import argparse
import os
import json
import datetime
import jinja2


def is_valid_file(parser, arg):
    if not os.path.exists(arg):
        parser.error("%s does not exist." % arg)
    else:
        return arg


def simpledate(date_string):
    try:
        d = datetime.datetime.strptime(date_string, '%Y-%M-%d')
        return d.strftime('%M/%Y')
    except ValueError:
        # in case this is not a date, we return it verbatim
        return date_string


def create_template(args):
    env = jinja2.Environment(loader=jinja2.FileSystemLoader('.'))
    env.block_start_string = '((*'
    env.block_end_string = '*))'
    env.variable_start_string = '((('
    env.variable_end_string = ')))'
    env.comment_start_string = '((='
    env.comment_end_string = '=))'
    env.filters['simpledate'] = simpledate
    return env.get_template(args.template)


def main():
    parser = argparse.ArgumentParser()

    parser.add_argument('-t', '--template',
                        type=lambda x: is_valid_file(parser, x),
                        help="Jinja2 input template", required=True)
    parser.add_argument('-r', '--resume', 
                        type=lambda x: is_valid_file(parser, x),
                        help="JSON resume", required=True)

    args = parser.parse_args()
    data = json.load(open(args.resume, 'r'))
    template = create_template(args)
    result = template.render(resume=data).encode('utf-8')
    print(result)


if __name__ == '__main__':
    main()