import json, os


class PBinCLIException(Exception):
    pass


def check_readable(f):
    """Checks if path exists and readable"""
    if not os.path.exists(f) or not os.access(f, os.R_OK):
        raise PBinCLIException("Error accessing path: {}".format(f))


def check_writable(f):
    """Checks if path is writable"""
    if not os.access(os.path.dirname(f) or ".", os.W_OK):
        raise PBinCLIException("Path is not writable: {}".format(f))


"""http://stackoverflow.com/a/33571117"""
def json_load_byteified(file_handle):
    return _byteify(
        json.load(file_handle, object_hook=_byteify),
        ignore_dicts=True
    )


def json_loads_byteified(json_text):
    return _byteify(
        json.loads(json_text, object_hook=_byteify),
        ignore_dicts=True
    )


def _byteify(data, ignore_dicts = False):
    # if this is a unicode string, return its string representation
    if isinstance(data, unicode):
        return data.encode('utf-8')
    # if this is a list of values, return list of byteified values
    if isinstance(data, list):
        return [ _byteify(item, ignore_dicts=True) for item in data ]
    # if this is a dictionary, return dictionary of byteified keys and values
    # but only if we haven't already byteified it
    if isinstance(data, dict) and not ignore_dicts:
        return {
            _byteify(key, ignore_dicts=True): _byteify(value, ignore_dicts=True)
            for key, value in data.iteritems()
        }
    # if it's anything else, return it in its original form
    return data