//! Hold-`/` hotkey cheat sheet (Phase J).
//!
//! While `/` is held on a keyboard platform, a lightweight overlay
//! lists every binding from [`crate::hotkeys::HOTKEYS`] — the same
//! table the onboarding slide teaches from, so the two can never
//! disagree. Releasing the key hides it instantly; it never captures
//! input, never pauses the game, and never spawns while a modal owns
//! the screen (which also keeps it out of the seed-entry text field's
//! way).
//!
//! Not a `spawn_modal` modal on purpose: modals are sticky and guarded;
//! this is a momentary reference card, closer to a tooltip than a
//! dialog.

use bevy::input::ButtonInput;
use bevy::prelude::*;

use crate::font_plugin::FontResource;
use crate::hotkeys::HOTKEYS;
use crate::platform::SHOW_KEYBOARD_ACCELERATORS;
use crate::ui_modal::ModalScrim;
use crate::ui_theme::{
    ACCENT_PRIMARY, BG_ELEVATED, BORDER_STRONG, HighContrastBorder, RADIUS_MD, TEXT_PRIMARY,
    TEXT_SECONDARY, TYPE_BODY, TYPE_CAPTION, VAL_SPACE_1, VAL_SPACE_2, VAL_SPACE_3, VAL_SPACE_4,
    Z_TOOLTIP,
};

/// Marker on the cheat-sheet overlay root.
#[derive(Component, Debug)]
pub struct CheatSheetOverlay;

/// Registers the hold-`/` driver. Inert on touch-first builds.
pub struct CheatSheetPlugin;

impl Plugin for CheatSheetPlugin {
    fn build(&self, app: &mut App) {
        app.init_resource::<ButtonInput<KeyCode>>()
            .add_systems(Update, drive_cheat_sheet);
    }
}

/// Shows the overlay while `/` is held (and no modal owns the screen);
/// hides it the frame the key releases.
fn drive_cheat_sheet(
    keys: Res<ButtonInput<KeyCode>>,
    scrims: Query<(), With<ModalScrim>>,
    existing: Query<Entity, With<CheatSheetOverlay>>,
    font_res: Option<Res<FontResource>>,
    mut commands: Commands,
) {
    if !SHOW_KEYBOARD_ACCELERATORS {
        return;
    }
    let held = keys.pressed(KeyCode::Slash);
    if held && existing.is_empty() && scrims.is_empty() {
        spawn_cheat_sheet(&mut commands, font_res.as_deref());
    } else if !held {
        for entity in &existing {
            commands.entity(entity).despawn();
        }
    }
}

fn spawn_cheat_sheet(commands: &mut Commands, font_res: Option<&FontResource>) {
    let font_handle = font_res.map(|f| f.0.clone()).unwrap_or_default();
    let font_header = TextFont {
        font: font_handle.clone(),
        font_size: TYPE_BODY,
        ..default()
    };
    let font_keys = TextFont {
        font: font_handle.clone(),
        font_size: TYPE_CAPTION,
        ..default()
    };
    let font_desc = TextFont {
        font: font_handle,
        font_size: TYPE_CAPTION,
        ..default()
    };

    commands
        .spawn((
            CheatSheetOverlay,
            Node {
                position_type: PositionType::Absolute,
                right: Val::Px(16.0),
                top: Val::Percent(8.0),
                flex_direction: FlexDirection::Column,
                row_gap: VAL_SPACE_1,
                padding: UiRect::all(VAL_SPACE_4),
                border: UiRect::all(Val::Px(1.0)),
                border_radius: BorderRadius::all(Val::Px(RADIUS_MD)),
                max_height: Val::Percent(84.0),
                overflow: Overflow::scroll_y(),
                ..default()
            },
            BackgroundColor(BG_ELEVATED),
            BorderColor::all(BORDER_STRONG),
            HighContrastBorder::with_default(BORDER_STRONG),
            GlobalZIndex(Z_TOOLTIP),
        ))
        .with_children(|panel| {
            panel.spawn((
                Text::new("Keyboard shortcuts"),
                font_header.clone(),
                TextColor(TEXT_PRIMARY),
                Node {
                    margin: UiRect::bottom(VAL_SPACE_2),
                    ..default()
                },
            ));
            for row in HOTKEYS {
                panel
                    .spawn(Node {
                        flex_direction: FlexDirection::Row,
                        column_gap: VAL_SPACE_3,
                        ..default()
                    })
                    .with_children(|line| {
                        line.spawn((
                            Text::new(row.keys),
                            font_keys.clone(),
                            TextColor(ACCENT_PRIMARY),
                            Node {
                                min_width: Val::Px(110.0),
                                ..default()
                            },
                        ));
                        line.spawn((
                            Text::new(row.description),
                            font_desc.clone(),
                            TextColor(TEXT_SECONDARY),
                        ));
                    });
            }
        });
}

#[cfg(test)]
mod tests {
    use super::*;

    fn app() -> App {
        let mut app = App::new();
        app.add_plugins(MinimalPlugins)
            .add_plugins(CheatSheetPlugin);
        app.update();
        app
    }

    fn overlay_count(app: &mut App) -> usize {
        app.world_mut()
            .query::<&CheatSheetOverlay>()
            .iter(app.world())
            .count()
    }

    #[test]
    fn holding_slash_shows_and_release_hides() {
        let mut app = app();
        app.world_mut()
            .resource_mut::<ButtonInput<KeyCode>>()
            .press(KeyCode::Slash);
        app.update();
        assert_eq!(overlay_count(&mut app), 1, "held / must show the sheet");
        // Still held on later frames: exactly one overlay, no stacking.
        app.update();
        assert_eq!(overlay_count(&mut app), 1);

        app.world_mut()
            .resource_mut::<ButtonInput<KeyCode>>()
            .release(KeyCode::Slash);
        app.update();
        app.update();
        assert_eq!(overlay_count(&mut app), 0, "release must hide the sheet");
    }

    #[test]
    fn suppressed_while_a_modal_is_open() {
        let mut app = app();
        app.world_mut().spawn(ModalScrim);
        app.update();
        app.world_mut()
            .resource_mut::<ButtonInput<KeyCode>>()
            .press(KeyCode::Slash);
        app.update();
        assert_eq!(
            overlay_count(&mut app),
            0,
            "the sheet must not spawn over a modal (or into a text field)"
        );
    }
}