//! All the UI elements for the Pong game client.

use bevy::{
    color::palettes::css::{DARK_GRAY, GRAY},
    prelude::*,
};

use crate::GameState;

pub const BTN_BORDER_COLOR: Color = Color::WHITE;
pub const BTN_BG_COLOR: Color = Color::BLACK;
pub const BTN_BG_SELECTED: Color = bevy::prelude::Color::Srgba(DARK_GRAY);

pub fn spawn_main_menu(mut commands: Commands) {
    commands
        .spawn((Node {
            width: Val::Percent(100.0),
            height: Val::Percent(100.0),
            align_items: AlignItems::Center,
            justify_content: JustifyContent::Center,
            flex_direction: FlexDirection::Column,
            ..Default::default()
        },))
        .with_children(|cmds| {
            cmds.spawn((
                // TODO: A more sharp and square font, maybe "pixel art" bitmap
                // to really get the chunky feel of Pong.
                Text::new("Robert's Bad Pong Game"),
                TextFont::from_font_size(50.0),
                TextLayout::new_with_justify(Justify::Center),
                TextShadow::default(),
            ));
            let mut start_button = cmds.spawn(button_bundle("Start game"));
            start_button.observe(
                |_trigger: On<Pointer<Click>>, mut game_state: ResMut<NextState<GameState>>| {
                    game_state.set(GameState::Connecting);
                },
            );
            let mut quit_button = cmds.spawn(button_bundle("Quit Game"));
            quit_button.observe(
                |_trigger: On<Pointer<Click>>, mut messages: MessageWriter<AppExit>| {
                    // Quit the game if the quit button was pressed.
                    messages.write(AppExit::Success);
                },
            );
        });
}

/// Despawns the main menu (which is assumed to be the top-most node)
///
/// TODO: Add a marker component, but only in debug builds. A unit test can
/// assert this condition so I don't actually have to check it at runtime
/// on release builds.
pub fn despawn_main_menu(
    mut commands: Commands,
    top_node: Single<Entity, (With<Node>, Without<ChildOf>)>,
) {
    commands.entity(top_node.into_inner()).despawn();
}

pub fn spawn_connection_wait_screen(mut commands: Commands) {
    info!("Spawning connecting notice.");
    commands.spawn((
        Node {
            width: Val::Percent(100.0),
            height: Val::Percent(100.0),
            align_items: AlignItems::Center,
            justify_content: JustifyContent::Center,
            flex_direction: FlexDirection::Column,
            ..Default::default()
        },
        children![Text::new("Connecting...")],
    ));
}

pub fn despawn_connection_wait_screen(
    mut commands: Commands,
    text_nodes: Single<Entity, (With<Node>, With<Text>)>,
) {
    info!("Despawning connecting notice.");
    commands.entity(text_nodes.into_inner()).despawn();
}

/// The basic bundle for generic buttons.
///
/// It's mostly so I don't have to copy & paste this everywhere I want to use it.
fn button_bundle(text: &str) -> impl Bundle {
    (
        Button,
        Node {
            width: Val::Px(150.0),
            height: Val::Px(65.0),
            border: UiRect::all(Val::Px(4.0)),
            justify_content: JustifyContent::Center,
            align_items: AlignItems::Center,
            margin: UiRect::all(Val::Px(10.0)),
            ..Default::default()
        },
        BorderColor::all(BTN_BORDER_COLOR),
        BorderRadius::ZERO,
        BackgroundColor(BTN_BG_COLOR),
        children![(
            Text::new(text),
            TextColor(GRAY.into()),
            TextShadow::default(),
        )],
    )
}

pub fn button_hover_start(
    trigger: On<Pointer<Over>>,
    mut button_colors: Query<(&mut BackgroundColor, &mut BorderColor), With<Button>>,
) {
    if let Ok((mut bg, mut _border)) = button_colors.get_mut(trigger.entity) {
        bg.0 = BTN_BG_SELECTED;
    }
}

pub fn button_hover_stop(
    trigger: On<Pointer<Out>>,
    mut button_colors: Query<(&mut BackgroundColor, &mut BorderColor), With<Button>>,
) {
    if let Ok((mut bg, mut _border)) = button_colors.get_mut(trigger.entity) {
        bg.0 = BTN_BG_COLOR;
    }
}