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# coding=utf-8
#
# Copyright © Cloud Linux GmbH & Cloud Linux Software, Inc 2010-2019 All Rights Reserved
#
# Licensed under CLOUD LINUX LICENSE AGREEMENT
# http://cloudlinux.com/docs/LICENSE.TXT
from __future__ import print_function
from __future__ import absolute_import
import logging
import pathlib

import sqlalchemy.engine
from sqlalchemy import delete, func
from sqlalchemy.engine.reflection import Inspector
from sqlalchemy.engine.url import make_url
from sqlalchemy.ext.declarative.clsregistry import _ModuleMarker
from sqlalchemy.orm import RelationshipProperty, sessionmaker

from clcommon import mysql_lib
from clcommon.clexception import FormattedException
from lvestats.orm import Base, history
from lvestats.orm import LVE_STATS_2_TABLENAME_PREFIX
from lvestats.utils.dbmigrator import alembic_migrate

DEFAULT_DB_PATH = '/var/lve/lvestats2.db'
MYSQL, POSTGRESQL, SQLITE = 'mysql', 'postgresql', 'sqlite'
SUPPORTED_DATABASES = [MYSQL, POSTGRESQL, SQLITE]
DB_CLIENT_LIBRARY_MAP = {
    MYSQL: 'pymysql',
    POSTGRESQL: 'psycopg2',
}

__author__ = 'shaman'


def find_not_existing_tables_or_views(engine, names):
    """
    Checks if views exist.
    :param sqlalchemy.engine.base.Engine engine:
    :return:
    """
    inspector = Inspector.from_engine(engine)
    existing = set(inspector.get_view_names())
    not_existing = {LVE_STATS_2_TABLENAME_PREFIX+n for n in names} - existing
    return tuple(x.replace(LVE_STATS_2_TABLENAME_PREFIX, '') for x in tuple(not_existing))


def get_list_of_tables_without_views():
    """
    Used to call engine.create_all() without views that are described as Table()
    :return:
    """
    tables = dict(Base.metadata.tables).values()
    tables_for_disabled_features = []

    burstable_limits_feature_flag = '/opt/cloudlinux/flags/enabled-flags.d/burstable-limits.flag'
    if not pathlib.Path(burstable_limits_feature_flag).exists():
        tables_for_disabled_features.append(LVE_STATS_2_TABLENAME_PREFIX + 'bursting_events')

    return [t for t in tables if t.name not in tables_for_disabled_features]


class MakeDbException(FormattedException):
    pass


class DatabaseConfigError(FormattedException):
    pass


def cfg_get_uri(cfg, check_support=True):
    """
    Extract and validate database connection uri from config
    :param dict cfg:
    :param bool check_support:
    :return str:
    """
    # check present "db_type"
    db_type = cfg.get('db_type')
    if db_type is None:
        raise DatabaseConfigError({
            'message': '"%(config_variable)s" not in config',
            'context': {
                'config_variable': 'db_type'
            }
        })

    # check supported databases
    if check_support and db_type not in SUPPORTED_DATABASES:
        raise DatabaseConfigError({
            'message': 'Incorrect database type %(database_type)s. You should only use %(database_types)s. '
                       'The correct db_type for mariadb is "mysql"',
            'context': {
                'database_type': db_type,
                'database_types': '", "'.join(SUPPORTED_DATABASES)
            }
        })

    # check present "connect_string"
    connect_string = cfg.get('connect_string')
    if db_type != SQLITE and connect_string is None:
        raise DatabaseConfigError({
            'message': '"%(config_variable)s" not in config',
            'context': {
                'config_variable': 'connect_string'
            }
        })

    # generate database uri
    if db_type == SQLITE:
        uri = SQLITE + ':///' + cfg.get('sqlite_db_path', DEFAULT_DB_PATH)
    else:
        client_library = get_db_client_library_name(db_type)
        uri = '{0}+{1}://{2}'.format(db_type, client_library, connect_string)
        uri = get_fixed_uri(db_type, uri)
    return uri


def make_db_engine(cfg, just_print=False, debug=False, pool_class=None,
                   check_support=True):
    """
    Create sqlalchemy database engine
    :param dict cfg:
    :param bool just_print:
    :param bool debug:
    :param pool_class:
    :param bool check_support:
    :return:
    """
    log = logging.getLogger('init_db_engine')

    try:
        connect_string = cfg_get_uri(cfg, check_support=check_support)
    except DatabaseConfigError as e:
        msg = 'Unable to configure database connection. %(error)s'
        context = {'error': str(e)}
        log.error(msg % context)
        raise MakeDbException({
            'message': msg,
            'context': context
        })

    log.info('Connecting to database: %s', cfg['db_type'])

    if debug is False and 'debug' in cfg:
        debug = cfg['debug']

    if just_print:
        def dump(sql, *multiparams, **params):
            print(sql)
        engine = sqlalchemy.engine.create_engine(connect_string, strategy='mock', executor=dump)
    else:
        engine = sqlalchemy.engine.create_engine(connect_string, echo=debug, poolclass=pool_class)

    return engine


def validate_database(engine, hide_logging=False, base=Base):
    log = logging.getLogger('validate_database')
    if hide_logging:
        log.propagate = False
        log.addHandler(logging.NullHandler())
    result = {"table_error": False, "column_error": False,
              "missing_tables": list(), "orm_tables": list()}
    database_inspection = Inspector.from_engine(engine)
    real_tables = database_inspection.get_table_names()
    for _, _class in list(base._decl_class_registry.items()):
        if isinstance(_class, _ModuleMarker):
            continue
        table = _class.__tablename__
        result['orm_tables'].append(table)
        if table in real_tables:
            real_columns = [c["name"] for c in database_inspection.get_columns(table)]
            mapper = sqlalchemy.inspect(_class)
            for column_prop in mapper.attrs:
                if isinstance(column_prop, RelationshipProperty):
                    # We have no relationships
                    pass
                else:
                    for column in column_prop.columns:
                        if column.key not in real_columns:
                            log.critical(
                                "Model %s declares column %s which does not exist in database %s",
                                _class, column.key, engine)
                            result["column_error"] = True
        else:
            log.critical("Model %s declares table %s which does not exist in database %s", _class, table, engine)
            result["table_error"] = True
            result["missing_tables"].append(table)
    if result["table_error"]:
        log.critical("You can run 'lve-create-db --create-missing-tables' command to recreate missing tables.")
    if result["column_error"]:
        log.critical("You can try to recreate malformed table, or ask CloudLinux support for help.")
    return result


def check_need_create_db(engine):
    inspect_result = validate_database(engine, hide_logging=True)
    return inspect_result['missing_tables'] == inspect_result['orm_tables']


def create_db(engine):
    Base.metadata.create_all(engine, tables=get_list_of_tables_without_views())
    # write revision version to database only after create all tables
    alembic_migrate(engine, stamp=True)


def setup_db(engine, create_missing_tables=False, cfg=None):
    if create_missing_tables or check_need_create_db(engine):
        create_db(engine)
    else:
        alembic_migrate(engine, lve_stats_cfg=cfg)


def drop_tables(engine):
    Base.metadata.drop_all(engine)


def clear_rows(engine, server_id=None):
    conn_ = engine.connect()
    trans = conn_.begin()  # delete all rows in one transaction
    try:
        for _, table_object in list(Base.metadata.tables.items()):
            if server_id is None:
                delete_query = delete(table_object)
            elif isinstance(server_id, (list, tuple)):
                delete_query = delete(table_object, table_object.c.server_id in server_id)
            else:
                delete_query = delete(table_object, table_object.c.server_id == server_id)
            conn_.execute(delete_query)
        trans.commit()
    except:
        trans.rollback()
        raise


def recreate_db(engine):
    drop_tables(engine)
    create_db(engine)


def find_lost_keep_alive(session, server_id, from_timestmp=None, to_timestamp=None):
    # query for find timestmps with lost keepalive records
    # SELECT created FROM lve_stats2_history WHERE server_id = 'server_id'
    # GROUP BY created HAVING max(id) > 0 AND min(id) > 0
    lost_keepalive = session.query(
        history.created
    ).filter(
        history.server_id == server_id
    ).group_by(
        history.created
    ).having(func.max(history.id) > 0).having(func.min(history.id) > 0)
    if to_timestamp is not None:
        lost_keepalive = lost_keepalive.filter(history.created <= to_timestamp)
    if from_timestmp is not None:
        lost_keepalive = lost_keepalive.filter(history.created >= from_timestmp)
    return [record_[0] for record_ in lost_keepalive]


def fix_lost_keep_alive(session, server_id, from_timestmp=None, to_timestamp=None, log_=None):
    lost_keep_alive = find_lost_keep_alive(session, server_id, from_timestmp, to_timestamp)
    if not lost_keep_alive:
        return
    # add losted keep alive records
    v2_keepalive_row = {col: 0 for col in list(history.__table__.columns.keys())}
    v2_keepalive_row[history.server_id.key] = server_id

    for timestamp in lost_keep_alive:
        history_keepalive = history(**v2_keepalive_row)
        history_keepalive.created = timestamp  # setup timestamp
        session.add(history_keepalive)
    session.commit()
    if log_:
        log_.info('Was fixed %s losted keep alive records: %s' % (len(lost_keep_alive), lost_keep_alive))


def fix_db(engine, cfg, from_timestmp=None, to_timestamp=None, log_=None):
    # autocommit=True using for clear cache in mariadb between queries
    session = sessionmaker(bind=engine)()
    fix_lost_keep_alive(session, cfg['server_id'],
                        from_timestmp=from_timestmp, to_timestamp=to_timestamp, log_=log_)
    session.close()


def get_db_client_library_name(db_type):
    """
    Get database Python client library name
    :param str db_type:
    :return str:
    """
    client_library = DB_CLIENT_LIBRARY_MAP.get(db_type)
    if client_library is None:
        raise DatabaseConfigError({
            'message': 'The client library to connect to the "%(database_type)s" '
                       'database cannot be detected',
            'context': {
                'database_type': db_type,
            }
        })
    return client_library


def get_fixed_uri(db_type, uri):
    """
    Get fixed URI for the specified database
    :param str db_type:
    :param str uri:
    :return str:
    """
    if db_type != MYSQL:
        return uri

    u = make_url(uri)
    return str(mysql_lib.get_rfc1738_db_uri(u))