# Copyright (c) Streamlit Inc. (2018-2022) Snowflake Inc. (2022)
#
# 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,
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"""Useful classes for our native Altair-based charts.

These classes are used to pass some important info to add_rows.
"""

from dataclasses import dataclass
from typing import Hashable, List, Optional, TypedDict


class PrepDataColumns(TypedDict):
    """Columns used for the prep_data step in Altair Arrow charts."""

    x_column: Optional[str]
    y_column_list: List[str]
    color_column: Optional[str]
    size_column: Optional[str]


@dataclass
class AddRowsMetadata:
    """Metadata needed by add_rows on native charts."""

    last_index: Optional[Hashable]
    columns: PrepDataColumns
