from typing import List, Optional, Union

import cv2
import numpy as np

from supervision.detection.core import Detections
from supervision.draw.color import Color, ColorPalette


class BoxAnnotator:
    """
    A class for drawing bounding boxes on an image using detections provided.

    Attributes:
        color (Union[Color, ColorPalette]): The color to draw the bounding box,
            can be a single color or a color palette
        thickness (int): The thickness of the bounding box lines, default is 2
        text_color (Color): The color of the text on the bounding box, default is white
        text_scale (float): The scale of the text on the bounding box, default is 0.5
        text_thickness (int): The thickness of the text on the bounding box,
            default is 1
        text_padding (int): The padding around the text on the bounding box,
            default is 5

    """

    def __init__(
        self,
        color: Union[Color, ColorPalette] = ColorPalette.default(),
        thickness: int = 2,
        text_color: Color = Color.black(),
        text_scale: float = 0.5,
        text_thickness: int = 1,
        text_padding: int = 10,
    ):
        self.color: Union[Color, ColorPalette] = color
        self.thickness: int = thickness
        self.text_color: Color = text_color
        self.text_scale: float = text_scale
        self.text_thickness: int = text_thickness
        self.text_padding: int = text_padding

    def annotate(
        self,
        scene: np.ndarray,
        detections: Detections,
        labels: Optional[List[str]] = None,
        skip_label: bool = False,
    ) -> np.ndarray:
        """
        Draws bounding boxes on the frame using the detections provided.

        Args:
            scene (np.ndarray): The image on which the bounding boxes will be drawn
            detections (Detections): The detections for which the
                bounding boxes will be drawn
            labels (Optional[List[str]]): An optional list of labels
                corresponding to each detection. If `labels` are not provided,
                corresponding `class_id` will be used as label.
            skip_label (bool): Is set to `True`, skips bounding box label annotation.
        Returns:
            np.ndarray: The image with the bounding boxes drawn on it

        Example:
            ```python
            >>> import supervision as sv

            >>> classes = ['person', ...]
            >>> image = ...
            >>> detections = sv.Detections(...)

            >>> box_annotator = sv.BoxAnnotator()
            >>> labels = [
            ...     f"{classes[class_id]} {confidence:0.2f}"
            ...     for _, _, confidence, class_id, _
            ...     in detections
            ... ]
            >>> annotated_frame = box_annotator.annotate(
            ...     scene=image.copy(),
            ...     detections=detections,
            ...     labels=labels
            ... )
            ```
        """
        font = cv2.FONT_HERSHEY_SIMPLEX
        for i in range(len(detections)):
            x1, y1, x2, y2 = detections.xyxy[i].astype(int)
            class_id = (
                detections.class_id[i] if detections.class_id is not None else None
            )
            idx = class_id if class_id is not None else i
            color = (
                self.color.by_idx(idx)
                if isinstance(self.color, ColorPalette)
                else self.color
            )
            cv2.rectangle(
                img=scene,
                pt1=(x1, y1),
                pt2=(x2, y2),
                color=color.as_bgr(),
                thickness=self.thickness,
            )
            if skip_label:
                continue

            text = (
                f"{class_id}"
                if (labels is None or len(detections) != len(labels))
                else labels[i]
            )

            text_width, text_height = cv2.getTextSize(
                text=text,
                fontFace=font,
                fontScale=self.text_scale,
                thickness=self.text_thickness,
            )[0]

            text_x = x1 + self.text_padding
            text_y = y1 - self.text_padding

            text_background_x1 = x1
            text_background_y1 = y1 - 2 * self.text_padding - text_height

            text_background_x2 = x1 + 2 * self.text_padding + text_width
            text_background_y2 = y1

            cv2.rectangle(
                img=scene,
                pt1=(text_background_x1, text_background_y1),
                pt2=(text_background_x2, text_background_y2),
                color=color.as_bgr(),
                thickness=cv2.FILLED,
            )
            cv2.putText(
                img=scene,
                text=text,
                org=(text_x, text_y),
                fontFace=font,
                fontScale=self.text_scale,
                color=self.text_color.as_rgb(),
                thickness=self.text_thickness,
                lineType=cv2.LINE_AA,
            )
        return scene