from dataclasses import dataclass

from flet.controls.base_control import control
from flet.controls.control import Control
from flet.controls.control_event import ControlEvent
from flet.controls.transform import Offset
from flet.controls.types import OptionalControlEventCallable, OptionalEventCallable

__all__ = ["DragTarget", "DragTargetEvent"]


@control("DragTarget")
class DragTarget(Control):
    """
    A control that completes drag operation when a `Draggable` widget is dropped.

    When a draggable is dragged on top of a drag target, the drag target is asked whether it will accept the data the draggable is carrying. The drag target will accept incoming drag if it belongs to the same group as draggable. If the user does drop the draggable on top of the drag target (and the drag target has indicated that it will accept the draggable's data), then the drag target is asked to accept the draggable's data.

    Example:
    ```
    import flet as ft

    def main(page: ft.Page):
        page.title = "Drag and Drop example"

        def drag_will_accept(e):
            e.control.content.border = ft.border.all(
                2, ft.colors.BLACK45 if e.data == "true" else ft.colors.RED
            )
            e.control.update()

        def drag_accept(e: ft.DragTargetEvent):
            src = page.get_control(e.src_id)
            e.control.content.bgcolor = src.content.bgcolor
            e.control.content.border = None
            e.control.update()

        def drag_leave(e):
            e.control.content.border = None
            e.control.update()

        page.add(
            ft.Row(
                [
                    ft.Column(
                        [
                            ft.Draggable(
                                group="color",
                                content=ft.Container(
                                    width=50,
                                    height=50,
                                    bgcolor=ft.colors.CYAN,
                                    border_radius=5,
                                ),
                                content_feedback=ft.Container(
                                    width=20,
                                    height=20,
                                    bgcolor=ft.colors.CYAN,
                                    border_radius=3,
                                ),
                            ),
                            ft.Draggable(
                                group="color",
                                content=ft.Container(
                                    width=50,
                                    height=50,
                                    bgcolor=ft.colors.YELLOW,
                                    border_radius=5,
                                ),
                            ),
                            ft.Draggable(
                                group="color1",
                                content=ft.Container(
                                    width=50,
                                    height=50,
                                    bgcolor=ft.colors.GREEN,
                                    border_radius=5,
                                ),
                            ),
                        ]
                    ),
                    ft.Container(width=100),
                    ft.DragTarget(
                        group="color",
                        content=ft.Container(
                            width=50,
                            height=50,
                            bgcolor=ft.colors.BLUE_GREY_100,
                            border_radius=5,
                        ),
                        on_will_accept=drag_will_accept,
                        on_accept=drag_accept,
                        on_leave=drag_leave,
                    ),
                ]
            )
        )

    ft.app(target=main)
    ```

    -----

    Online docs: https://flet.dev/docs/controls/dragtarget
    """

    content: Control
    group: str = "default"
    on_will_accept: OptionalControlEventCallable = None
    on_accept: OptionalEventCallable["DragTargetEvent"] = None
    on_leave: OptionalControlEventCallable = None
    on_move: OptionalEventCallable["DragTargetEvent"] = None

    def before_update(self):
        super().before_update()
        assert self.content.visible, "content must be visible"


@dataclass
class DragTargetEvent(ControlEvent):
    src_id: int
    x: float
    y: float

    @property
    def offset(self) -> Offset:
        return Offset(self.x, self.y)