cx-keys/assets/settings.py

import json
import pathlib
import ipaddress
import sqlalchemy

class config_error(TypeError):
    pass

class settings:
    """
    This class is responsible for handling settings in app. It read config 
    file from specified path, and handle options from it. When any config
    option is specified wrong, for example bad formated IP address, then
    config_error will be raised.
    """

    def __init__(self, path: pathlib.Path) -> None:
        """
        This function initialize settings, it require path to parse it as 
        config file, and reading parameters from it.

        Parameters:
            path (pathlib.Path): Path of config file
        """

        if not path.is_file():
            raise FileNotFoundError("Config JSON not found.")

        with path.open() as config:
            try:
                self.__source = json.loads(config.read())
            except:
                raise config_error("Syntax error in config file.")

    @property 
    def app_name(self) -> str:
        """ It return provider app name. """
        
        return self.__get("provider.app_name", str) or "Key App"

    @property
    def app_description(self) -> str:
        """ It return description of app given by provider. """

        return self.__get("provider.description", str) or "Secure keys store."

    @property
    def organization_name(self) -> str:
        """ This return name of organization which own app. """

        return self.__get("provider.organization_name", str) or "cx-org"

    @property
    def database(self) -> str:
        """
        This return URL of the database, to build database connector. It
        parse all options, that mean user could give all parameters one
        by one, or URL as string.

        Returns:
            (str): URL of the database connection 
        """

        username = self.__get("database.username", str) or None
        password = self.__get("database.password", str) or None
        port = self.__get("database.port", int) or None
        host = self.__get("database.host", str) or None
        engine = self.__get("database.engine", str) or None
        database = self.__get("database.name", str) or None
        url = self.__get("database.url", str) or None

        if url is not None:
            check = username or None
            check = check or password or None
            check = check or port or None
            check = check or host or None
            check = check or engine or None
            check = check or database or None

            if check is None:
                return url

            error = "When database URL config parameter is in use, any other "
            error = error + "database config can not being specified. Decide "
            error = error + "which method to setting database connection use."

            raise config_rror(error)
        
        engine = engine or "sqlite"
        database = database or "database.sqlite3"

        url = sqlalchemy.URL(
            engine,
            username = username,
            password = password,
            host = host,
            database = database,
            port = port,
            query = None
        )

        return str(url)

    @property
    def host(self) -> str:
        """
        This return host to listen on. When in config is not valid ip address
        v4 or v6, then raise error.

        Returns:
            (str): Host to app listen on
        """

        host = self.__get("listen.ip", str) or "0.0.0.0"

        try:
            ipaddress.ip_address(host)
        except:
            raise config_error("IP address is in invald form.")

        return host

    @property
    def port(self) -> int:
        """
        This return port, or raise exception when port is failed.

        Returns:
            (int): Number of port to listen on
        """

        port = self.__get("listen.port", int) or 8000

        if not self.__is_port(port):
            raise config_error("Port is not in valid range.")

        return port

    @property
    def address(self) -> str:
        """
        This is address of app to make server listen on. 

        Returns:
            (str): Address of app to listen on
        """

        port = self.port
        address = self.host

        ip_type = ipaddress.ip_address(host)

        if type(ip_type) is ipaddress.IPv4Address:
            return "http://" + address + ":" + port
            
        return "http://[" + address + "]:" + port

    def __is_port(self, port: int) -> bool:
        """
        This function check that given number is proof port.

        Parameters:
            port (int): Port number to check

        Returns:
            (bool): True when this is valid port, false when not
        """

        return port >= 0 and port <= 65535

    def __get(
        self, 
        name: str, 
        typed: type | None = None
    ) -> str | int | float | bool | None:
        """
        This function load parameter, from source config file. It could 
        check type of loaded parameter, and raise error, if type is not
        valid. When typed parameter is not provided, then it skip 
        check of parameter type. When item not exists in config file, then
        return None. It could be used with "or". Config file has parts, to 
        navigate in parts use ".". For example: ["x"]["y"]["z"] => "x.y.z".
        
        Example:
            param = self.__get("default.param", str) or "default"
            
        Parameters:
            name (str): Name of the parameter, with dot "." notation
            typed (type | None): Type of returned parameter, None to skip 
                                 checking. Default = None
        
        Returns:
            (str | int | float | bool | None): Value of parameter, of None
                                               when not exists
        """

        parts = name.split(".")
        result = self.__source

        for part in parts:
            if not part in result:
                return None

            result = result[part]

        if typed is not None and type(result) is not typed:
            error = ""
            error = error + "Error, type of " + name + " "
            error = error + "must be in " + str(type(default)) + " type, "
            error = error + "but it is in " + str(type(result)) + "type."
            error = error + "Change it in config file."

            raise config_error(error)

        return result