# Copyright (c) 2024 PaddlePaddle Authors. 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.

__all__ = ["convert_points_to_boxes"]

import numpy as np


def convert_points_to_boxes(dt_polys: list) -> np.ndarray:
    """
    Converts a list of polygons to a numpy array of bounding boxes.

    Args:
        dt_polys (list): A list of polygons, where each polygon is represented
                        as a list of (x, y) points.

    Returns:
        np.ndarray: A numpy array of bounding boxes, where each box is represented
                    as [left, top, right, bottom].
                    If the input list is empty, returns an empty numpy array.
    """

    if len(dt_polys) > 0:
        dt_polys_tmp = dt_polys.copy()
        dt_polys_tmp = np.array(dt_polys_tmp)
        boxes_left = np.min(dt_polys_tmp[:, :, 0], axis=1)
        boxes_right = np.max(dt_polys_tmp[:, :, 0], axis=1)
        boxes_top = np.min(dt_polys_tmp[:, :, 1], axis=1)
        boxes_bottom = np.max(dt_polys_tmp[:, :, 1], axis=1)
        dt_boxes = np.array([boxes_left, boxes_top, boxes_right, boxes_bottom])
        dt_boxes = dt_boxes.T
    else:
        dt_boxes = np.array([])
    return dt_boxes