# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# 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
from abc import abstractmethod
from functools import partial
from typing import Any, Optional, TypedDict

import pandas as pd
from flask import current_app
from flask_babel import lazy_gettext as _
from werkzeug.datastructures import FileStorage

from superset import db
from superset.commands.base import BaseCommand
from superset.commands.database.exceptions import (
    DatabaseNotFoundError,
    DatabaseSchemaUploadNotAllowed,
    DatabaseUploadFailed,
    DatabaseUploadFileTooLarge,
    DatabaseUploadNotSupported,
    DatabaseUploadSaveMetadataFailed,
    DatabaseUploadSoftDeletedDatasetExistsError,
)
from superset.connectors.sqla.models import SqlaTable
from superset.daos.database import DatabaseDAO
from superset.models.core import Database
from superset.sql.parse import Table
from superset.utils.backports import StrEnum
from superset.utils.core import get_user
from superset.utils.decorators import on_error, transaction
from superset.views.database.validators import schema_allows_file_upload

logger = logging.getLogger(__name__)

READ_CHUNK_SIZE = 1000


class UploadFileType(StrEnum):
    CSV = "csv"
    EXCEL = "excel"
    COLUMNAR = "columnar"


class ReaderOptions(TypedDict, total=False):
    already_exists: str
    index_label: str
    dataframe_index: bool


class FileMetadataItem(TypedDict):
    sheet_name: Optional[str]
    column_names: list[str]


class FileMetadata(TypedDict, total=False):
    items: list[FileMetadataItem]


class BaseDataReader:
    """
    Base class for reading data from a file and uploading it to a database
    These child objects are used by the UploadCommand as a dependency injection
    to read data from multiple file types (e.g. CSV, Excel, etc.)
    """

    def __init__(self, options: Optional[dict[str, Any]] = None) -> None:
        self._options = options or {}

    @abstractmethod
    def file_to_dataframe(self, file: FileStorage) -> pd.DataFrame: ...

    @abstractmethod
    def file_metadata(self, file: FileStorage) -> FileMetadata: ...

    def read(
        self,
        file: FileStorage,
        database: Database,
        table_name: str,
        schema_name: Optional[str],
    ) -> None:
        self._dataframe_to_database(
            self.file_to_dataframe(file), database, table_name, schema_name
        )

    def _dataframe_to_database(
        self,
        df: pd.DataFrame,
        database: Database,
        table_name: str,
        schema_name: Optional[str],
    ) -> None:
        """
        Upload DataFrame to database

        :param df:
        :throws DatabaseUploadFailed: if there is an error uploading the DataFrame
        """
        try:
            data_table = Table(table=table_name, schema=schema_name)
            to_sql_kwargs = {
                "chunksize": READ_CHUNK_SIZE,
                "if_exists": self._options.get("already_exists", "fail"),
                "index": self._options.get("dataframe_index", False),
            }
            if self._options.get("index_label") and self._options.get(
                "dataframe_index"
            ):
                to_sql_kwargs["index_label"] = self._options.get("index_label")
            database.db_engine_spec.df_to_sql(
                database,
                data_table,
                df,
                to_sql_kwargs=to_sql_kwargs,
            )
        except ValueError as ex:
            raise DatabaseUploadFailed(
                message=_(
                    "Table already exists. You can change your "
                    "'if table already exists' strategy to append or "
                    "replace or provide a different Table Name to use."
                )
            ) from ex
        except Exception as ex:
            message = ex.message if hasattr(ex, "message") and ex.message else str(ex)
            raise DatabaseUploadFailed(message=message, exception=ex) from ex


class UploadCommand(BaseCommand):
    def __init__(  # pylint: disable=too-many-arguments
        self,
        model_id: int,
        table_name: str,
        file: Any,
        schema: Optional[str],
        reader: BaseDataReader,
    ) -> None:
        self._model_id = model_id
        self._model: Optional[Database] = None
        self._table_name = table_name
        self._schema = schema
        self._file = file
        self._reader = reader

    @transaction(on_error=partial(on_error, reraise=DatabaseUploadSaveMetadataFailed))
    def run(self) -> None:
        self.validate()
        if not self._model:
            return

        self._table_name, self._schema = (
            self._model.db_engine_spec.normalize_table_name_for_upload(
                self._table_name, self._schema
            )
        )

        sqla_table = (
            db.session.query(SqlaTable)
            .filter_by(
                table_name=self._table_name,
                schema=self._schema,
                database_id=self._model_id,
            )
            .one_or_none()
        )
        if not sqla_table:
            from superset.subjects.utils import get_user_subject

            user = get_user()
            editors = []
            if user:
                subj = get_user_subject(user.id)
                if subj:
                    editors.append(subj)

            # The lookup above runs through the soft-delete visibility filter,
            # so a soft-deleted dataset over this table is invisible here.
            # Without this guard the upload would create an active twin of the
            # hidden row — permanently blocking its restore — or die on the
            # legacy unique constraint. Check BEFORE ``reader.read`` writes
            # the file's contents into the analytics database: that write is
            # outside this command's metadata transaction and would not roll
            # back. With SOFT_DELETE off, leftover soft-deleted rows are
            # visible to the lookup above, so this branch is never reached
            # for them (degraded-mode semantics, consistent with the create
            # paths).
            # Deferred import: daos.dataset pulls in views.base, which
            # circularly imports back into the commands package at app init
            # (same constraint documented in daos/dataset.py re: PR #40573).
            from superset.daos.dataset import (  # noqa: PLC0415
                DatasetDAO,
            )

            if soft_twin := DatasetDAO.find_soft_deleted_logical_duplicate(
                self._model, Table(self._table_name, self._schema)
            ):
                raise DatabaseUploadSoftDeletedDatasetExistsError(str(soft_twin.uuid))

        self._reader.read(self._file, self._model, self._table_name, self._schema)

        if not sqla_table:
            sqla_table = SqlaTable(
                table_name=self._table_name,
                database=self._model,
                database_id=self._model_id,
                editors=editors,
                schema=self._schema,
            )
            db.session.add(sqla_table)

        sqla_table.fetch_metadata()

    @staticmethod
    def _file_size_bytes(file: Any) -> Optional[int]:
        """
        Return the size of an uploaded file without consuming its stream.

        Returns ``None`` when the stream is not seekable, in which case the
        size cannot be determined cheaply and the size check is skipped in
        favour of downstream guards.
        """
        stream = getattr(file, "stream", file)
        try:
            position = stream.tell()
            stream.seek(0, 2)  # seek to end
            size = stream.tell()
            stream.seek(position)  # restore the original position
        except (AttributeError, OSError):
            return None
        return size

    @classmethod
    def validate_file_size(cls, file: Any) -> None:
        """
        Reject a file whose size exceeds ``UPLOAD_MAX_FILE_SIZE_BYTES``.

        Shared by the upload command and the metadata endpoint so oversized
        files are rejected before their contents are read into memory,
        regardless of which path is used.

        :raises DatabaseUploadFileTooLarge: if the file is larger than the limit
        """
        max_file_size = current_app.config.get("UPLOAD_MAX_FILE_SIZE_BYTES")
        if max_file_size is None or file is None:
            return
        size = cls._file_size_bytes(file)
        if size is not None and size > max_file_size:
            raise DatabaseUploadFileTooLarge()

    def validate(self) -> None:
        self._model = DatabaseDAO.find_by_id(self._model_id)
        if not self._model:
            raise DatabaseNotFoundError()
        if not schema_allows_file_upload(self._model, self._schema):
            raise DatabaseSchemaUploadNotAllowed()
        if not self._model.db_engine_spec.supports_file_upload:
            raise DatabaseUploadNotSupported()

        self.validate_file_size(self._file)