from functools import partial
from typing import Optional

from prompt_toolkit.filters import Condition
from prompt_toolkit.formatted_text import AnyFormattedText, Template
from prompt_toolkit.key_binding import KeyBindings
from prompt_toolkit.layout import (
    AnyContainer,
    AnyDimension,
    ConditionalContainer,
    Container,
    DynamicContainer,
    HSplit,
    VSplit,
    Window,
)
from prompt_toolkit.widgets.base import Border, Label


class SelectableFrame:
    """
    Draw a border around any container, optionally with a title text.

    Changing the title and body of the frame is possible at runtime by
    assigning to the `body` and `title` attributes of this class.

    :param body: Another container object.
    :param title: Text to be displayed in the top of the frame (can be formatted text).
    :param style: Style string to be applied to this widget.
    """

    def __init__(
        self,
        body: AnyContainer,
        title: AnyFormattedText = "",
        style: str = "",
        width: AnyDimension = None,
        height: AnyDimension = None,
        key_bindings: Optional[KeyBindings] = None,
        modal: bool = False,
        activated: bool = False,
    ) -> None:
        self.title = title
        self.body = body
        self.activated = activated

        def get_style() -> str:
            if self.activated:
                return "class:frame.border.selected"
            else:
                return "class:frame.border"

        fill = partial(Window, style=get_style)
        style = "class:frame " + style

        top_row_with_title = VSplit(
            [
                fill(width=1, height=1, char=Border.TOP_LEFT),
                fill(char=Border.HORIZONTAL),
                fill(width=1, height=1, char="|"),
                # Notice: we use `Template` here, because `self.title` can be an
                # `HTML` object for instance.
                Label(
                    lambda: Template(" {} ").format(self.title),
                    style="class:frame.label",
                    dont_extend_width=True,
                ),
                fill(width=1, height=1, char="|"),
                fill(char=Border.HORIZONTAL),
                fill(width=1, height=1, char=Border.TOP_RIGHT),
            ],
            height=1,
        )

        top_row_without_title = VSplit(
            [
                fill(width=1, height=1, char=Border.TOP_LEFT),
                fill(char=Border.HORIZONTAL),
                fill(width=1, height=1, char=Border.TOP_RIGHT),
            ],
            height=1,
        )

        @Condition
        def has_title() -> bool:
            return bool(self.title)

        self.container = HSplit(
            [
                ConditionalContainer(
                    content=top_row_with_title, filter=has_title
                ),
                ConditionalContainer(
                    content=top_row_without_title, filter=~has_title
                ),
                VSplit(
                    [
                        fill(width=1, char=Border.VERTICAL),
                        DynamicContainer(self.body),
                        fill(width=1, char=Border.VERTICAL),
                        # Padding is required to make sure that if the content is
                        # too small, the right frame border is still aligned.
                    ],
                    padding=0,
                ),
                VSplit(
                    [
                        fill(width=1, height=1, char=Border.BOTTOM_LEFT),
                        fill(char=Border.HORIZONTAL),
                        fill(width=1, height=1, char=Border.BOTTOM_RIGHT),
                    ],
                    # specifying height here will increase the rendering speed.
                    height=1,
                ),
            ],
            width=width,
            height=height,
            style=style,
            key_bindings=key_bindings,
            modal=modal,
        )

    def __pt_container__(self) -> Container:
        return self.container