import re
import ssl
import subprocess
import uuid
import os
from subprocess import check_output
from time import sleep
from hashlib import sha256
from io import BytesIO

import certifi
from aiohttp.web import Response, middleware
from aiohttp import ClientSession

REMOTE_DEBUGGER_UNIT = "steam-web-debug-portforward.service"

# global vars
csrf_token = str(uuid.uuid4())
ssl_ctx = ssl.create_default_context(cafile=certifi.where())
user = None
group = None

assets_regex = re.compile("^/plugins/.*/assets/.*")
frontend_regex = re.compile("^/frontend/.*")

def get_ssl_context():
    return ssl_ctx

def get_csrf_token():
    return csrf_token

@middleware
async def csrf_middleware(request, handler):
    if str(request.method) == "OPTIONS" or request.headers.get('Authentication') == csrf_token or str(request.rel_url) == "/auth/token" or str(request.rel_url).startswith("/plugins/load_main/") or str(request.rel_url).startswith("/static/") or str(request.rel_url).startswith("/legacy/") or str(request.rel_url).startswith("/steam_resource/") or str(request.rel_url).startswith("/frontend/") or assets_regex.match(str(request.rel_url)) or frontend_regex.match(str(request.rel_url)):
        return await handler(request)
    return Response(text='Forbidden', status='403')

# Get the user by checking for the first logged in user. As this is run
# by systemd at startup the process is likely to start before the user
# logs in, so we will wait here until they are available. Note that
# other methods such as getenv wont work as there was no $SUDO_USER to
# start the systemd service.
def set_user():
    global user
    cmd = "who | awk '{print $1}' | sort | head -1"
    while user == None:
        name = check_output(cmd, shell=True).decode().strip()
        if name not in [None, '']:
            user = name
        sleep(0.1)

# Get the global user. get_user must be called first.
def get_user() -> str:
    global user
    if user == None:
        raise ValueError("helpers.get_user method called before user variable was set. Run helpers.set_user first.")
    return user

# Set the global user group. get_user must be called first
def set_user_group() -> str:
    global group
    global user
    if user == None:
        raise ValueError("helpers.set_user_dir method called before user variable was set. Run helpers.set_user first.")
    if group == None:
        group = check_output(["id", "-g", "-n", user]).decode().strip()

# Get the group of the global user. set_user_group must be called first.
def get_user_group() -> str:
    global group
    if group == None:
        raise ValueError("helpers.get_user_group method called before group variable was set. Run helpers.set_user_group first.")
    return group

# Get the default home path unless a user is specified
def get_home_path(username = None) -> str:
    if username == None:
        raise ValueError("Username not defined, no home path can be found.")
    else:
        return str("/home/"+username)

# Get the default homebrew path unless a user is specified
def get_homebrew_path(home_path = None) -> str:
    if home_path == None:
        raise ValueError("Home path not defined, homebrew dir cannot be determined.")
    else:
        return str(home_path+"/homebrew")
    # return str(home_path+"/homebrew")

# Download Remote Binaries to local Plugin
async def download_remote_binary_to_path(url, binHash, path) -> bool:
    rv = False
    try:
        if os.access(os.path.dirname(path), os.W_OK):
            async with ClientSession() as client:
                res = await client.get(url, ssl=get_ssl_context())
                if res.status == 200:
                    data = BytesIO(await res.read())
                    remoteHash = sha256(data.getbuffer()).hexdigest()
                    if binHash == remoteHash:
                        data.seek(0)
                        with open(path, 'wb') as f:
                            f.write(data.getbuffer())
                            rv = True
                    else:
                        raise Exception(f"Fatal Error: Hash Mismatch for remote binary {path}@{url}")
                else:
                    rv = False
    except:
        rv = False

    return rv

async def is_systemd_unit_active(unit_name: str) -> bool:
    res = subprocess.run(["systemctl", "is-active", unit_name], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
    return res.returncode == 0

async def stop_systemd_unit(unit_name: str) -> subprocess.CompletedProcess:
    cmd = ["systemctl", "stop", unit_name]

    return subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)

async def start_systemd_unit(unit_name: str) -> subprocess.CompletedProcess:
    cmd = ["systemctl", "start", unit_name]

    return subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)