#!/usr/bin/env python3



from pprint import pprint
import daemon
import time
import argparse
import os
import json
from pyf import download, prt

WORKDIR = os.getcwd()



TMP = '/tmp/quickos.log'



def init_parser():
    ''' initialize the argument parser
        @return agrs: the parsed arguments
    '''
    parser = argparse.ArgumentParser(description='flash linux operating systems on the fly')
    parser.add_argument('os',
                        default='arch',
                        metavar='os',
                        help='the operating system that should be flashed')
    parser.add_argument('storage',
                        metavar='storage',
                        help='the storage where the os shall be flashed')
    return parser.parse_args()



def log(message):
    ''' write to logfile TMP
        @param message: the message which shall be written to the log file
    '''
    with open(TMP, 'a') as f:
        f.write('{} {}\n'.format(time.ctime(), message))



# algo check if new version should be downloaded
# a: is image file there?
# -> no: download image file
# -> yes: goto b
# 
# b: is the age of the file older than *today* - *interval*
# -> no: break
# -> yes: goto c
# 
# c: is there a *testfile_sha256* sum?
# -> no: download image file
# -> yes: goto d
# 
# d: download testfile
# is sha256 sum of testfile and *testfile_sha256* equivalent?
# -> no: download image file
# -> yes: break
def check_update(database):
    ''' check if update is necessary '''
    from urllib.parse import urlparse
    from os import path
    for name, ops in database.items():
        prt('checking operating system {} ...'.format(name))

        if ops['file_name'] == '':
            file_name = urlparse(ops['file_url'])
            file_name = file_name.path
            file_name = path.basename(file_name)
            print(file_name)
            download(ops['file_url'], file_name)
            continue



def read_os_database():
    ''' read the os database.txt file
        @return a json object of the database
    '''
    with open('{}/database.txt'.format(WORKDIR), 'r') as f:
        return json.load(f)



# https://stackoverflow.com/questions/4637420/efficient-python-daemon#8375012
def run_daemon():
    ''' run the daemon '''
    with daemon.DaemonContext():
        check_update()



if __name__ == '__main__':
    args = init_parser()
    database = read_os_database()
    check_update(database)
#     run_daemon()