use bevy::{input::mouse::MouseMotion, prelude::*, ui::Interaction};
use bevy_inspector_egui::quick::WorldInspectorPlugin;
use bevy_simple_scroll_view::*;

const BORDER_COLOR_ACTIVE: Color = Color::rgb(0.75, 0.52, 0.99);
const BACKGROUND_COLOR: Color = Color::rgb(0.15, 0.15, 0.15);

fn main() {
    App::new()
        .add_plugins((
            DefaultPlugins,
            ScrollViewPlugin,
            WorldInspectorPlugin::new(),
        ))
        .add_systems(Startup, prepare)
        .add_systems(Update, add_content)
        .run();
}

fn prepare(mut commands: Commands) {
    commands.spawn(Camera2dBundle::default());
    commands.spawn((
        NodeBundle {
            style: Style {
                width: Val::Percent(100.0),
                height: Val::Percent(100.0),
                align_items: AlignItems::Center,
                justify_content: JustifyContent::Center,
                ..default()
            },
            ..default()
        },
        ScrollView,
    ));
}

fn add_content(mut commands: Commands, q: Query<Entity, Added<ScrollViewContent>>) {
    for e in q.iter() {
        commands.entity(e).with_children(|parent| {
            for _ in 0..10 {
                parent.spawn(
                    (NodeBundle {
                        style: Style {
                            width: Val::Px(200.0),
                            height: Val::Px(200.0),
                            margin: UiRect::all(Val::Px(5.0)),
                            border: UiRect::all(Val::Px(5.0)),
                            padding: UiRect::all(Val::Px(5.0)),
                            ..default()
                        },
                        border_color: BORDER_COLOR_ACTIVE.into(),
                        background_color: BACKGROUND_COLOR.into(),
                        ..default()
                    }),
                );
            }
        });
    }
}

fn input_mouse_scroll(
    mut motion_evr: EventReader<MouseMotion>,
    mut q: Query<(Entity, &mut Style, &Interaction), With<ScrollViewport>>,
) {
    for evt in motion_evr.read() {
        for (e, mut style, &interaction) in q.iter_mut() {
            if interaction == Interaction::Hovered {
                style.top = match style.top {
                    Val::Px(px) => Val::Px(px + evt.delta.y),
                    _ => Val::Px(0.0),
                }
            }
        }
    }
}