import struct

from .rpc import RPC

#
# Author: Hegusung
#

class Portmap(RPC):
    program = 100000 # Portmap
    program_version = 2

    def null(self):
        procedure = 0 # Null

        super(Portmap, self).request(self.program, self.program_version, procedure)

        # no exception raised
        return True

    def dump(self):
        procedure = 4 # Dump

        proto = struct.pack(
            '!LL',
            self.program_version,
            procedure
        )

        portmap = super(Portmap, self).request(self.program, self.program_version, procedure, data=proto)

        rpc_map_entries = []

        if len(portmap) <= 4:  # portmap_Value_Follows + one portmap_Map_entry
            return rpc_map_entries

        portmap_Value_Follows = portmap[0:4]
        portmap_Map_Entries = portmap[4:]

        while portmap_Value_Follows == b'\x00\x00\x00\x01':
            (
                program,
                version,
                protocol,
                port
            ) = struct.unpack('!LLLL', portmap_Map_Entries[:16])
            portmap_Map_Entries = portmap_Map_Entries[16:]

            if protocol == 0x06:
                protocol = 'tcp'
            elif protocol == 0x11:
                protocol = 'udp'
            else:
                protocol = 'unknown'.format(protocol)

            _ = {
                'program': program, 'version': version,
                'protocol': protocol, 'port': port
            }
            if _ not in rpc_map_entries:
                rpc_map_entries.append(_)

            portmap_Value_Follows = portmap_Map_Entries[0:4]
            portmap_Map_Entries = portmap_Map_Entries[4:]


        return rpc_map_entries

    def getport(self, getport_program, getport_program_version, getport_protocol=6):
        # RPC
        program = 100000 # Portmap
        program_version = 2
        procedure = 3 # GetPort

        # GetPort
        getport_port = 0

        proto = struct.pack(
            '!LLLL',
            getport_program,
            getport_program_version,
            getport_protocol,
            getport_port
        )

        getport = super(Portmap, self).request(program, program_version, procedure, data=proto)

        (port,) = struct.unpack('!L', getport)
        return port