# -*- python -*-

# This example demonstrates how to use adjust backlight
# without interfering to much with manual adjustments.
# The example with oscillate the backlight between 50 %
# and 100 % but include any manual adjustments.


# This file is dual-licensed under GNU General Public License
# version 3 and GNU Free Documentation License version 1.3.


# Copyright © 2014, 2015, 2016, 2017  Mattias Andrée (maandree@kth.se)
# 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


# Copyright © 2014, 2015, 2016, 2017  Mattias Andrée (maandree@kth.se)
# 
# Permission is granted to copy, distribute and/or modify this document
# under the terms of the GNU Free Documentation License, Version 1.3
# or any later version published by the Free Software Foundation;
# with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
# You should have received a copy of the GNU General Public License
# along with this software package.  If not, see <http://www.gnu.org/licenses/>.


import math


# Get backlight controller.
controller = list_backlights()[0]
controller = Backlight(controller, adjbacklight = True, minimum = 0)
# `adjbacklight = True` requires the `adjbacklight` command/package
# and lets us avoid hassling with permissions.
# `minimum = 0` is optional.

# The users brightness adjustment
user_adjustment = controller.brightness / controller.maximum


# Do not fade in or out, apply settings immediately.
fadein_time, fadeout_time = None, None

# Update the backlight ten times per second.
wait_period = 0.1


cycle, adj, last = 0, 1, controller.brightness
def periodically(year, month, day, hour, minute, second, weekday, fade):
    '''
    Invoked periodically
    
    If you want to control at what to invoke this function next time
    you can set the value of the global variable `wait_period` to the
    number of seconds to wait before invoking this function again.
    The value does not need to be an integer.
    
    @param  year:int     The year
    @param  month:int    The month, 1 = January, 12 = December
    @param  day:int      The day, minimum value is 1, probable maximum value is 31 (*)
    @param  hour:int     The hour, minimum value is 0, maximum value is 23
    @param  minute:int   The minute, minimum value is 0, maximum value is 59
    @param  second:int   The second, minimum value is 0, probable maximum value is 60 (**)
    @param  weekday:int  The weekday, 1 = Monday, 7 = Sunday
    @param  fade:float?  Blueshift can use this function to fade into a state when it start
                         or exits. `fade` can either be negative, zero or positive or `None`,
                         but the magnitude of value cannot exceed 1. When Blueshift starts,
                         this function will be invoked multiple with the time parameters
                         of the time it is invoked and each time `fade` will increase towards
                         1, starting at 0, when the value is 1, the settings should be applied
                         to 100 %. After this this function will be invoked once again with
                         `fade` being `None`. When Blueshift exits the same behaviour is used
                         except, `fade` decrease towards -1 but start slightly below 0, when
                         -1 is reached all settings should be normal. Then Blueshift will NOT
                         invoke this function with `fade` being `None`, instead it will by
                         itself revert all settings and quit.
    
    (*)  Can be exceeded if the calendar system is changed, like in 1712-(02)Feb-30
    (**) See https://en.wikipedia.org/wiki/Leap_second
    '''
    global cycle, adj, last, user_adjustment
    
    if not controller.brightness == last:
        user_adjustment = controller.brightness / (controller.maximum * adj)
    
    cycle = (cycle + 0.5) % 1
    adj = (1 + math.cos(cycle * 2 * math.pi)) / 2
    adj = (1 + adj) / 2
    controller.brightness = adj * user_adjustment * controller.maximum
    last = controller.brightness
    


def reset():
    '''
    Invoked to reset the displays
    '''
    controller.brightness = round(user_adjustment * controller.maximum)