Make this program more pythonic (#589)

#!/usr/bin/env python

"""This program builds shell scripts that define ISIS3 environment variables during conda environment activation and deactivation, and creates some directories."""

import argparse

import os

import sys

##########################################################################################################

#   Author:  Tyler Wilson

#   Date  :  2018-10-05

#   Description:  This script sets ISISROOT/ISIS3DATA/ISIS3TESTDATA for the user and is executed

#   within the conda environment created for the ISIS3 installation.

#   The data directory and test directory are optional command line arguments.  If the user chooses

#   not to set them, they will both be placed created on the same level as the $ISISROOT directory

#   within the conda environment.

#

#  This work is free and unencumbered software released into the public domain.

#  In jurisdictions that recognize copyright laws, the author or authors

#  of this software dedicate any and all copyright interest in the

#  software to the public domain.

#

#

#   Description:  This program builds the shell scripts that define the 

#       ISISROOT/ISIS3DATA/ISIS3TESTDATA environment variables for the user 

#       when the ISIS3 conda environment is activated, and clean up when it is

#       deactivated.

#

#       The data directory and test directory are optional command line arguments.  

#       If the user chooses not to set them, they will both be created in the

#       $ISISROOT directory.

#

#   History:

#       Author:  Tyler Wilson

#       Author:  Tyler Wilson, USGS

#       Date:    2018-10-05

#       Description: Initial commit.

#

#       Author:  Tyler Wilson, USGS

#       Date:    2018-11-01

#       Description:  Removed a pair of lines which were causing output errors on Mac OS X and were not

#                     required anyway.

#

#       Author:  Ross Beyer

#       Date:    2018-11-19

#       Description: Streamlined the program, improved documentation, and made the directory and

#                    file creation more `pythonic' rather than using system calls.

#

#

##########################################################################################################

parser = argparse.ArgumentParser(description='Usage:  ./isis3VarInit --data_dir <data dir path> --test_dir <test dir path')

# There are still a lot of Python 2 installations out there, and if people don't have

# their conda environment set up properly, the error message they'll get will be hard

# to decipher.  This might help:

assert( sys.version_info >= (3,2) ) # Must be using Python 3.2 or later, is conda set up?

# This just wraps and reports on the directory creation:

def mkdir( p ):

    if os.path.exists( p ): print( 'Tried to create '+p+', but it already exists.' )

    else:

        os.makedirs( p )

        print( 'Created '+p )

    return

isisroot = '$CONDA_PREFIX'

data_dir='$CONDA_PREFIX/data'

testdata_dir='$CONDA_PREFIX/testData'

parser.add_argument("--data-dir",default= data_dir,help="ISIS3 Mission Data Directory")

parser.add_argument("--test-dir",default=testdata_dir,help="ISIS3 Mission Test Data Directory")

# Set up and then parse the command line:

parser = argparse.ArgumentParser( description=__doc__ )

parser.add_argument('-d','--data-dir', 

                    default=os.environ['CONDA_PREFIX']+'/data',

                    help='ISIS3 Data Directory, default: %(default)s' )

parser.add_argument('-t','--test-dir',

                    default=os.environ['CONDA_PREFIX']+'/testData',

                    help='ISIS3 Test Data Directory, default: %(default)s')

args=parser.parse_args()

if (data_dir != args.data_dir):

    os.system("mkdir -p "+args.data_dir)

    data_dir = args.data_dir

else:    

    os.system("mkdir -p "+data_dir)

if (testdata_dir != args.test_dir):

    os.system("mkdir -p "+args.test_dir)

    testdata_dir=args.test_dir

else:

    os.system("mkdir -p "+testdata_dir)

os.popen('mkdir -p '+isisroot+'/etc/conda/activate.d')

os.popen('mkdir -p '+isisroot+'/etc/conda/deactivate.d')

# Create the data directories:

mkdir( args.data_dir )

mkdir( args.test_dir )

# Create the conda activation and deactivation directories:

activate_dir   = os.environ['CONDA_PREFIX']+'/etc/conda/activate.d'

deactivate_dir = os.environ['CONDA_PREFIX']+'/etc/conda/deactivate.d'

mkdir( activate_dir )

mkdir( deactivate_dir )

os.popen("echo '#!/bin/sh' > "+isisroot+ "/etc/conda/activate.d/env_vars.sh")

os.popen("echo 'export ISISROOT="+isisroot+"' >>"+isisroot+"/etc/conda/activate.d/env_vars.sh")

os.popen("echo 'export ISIS3DATA="+data_dir+"' >>"+isisroot+"/etc/conda/activate.d/env_vars.sh")

os.popen("echo 'export ISIS3TESTDATA="+testdata_dir+"' >>"+isisroot+"/etc/conda/activate.d/env_vars.sh")

# Write the files that manage the ISIS3 environments:

activate_vars   =   activate_dir+'/env_vars.sh'

deactivate_vars = deactivate_dir+'/env_vars.sh'

os.popen("echo '#!/bin/sh' > "+isisroot+ "/etc/conda/deactivate.d/env_vars.sh")

os.popen("echo 'unset ISISROOT' >>"+isisroot+"/etc/conda/deactivate.d/env_vars.sh")

os.popen("echo 'unset ISIS3DATA' >>"+isisroot+"/etc/conda/deactivate.d/env_vars.sh")

os.popen("echo 'unset ISIS3TESTDATA' >>"+isisroot+"/etc/conda/deactivate.d/env_vars.sh")

with open( activate_vars, mode='w' ) as a:

    a.write('#!/bin/sh\n')

    a.write('export ISISROOT='+      os.environ['CONDA_PREFIX']+'\n')

    a.write('export ISIS3DATA='+     args.data_dir +'\n')

    a.write('export ISIS3TESTDATA='+ args.test_dir +'\n')

print( 'Wrote '+activate_vars )

with open( deactivate_vars, mode='w' ) as d:

    d.write('#!/bin/sh\n')

    d.write('unset ISISROOT\n')

    d.write('unset ISIS3DATA\n')

    d.write('unset ISIS3TESTDATA\n')

print( 'Wrote '+deactivate_vars )