// Copyright 2022 System76 <info@system76.com>
// SPDX-License-Identifier: MPL-2.0

use crate::components::{InfoButton, InfoButtonInput, InfoButtonOutput};
use ccs::*;
use gtk::prelude::*;

/// An input event that is used to update the model.
pub enum AppEvent {
    Destroy,
    Increment,
}

component! {
    /// The model where component state is stored.
    #[derive(Default)]
    pub struct App(gtk::Application) {
        pub counter: usize,
    }

    /// Widgets that are initialized in the view.
    pub struct AppWidgets(gtk::ApplicationWindow) {
        list: gtk::ListBox,
        destroyable: Option<Handle<gtk::Box, InfoButtonInput>>,
        counter: Handle<gtk::Box, InfoButtonInput>,
    }

    type Input = AppEvent;
    type Output = ();

    fn init_view(self, app, input, _output) {
        let button_group = gtk::SizeGroup::new(gtk::SizeGroupMode::Both);

        // Create an `InfoButton` component.
        let destroyable = InfoButton::default()
            .register((String::new(), "Destroy".into(), button_group.clone()))
            .forward(input.clone(), |event| match event {
                InfoButtonOutput::Clicked => AppEvent::Destroy,
            });

        // Instruct the component to update its description.
        let _ = destroyable.emit(InfoButtonInput::SetDescription(
            "Click this button to destroy me".into(),
        ));

        // Create a counter component, too.
        let counter = InfoButton::default()
            .register(("Click me too".into(), "Click".into(), button_group))
            .forward(input.clone(), |event| match event {
                InfoButtonOutput::Clicked => AppEvent::Increment,
            });

        // Construct the view for this component, attaching the component's widget.
        ccs::view! {
            window = gtk::ApplicationWindow {
                set_application: Some(&app),
                set_child = Some(&gtk::Box) {
                    set_halign: gtk::Align::Center,
                    set_size_request: args!(400, -1),
                    set_orientation: gtk::Orientation::Vertical,

                    append: list = &gtk::ListBox {
                        set_selection_mode: gtk::SelectionMode::None,
                        set_hexpand: true,

                        append: destroyable.widget(),
                        append: counter.widget(),
                    },
                }
            }
        }

        window.show();

        (
            AppWidgets {
                list,
                counter,
                destroyable: Some(destroyable),
            },
            window,
        )
    }

    /// Updates the view
    fn update(self, widgets, event, _input, _output) {
        match event {
            AppEvent::Increment => {
                self.counter += 1;

                widgets
                    .counter
                    .emit(InfoButtonInput::SetDescription(format!(
                        "Clicked {} times",
                        self.counter
                    )));
            }

            AppEvent::Destroy => {
                // Components are kept alive by their root GTK widget.
                if let Some(handle) = widgets.destroyable.take() {
                    if let Some(parent) = handle.widget().parent() {
                        widgets.list.remove(&parent);
                    }
                }
            }
        }
    }
}