#!/data_systems/opt/bin/python3

""" check_for_new_prelim_daisy

See if a new preliminary daisy has been created. If so copy it to
the destination directory and send out the daily email

Created June 2018

@author: Bill Barrett

"""

import os
import re
import glob
import subprocess
import socket

# The current AIM CIPS season
CURRENT_SEASON = 'north_2018'

# The pattern for the preliminary daisy. A typical file name is:
#  cips_sci_3a_2018-158_v05.20_r01_prelim.png
FILE_PATTERN = re.compile(r'''.*(?P<filename>cips_sci_3a_
                          (?P<year>20\d{2})
                          \-(?P<day_of_year>\d{3})
                          _v(?P<version>0\d\.\d{2})
                          _r(?P<revision>\d{2})
                          _prelim.png)''', re.VERBOSE)
# The directory where the file is initially
CREATION_DIRECTORY = os.environ.get('SDS_ROOT', '/aim/sds')
# The root for the destination directory
DESTINATION_DIRECTORY_ROOT = os.environ.get('DATA_1A', '/aim/data/cips/')


def main(season):
    """The main driver.

    Parameters
    ----------
    season : str
        An AIM CIPS season which is either 'north' or 'south' + _ + the four digit year
        Examples are 'north_2018', 'south_2009'

    """
    destination_directory = ''
    processed_daisies = []
    # The file is created in '/aim/sds'
    candidate_files = glob.glob('/aim/sds/*prelim.png')
    for file in glob.glob('/aim/sds/*prelim.png'):
        file_match = FILE_PATTERN.match(file)
        if file_match is not None:
            filename = file_match.group('filename')
            if len(destination_directory) == 0:
                destination_directory = (DESTINATION_DIRECTORY_ROOT + season + '/level_3/ver_' +
                                         file_match.group('version') + '/rev_' + file_match.group('revision'))
                processed_daisies = glob.glob(destination_directory + '/*prelim.png')
            for daisy in processed_daisies:
                if daisy.endswith(filename):
                    print('{0} is already in {1}'.format(filename, destination_directory))
                    candidate_files.remove(file)

    # Are there any available files to be sent out and has the destination been established?
    if len(candidate_files) > 0 and len(destination_directory) > 0:
        for file in candidate_files:
            file_match = FILE_PATTERN.match(file)
            create_and_execute_commands(file_match.group('filename'), destination_directory, file_match.group('year'),
                                        file_match.group('day_of_year'))
    else:
        print('No new preliminary daisy files are available at present')


def create_and_execute_commands(file, destination_directory, year, day_of_year):
    """ Create the commands to copy the file to the destination directory and
    send out the preliminary daisy email

    Parameters
    ----------
    file : str
        the name of the file to be transferred
    destination_directory : str
        the directory to which the file is being written
    year : str
        a four digit year as a string, e.g. '2018'
    day_of_year : str
        a three digit day of year as a string, e.g. '014'
    """
    # Preserve as many of the file attributes, especially the date, as possible
    #  when copying the file to the destination directory
    copy_command = 'cp -p ' + file + ' ' + destination_directory + '/'
    print_and_execute_command(copy_command)
    # Send the email out
    perl_command = '/aim/sds/cips/scripts/send_prelim_images.pl ' + year + day_of_year
    print_and_execute_command(perl_command)


def print_and_execute_command(command):
    """ Print a shell command, execute it, and print the results

    Parameters
    ----------
    command : str
        a command to be executed by the shell
    """
    print(command)
    result = execute_shell_command(command)
    print(result)


def execute_shell_command(command):
    """ Tokenize a string assumed to a shell command, execute it, and return stdout and stderr as a string

    Parameters
    ----------
    command : str
        a command to be executed by the shell

    Returns
    -------
     : str
        the output, decoded to a string, from executing the command

    """
    # This fails unless the command is tokenized
    command_and_args = command.split()
    result = subprocess.run(command_and_args, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    # convert the annoying byte array to a string before returning it
    return result.stdout.decode('utf-8')


if __name__ == '__main__':
    """ Making this executable
    """
    # This should only be run from aimcips-gpu because it is at present the only aim
    #   server allowed to send out email
    if socket.gethostname().find('.') >= 0:
        hostname = socket.gethostname()
    else:
        hostname = socket.gethostbyaddr(socket.gethostname())[0]
    print('hostname: {0}'.format(hostname))
    if not hostname.startswith('aimcips-gpu'):
        print('This program must be run from aimcips-gpu in order to send out the preliminary daisy email')
        exit(1)

    # On the right host so lets do it
    main(CURRENT_SEASON)