use std::{cell::RefCell, rc::Rc};

use gpui::{
    Context, IntoElement, Modifiers, MouseButton, ParentElement as _, Render, Styled as _,
    TestAppContext, VisualTestContext, Window, WindowHandle, div, point, px,
};
use gpui_native_data::list::{List, ListItem};
use gpui_native_theme::Theme;

struct Harness {
    selected: Option<usize>,
    changes: Rc<RefCell<Vec<Option<usize>>>>,
}

impl Render for Harness {
    fn render(&mut self, _window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
        let changes = self.changes.clone();
        let view = cx.entity();
        div().size_full().child(
            List::new("test-list")
                .selected(self.selected)
                .on_change(move |next, _, cx| {
                    changes.borrow_mut().push(next);
                    view.update(cx, |harness, cx| {
                        harness.selected = next;
                        cx.notify();
                    });
                })
                .items(|_, _| {
                    vec![
                        ListItem::new("One"),
                        ListItem::new("Two"),
                        ListItem::new("Unavailable").disabled(true),
                        ListItem::new("Three"),
                    ]
                }),
        )
    }
}

type Changes = Rc<RefCell<Vec<Option<usize>>>>;

type ListWindow = (
    TestAppContext,
    VisualTestContext,
    WindowHandle<Harness>,
    Changes,
);

/// Rows paint at the top-left with no outer padding: one row per ~34 px band
/// (16 px text line + 2×4 px padding + 2 px gap), so clicks at `(50, 16/48/80/112)`
/// land on One / Two / the disabled Unavailable / Three.
fn list_window(selected: Option<usize>) -> ListWindow {
    let mut cx = TestAppContext::single();
    cx.update(Theme::init);
    let changes = Rc::new(RefCell::new(Vec::new()));
    let harness_changes = changes.clone();
    let window = cx.add_window(move |_, _| Harness {
        selected,
        changes: harness_changes,
    });
    let mut visual = VisualTestContext::from_window(window.into(), &cx);
    visual.update(|window, cx| {
        window.draw(cx).clear(cx);
    });
    (cx, visual, window, changes)
}

fn draw(visual: &mut VisualTestContext) {
    visual.update(|window, cx| {
        window.draw(cx).clear(cx);
    });
}

fn click(visual: &mut VisualTestContext, position: gpui::Point<gpui::Pixels>) {
    visual.simulate_mouse_down(position, MouseButton::Left, Modifiers::default());
    visual.simulate_mouse_up(position, MouseButton::Left, Modifiers::default());
}

#[test]
fn clicking_a_row_selects_it_and_hands_the_list_the_keyboard() {
    let (_cx, mut visual, _window, changes) = list_window(None);

    click(&mut visual, point(px(50.), px(16.)));
    assert_eq!(*changes.borrow(), vec![Some(0)]);

    // The click focused the list, so the arrows navigate from here.
    visual.simulate_keystrokes("down");
    draw(&mut visual);
    assert_eq!(*changes.borrow(), vec![Some(0), Some(1)]);
}

#[test]
fn clicking_a_disabled_row_reports_nothing() {
    let (_cx, mut visual, _window, changes) = list_window(None);

    click(&mut visual, point(px(50.), px(80.)));
    draw(&mut visual);
    assert_eq!(*changes.borrow(), Vec::<Option<usize>>::new());
}

#[test]
fn keyboard_navigation_skips_disabled_rows_and_never_wraps() {
    let (_cx, mut visual, _window, changes) = list_window(None);

    click(&mut visual, point(px(50.), px(16.)));
    visual.simulate_keystrokes("down"); // over the disabled row → Two
    visual.simulate_keystrokes("down"); // over the disabled row → Three
    visual.simulate_keystrokes("down"); // last selectable; no wrap
    draw(&mut visual);
    assert_eq!(*changes.borrow(), vec![Some(0), Some(1), Some(3)]);

    visual.simulate_keystrokes("home");
    visual.simulate_keystrokes("end");
    visual.simulate_keystrokes("up"); // over the disabled row → Two
    draw(&mut visual);
    assert_eq!(
        *changes.borrow(),
        vec![Some(0), Some(1), Some(3), Some(0), Some(3), Some(1)]
    );
}

#[test]
fn arrow_down_with_no_selection_picks_the_first_selectable_row() {
    let (mut cx, mut visual, window, changes) = list_window(Some(1));

    // Focus the list, then clear the selection app-side.
    click(&mut visual, point(px(50.), px(48.)));
    window
        .update(&mut cx, |harness, _, cx| {
            harness.selected = None;
            cx.notify();
        })
        .unwrap();
    draw(&mut visual);

    visual.simulate_keystrokes("down");
    draw(&mut visual);
    assert_eq!(*changes.borrow(), vec![Some(1), Some(0)]);
}