# Copyright 2012 Hewlett-Packard Development Company, L.P.
#
# 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.

# Base class for a jenkins_jobs module

import xml.etree.ElementTree as XML


def add_nonblank_xml_subelement(parent, tag, value):
    """
    Adds an XML SubElement with the name tag to parent if value is a non-empty
    string
    """
    if value is not None and value != '':
        XML.SubElement(parent, tag).text = value


class Base(object):
    """
    A base class for a Jenkins Job Builder Module.

    The module is initialized before any YAML is parsed.

    :arg ModuleRegistry registry: the global module registry.
    """

    #: The sequence number for the module.  Modules are invoked in the
    #: order of their sequence number in order to produce consistently
    #: ordered XML output.
    sequence = 10

    #: The component type for components of this module.  This will be
    #: used to look for macros (they are defined singularly, and should
    #: not be plural).
    #: Set both component_type and component_list_type to None if module
    #: doesn't have components.
    component_type = None

    #: The component list type will be used to look up possible
    #: implementations of the component type via entry points (entry
    #: points provide a list of components, so it should be plural).
    #: Set both component_type and component_list_type to None if module
    #: doesn't have components.
    component_list_type = None

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

    def handle_data(self, job_data):
        """This method is called before any XML is generated.  By
        overriding this method, a module may arbitrarily modify a data
        structure which will probably be the JJB YamlParser's intermediate data
        representation. If it has changed the data structure at all, it must
        return ``True``, otherwise, it must return ``False``.

        :arg dict job_data: the intermediate representation of job data
        loaded from JJB Yaml files without variables interpolation or other
        yaml expansions.
        :rtype: boolean
        """

        return False

    def gen_xml(self, xml_parent, data):
        """Update the XML element tree based on YAML data.  Override
        this method to add elements to the XML output.  Create new
        Element objects and add them to the xml_parent.  The YAML data
        structure must not be modified.

        :arg YAMLParser parser: the global YAML Parser
        :arg Element xml_parent: the parent XML element
        :arg dict data: the YAML data structure
        """

        pass
