import json


def read_input_json(jsonfile):
    """Read the JSON supplied from the data manager tool

    Returns a tuple (param_dict,extra_files_path)

    'param_dict' is an arbitrary dictionary of parameters
    input into the tool; 'extra_files_path' is the path
    to a directory where output files must be put for the
    receiving data manager to pick them up.

    NB the directory pointed to by 'extra_files_path'
    doesn't exist initially, it is the job of the script
    to create it if necessary.

    """
    params = json.loads(open(jsonfile).read())
    return (params['param_dict'],
            params['output_data'][0]['extra_files_path'])