###############################################################################
#
# Connection - A class for writing connections to Tableau files
#
###############################################################################
import xml.etree.ElementTree as ET
from tableaudocumentapi.dbclass import is_valid_dbclass


class Connection(object):
    """
    A class for writing connections to Tableau files.

    """

    ###########################################################################
    #
    # Public API.
    #
    ###########################################################################

    def __init__(self, connxml):
        """
        Constructor.

        """
        self._connectionXML = connxml
        self._dbname = connxml.get('dbname')
        self._server = connxml.get('server')
        self._username = connxml.get('username')
        self._authentication = connxml.get('authentication')
        self._class = connxml.get('class')
        self._port = connxml.get('port', None)

    def __repr__(self):
        return "'<Connection server='{}' dbname='{}' @ {}>'".format(self._server, self._dbname, hex(id(self)))

    @classmethod
    def from_attributes(cls, server, dbname, username, dbclass, port=None, authentication=''):
        root = ET.Element('connection', authentication=authentication)
        xml = cls(root)
        xml.server = server
        xml.dbname = dbname
        xml.username = username
        xml.dbclass = dbclass
        xml.port = port

        return xml

    ###########
    # dbname
    ###########
    @property
    def dbname(self):
        return self._dbname

    @dbname.setter
    def dbname(self, value):
        """
        Set the connection's database name property.

        Args:
            value:  New name of the database. String.

        Returns:
            Nothing.

        """
        self._dbname = value
        self._connectionXML.set('dbname', value)

    ###########
    # server
    ###########
    @property
    def server(self):
        return self._server

    @server.setter
    def server(self, value):
        """
        Set the connection's server property.

        Args:
            value:  New server. String.

        Returns:
            Nothing.

        """
        self._server = value
        self._connectionXML.set('server', value)

    ###########
    # username
    ###########
    @property
    def username(self):
        return self._username

    @username.setter
    def username(self, value):
        """
        Set the connection's username property.

        Args:
            value:  New username value. String.

        Returns:
            Nothing.

        """
        self._username = value
        self._connectionXML.set('username', value)

    ###########
    # authentication
    ###########
    @property
    def authentication(self):
        return self._authentication

    ###########
    # dbclass
    ###########
    @property
    def dbclass(self):
        return self._class

    @dbclass.setter
    def dbclass(self, value):

        if not is_valid_dbclass(value):
            raise AttributeError("'{}' is not a valid database type".format(value))

        self._class = value
        self._connectionXML.set('class', value)

    ###########
    # port
    ###########
    @property
    def port(self):
        return self._port

    @port.setter
    def port(self, value):
        self._port = value
        # If port is None we remove the element and don't write it to XML
        if value is None:
            try:
                del self._connectionXML.attrib['port']
            except KeyError:
                pass
        else:
            self._connectionXML.set('port', value)