# Copyright (c) 2014 Openstack Foundation
#
#    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.

import collections
import itertools
import uuid

from oslo_log import log as logging
from oslo_serialization import jsonutils
from oslo_utils import excutils

from neutron.agent.linux import utils
from neutron.agent.ovsdb import api as ovsdb
from neutron.i18n import _LE

LOG = logging.getLogger(__name__)


class Transaction(ovsdb.Transaction):
    def __init__(self, context, check_error=False, log_errors=True, opts=None):
        self.context = context
        self.check_error = check_error
        self.log_errors = log_errors
        self.opts = ["--timeout=%d" % self.context.vsctl_timeout,
                     '--oneline', '--format=json']
        if opts:
            self.opts += opts
        self.commands = []

    def add(self, command):
        self.commands.append(command)
        return command

    def commit(self):
        args = []
        for cmd in self.commands:
            cmd.result = None
            args += cmd.vsctl_args()
        res = self.run_vsctl(args)
        if res is None:
            return
        res = res.replace(r'\\', '\\').splitlines()
        for i, record in enumerate(res):
            self.commands[i].result = record
        return [cmd.result for cmd in self.commands]

    def run_vsctl(self, args):
        full_args = ["ovs-vsctl"] + self.opts + args
        try:
            # We log our own errors, so never have utils.execute do it
            return utils.execute(full_args, run_as_root=True,
                                 log_fail_as_error=False).rstrip()
        except Exception:
            with excutils.save_and_reraise_exception() as ctxt:
                if self.log_errors:
                    LOG.exception(_LE("Unable to execute %(cmd)s."),
                                  {'cmd': full_args})
                if not self.check_error:
                    ctxt.reraise = False


class BaseCommand(ovsdb.Command):
    def __init__(self, context, cmd, opts=None, args=None):
        self.context = context
        self.cmd = cmd
        self.opts = [] if opts is None else opts
        self.args = [] if args is None else args

    def execute(self, check_error=False, log_errors=True):
        with Transaction(self.context, check_error=check_error,
                         log_errors=log_errors) as txn:
            txn.add(self)
        return self.result

    def vsctl_args(self):
        return itertools.chain(('--',), self.opts, (self.cmd,), self.args)


class MultiLineCommand(BaseCommand):
    """Command for ovs-vsctl commands that return multiple lines"""
    @property
    def result(self):
        return self._result

    @result.setter
    def result(self, raw_result):
        self._result = raw_result.split(r'\n') if raw_result else []


class DbCommand(BaseCommand):
    def __init__(self, context, cmd, opts=None, args=None, columns=None):
        if opts is None:
            opts = []
        if columns:
            opts += ['--columns=%s' % ",".join(columns)]
        super(DbCommand, self).__init__(context, cmd, opts, args)

    @property
    def result(self):
        return self._result

    @result.setter
    def result(self, raw_result):
        # If check_error=False, run_vsctl can return None
        if not raw_result:
            self._result = None
            return

        try:
            json = jsonutils.loads(raw_result)
        except (ValueError, TypeError):
            # This shouldn't happen, but if it does and we check_errors
            # log and raise.
            with excutils.save_and_reraise_exception():
                LOG.exception(_LE("Could not parse: %s"), raw_result)

        headings = json['headings']
        data = json['data']
        results = []
        for record in data:
            obj = {}
            for pos, heading in enumerate(headings):
                obj[heading] = _val_to_py(record[pos])
            results.append(obj)
        self._result = results


class DbGetCommand(DbCommand):
    @DbCommand.result.setter
    def result(self, val):
        # super()'s never worked for setters http://bugs.python.org/issue14965
        DbCommand.result.fset(self, val)
        # DbCommand will return [{'column': value}] and we just want value.
        if self._result:
            self._result = self._result[0].values()[0]


class BrExistsCommand(DbCommand):
    @DbCommand.result.setter
    def result(self, val):
        self._result = val is not None

    def execute(self):
        return super(BrExistsCommand, self).execute(check_error=False,
                                                    log_errors=False)


class OvsdbVsctl(ovsdb.API):
    def transaction(self, check_error=False, log_errors=True, **kwargs):
        return Transaction(self.context, check_error, log_errors, **kwargs)

    def add_br(self, name, may_exist=True):
        opts = ['--may-exist'] if may_exist else None
        return BaseCommand(self.context, 'add-br', opts, [name])

    def del_br(self, name, if_exists=True):
        opts = ['--if-exists'] if if_exists else None
        return BaseCommand(self.context, 'del-br', opts, [name])

    def br_exists(self, name):
        return BrExistsCommand(self.context, 'list', args=['Bridge', name])

    def port_to_br(self, name):
        return BaseCommand(self.context, 'port-to-br', args=[name])

    def iface_to_br(self, name):
        return BaseCommand(self.context, 'iface-to-br', args=[name])

    def list_br(self):
        return MultiLineCommand(self.context, 'list-br')

    def br_get_external_id(self, name, field):
        return BaseCommand(self.context, 'br-get-external-id',
                           args=[name, field])

    def db_set(self, table, record, *col_values):
        args = [table, record]
        args += _set_colval_args(*col_values)
        return BaseCommand(self.context, 'set', args=args)

    def db_clear(self, table, record, column):
        return BaseCommand(self.context, 'clear', args=[table, record,
                                                        column])

    def db_get(self, table, record, column):
        # Use the 'list' command as it can return json and 'get' cannot so that
        # we can get real return types instead of treating everything as string
        # NOTE: openvswitch can return a single atomic value for fields that
        # are sets, but only have one value. This makes directly iterating over
        # the result of a db_get() call unsafe.
        return DbGetCommand(self.context, 'list', args=[table, record],
                            columns=[column])

    def db_list(self, table, records=None, columns=None, if_exists=False):
        opts = ['--if-exists'] if if_exists else None
        args = [table]
        if records:
            args += records
        return DbCommand(self.context, 'list', opts=opts, args=args,
                         columns=columns)

    def db_find(self, table, *conditions, **kwargs):
        columns = kwargs.pop('columns', None)
        args = itertools.chain([table],
                               *[_set_colval_args(c) for c in conditions])
        return DbCommand(self.context, 'find', args=args, columns=columns)

    def set_controller(self, bridge, controllers):
        return BaseCommand(self.context, 'set-controller',
                           args=[bridge] + list(controllers))

    def del_controller(self, bridge):
        return BaseCommand(self.context, 'del-controller', args=[bridge])

    def get_controller(self, bridge):
        return MultiLineCommand(self.context, 'get-controller', args=[bridge])

    def set_fail_mode(self, bridge, mode):
        return BaseCommand(self.context, 'set-fail-mode', args=[bridge, mode])

    def add_port(self, bridge, port, may_exist=True):
        opts = ['--may-exist'] if may_exist else None
        return BaseCommand(self.context, 'add-port', opts, [bridge, port])

    def del_port(self, port, bridge=None, if_exists=True):
        opts = ['--if-exists'] if if_exists else None
        args = filter(None, [bridge, port])
        return BaseCommand(self.context, 'del-port', opts, args)

    def list_ports(self, bridge):
        return MultiLineCommand(self.context, 'list-ports', args=[bridge])


def _set_colval_args(*col_values):
    args = []
    # TODO(twilson) This is ugly, but set/find args are very similar except for
    # op. Will try to find a better way to default this op to '='
    for entry in col_values:
        if len(entry) == 2:
            col, op, val = entry[0], '=', entry[1]
        else:
            col, op, val = entry
        if isinstance(val, collections.Mapping):
            args += ["%s:%s%s%s" % (
                col, k, op, _py_to_val(v)) for k, v in val.items()]
        elif (isinstance(val, collections.Sequence)
                and not isinstance(val, basestring)):
            args.append("%s%s%s" % (col, op, ",".join(map(_py_to_val, val))))
        else:
            args.append("%s%s%s" % (col, op, _py_to_val(val)))
    return args


def _val_to_py(val):
    """Convert a json ovsdb return value to native python object"""
    if isinstance(val, collections.Sequence) and len(val) == 2:
        if val[0] == "uuid":
            return uuid.UUID(val[1])
        elif val[0] == "set":
            return [_val_to_py(x) for x in val[1]]
        elif val[0] == "map":
            return {_val_to_py(x): _val_to_py(y) for x, y in val[1]}
    return val


def _py_to_val(pyval):
    """Convert python value to ovs-vsctl value argument"""
    if isinstance(pyval, bool):
        return 'true' if pyval is True else 'false'
    elif pyval == '':
        return '""'
    else:
        return pyval
