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import argparse

from pqos import Pqos
from pqos.cpuinfo import PqosCpuInfo
from pqos.l2ca import PqosCatL2


def str_to_int(num_str):
    """
    Converts string into number.

    Parameters:
        num_str: a string to be converted into number

    Returns:
        numeric value of the string representing the number
    """

    if num_str.lower().startswith('0x'):
        return int(num_str[2:], 16)

    return int(num_str)

# /**
#  * @brief Verifies and translates definition of single
#  *        allocation class of service
#  *        from args into internal configuration.
#  *
#  * @param argc Number of arguments in input command
#  * @param argv Input arguments for COS allocation
#  */

def set_allocation_class(l2_ids, class_id, mask):
    """
    Sets up allocation classes of service on selected CPU sockets

    Parameters:
        l2_ids: a list of L2 IDs
        class_id: class of service ID
        mask: COS bitmask
    """

    l2ca = PqosCatL2()
    cos = l2ca.COS(class_id, mask)

    for l2_id in l2_ids:
        try:
            l2ca.set(l2_id, [cos])
        except:
            print("Setting up cache allocation class of service failed!")


def print_allocation_config(l2_ids):
    """
    Prints allocation configuration.

    Parameters:
        l2_ids: a list of L2 IDs
    """

    l2ca = PqosCatL2()

    for l2_id in l2_ids:
        try:
            coses = l2ca.get(l2_id)

            print("L2CA COS definitions for L2 ID %u:" % l2_id)

            for cos in coses:
                cos_params = (cos.class_id, cos.mask)
                print("    L2CA COS%u => MASK 0x%x" % cos_params)
        except:
            print("Error")
            raise


def parse_args():
    """
    Parses command line arguments.

    Returns:
        an object with parsed command line arguments
    """

    def int_dec_or_hex(num):
        try:
            return str_to_int(num)
        except:
            msg = 'Cannot convert a parameter to a number'
            raise argparse.ArgumentError(msg)

    description = 'PQoS Library Python wrapper - L2 CAT allocation example'
    parser = argparse.ArgumentParser(description=description)
    parser.add_argument('-I', dest='interface', action='store_const',
                        const='OS', default='MSR',
                        help='select library OS interface')
    parser.add_argument('class_id', type=int, help='COS ID')
    parser.add_argument('mask', type=int_dec_or_hex, help='COS bitmask')

    args = parser.parse_args()
    return args


class PqosContextManager:
    """
    Helper class for using PQoS library Python wrapper as a context manager
    (in a with statement).
    """

    def __init__(self, *args, **kwargs):
        self.args = args
        self.kwargs = kwargs
        self.pqos = Pqos()

    def __enter__(self):
        "Initializes PQoS library."

        self.pqos.init(*self.args, **self.kwargs)
        return self.pqos

    def __exit__(self, *args, **kwargs):
        "Finalizes PQoS library."

        self.pqos.fini()
        return None


def main():
    args = parse_args()

    try:
        with PqosContextManager(args.interface):
            cpu = PqosCpuInfo()
            l2_ids = cpu.get_l2ids()

            set_allocation_class(l2_ids, args.class_id, args.mask)
            print_allocation_config(l2_ids)
    except:
        print("Error!")
        raise


if __name__ == "__main__":
    main()
