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# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you 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 logging
import uuid
from contextlib import closing
from datetime import datetime
from sys import getsizeof
from typing import Any, cast, Dict, Iterator, List, Optional, Tuple, Union

import backoff
import msgpack
import pyarrow as pa
import simplejson as json
import sqlalchemy
from celery.exceptions import SoftTimeLimitExceeded
from celery.task.base import Task
from contextlib2 import contextmanager
from flask_babel import lazy_gettext as _
from sqlalchemy.orm import Session, sessionmaker
from sqlalchemy.pool import NullPool

from superset import (
    app,
    db,
    results_backend,
    results_backend_use_msgpack,
    security_manager,
)
from superset.dataframe import df_to_records
from superset.db_engine_specs import BaseEngineSpec
from superset.extensions import celery_app
from superset.models.sql_lab import Query
from superset.result_set import SupersetResultSet
from superset.sql_parse import ParsedQuery
from superset.utils.core import (
    json_iso_dttm_ser,
    QuerySource,
    QueryStatus,
    zlib_compress,
)
from superset.utils.dates import now_as_float
from superset.utils.decorators import stats_timing

config = app.config
stats_logger = config["STATS_LOGGER"]
SQLLAB_TIMEOUT = config["SQLLAB_ASYNC_TIME_LIMIT_SEC"]
SQLLAB_HARD_TIMEOUT = SQLLAB_TIMEOUT + 60
SQL_MAX_ROW = config["SQL_MAX_ROW"]
SQLLAB_CTAS_NO_LIMIT = config["SQLLAB_CTAS_NO_LIMIT"]
SQL_QUERY_MUTATOR = config["SQL_QUERY_MUTATOR"]
log_query = config["QUERY_LOGGER"]
logger = logging.getLogger(__name__)


class SqlLabException(Exception):
    pass


class SqlLabSecurityException(SqlLabException):
    pass


class SqlLabTimeoutException(SqlLabException):
    pass


def handle_query_error(
    msg: str, query: Query, session: Session, payload: Optional[Dict[str, Any]] = None
) -> Dict[str, Any]:
    """Local method handling error while processing the SQL"""
    payload = payload or {}
    troubleshooting_link = config["TROUBLESHOOTING_LINK"]
    query.error_message = msg
    query.status = QueryStatus.FAILED
    query.tmp_table_name = None
    session.commit()
    payload.update({"status": query.status, "error": msg})
    if troubleshooting_link:
        payload["link"] = troubleshooting_link
    return payload


def get_query_backoff_handler(details: Dict[Any, Any]) -> None:
    query_id = details["kwargs"]["query_id"]
    logger.error("Query with id `%s` could not be retrieved", str(query_id))
    stats_logger.incr("error_attempting_orm_query_{}".format(details["tries"] - 1))
    logger.error("Query %s: Sleeping for a sec before retrying...", str(query_id))


def get_query_giveup_handler(_: Any) -> None:
    stats_logger.incr("error_failed_at_getting_orm_query")


@backoff.on_exception(
    backoff.constant,
    SqlLabException,
    interval=1,
    on_backoff=get_query_backoff_handler,
    on_giveup=get_query_giveup_handler,
    max_tries=5,
)
def get_query(query_id: int, session: Session) -> Query:
    """attempts to get the query and retry if it cannot"""
    try:
        return session.query(Query).filter_by(id=query_id).one()
    except Exception:
        raise SqlLabException("Failed at getting query")


@contextmanager
def session_scope(nullpool: bool) -> Iterator[Session]:
    """Provide a transactional scope around a series of operations."""
    database_uri = app.config["SQLALCHEMY_DATABASE_URI"]
    if "sqlite" in database_uri:
        logger.warning(
            "SQLite Database support for metadata databases will be removed \
            in a future version of Superset."
        )
    if nullpool:
        engine = sqlalchemy.create_engine(database_uri, poolclass=NullPool)
        session_class = sessionmaker()
        session_class.configure(bind=engine)
        session = session_class()
    else:
        session = db.session()
        session.commit()  # HACK

    try:
        yield session
        session.commit()
    except Exception as ex:
        session.rollback()
        logger.exception(ex)
        raise
    finally:
        session.close()


@celery_app.task(
    name="sql_lab.get_sql_results",
    bind=True,
    time_limit=SQLLAB_HARD_TIMEOUT,
    soft_time_limit=SQLLAB_TIMEOUT,
)
def get_sql_results(  # pylint: disable=too-many-arguments
    ctask: Task,
    query_id: int,
    rendered_query: str,
    return_results: bool = True,
    store_results: bool = False,
    user_name: Optional[str] = None,
    start_time: Optional[float] = None,
    expand_data: bool = False,
    log_params: Optional[Dict[str, Any]] = None,
) -> Optional[Dict[str, Any]]:
    """Executes the sql query returns the results."""
    with session_scope(not ctask.request.called_directly) as session:

        try:
            return execute_sql_statements(
                query_id,
                rendered_query,
                return_results,
                store_results,
                user_name,
                session=session,
                start_time=start_time,
                expand_data=expand_data,
                log_params=log_params,
            )
        except Exception as ex:  # pylint: disable=broad-except
            logger.error("Query %d", query_id)
            logger.debug("Query %d: %s", query_id, ex)
            stats_logger.incr("error_sqllab_unhandled")
            query = get_query(query_id, session)
            return handle_query_error(str(ex), query, session)


# pylint: disable=too-many-arguments
def execute_sql_statement(
    sql_statement: str,
    query: Query,
    user_name: Optional[str],
    session: Session,
    cursor: Any,
    log_params: Optional[Dict[str, Any]],
) -> SupersetResultSet:
    """Executes a single SQL statement"""
    database = query.database
    db_engine_spec = database.db_engine_spec
    parsed_query = ParsedQuery(sql_statement)
    sql = parsed_query.stripped()

    if not parsed_query.is_readonly() and not database.allow_dml:
        raise SqlLabSecurityException(
            _("Only `SELECT` statements are allowed against this database")
        )
    if query.select_as_cta:
        if not parsed_query.is_select():
            raise SqlLabException(
                _(
                    "Only `SELECT` statements can be used with the CREATE TABLE "
                    "feature."
                )
            )
        if not query.tmp_table_name:
            start_dttm = datetime.fromtimestamp(query.start_time)
            query.tmp_table_name = "tmp_{}_table_{}".format(
                query.user_id, start_dttm.strftime("%Y_%m_%d_%H_%M_%S")
            )
        sql = parsed_query.as_create_table(
            query.tmp_table_name,
            schema_name=query.tmp_schema_name,
            method=query.ctas_method,
        )
        query.select_as_cta_used = True

    # Do not apply limit to the CTA queries when SQLLAB_CTAS_NO_LIMIT is set to true
    if parsed_query.is_select() and not (
        query.select_as_cta_used and SQLLAB_CTAS_NO_LIMIT
    ):
        if SQL_MAX_ROW and (not query.limit or query.limit > SQL_MAX_ROW):
            query.limit = SQL_MAX_ROW
        if query.limit:
            sql = database.apply_limit_to_sql(sql, query.limit)

    # Hook to allow environment-specific mutation (usually comments) to the SQL
    if SQL_QUERY_MUTATOR:
        sql = SQL_QUERY_MUTATOR(sql, user_name, security_manager, database)

    try:
        if log_query:
            log_query(
                query.database.sqlalchemy_uri,
                query.executed_sql,
                query.schema,
                user_name,
                __name__,
                security_manager,
                log_params,
            )
        query.executed_sql = sql
        session.commit()
        with stats_timing("sqllab.query.time_executing_query", stats_logger):
            logger.debug("Query %d: Running query: %s", query.id, sql)
            db_engine_spec.execute(cursor, sql, async_=True)
            logger.debug("Query %d: Handling cursor", query.id)
            db_engine_spec.handle_cursor(cursor, query, session)

        with stats_timing("sqllab.query.time_fetching_results", stats_logger):
            logger.debug(
                "Query %d: Fetching data for query object: %s",
                query.id,
                str(query.to_dict()),
            )
            data = db_engine_spec.fetch_data(cursor, query.limit)

    except SoftTimeLimitExceeded as ex:
        logger.error("Query %d: Time limit exceeded", query.id)
        logger.debug("Query %d: %s", query.id, ex)
        raise SqlLabTimeoutException(
            "SQL Lab timeout. This environment's policy is to kill queries "
            "after {} seconds.".format(SQLLAB_TIMEOUT)
        )
    except Exception as ex:
        logger.error("Query %d: %s", query.id, type(ex))
        logger.debug("Query %d: %s", query.id, ex)
        raise SqlLabException(db_engine_spec.extract_error_message(ex))

    logger.debug("Query %d: Fetching cursor description", query.id)
    cursor_description = cursor.description
    return SupersetResultSet(data, cursor_description, db_engine_spec)


def _serialize_payload(
    payload: Dict[Any, Any], use_msgpack: Optional[bool] = False
) -> Union[bytes, str]:
    logger.debug("Serializing to msgpack: %r", use_msgpack)
    if use_msgpack:
        return msgpack.dumps(payload, default=json_iso_dttm_ser, use_bin_type=True)

    return json.dumps(payload, default=json_iso_dttm_ser, ignore_nan=True)


def _serialize_and_expand_data(
    result_set: SupersetResultSet,
    db_engine_spec: BaseEngineSpec,
    use_msgpack: Optional[bool] = False,
    expand_data: bool = False,
) -> Tuple[Union[bytes, str], List[Any], List[Any], List[Any]]:
    selected_columns = result_set.columns
    all_columns: List[Any]
    expanded_columns: List[Any]

    if use_msgpack:
        with stats_timing(
            "sqllab.query.results_backend_pa_serialization", stats_logger
        ):
            data = (
                pa.default_serialization_context()
                .serialize(result_set.pa_table)
                .to_buffer()
                .to_pybytes()
            )

        # expand when loading data from results backend
        all_columns, expanded_columns = (selected_columns, [])
    else:
        df = result_set.to_pandas_df()
        data = df_to_records(df) or []

        if expand_data:
            all_columns, data, expanded_columns = db_engine_spec.expand_data(
                selected_columns, data
            )
        else:
            all_columns = selected_columns
            expanded_columns = []

    return (data, selected_columns, all_columns, expanded_columns)


def execute_sql_statements(  # pylint: disable=too-many-arguments, too-many-locals, too-many-statements
    query_id: int,
    rendered_query: str,
    return_results: bool,
    store_results: bool,
    user_name: Optional[str],
    session: Session,
    start_time: Optional[float],
    expand_data: bool,
    log_params: Optional[Dict[str, Any]],
) -> Optional[Dict[str, Any]]:
    """Executes the sql query returns the results."""
    if store_results and start_time:
        # only asynchronous queries
        stats_logger.timing("sqllab.query.time_pending", now_as_float() - start_time)

    query = get_query(query_id, session)
    payload: Dict[str, Any] = dict(query_id=query_id)
    database = query.database
    db_engine_spec = database.db_engine_spec
    db_engine_spec.patch()

    if database.allow_run_async and not results_backend:
        raise SqlLabException("Results backend isn't configured.")

    # Breaking down into multiple statements
    parsed_query = ParsedQuery(rendered_query)
    statements = parsed_query.get_statements()
    logger.info("Query %s: Executing %i statement(s)", str(query_id), len(statements))

    logger.info("Query %s: Set query to 'running'", str(query_id))
    query.status = QueryStatus.RUNNING
    query.start_running_time = now_as_float()
    session.commit()

    engine = database.get_sqla_engine(
        schema=query.schema,
        nullpool=True,
        user_name=user_name,
        source=QuerySource.SQL_LAB,
    )
    # Sharing a single connection and cursor across the
    # execution of all statements (if many)
    with closing(engine.raw_connection()) as conn:
        with closing(conn.cursor()) as cursor:
            statement_count = len(statements)
            for i, statement in enumerate(statements):
                # Check if stopped
                query = get_query(query_id, session)
                if query.status == QueryStatus.STOPPED:
                    return None

                # Run statement
                msg = f"Running statement {i+1} out of {statement_count}"
                logger.info("Query %s: %s", str(query_id), msg)
                query.set_extra_json_key("progress", msg)
                session.commit()
                try:
                    result_set = execute_sql_statement(
                        statement, query, user_name, session, cursor, log_params
                    )
                except Exception as ex:  # pylint: disable=broad-except
                    msg = str(ex)
                    if statement_count > 1:
                        msg = f"[Statement {i+1} out of {statement_count}] " + msg
                    payload = handle_query_error(msg, query, session, payload)
                    return payload

        # Commit the connection so CTA queries will create the table.
        conn.commit()

    # Success, updating the query entry in database
    query.rows = result_set.size
    query.progress = 100
    query.set_extra_json_key("progress", None)
    if query.select_as_cta:
        query.select_sql = database.select_star(
            query.tmp_table_name,
            schema=query.tmp_schema_name,
            limit=query.limit,
            show_cols=False,
            latest_partition=False,
        )
    query.end_time = now_as_float()

    use_arrow_data = store_results and cast(bool, results_backend_use_msgpack)
    data, selected_columns, all_columns, expanded_columns = _serialize_and_expand_data(
        result_set, db_engine_spec, use_arrow_data, expand_data
    )

    # TODO: data should be saved separately from metadata (likely in Parquet)
    payload.update(
        {
            "status": QueryStatus.SUCCESS,
            "data": data,
            "columns": all_columns,
            "selected_columns": selected_columns,
            "expanded_columns": expanded_columns,
            "query": query.to_dict(),
        }
    )
    payload["query"]["state"] = QueryStatus.SUCCESS

    if store_results and results_backend:
        key = str(uuid.uuid4())
        logger.info(
            "Query %s: Storing results in results backend, key: %s", str(query_id), key
        )
        with stats_timing("sqllab.query.results_backend_write", stats_logger):
            with stats_timing(
                "sqllab.query.results_backend_write_serialization", stats_logger
            ):
                serialized_payload = _serialize_payload(
                    payload, cast(bool, results_backend_use_msgpack)
                )
            cache_timeout = database.cache_timeout
            if cache_timeout is None:
                cache_timeout = config["CACHE_DEFAULT_TIMEOUT"]

            compressed = zlib_compress(serialized_payload)
            logger.debug(
                "*** serialized payload size: %i", getsizeof(serialized_payload)
            )
            logger.debug("*** compressed payload size: %i", getsizeof(compressed))
            results_backend.set(key, compressed, cache_timeout)
        query.results_key = key

    query.status = QueryStatus.SUCCESS
    session.commit()

    if return_results:
        # since we're returning results we need to create non-arrow data
        if use_arrow_data:
            (
                data,
                selected_columns,
                all_columns,
                expanded_columns,
            ) = _serialize_and_expand_data(
                result_set, db_engine_spec, False, expand_data
            )
            payload.update(
                {
                    "data": data,
                    "columns": all_columns,
                    "selected_columns": selected_columns,
                    "expanded_columns": expanded_columns,
                }
            )
        return payload

    return None