import asyncio
import itertools
import random
import struct
import subprocess
import tempfile

import aiomqtt
from PIL import Image, ImageChops


class WebRenderer:

    def __init__(self):
        self.chrome_proc = subprocess.Popen(["google-chrome", "--headless"])
        print("Chrome subprocess started.")

    async def capture_screenshot(self, url) -> Image.Image:
        out = tempfile.NamedTemporaryFile(suffix=".png", prefix='webrenderer_')
        screenshot_command = [
            "google-chrome",
            "--headless",
            "--window-size=320,320",
            f"--screenshot={out.name}",
            url,
        ]
        subprocess.run(screenshot_command,
                       stdout=subprocess.DEVNULL,
                       stderr=subprocess.DEVNULL)
        return Image.open(out.name).convert('RGB')


block = 320 // 10

dirtyQueue = {}


async def check_for_changes(renderer, client, last_image):
    current_image = await renderer.capture_screenshot(
        "http://localhost:8002/front-door-display/scheduleLcd.html")
    diff_image = ImageChops.difference(last_image, current_image)
    for y in range(0, current_image.height, block):
        for x in range(0, current_image.width, block):
            box = (x, y, x + block, y + block)
            region = diff_image.crop(box)
            if region.getbbox():
                dirtyQueue[(x, y)] = current_image.crop(box)
                await asyncio.sleep(0)

    return current_image


async def sendDirty(client):
    while True:
        if dirtyQueue:
            # pos = random.choice(list(dirtyQueue.keys()))
            pos = min(list(dirtyQueue.keys()))
            img = dirtyQueue.pop(pos)
            await tell_lcd(client, pos[0], pos[1], img)
        await asyncio.sleep(.15)

framesSent = itertools.count()


async def tell_lcd(client: aiomqtt.Client, x: int, y: int,
                   region: Image.Image):
    seq = next(framesSent)
    msg = struct.pack('HHHHH', seq, x, y, region.width, region.height) + region.tobytes()
    print(f'send {seq=} {x=} {y=} {region.width=} {region.height=}  ', end='\r', flush=True)
    await client.publish('display/squib/updates', msg, qos=0)


async def main():
    # also listen for dirty msgs from the web page; see ts.
    # also get notified of new mqtt listeners who need a full image refresh.
    renderer = WebRenderer()
    async with aiomqtt.Client("mqtt2") as client:
        asyncio.create_task(sendDirty(client))
        last_image = Image.new('RGB', (320, 320))
        while True:
            last_image = await check_for_changes(renderer, client, last_image)
            # we could get the web page to tell us when any dom changes
            await asyncio.sleep(5)


if __name__ == "__main__":
    asyncio.run(main())