pub mod widget;

pub(crate) mod flex;

pub use widget::*;

use iced_native::event::{self, Event};
use iced_native::layout::{self, Layout};
use iced_native::mouse;
use iced_native::renderer;
use iced_native::{Clipboard, Hasher, Length, Point, Rectangle, Shell};

pub struct Pure<'a, Message, Renderer> {
    state: &'a mut State<Message, Renderer>,
}

impl<'a, Message, Renderer> Pure<'a, Message, Renderer>
where
    Message: 'static,
    Renderer: iced_native::Renderer + 'static,
{
    pub fn new(
        state: &'a mut State<Message, Renderer>,
        content: impl Into<Element<Message, Renderer>>,
    ) -> Self {
        let _ = state.diff(content.into());

        Self { state }
    }
}

pub struct State<Message, Renderer> {
    state_tree: widget::Tree<Message, Renderer>,
    last_element: Element<Message, Renderer>,
}

impl<Message, Renderer> State<Message, Renderer>
where
    Message: 'static,
    Renderer: iced_native::Renderer + 'static,
{
    pub fn new() -> Self {
        let last_element = Element::new(widget::Column::new());

        Self {
            state_tree: widget::Tree::new(&last_element),
            last_element,
        }
    }

    fn diff(&mut self, new_element: Element<Message, Renderer>) {
        self.state_tree.diff(&self.last_element, &new_element);

        self.last_element = new_element;
    }
}

impl<'a, Message, Renderer> iced_native::Widget<Message, Renderer>
    for Pure<'a, Message, Renderer>
where
    Renderer: iced_native::Renderer,
{
    fn width(&self) -> Length {
        self.state.last_element.as_widget().width()
    }

    fn height(&self) -> Length {
        self.state.last_element.as_widget().height()
    }

    fn hash_layout(&self, state: &mut Hasher) {
        self.state.last_element.as_widget().hash_layout(state)
    }

    fn layout(
        &self,
        renderer: &Renderer,
        limits: &layout::Limits,
    ) -> layout::Node {
        self.state.last_element.as_widget().layout(renderer, limits)
    }

    fn on_event(
        &mut self,
        event: Event,
        layout: Layout<'_>,
        cursor_position: Point,
        renderer: &Renderer,
        clipboard: &mut dyn Clipboard,
        shell: &mut Shell<'_, Message>,
    ) -> event::Status {
        self.state.last_element.as_widget_mut().on_event(
            &mut self.state.state_tree,
            event,
            layout,
            cursor_position,
            renderer,
            clipboard,
            shell,
        )
    }

    fn draw(
        &self,
        renderer: &mut Renderer,
        style: &renderer::Style,
        layout: Layout<'_>,
        cursor_position: Point,
        viewport: &Rectangle,
    ) {
        self.state.last_element.as_widget().draw(
            &self.state.state_tree,
            renderer,
            style,
            layout,
            cursor_position,
            viewport,
        )
    }

    fn mouse_interaction(
        &self,
        layout: Layout<'_>,
        cursor_position: Point,
        viewport: &Rectangle,
        renderer: &Renderer,
    ) -> mouse::Interaction {
        self.state.last_element.as_widget().mouse_interaction(
            &self.state.state_tree,
            layout,
            cursor_position,
            viewport,
            renderer,
        )
    }
}

impl<'a, Message, Renderer> Into<iced_native::Element<'a, Message, Renderer>>
    for Pure<'a, Message, Renderer>
where
    Renderer: iced_native::Renderer,
{
    fn into(self) -> iced_native::Element<'a, Message, Renderer> {
        iced_native::Element::new(self)
    }
}