#!/usr/bin/env python3

import os
import pydbus
import sys
import time
import urllib.request

DBUS_NAME = 'com.witekio.update1'
DBUS_OBJECT = '/com/witekio/update1'
DBUS_INTERFACE = 'com.witekio.update1.Manager'

AUTOUPDATE_INSTALLED = "/var/lib/autoupdate/installed"  # used to keep track of which version got installed
AUTOUPDATE_PENDING = "/var/lib/autoupdate/pending"      # will be moved to _INSTALLED after confirmation
AUTOUPDATE_ACTIVE_PARTITIONS = "/var/lib/autoupdate/latest-active-partitions" # used to detect rollback after reboot


def dbus_init():
    bus = pydbus.SystemBus()
    obj = bus.get(DBUS_NAME, DBUS_OBJECT)
    itf = obj[DBUS_INTERFACE]
    return obj, itf


def dbus_install(filename):
    DBUS_INTERFACE.BeginUpdate()
    try:
        DBUS_INTERFACE.InstallLocalFile(filename)
        DBUS_INTERFACE.SubmitUpdate()
    except Exception:
        DBUS_INTERFACE.AbortUpdate()


def wait_for_network(url):
    while True:
        try:
            print(f"wait_for_network: GET {url}")
            urllib.request.urlopen(f"{url}").read()  # read() leads to closing the socket
            break
        except Exception:
            # Retry in 5 s
            time.sleep(5)


def get_active_partitions():
    """Get a determinist footprint of active partitions"""
    dir_active = "/dev/disk/partitions/active"
    partitions = [os.readlink(f"{dir_active}/{f}") for f in os.listdir(dir_active)]
    partitions.sort()
    return ' '.join(partitions)


def complete_pending_install(url):
    """Complete a pending installation and report to 'url'"""
    if os.path.exists(AUTOUPDATE_PENDING):
        # Let's find out if the update was successful or if we rolled back
        with open(AUTOUPDATE_ACTIVE_PARTITIONS) as fd:
            if get_active_partitions().strip() == fd.read().strip():
                # No change. That's a rollback.
                urllib.request.urlopen(f"{url}/update/rollback", data=b'')  # data= implies method POST
                os.unlink(AUTOUPDATE_PENDING)
            else:
                # Partitions changed. That means a successful update.
                urllib.request.urlopen(f"{url}/update/ok", data=b'')  # data= implies method POST
                os.rename(AUTOUPDATE_PENDING, AUTOUPDATE_INSTALLED)


# Main

host = sys.argv[1]
port = sys.argv[2]

URL_BASE = f"http://{host}:{port}"

DBUS_OBJECT, DBUS_INTERFACE = dbus_init()

wait_for_network(URL_BASE)

if DBUS_OBJECT.State == 'under-test':
    DBUS_INTERFACE.ConfirmUpdate()

complete_pending_install(URL_BASE)

while True:
    try:
        # Get latest revision to be installed
        print(f"GET {URL_BASE}/applicable")
        applicable = urllib.request.urlopen(f"{URL_BASE}/applicable").read()
        applicable = applicable.decode('utf-8').strip()
        try:
            # Get revision of locally installed package
            with open(AUTOUPDATE_INSTALLED) as fd:
                installed = fd.read().strip()
        except Exception:
            installed = None

        print(f"installed={installed}, applicable={applicable}")
        if installed is None or installed != applicable:
            # A new package is available. Download and install it.
            print(f"GET {URL_BASE}/{applicable}")
            urllib.request.urlretrieve(f"{URL_BASE}/{applicable}", "/tmp/autoupdate.pkg")
            # Call install via d-bus
            dbus_install("/tmp/autoupdate.pkg")
            # Save active partitions
            with open(AUTOUPDATE_ACTIVE_PARTITIONS, 'w') as fd:
                fd.write(get_active_partitions()+"\n")
            # Save the revision that we installed
            with open(AUTOUPDATE_PENDING, 'w') as fd:
                fd.write(f"{applicable}\n")
            # Exit normally. The systemd config should trigger a reboot.
            break
    except Exception as e:
        print(f"Failed: {e}")

    time.sleep(20)