#!/usr/bin/python
#
# This module is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This software is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this software.  If not, see <http://www.gnu.org/licenses/>.

try:
    import shade
    HAS_SHADE = True
except ImportError:
    HAS_SHADE = False


DOCUMENTATION = '''
---
module: os_router
short_description: Create or delete routers from OpenStack
extends_documentation_fragment: openstack
version_added: "2.0"
author: "David Shrewsbury (@Shrews)"
description:
   - Create or Delete routers from OpenStack. Although Neutron allows
     routers to share the same name, this module enforces name uniqueness
     to be more user friendly.
options:
   state:
     description:
        - Indicate desired state of the resource
     choices: ['present', 'absent']
     default: present
   name:
     description:
        - Name to be give to the router
     required: true
   admin_state_up:
     description:
        - Desired admin state of the created or existing router.
     required: false
     default: true
   enable_snat:
     description:
        - Enable Source NAT (SNAT) attribute.
     required: false
     default: true
   network:
     description:
        - Unique name or ID of the external gateway network.
        - required I(interfaces) or I(enable_snat) are provided.
     type: string
     required: false
     default: None
   external_fixed_ips:
     description:
        - The IP address parameters for the external gateway network. Each
          is a dictionary with the subnet name or ID (subnet) and the IP
          address to assign on the subnet (ip). If no IP is specified,
          one is automatically assigned from that subnet.
     required: false
     default: None
   interfaces:
     description:
        - List of subnets to attach to the router internal interface.
     required: false
     default: None
requirements: ["shade"]
'''

EXAMPLES = '''
# Create a simple router, not attached to a gateway or subnets.
- os_router:
    cloud: mycloud
    state: present
    name: simple_router

# Creates a router attached to ext_network1 on an IPv4 subnet and one
# internal subnet interface.
- os_router:
    cloud: mycloud
    state: present
    name: router1
    network: ext_network1
    external_fixed_ips:
      - subnet: public-subnet
        ip: 172.24.4.2
    interfaces:
      - private-subnet

# Update existing router1 external gateway to include the IPv6 subnet.
# Note that since 'interfaces' is not provided, any existing internal
# interfaces on an existing router will be left intact.
- os_router:
    cloud: mycloud
    state: present
    name: router1
    network: ext_network1
    external_fixed_ips:
      - subnet: public-subnet
        ip: 172.24.4.2
      - subnet: ipv6-public-subnet
        ip: 2001:db8::3

# Delete router1
- os_router:
    cloud: mycloud
    state: absent
    name: router1
'''

RETURN = '''
router:
    description: Dictionary describing the router.
    returned: On success when I(state) is 'present'
    type: dictionary
    contains:
        id:
            description: Router ID.
            type: string
            sample: "474acfe5-be34-494c-b339-50f06aa143e4"
        name:
            description: Router name.
            type: string
            sample: "router1"
        admin_state_up:
            description: Administrative state of the router.
            type: boolean
            sample: true
        status:
            description: The router status.
            type: string
            sample: "ACTIVE"
        tenant_id:
            description: The tenant ID.
            type: string
            sample: "861174b82b43463c9edc5202aadc60ef"
        external_gateway_info:
            description: The external gateway parameters.
            type: dictionary
            sample: {
                      "enable_snat": true,
                      "external_fixed_ips": [
                         {
                           "ip_address": "10.6.6.99",
                           "subnet_id": "4272cb52-a456-4c20-8f3c-c26024ecfa81"
                         }
                       ]
                    }
        routes:
            description: The extra routes configuration for L3 router.
            type: list
'''


def _needs_update(cloud, module, router, network, internal_subnet_ids):
    """Decide if the given router needs an update.
    """
    if router['admin_state_up'] != module.params['admin_state_up']:
        return True
    if router['external_gateway_info']:
        if router['external_gateway_info'].get('enable_snat', True) != module.params['enable_snat']:
            return True
    if network:
        if not router['external_gateway_info']:
            return True
        elif router['external_gateway_info']['network_id'] != network['id']:
            return True

    # check external interfaces
    if module.params['external_fixed_ips']:
        for new_iface in module.params['external_fixed_ips']:
            subnet = cloud.get_subnet(new_iface['subnet'])
            exists = False

            # compare the requested interface with existing, looking for an existing match
            for existing_iface in router['external_gateway_info']['external_fixed_ips']:
                if existing_iface['subnet_id'] == subnet['id']:
                    if 'ip' in new_iface:
                        if existing_iface['ip_address'] == new_iface['ip']:
                            # both subnet id and ip address match
                            exists = True
                            break
                    else:
                        # only the subnet was given, so ip doesn't matter
                        exists = True
                        break

            # this interface isn't present on the existing router
            if not exists:
                return True

    # check internal interfaces
    if module.params['interfaces']:
        existing_subnet_ids = []
        for port in cloud.list_router_interfaces(router, 'internal'):
            if 'fixed_ips' in port:
                for fixed_ip in port['fixed_ips']:
                    existing_subnet_ids.append(fixed_ip['subnet_id'])

        if set(internal_subnet_ids) != set(existing_subnet_ids):
            return True

    return False

def _system_state_change(cloud, module, router, network, internal_ids):
    """Check if the system state would be changed."""
    state = module.params['state']
    if state == 'absent' and router:
        return True
    if state == 'present':
        if not router:
            return True
        return _needs_update(cloud, module, router, network, internal_ids)
    return False

def _build_kwargs(cloud, module, router, network):
    kwargs = {
        'admin_state_up': module.params['admin_state_up'],
    }

    if router:
        kwargs['name_or_id'] = router['id']
    else:
        kwargs['name'] = module.params['name']

    if network:
        kwargs['ext_gateway_net_id'] = network['id']
        # can't send enable_snat unless we have a network
        kwargs['enable_snat'] = module.params['enable_snat']

    if module.params['external_fixed_ips']:
        kwargs['ext_fixed_ips'] = []
        for iface in module.params['external_fixed_ips']:
            subnet = cloud.get_subnet(iface['subnet'])
            d = {'subnet_id': subnet['id']}
            if 'ip' in iface:
                d['ip_address'] = iface['ip']
            kwargs['ext_fixed_ips'].append(d)

    return kwargs

def _validate_subnets(module, cloud):
    external_subnet_ids = []
    internal_subnet_ids = []
    if module.params['external_fixed_ips']:
        for iface in module.params['external_fixed_ips']:
            subnet = cloud.get_subnet(iface['subnet'])
            if not subnet:
                module.fail_json(msg='subnet %s not found' % iface['subnet'])
            external_subnet_ids.append(subnet['id'])

    if module.params['interfaces']:
        for iface in module.params['interfaces']:
            subnet = cloud.get_subnet(iface)
            if not subnet:
                module.fail_json(msg='subnet %s not found' % iface)
            internal_subnet_ids.append(subnet['id'])

    return (external_subnet_ids, internal_subnet_ids)

def main():
    argument_spec = openstack_full_argument_spec(
        state=dict(default='present', choices=['absent', 'present']),
        name=dict(required=True),
        admin_state_up=dict(type='bool', default=True),
        enable_snat=dict(type='bool', default=True),
        network=dict(default=None),
        interfaces=dict(type='list', default=None),
        external_fixed_ips=dict(type='list', default=None),
    )

    module_kwargs = openstack_module_kwargs()
    module = AnsibleModule(argument_spec,
                           supports_check_mode=True,
                           **module_kwargs)

    if not HAS_SHADE:
        module.fail_json(msg='shade is required for this module')

    state = module.params['state']
    name = module.params['name']
    network = module.params['network']

    if module.params['external_fixed_ips'] and not network:
        module.fail_json(msg='network is required when supplying external_fixed_ips')

    try:
        cloud = shade.openstack_cloud(**module.params)
        router = cloud.get_router(name)

        net = None
        if network:
            net = cloud.get_network(network)
            if not net:
                module.fail_json(msg='network %s not found' % network)

        # Validate and cache the subnet IDs so we can avoid duplicate checks
        # and expensive API calls.
        external_ids, internal_ids = _validate_subnets(module, cloud)

        if module.check_mode:
            module.exit_json(
                changed=_system_state_change(cloud, module, router, net, internal_ids)
            )

        if state == 'present':
            changed = False

            if not router:
                kwargs = _build_kwargs(cloud, module, router, net)
                router = cloud.create_router(**kwargs)
                for internal_subnet_id in internal_ids:
                    cloud.add_router_interface(router, subnet_id=internal_subnet_id)
                changed = True
            else:
                if _needs_update(cloud, module, router, net, internal_ids):
                    kwargs = _build_kwargs(cloud, module, router, net)
                    router = cloud.update_router(**kwargs)

                    # On a router update, if any internal interfaces were supplied,
                    # just detach all existing internal interfaces and attach the new.
                    if internal_ids:
                        ports = cloud.list_router_interfaces(router, 'internal')
                        for port in ports:
                            cloud.remove_router_interface(router, port_id=port['id'])
                        for internal_subnet_id in internal_ids:
                            cloud.add_router_interface(router, subnet_id=internal_subnet_id)

                    changed = True

            module.exit_json(changed=changed,
                             router=router,
                             id=router['id'])

        elif state == 'absent':
            if not router:
                module.exit_json(changed=False)
            else:
                # We need to detach all internal interfaces on a router before
                # we will be allowed to delete it.
                ports = cloud.list_router_interfaces(router, 'internal')
                for port in ports:
                    cloud.remove_router_interface(router, port_id=port['id'])
                cloud.delete_router(name)
                module.exit_json(changed=True)

    except shade.OpenStackCloudException as e:
        module.fail_json(msg=str(e))


# this is magic, see lib/ansible/module_common.py
from ansible.module_utils.basic import *
from ansible.module_utils.openstack import *
if __name__ == '__main__':
    main()
