend: onResume")

    -- Restore standby balance after onSuspend
    if self:_enabledStandby() and self.going_to_suspend then
        UIManager:allowStandby()
    end
    self.going_to_suspend = false

    if self:_enabledShutdown() and Device.wakeup_mgr then
        Device.wakeup_mgr:removeTasks(nil, UIManager.poweroff_action)
    end
    -- Unschedule in case we tripped onUnexpectedWakeupLimit first...
    self:_unschedule()
    -- We should always follow an InputEvent, so last_action_time is already up to date :).
    self:_start()
    self:_unschedule_standby()
    self:_start_standby()
end

function AutoSuspend:onLeaveStandby()
    logger.dbg("AutoSuspend: onLeaveStandby")
    -- Unschedule suspend and shutdown, as the realtime clock has ticked
    self:_unschedule()
    -- Reschedule suspend and shutdown (we'll recompute the delay based on the last user input, *not* the current time).
    -- i.e., the goal is to behave as if we'd never unscheduled it, making sure we do *NOT* reset the delay to the full timeout.
    self:_start()
    -- Assuming _start didn't send us straight to onSuspend (i.e., we were woken from standby by the scheduled suspend task!)...
    if not self.going_to_suspend then
        -- Reschedule standby, too (we're guaranteed that no standby task is currently scheduled, hence the lack of unscheduling).
        self:_start_standby()
    end
end

function AutoSuspend:onUnexpectedWakeupLimit()
    logger.dbg("AutoSuspend: onUnexpectedWakeupLimit")
    -- Should be unnecessary, because we should *always* follow onSuspend, which already does this...
    -- Better safe than sorry, though ;).
    self:_unschedule()
    -- Only re-engage the *shutdown* schedule to avoid doing the same dance indefinitely.
    self:_restart()
end

function AutoSuspend:onNotCharging()
    logger.dbg("AutoSuspend: onNotCharging")
    -- Make sure both the suspend & shutdown timers are re-engaged on unplug,
    -- in case we hit an UnexpectedWakeupLimit during the charge cycle...
    self:_unschedule()
    self:_start()
end

-- time_scale:
-- 2 ... display day:hour
-- 1 ... display hour:min
-- else ... display min:sec
function AutoSuspend:pickTimeoutValue(touchmenu_instance, title, info, setting,
        default_value, range, time_scale)
    -- NOTE: if is_day_hour then time.hour stands for days and time.min for hours

    local InfoMessage = require("ui/widget/infomessage")
    local DateTimeWidget = require("ui/widget/datetimewidget")

    local setting_val = self[setting] > 0 and self[setting] or default_value

    -- Standby uses a different scheduled task than suspend/shutdown
    local is_standby = setting == "auto_standby_timeout_seconds"

    local day, hour, minute, second
    local day_max, hour_max, min_max, sec_max
    if time_scale == 2 then
        day = math.floor(setting_val * (1/(24*3600)))
        hour = math.floor(setting_val * (1/3600)) % 24
        day_max = math.floor(range[2] * (1/(24*3600))) - 1
        hour_max = 23
    elseif time_scale == 1 then
        hour = math.floor(setting_val * (1/3600))
        minute = math.floor(setting_val * (1/60)) % 60
        hour_max = math.floor(range[2] * (1/3600)) - 1
        min_max = 59
    else
        minute = math.floor(setting_val * (1/60))
        second = math.floor(setting_val) % 60
        min_max =  math.floor(range[2] * (1/60)) - 1
        sec_max = 59
    end

    local time_spinner
    time_spinner = DateTimeWidget:new {
        day = day,
        hour = hour,
        min = minute,
        sec = second,
        day_hold_step = 5,
        hour_hold_step = 5,
        min_hold_step = 10,
        sec_hold_step = 10,
        day_max = day_max,
        hour_max = hour_max,
        min_max = min_max,
        sec_max = sec_max,
        ok_text = _("Set timeout"),
        title_text = title,
        info_text = info,
        callback = function(t)
            self[setting] = (((t.day or 0) * 24 +
                             (t.hour or 0)) * 60 +
                             (t.min or 0)) * 60 +
                             (t.sec or 0)
            self[setting] = Math.clamp(self[setting], range[1], range[2])
            G_reader_settings:saveSetting(setting, self[setting])
            if is_standby then
                self:_unschedule_standby()
                self:toggleStandbyHandler(self:_enabledStandby())
                self:_start_standby()
            else
                self:_unschedule()
                self:_start()
            end
            if touchmenu_instance then touchmenu_instance:updateItems() end
            local time_string = util.secondsToClockDuration("modern", self[setting],
                time_scale == 2 or time_scale == 1, true, true)
            UIManager:show(InfoMessage:new{
                text = T(_("%1: %2"), title, time_string),
                timeout = 3,
            })
        end,
        default_value = util.secondsToClockDuration("modern", default_value,
            time_scale == 2 or time_scale == 1, true, true),
        default_callback = function()
            local day, hour, min, sec -- luacheck: ignore 431
            if time_scale == 2 then
                day = math.floor(default_value * (1/(24*3600)))
                hour = math.floor(default_value * (1/3600)) % 24
            elseif time_scale == 1 then
                hour = math.floor(default_value * (1/3600))
                min = math.floor(default_value * (1/60)) % 60
            else
                min = math.floor(default_value * (1/60))
                sec = math.floor(default_value % 60)
            end
            time_spinner:update(nil, nil, day, hour, min, sec) -- It is ok to pass nils here.
        end,
        extra_text = _("Disable"),
        extra_callback = function(this)
            self[setting] = -1 -- disable with a negative time/number
            G_reader_settings:saveSetting(setting, -1)
            if is_standby then
                self:_unschedule_standby()
                self:toggleStandbyHandler(false)
            else
                self:_unschedule()
            end
            if touchmenu_instance then touchmenu_instance:updateItems() end
            UIManager:show(InfoMessage:new{
                text = T(_("%1: disabled"), title),
                timeout = 3,
            })
            this:onClose()
        end,
        keep_shown_on_apply = true,
    }
    UIManager:show(time_spinner)
end

function AutoSuspend:addToMainMenu(menu_items)
    -- Device:canSuspend() check elided because it's a plugin requirement
    menu_items.autosuspend = {
        sorting_hint = "device",
        checked_func = function()
            return self:_enabled()
        end,
        text_func = function()
            if self.auto_suspend_timeout_seconds and self.auto_suspend_timeout_seconds > 0 then
                local time_string = util.secondsToClockDuration("modern",
                    self.auto_suspend_timeout_seconds, true, true, true)
                return T(_("Autosuspend timeout: %1"), time_string)
            else
                return _("Autosuspend timeout")
            end
        end,
        keep_menu_open = true,
        callback = function(touchmenu_instance)
            -- 60 sec (1') is the minimum and 24*3600 sec (1day) is the maximum suspend time.
            -- A suspend time of one day seems to be excessive.
            -- But it might make sense for battery testing.
            self:pickTimeoutValue(touchmenu_instance,
                _("Timeout for autosuspend"), _("Enter time in hours and minutes."),
                "auto_suspend_timeout_seconds", default_auto_suspend_timeout_seconds,
                {60, 24*3600}, 1)
        end,
    }
    if Device:canPowerOff() then
        menu_items.autoshutdown = {
            sorting_hint = "device",
            checked_func = function()
                return self:_enabledShutdown()
            end,
            text_func = function()
                if self.autoshutdown_timeout_seconds and self.autoshutdown_timeout_seconds > 0 then
                    local time_string = util.secondsToClockDuration("modern", self.autoshutdown_timeout_seconds,
                        true, true, true)
                    return T(_("Autoshutdown timeout: %1"), time_string)
                else
                    return _("Autoshutdown timeout")
                end
            end,
            keep_menu_open = true,
            callback = function(touchmenu_instance)
                -- 5*60 sec (5') is the minimum and 28*24*3600 (28days) is the maximum shutdown time.
                -- Minimum time has to be big enough, to avoid start-stop death scenarious.
                -- Maximum more than four weeks seems a bit excessive if you want to enable authoshutdown,
                -- even if the battery can last up to three months.
                self:pickTimeoutValue(touchmenu_instance,
                    _("Timeout for autoshutdown"), _("Enter time in days and hours."),
                    "autoshutdown_timeout_seconds", default_autoshutdown_timeout_seconds,
                    {5*60, 28*24*3600}, 2)
            end,
        }
    end
    if Device:canStandby() then
        --- @fixme: Reword the final warning when we have more data on the hangs on some Kobo kernels (e.g., #9038).
        local standby_help = _([[Standby puts the device into a power-saving state in which the screen is on and user input can be performed.

Standby can not be entered if Wi-Fi is on.

Upon user input, the device needs a certain amount of time to wake up. Generally, the newer the device, the less noticeable this delay will be, but it can be fairly aggravating on slower devices.

This is experimental on most devices, except those running on a sunxi SoC (Kobo Elipsa & Sage), so much so that it might in fact hang some of the more broken kernels out there (Kobo Libra 2).]])

        menu_items.autostandby = {
            sorting_hint = "device",
            checked_func = function()
                return self:_enabledStandby()
            end,
            text_func = function()
                if self.auto_standby_timeout_seconds and self.auto_standby_timeout_seconds > 0 then
                    local time_string = util.secondsToClockDuration("modern", self.auto_standby_timeout_seconds,
                        false, true, true, true)
                    return T(_("Autostandby timeout: %1"), time_string)
                else
                    return _("Autostandby timeout")
                end
            end,
            help_text = standby_help,
            keep_menu_open = true,
            callback = function(touchmenu_instance)
                -- 4 sec is the minimum and 15*60 sec (15min) is the maximum standby time.
                -- We need a minimum time, so that scheduled function have a chance to execute.
                -- A standby time of 15 min seem excessive.
                -- But or battery testing it might give some sense.
                self:pickTimeoutValue(touchmenu_instance,
                    _("Timeout for autostandby"), _("Enter time in minutes and seconds."),
                    "auto_standby_timeout_seconds", default_auto_standby_timeout_seconds,
                    {3, 15*60}, 0)
            end,
        }
    end
end

-- KOReader is merely waiting for user input right now.
-- UI signals us that standby is allowed at this very moment because nothing else goes on in the background.
-- NOTE: To make sure this will not even run when autostandby is disabled,
--       this is only aliased as `onAllowStandby` when necessary.
--       (Because the Event is generated regardless of us, as many things can call UIManager:allowStandby).
function AutoSuspend:AllowStandbyHandler()
    logger.dbg("AutoSuspend: onAllowStandby")
    -- This piggy-backs minimally on the UI framework implemented for the PocketBook autostandby plugin,
    -- see its own AllowStandby handler for more details.

    local wake_in
    -- Wake up before the next scheduled function executes (e.g. footer update, suspend ...)
    local next_task_time = UIManager:getNextTaskTime()
    if next_task_time then
        -- Wake up slightly after the formerly scheduled event,
        -- to avoid resheduling the same function after a fraction of a second again (e.g. don't draw footer twice).
        wake_in = math.floor(time.to_number(next_task_time)) + 1
    else
        wake_in = math.huge
    end

    if wake_in >= 3 then -- don't go into standby, if scheduled wakeup is in less than 3 secs
        UIManager:broadcastEvent(Event:new("EnterStandby"))
        logger.dbg("AutoSuspend: entering standby with a wakeup alarm in", wake_in, "s")

        -- This obviously needs a matching implementation in Device, the canonical one being Kobo.
        Device:standby(wake_in)

        logger.dbg("AutoSuspend: left standby after", time.format_time(Device.last_standby_time), "s")

        -- We delay the LeaveStandby event (our onLeaveStandby handler is responsible for rescheduling everything properly),
        -- to make sure UIManager will consume the input events that woke us up first
        -- (in case we were woken up by user input, as opposed to an rtc wake alarm)!
        -- (This ensures we'll use an up to date last_action_time, and that it only ever gets updated from *user* input).
        -- NOTE: While UIManager consumes scheduled tasks before input events, we do *NOT* have to rely on tickAfterNext,
        --       solely because of where we run inside an UI frame (via UIManager:_standbyTransition):
        --       we're neither a scheduled task nor an input event, we run *between* scheduled tasks and input polling.
        --       That means we go straight to input polling when returning, *without* a trip through the task queue
        --       (c.f., UIManager:_checkTasks in UIManager:handleInput).
        UIManager:nextTick(self.leave_standby_task)

        -- Since we go straight to input polling, and that our time spent in standby won't have affected the already computed
        -- input polling deadline (because MONOTONIC doesn't tick during standby/suspend),
        -- tweak said deadline to make sure poll will return immediately, so we get a chance to run through the task queue ASAP.
        -- This ensures we get a LeaveStandby event in a timely fashion,
        -- even when there isn't actually any user input happening (e.g., woken up by the rtc alarm).
        -- This shouldn't prevent us from actually consuming any pending input events first,
        -- because if we were woken up by user input, those events should already be in the evdev queue...
        UIManager:consumeInputEarlyAfterPM(true)
    else
        if not self.going_to_suspend then
            self:_start_standby()
        end
    end
end

function AutoSuspend:toggleStandbyHandler(toggle)
    if toggle then
        self.onAllowStandby = self.AllowStandbyHandler
    else
        self.onAllowStandby = nil
    end
end

return AutoSuspend