# Copyright 2015 NEC Corporation
# All Rights Reserved.
#
# 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.

"""SQLAlchemy models for inspection data and shared database code."""

import contextlib

from oslo_concurrency import lockutils
from oslo_config import cfg
from oslo_db import options as db_opts
from oslo_db.sqlalchemy import enginefacade
from oslo_db.sqlalchemy import models
from oslo_db.sqlalchemy import types as db_types
from sqlalchemy import (Boolean, Column, DateTime, Enum, ForeignKey,
                        Integer, String, Text)
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import orm

from ironic_inspector import conf  # noqa
from ironic_inspector import introspection_state as istate


class ModelBase(models.ModelBase):
    __table_args__ = {'mysql_engine': "InnoDB",
                      'mysql_charset': "utf8"}


Base = declarative_base(cls=ModelBase)
CONF = cfg.CONF
_DEFAULT_SQL_CONNECTION = 'sqlite:///ironic_inspector.sqlite'
_CTX_MANAGER = None

db_opts.set_defaults(CONF, connection=_DEFAULT_SQL_CONNECTION)

_synchronized = lockutils.synchronized_with_prefix("ironic-inspector-")


class Node(Base):
    __tablename__ = 'nodes'
    uuid = Column(String(36), primary_key=True)
    version_id = Column(String(36), server_default='')
    state = Column(Enum(*istate.States.all()), nullable=False,
                   default=istate.States.finished,
                   server_default=istate.States.finished)
    started_at = Column(DateTime, nullable=True)
    finished_at = Column(DateTime, nullable=True)
    error = Column(Text, nullable=True)

    # version_id is being tracked in the NodeInfo object
    # for the sake of consistency. See also SQLAlchemy docs:
    # http://docs.sqlalchemy.org/en/latest/orm/versioning.html
    __mapper_args__ = {
        'version_id_col': version_id,
        'version_id_generator': False,
    }


class Attribute(Base):
    __tablename__ = 'attributes'
    uuid = Column(String(36), primary_key=True)
    node_uuid = Column(String(36), ForeignKey('nodes.uuid',
                                              name='fk_node_attribute'))
    name = Column(String(255), nullable=False)
    value = Column(String(255), nullable=True)


class Option(Base):
    __tablename__ = 'options'
    uuid = Column(String(36), ForeignKey('nodes.uuid'), primary_key=True)
    name = Column(String(255), primary_key=True)
    value = Column(Text)


class Rule(Base):
    __tablename__ = 'rules'
    uuid = Column(String(36), primary_key=True)
    created_at = Column(DateTime, nullable=False)
    description = Column(Text)
    # NOTE(dtantsur): in the future we might need to temporary disable a rule
    disabled = Column(Boolean, default=False)

    conditions = orm.relationship('RuleCondition', lazy='joined',
                                  order_by='RuleCondition.id',
                                  cascade="all, delete-orphan")
    actions = orm.relationship('RuleAction', lazy='joined',
                               order_by='RuleAction.id',
                               cascade="all, delete-orphan")


class RuleCondition(Base):
    __tablename__ = 'rule_conditions'
    id = Column(Integer, primary_key=True)
    rule = Column(String(36), ForeignKey('rules.uuid'))
    op = Column(String(255), nullable=False)
    multiple = Column(String(255), nullable=False)
    invert = Column(Boolean, default=False)
    # NOTE(dtantsur): while all operations now require a field, I can also
    # imagine user-defined operations that do not, thus it's nullable.
    field = Column(Text)
    params = Column(db_types.JsonEncodedDict)

    def as_dict(self):
        res = self.params.copy()
        res['op'] = self.op
        res['field'] = self.field
        res['multiple'] = self.multiple
        res['invert'] = self.invert
        return res


class RuleAction(Base):
    __tablename__ = 'rule_actions'
    id = Column(Integer, primary_key=True)
    rule = Column(String(36), ForeignKey('rules.uuid'))
    action = Column(String(255), nullable=False)
    params = Column(db_types.JsonEncodedDict)

    def as_dict(self):
        res = self.params.copy()
        res['action'] = self.action
        return res


def init():
    """Initialize the database.

    Method called on service start up, initialize transaction
    context manager and try to create db session.
    """
    get_writer_session()


def model_query(model, *args, **kwargs):
    """Query helper for simpler session usage.

    :param session: if present, the session to use
    """
    session = kwargs.get('session') or get_reader_session()
    query = session.query(model, *args)
    return query


@contextlib.contextmanager
def ensure_transaction(session=None):
    session = session or get_writer_session()
    with session.begin(subtransactions=True):
        yield session


@_synchronized("transaction-context-manager")
def _create_context_manager():
    _ctx_mgr = enginefacade.transaction_context()
    # TODO(aarefiev): enable foreign keys for SQLite once all unit
    #                 tests with failed constraint will be fixed.
    _ctx_mgr.configure(sqlite_fk=False)

    return _ctx_mgr


def get_context_manager():
    """Create transaction context manager lazily.

    :returns: The transaction context manager.
    """
    global _CTX_MANAGER
    if _CTX_MANAGER is None:
        _CTX_MANAGER = _create_context_manager()

    return _CTX_MANAGER


def get_reader_session():
    """Help method to get reader session.

    :returns: The reader session.
    """
    return get_context_manager().reader.get_sessionmaker()()


def get_writer_session():
    """Help method to get writer session.

    :returns: The writer session.
    """
    return get_context_manager().writer.get_sessionmaker()()