#!/usr/bin/env python
"""create links for a CESM archive source directory to 
   a user specified destination directory.
"""


from __future__ import print_function

import sys

# check the system python version and require 2.7.x or greater
if sys.hexversion < 0x02070000:
    print(70 * "*")
    print("ERROR: {0} requires python >= 2.7.x. ".format(sys.argv[0]))
    print("It appears that you are running python {0}".format(
            ".".join(str(x) for x in sys.version_info[0:3])))
    print(70 * "*")
    sys.exit(1)

#
# built-in modules
#
import argparse
import glob
import os
import shutil


# -------------------------------------------------------------------------------
# commandline_options - parse any command line options
# -------------------------------------------------------------------------------

def commandline_options():
    """Process the command line arguments.

    """
    parser = argparse.ArgumentParser(
        description='Create symbolic links between CESM source archive directory component monthly history files and a specified link directory for a range of specified years. Also copy the log files for ocean timeseries diagnostics.')

    parser.add_argument('-sourcedir', '--sourcedir', required=True, nargs=1,
                        help='source archive directory')

    parser.add_argument('-linkdir', '--linkdir', required=True, nargs=1,
                        help='link directory')

    parser.add_argument('-startyear', '--startyear', required=True, nargs=1,
                        help='start year')

    parser.add_argument('-endyear', '--endyear', required=True, nargs=1,
                        help='start year')

    options = parser.parse_args()
    return options

# -------------------------------------------------------------------------------
# main
# -------------------------------------------------------------------------------
def main(options):
    """ main
    """
    comps = {'atm':'cam.h0','ice':'cice.h','lnd':'clm2.h0','ocn':'pop.h','rof':'mosart.h0'}
    logs = ['cesm.log','cpl.log','ocn.log']
    months = ['01','02','03','04','05','06','07','08','09','10','11','12']
    years = []

    # create the years list
    syear = int(options.startyear[0])
    eyear = int(options.endyear[0])
    while syear <= eyear:
        years.append(str(syear).zfill(4))
        syear += 1
        
    # check if sourcedir exists
    try:
        os.path.isdir(options.sourcedir[0])
    except:
        raise OSError('{0} does not exist. Exiting...'.format(options.sourcedir[0]))

    # check if linkdir exists
    if not os.path.exists(options.linkdir[0]):
        os.makedirs(options.linkdir[0])
    else:
        raise OSError('{0} already exists. Exiting...'.format(options.linkdir[0]))
    
    # loop through the components, years and months
    for comp in comps:
        srcdir = '{0}/{1}/hist'.format(options.sourcedir[0], comp)
        lkdir = '{0}/{1}/hist'.format(options.linkdir[0], comp)
        if not os.path.exists(lkdir):
            os.makedirs(lkdir)
        else:
            raise OSError('{0} already exists. Exiting...'.format(lkdir))
        for year in years:
            for month in months:
                filepath = srcdir.split('/')
                filename = '{0}.{1}.{2}-{3}.nc'.format(filepath[-3],comps[comp],year,month)
                try:
                    os.symlink(os.path.join(srcdir, filename), os.path.join(lkdir, filename))
                except:
                    raise OSError('Unable to create symlink {0}/{1} -> {2}/{3}. Exiting...'.format(srcdir, filename, lkdir, filename))

    # copy the cesm, cpl, and ocn logs files as those files may be compressed and write permissions may be prohibitive
    if not os.path.exists('{0}/logs'.format(options.linkdir[0])):
        os.makedirs('{0}/logs'.format(options.linkdir[0]))
    else:
        raise OSError('{0}/logs already exists. Exiting...'.format(options.linkdir[0]))

    for log in logs:
        for file in glob.glob(r'{0}/logs/{1}.*.gz'.format(options.sourcedir[0],log)):
            shutil.copy(file,'{0}/logs'.format(options.linkdir[0]))

#===================================

if __name__ == "__main__":
    options = commandline_options()
    try:
        status = main(options)
        sys.exit(status)
    except Exception as error:
        print(str(error))
        sys.exit(1)