# -*- 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.

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):
    '''
    :(int, int, int, int, int, int, int, float?)?→void  Place holder for periodically invoked function
    
    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)