#!/usr/bin/python3
import subprocess
import Pyro4
from pathlib import Path
import logging as log
import signal
import time
from os import getpid
from zfssmd_worker import ZFSSMDaemonRefresh

ENCODING = 'utf-8'
UNIX_SOCK=Path('/run/zfssmd.sock')
UNIX_PID=Path('/run/zfssmd.pid')
CONN_ID='058b7dde9ec53de9235cfc57a07ce17a9eabfce3'

class ZfsSnapshotManagerDaemon(object):
    # TODO docstrings class and methods
    snapshots = list()
    last_refreshed=0
    def __init__(self):
        self.last_refreshed = self.call_zfs_list_snapshots()

    @Pyro4.expose
    def call_zfs_list_snapshots(self):
        command = 'zfs list -Hp -t snapshot -o name,creation,used,referenced -s name'
        try:
            p = subprocess.Popen(command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
        except Exception as e:
            log.error("Couldn't run ZFS list command. " + e)
        snapshot_list = [snapshot.decode(ENCODING) for snapshot in p.stdout]
        last_refreshed = time.time()
        self.snapshots = snapshot_list
        self.last_refreshed = last_refreshed
        return last_refreshed

    @Pyro4.expose
    def get_current_list(self):
        return {self.last_refreshed:self.snapshots}


def check_start_conditions():
    if UNIX_PID.is_file():
        log.warning("Daemon already running or didn't exit gracefully. Trying to clean up.")
        try:
            UNIX_PID.unlink()
        except Exception as e:
            log.error("Couldn't delete PID file" + str(UNIX_PID))
            log.error(e)
            raise SystemExit(1)
    try:
        UNIX_PID.touch()
    except Exception as e:
        log.error("Couldn't create PID file. " + UNIX_PID + " Check Permissions")
        log.error(e)
        raise SystemExit(1)

    if UNIX_SOCK.is_socket() or UNIX_SOCK.is_file():
        log.warning("Daemon already running or didn't exit gracefully. Trying to clean up.")
        try:
            UNIX_SOCK.unlink()
        except Exception as e:
            log.error("Couldn't delete sock file" + str(UNIX_SOCK))
            log.error(e)
            raise SystemExit(1)
    else:
        log.debug("Socket not set. Continuing.")

def sigterm_handler(_signo, _stack_frame):
    log.warning("Received Termination signal. Cleaning up.")
    UNIX_SOCK.unlink()
    UNIX_PID.unlink()
    raise SystemExit(0)

def start_daemon():
    signal.signal(signal.SIGTERM, sigterm_handler)
    signal.signal(signal.SIGINT, sigterm_handler)
    check_start_conditions()
    daemon = Pyro4.Daemon(port=None,unixsocket=str(UNIX_SOCK))
    uri = daemon.register(ZfsSnapshotManagerDaemon(), CONN_ID)
    log.info(uri)
    ZFSSMDaemonRefresh()
    daemon.requestLoop()

start_daemon()