import logging

from jnpr.junos import Device
from lxml import etree

from inventory_provider.constants import JUNIPER_LOGGER_NAME

CONFIG_SCHEMA = """<?xml version="1.1" encoding="UTF-8" ?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

  <xs:complexType name="generic-sequence">
    <xs:sequence>
        <xs:any processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:anyAttribute processContents="skip" />
  </xs:complexType>

  <!-- NOTE: 'unit' content isn't validated -->
  <xs:complexType name="juniper-interface">
    <xs:sequence>
        <xs:choice minOccurs="1" maxOccurs="unbounded">
          <xs:element name="name" minOccurs="1" maxOccurs="1" type="xs:string" />
          <xs:element name="description" minOccurs="0" maxOccurs="1" type="xs:string" />
          <xs:any processContents="lax" minOccurs="0" maxOccurs="unbounded" />
        </xs:choice>
    </xs:sequence>
    <xs:attribute name="inactive" type="xs:string" />
  </xs:complexType>

  <xs:element name="configuration">
    <xs:complexType>
      <xs:sequence>
        <xs:choice minOccurs="1" maxOccurs="unbounded">
          <xs:element name="version" minOccurs="0" type="xs:string" />
          <xs:element name="groups" minOccurs="0" type="generic-sequence" />
          <xs:element name="apply-groups" minOccurs="0" type="xs:string" />
          <xs:element name="system" minOccurs="0" type="generic-sequence" />
          <xs:element name="logical-systems" minOccurs="0" type="generic-sequence" />
          <xs:element name="chassis" minOccurs="0" type="generic-sequence" />
          <xs:element name="services" minOccurs="0" type="generic-sequence" />
          <xs:element name="interfaces" minOccurs="0">
            <xs:complexType>
              <xs:sequence>
                <xs:choice minOccurs="1" maxOccurs="unbounded">
                    <xs:element name="apply-groups" minOccurs="0" type="xs:string" />
                    <xs:element name="interface" minOccurs="1" maxOccurs="unbounded" type="juniper-interface" />
                </xs:choice>
              </xs:sequence>
            </xs:complexType>
          </xs:element>
          <xs:element name="snmp" minOccurs="0" type="generic-sequence" />
          <xs:element name="forwarding-options" minOccurs="0" type="generic-sequence" />
          <xs:element name="routing-options" minOccurs="0" type="generic-sequence" />
          <xs:element name="protocols" minOccurs="0" type="generic-sequence" />
          <xs:element name="policy-options" minOccurs="0" type="generic-sequence" />
          <xs:element name="class-of-service" minOccurs="0" type="generic-sequence" />
          <xs:element name="firewall" minOccurs="0" type="generic-sequence" />
          <xs:element name="routing-instances" minOccurs="0" type="generic-sequence" />
          <xs:element name="bridge-domains" minOccurs="0" type="generic-sequence" />
        </xs:choice>
      </xs:sequence>
      <xs:attribute name="changed-seconds" type="xs:string" />
      <xs:attribute name="changed-localtime" type="xs:string" />
    </xs:complexType>
  </xs:element>

</xs:schema>
"""  # noqa: E501

UNIT_SCHEMA = """<?xml version="1.1" encoding="UTF-8" ?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

  <xs:complexType name="generic-sequence">
    <xs:sequence>
        <xs:any processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
    <xs:anyAttribute processContents="skip" />
  </xs:complexType>

  <xs:element name="unit">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="name" minOccurs="1" maxOccurs="1" type="xs:int" />
        <xs:element name="description" minOccurs="0" maxOccurs="1" type="xs:string" />
        <xs:any processContents="lax" minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
      <xs:attribute name="inactive" type="xs:string" />
    </xs:complexType>
  </xs:element>

</xs:schema>
"""  # noqa: E501


def _rpc(hostname, ssh):
    dev = Device(
        host=hostname,
        user=ssh['username'],
        ssh_private_key_file=ssh['private-key'])
    dev.open()
    return dev.rpc


def load_config(hostname, ssh_params):
    """
    loads netconf data from the router, validates and
    returns as an lxml etree doc

    :param hostname: router hostname
    :param ssh_params: 'ssh' config element(cf. config.py:CONFIG_SCHEMA)
    :return:
    """
    juniper_logger = logging.getLogger(JUNIPER_LOGGER_NAME)

    juniper_logger.info("capturing netconf data for '%s'" % hostname)

    def _validate(schema, doc):
        if schema.validate(doc):
            return
        for e in schema.error_log:
            juniper_logger.error("%d.%d: %s" % (e.line, e.column, e.message))
        assert False

    schema_doc = etree.XML(CONFIG_SCHEMA.encode('utf-8'))
    config_schema = etree.XMLSchema(schema_doc)

    config = _rpc(hostname, ssh_params).get_config()
    _validate(config_schema, config)

    # validate interfaces/interface/unit elements ...
    schema_doc = etree.XML(UNIT_SCHEMA.encode('utf-8'))
    unit_schema = etree.XMLSchema(schema_doc)
    for i in config.xpath('//configuration/interfaces/interface'):
        for u in i.xpath('./unit'):
            _validate(unit_schema, u)

    return config


def list_interfaces(netconf_config):
    """
    generator that parses netconf output and
    yields a list of interfaces

    :param netconf_config: xml doc that was generated by load_config
    :return:
    """

    def _ifc_info(e):
        name = e.find('name')
        assert name is not None, "expected interface 'name' child element"
        ifc = {
            'name': name.text,
            'description': ''
        }
        description = e.find('description')
        if description is not None:
            ifc['description'] = description.text

        ifc['ipv4'] = e.xpath('./family/inet/address/name/text()')
        ifc['ipv6'] = e.xpath('./family/inet6/address/name/text()')

        return ifc

    for i in netconf_config.xpath('//configuration/interfaces/interface'):
        info = _ifc_info(i)
        yield info
        for u in i.xpath('./unit'):
            unit_info = _ifc_info(u)
            unit_info['name'] = "%s.%s" % (info['name'], unit_info['name'])
            yield unit_info


def list_bgp_routes(netconf_config):
    for r in netconf_config.xpath(
            '//configuration/routing-instances/'
            'instance[name/text()="IAS"]/protocols/bgp/'
            'group[starts-with(name/text(), "GEANT-IX")]/'
            'neighbor'):
        name = r.find('name')
        description = r.find('description')
        local_as = r.find('local-as')
        if local_as is not None:
            local_as = local_as.find('as-number')
        peer_as = r.find('peer-as')
        yield {
            'name': name.text,
            'description': description.text,
            'as': {
                'local': int(local_as.text),
                'peer': int(peer_as.text)
            }
        }

# note for enabling vrr data parsing ...
# def fetch_vrr_config(hostname, ssh_params):
#
#     commands = [
#         _DISABLE_PAGING_COMMAND,
#         ('show configuration logical-systems '
#          'VRR protocols bgp | display json')
#     ]
#
#     output = list(ssh_exec_commands(hostname, ssh_params, commands))
#     assert len(output) == len(commands)
#
#     return _loads(output[1]) if output[1] else {}
#