"""
simple code to demo using the display for a virtual battery.
"""
from machine import Pin, I2C
import ssd1306
import time

time.sleep(0.1) # Wait for USB to become ready

print("Hello, CIT!")

# Setup OLED
i2c = I2C(0, scl=Pin(9), sda=Pin(8))
oled = ssd1306.SSD1306_I2C(128, 32, i2c)

# Constants
WIDTH = 128
HEIGHT = 32
BAR_Y = 24
BAR_HEIGHT = 8
DISCHARGE_TIME = 120
CHARGE_TIME = 60
FPS = 20

discharge_speed = WIDTH / (DISCHARGE_TIME * FPS)
charge_speed = WIDTH / (CHARGE_TIME * FPS)

charge = WIDTH
charging = False

def draw_battery_outline():
    for x in range(WIDTH):
        oled.pixel(x, BAR_Y, 1)  # Top
        oled.pixel(x, BAR_Y + BAR_HEIGHT - 1, 1)  # Bottom
    for y in range(BAR_Y, BAR_Y + BAR_HEIGHT):
        oled.pixel(0, y, 1)  # Left
        oled.pixel(WIDTH - 1, y, 1)  # Right

def draw_battery_fill(level):
    limit = int(level)
    if limit <= 2:
        return
    for x in range(1, limit - 1):  # Inside the outline
        for y in range(BAR_Y + 1, BAR_Y + BAR_HEIGHT - 1):
            oled.pixel(x, y, 1)

# Main loop
while True:
    oled.fill(0)
    oled.text("Battery Demo", 0, 0)
    draw_battery_outline()
    draw_battery_fill(charge)
    oled.text(f"{int(charge/128*100)}%", 90, 16)
    oled.show()

    if charging:
        charge += charge_speed
        if charge >= WIDTH:
            charge = WIDTH
            charging = False
    else:
        charge -= discharge_speed
        if charge <= 0:
            charge = 0
            charging = True

    time.sleep(1 / FPS)