import signal
import subprocess
import time

import adafruit_ssd1306
import busio
from board import SCL, SDA
from PIL import Image, ImageDraw, ImageFont

DISPLAY_WIDTH = 128
DISPLAY_HEIGHT = 64
SYSTEM_INFO_INTERVAL = 2.0
DISPLAY_REFRESH_INTERVAL = 0.1
FONT_PATH = '/usr/share/fonts/truetype/wqy/wqy-microhei.ttc'
FONT_SIZE_SMALL = 11
FONT_SIZE_DATE = 16
LINE_HEIGHT = 12

i2c = busio.I2C(SCL, SDA)
disp = adafruit_ssd1306.SSD1306_I2C(DISPLAY_WIDTH, DISPLAY_HEIGHT, i2c)
disp.fill(0)
disp.show()

image = Image.new("1", (DISPLAY_WIDTH, DISPLAY_HEIGHT))
draw = ImageDraw.Draw(image)


def load_font(path: str, size: int):
    try:
        return ImageFont.truetype(path, size)
    except OSError:
        return ImageFont.load_default()


font = load_font(FONT_PATH, FONT_SIZE_SMALL)
font_date = load_font(FONT_PATH, FONT_SIZE_DATE)

running = True


def signal_handler(signum, frame):
    global running
    running = False


signal.signal(signal.SIGINT, signal_handler)
signal.signal(signal.SIGTERM, signal_handler)


def run_command(cmd: str) -> str:
    try:
        result = subprocess.check_output(cmd, shell=True, stderr=subprocess.DEVNULL)
        return result.decode("utf-8").strip()
    except subprocess.CalledProcessError:
        return "N/A"


def get_system_info():
    ip = run_command("hostname -I | cut -d' ' -f1")
    cpu = run_command('cut -f 1 -d " " /proc/loadavg')
    mem = run_command("free -m | awk 'NR==2{printf \"Mem: %s/%s MB %.2f%%\", $3,$2,$3*100/$2 }'")
    disk = run_command('df -h | awk \'$NF=="/data"{printf "Disk: %d/%d GB  %s", $3,$2,$5}\'')
    return ip, cpu, mem, disk


def draw_text(line: int, text: str, font_obj=font):
    y = line * LINE_HEIGHT
    draw.text((0, y), text, font=font_obj, fill=255)


ip, cpu, mem, disk = get_system_info()
last_info_time = time.time()

while running:
    current_time = time.time()

    if current_time - last_info_time >= SYSTEM_INFO_INTERVAL:
        ip, cpu, mem, disk = get_system_info()
        last_info_time = current_time

    draw.rectangle((0, 0, DISPLAY_WIDTH, DISPLAY_HEIGHT), outline=0, fill=0)

    draw_text(0, f"IP: {ip}")
    draw_text(1, f"CPU: {cpu}")
    draw_text(2, mem)
    draw_text(3, disk)
    draw_text(4, time.strftime("%Y-%m-%d, %H:%M:%S"), font_date)

    disp.image(image)
    disp.show()
    time.sleep(DISPLAY_REFRESH_INTERVAL)

disp.fill(0)
disp.show()