"""
Mouse events.


How it works
------------

The renderer has a 2 dimensional grid of mouse event handlers.
(`prompt_toolkit.layout.MouseHandlers`.) When the layout is rendered, the
`Window` class will make sure that this grid will also be filled with
callbacks. For vt100 terminals, mouse events are received through stdin, just
like any other key press. There is a handler among the key bindings that
catches these events and forwards them to such a mouse event handler. It passes
through the `Window` class where the coordinates are translated from absolute
coordinates to coordinates relative to the user control, and there
`UIControl.mouse_handler` is called.
"""
from enum import Enum
from typing import FrozenSet

from .data_structures import Point

__all__ = ["MouseEventType", "MouseButton", "MouseModifier", "MouseEvent"]


class MouseEventType(Enum):
    # Mouse up: This same event type is fired for all three events: left mouse
    # up, right mouse up, or middle mouse up
    MOUSE_UP = "MOUSE_UP"

    # Mouse down: This implicitly refers to the left mouse down (this event is
    # not fired upon pressing the middle or right mouse buttons).
    MOUSE_DOWN = "MOUSE_DOWN"

    SCROLL_UP = "SCROLL_UP"
    SCROLL_DOWN = "SCROLL_DOWN"

    # Triggered when the left mouse button is held down, and the mouse moves
    MOUSE_MOVE = "MOUSE_MOVE"


class MouseButton(Enum):
    LEFT = "LEFT"
    MIDDLE = "MIDDLE"
    RIGHT = "RIGHT"

    # When we're scrolling, or just moving the mouse and not pressing a button.
    NONE = "NONE"

    # This is for when we don't know which mouse button was pressed, but we do
    # know that one has been pressed during this mouse event (as opposed to
    # scrolling, for example)
    UNKNOWN = "UNKNOWN"


class MouseModifier(Enum):
    SHIFT = "SHIFT"
    ALT = "ALT"
    CONTROL = "CONTROL"


class MouseEvent:
    """
    Mouse event, sent to `UIControl.mouse_handler`.

    :param position: `Point` instance.
    :param event_type: `MouseEventType`.
    """

    def __init__(
        self,
        position: Point,
        event_type: MouseEventType,
        button: MouseButton,
        modifiers: FrozenSet[MouseModifier],
    ) -> None:
        self.position = position
        self.event_type = event_type
        self.button = button
        self.modifiers = modifiers

    def __repr__(self) -> str:
        return "MouseEvent({!r},{!r},{!r},{!r})".format(
            self.position,
            self.event_type,
            self.button,
            self.modifiers,
        )
