command_factory.py

"""This module contains a factory class to create command objects based on command type.

Copyright 2023 [Abhishek Naik, Devin Headrick]. Licensed under the Apache License, Version 2.0
"""


# Factory pattern: Command Factory
class CommandFactory:
    """A factory class to create command objects based on command type.
    
    Commands are overriden as needed to provide functionality specific to the each subsystem.
    """

    def __init__(self, subsystem):
        self.subsystem = subsystem

    def command_request_data(self, params=None):
        """
        Executes a 'request' type command to get the current value of a parameter.
        Args:
            params (list): Name of the parameter to request from the IRIS subsystem state
        Returns:
            str: A string containing the requested parameter and its associated value
        """
        print("Request command received: " + params[0])
        if params and len(params) == 1 and params[0] in self.subsystem.state:
            return f"{params[0]}:{self.subsystem.state[params[0]]}\n"
        return "ERROR: Invalid request command \n"

    def command_update_parameter(self, params=None):
        """
        Executes an 'update' type command to update a parameter value.
        Args:
            params (list): Name of the parameter to request from the IRIS subsystem state
        Returns:
            str: A string containing the requested parameter and its associated value
        """
        print("Update command received: " + params[0])
        if params and len(params) == 2 and params[0] in self.subsystem.updatable_parameters:
            self.subsystem.state[params[0]] = params[1]
            return f"Updated {params[0]} to {params[1]}\n"
        return "ERROR: update command \n"

    def command_execute(self, params=None):
        """
        Executes an 'execute' type command to call a function.
        Args:
            params (list): Name of the function to call
        Returns:
            str: A string containing the return value from the function call
        """
        print("Execute command received: " + params[0])
        if params and len(params) == 1 and params[0] in self.subsystem.executable_commands:
            self.subsystem.executable_commands[params[0]]()
            return f"Command {params[0]} executed \n"
        return "ERROR: Invalid execute command \n"

    def create_command(self, command_type):
        """Creates a command object based on the command type.
        Args:
            command_type (str): The type of command to be created
        Returns:
            the method that was asked for in 'command_type'
        """
        if command_type == 'request':
            return self.command_request_data
        if command_type == 'update':
            return self.command_update_parameter
        if command_type == 'execute':
            return self.command_execute
        return None

# pylint: disable=duplicate-code
# no error
__author__ = "Abhishek Naik, Devin Headrick"
__copyright__ = """
    Copyright (C) 2023, University of Alberta.
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at
    http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License."""