'''
Mission 11 - Remix 2A - Medium
This remix changes the bubble indicator to a solid circle when 
degrees is 0, which means perfectly centered. It is based off of
Remix 1B, which adds an intro and ending to the program, but it
is not part of the challenge.
'''
from codex import *
from time import sleep
import math
# center of display (240 x 240)
CENTER = 120

# draw two lines on the screen
# leave space in the middle for the circle 
def set_screen():
    display.fill(WHITE)
    display.draw_line(CENTER, 0, CENTER, 105, BLACK)
    display.draw_line(CENTER, 135, CENTER, 239, BLACK)

def calc_degrees():
    global degrees
    # read from the accelerometer and get x value
    val = accel.read()
    tilt_x = val[0]
    # change accelerometer reading to degrees
    scaled = (tilt_x / 16384)
    scaled = min(max(scaled, -1), 1)
    degrees = math.asin(scaled) * 180 / math.pi
    degrees = int(degrees)

def intro():
    display.print("Spirit Level")
    display.print("")
    display.print("A to start")
    display.print("B to quit")
    while True:
        if buttons.was_pressed(BTN_A):
            break

# define a variable to use for the circle's position
x = CENTER

intro()
set_screen()
# start an infinite loop
while True:
    calc_degrees()
    # erase current circle, recalculate, and draw new circle
    display.fill_circle(x, CENTER, 15, WHITE)
    x = CENTER + degrees
    if degrees == 0:
        display.fill_circle(CENTER, CENTER, 15, RED)
    else:
        display.fill_circle(CENTER, CENTER, 15, WHITE)
        display.draw_circle(x, CENTER, 15, ORANGE)
    sleep(0.2)

    if buttons.was_pressed(BTN_B):
        break

# ending message
display.clear()
display.print("DONE", scale=6)