from lxml import etree
from sfa.util.plxrn import PlXrn
from sfa.util.xrn import Xrn
from sfa.rspecs.elements.link import Link
from sfa.rspecs.elements.interface import Interface
from sfa.rspecs.rspec_elements import RSpecElement, RSpecElements

class PGv2Link:

    elements = {
        'link': RSpecElement(RSpecElements.LINK, '//default:link | //link'),
        'component_manager': RSpecElement(RSpecElements.COMPONENT_MANAGER, './default:component_manager | ./component_manager'),
        'link_type': RSpecElement(RSpecElements.LINK_TYPE, './default:link_type | ./link_type'),
        'property': RSpecElement(RSpecElements.PROPERTY, './default:property | ./property'),
        'interface_ref': RSpecElement(RSpecElements.INTERFACE_REF, './default:interface_ref | ./interface_ref') 
    }
    
    @staticmethod
    def add_links(xml, links):
        root = xml.root
        for link in links:
            link_elem = etree.SubElement(root, 'link')
            for attrib in ['component_name', 'component_id', 'client_id']:
                if attrib in link and link[attrib]:
                    link_elem.set(attrib, link[attrib])
            if 'component_manager' in link and link['component_manager']:
                cm_element = etree.SubElement(link_elem, 'component_manager', name=link['component_manager'])
            for if_ref in [link['interface1'], link['interface2']]:
                if_ref_elem = etree.SubElement(link_elem, 'interface_ref')
                for attrib in Interface.fields:
                    if attrib in if_ref and if_ref[attrib]:
                        if_ref_elem.attrib[attrib] = if_ref[attrib]  
            prop1 = etree.SubElement(link_elem, 'property', source_id = link['interface1']['component_id'],
                dest_id = link['interface2']['component_id'], capacity=link['capacity'], 
                latency=link['latency'], packet_loss=link['packet_loss'])
            prop2 = etree.SubElement(link_elem, 'property', source_id = link['interface2']['component_id'],
                dest_id = link['interface1']['component_id'], capacity=link['capacity'], 
                latency=link['latency'], packet_loss=link['packet_loss'])
            if 'type' in link and link['type']:
                type_elem = etree.SubElement(link_elem, 'link_type', name=link['type'])             
   
    @staticmethod 
    def get_links(xml):
        links = []
        link_elems = xml.xpath(PGv2Link.elements['link'].path, namespaces=xml.namespaces)
        for link_elem in link_elems:
            # set client_id, component_id, component_name
            link = Link(link_elem.attrib, link_elem)
            # set component manager
            cm = link_elem.xpath('./default:component_manager', namespaces=xml.namespaces)
            if len(cm) >  0:
                cm = cm[0]
                if  'name' in cm.attrib:
                    link['component_manager'] = cm.attrib['name'] 
            # set link type
            link_types = link_elem.xpath(PGv2Link.elements['link_type'].path, namespaces=xml.namespaces)
            if len(link_types) > 0:
                link_type = link_types[0]
                if 'name' in link_type.attrib:
                    link['type'] = link_type.attrib['name']
          
            # get capacity, latency and packet_loss from first property  
            props = link_elem.xpath(PGv2Link.elements['property'].path, namespaces=xml.namespaces)
            if len(props) > 0:
                prop = props[0]
                for attrib in ['capacity', 'latency', 'packet_loss']:
                    if attrib in prop.attrib:
                        link[attrib] = prop.attrib[attrib]
                             
            # get interfaces 
            if_elems = link_elem.xpath(PGv2Link.elements['interface_ref'].path, namespaces=xml.namespaces)
            ifs = []
            for if_elem in if_elems:
                if_ref = Interface(if_elem.attrib, if_elem)
                ifs.append(if_ref)
            if len(ifs) > 1:
                link['interface1'] = ifs[0]
                link['interface2'] = ifs[1] 
            links.append(link)
        return links 

    @staticmethod
    def add_link_requests(xml, link_tuples, append=False):
        if not isinstance(link_tuples, set):
            link_tuples = set(link_tuples)

        available_links = PGv2Link.get_links(xml)
        recently_added = []
        for link in available_links:
            auth = Xrn(link['component_id']).get_authority_hrn()
            if_name1 =  Xrn(link['interface1']['component_id']).get_leaf()
            if_name2 =  Xrn(link['interface2']['component_id']).get_leaf()
            
            requested_link = None
            l_tup_1 = (if_name1, if_name2)
            l_tup_2 = (if_name2, if_name1) 
            if link_tuples.issuperset([(if_name1, if_name2)]):
                requested_link = (if_name1, if_name2)        
            elif link_tuples.issuperset([(if_name2, if_name2)]):
                requested_link = (if_name2, if_name1)
            
            if requested_link:
                # add client id to link ane interface elements 
                link.element.set('client_id', link['component_name'])
                link['interface1'].element.set('client_id', Xrn(link['interface1']['component_id']).get_leaf()) 
                link['interface2'].element.set('client_id', Xrn(link['interface2']['component_id']).get_leaf()) 
                recently_added.append(link['component_name'])

        if not append:
            # remove all links that don't have a client id 
            for link in PGv2Link.get_links(xml):
                if not link['client_id'] or link['component_name'] not in recently_added:
                    parent = link.element.getparent()
                    parent.remove(link.element)                  
             
    @staticmethod
    def get_link_requests(xml):
        link_requests = []
        for link in PGv2Link.get_links(xml):
            if link['client_id']:
                link_requests.append(link)
        return link_requests