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

use gpui::{
    Context, IntoElement, Modifiers, MouseButton, ParentElement as _, Render, Styled as _,
    TestAppContext, VisualTestContext, Window, div, point, px,
};
use gpui_native_data::tabs::{Tab, Tabs};
use gpui_native_theme::Theme;

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

struct Harness {
    selected: usize,
    changes: Changes,
}

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(
            Tabs::new("test-tabs")
                .selected(self.selected)
                .on_change(move |next, _, cx| {
                    changes.borrow_mut().push(next);
                    view.update(cx, |harness, cx| {
                        harness.selected = next;
                        cx.notify();
                    });
                })
                .tabs(|_, _| {
                    vec![
                        Tab::new("One"),
                        Tab::new("Two"),
                        Tab::new("Off").disabled(true),
                        Tab::new("End"),
                    ]
                }),
        )
    }
}

/// Same-length labels keep the strip's geometry predictable: each tab is
/// roughly 40 px wide with a 4 px gap, so clicks at `(20/62/104/146, 12)`
/// land on One / Two / the disabled Off / End.
fn tabs_window() -> (TestAppContext, VisualTestContext, Changes) {
    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: 0,
        changes: harness_changes,
    });
    let mut visual = VisualTestContext::from_window(window.into(), &cx);
    visual.update(|window, cx| {
        window.draw(cx).clear(cx);
    });
    (cx, visual, changes)
}

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_tab_selects_it_and_hands_the_strip_the_keyboard() {
    let (_cx, mut visual, changes) = tabs_window();

    // Tab 0 is already selected; selecting it again reports nothing.
    click(&mut visual, point(px(20.), px(12.)));
    assert!(changes.borrow().is_empty());

    // The click focused the strip, so the arrows switch from here.
    visual.simulate_keystrokes("right");
    assert_eq!(*changes.borrow(), vec![1]);
}

#[test]
fn clicking_a_disabled_tab_reports_nothing() {
    let (_cx, mut visual, changes) = tabs_window();

    click(&mut visual, point(px(104.), px(12.)));
    assert!(changes.borrow().is_empty());
}

#[test]
fn arrow_keys_skip_disabled_tabs_and_never_wrap() {
    let (_cx, mut visual, changes) = tabs_window();

    click(&mut visual, point(px(20.), px(12.))); // One: already selected, no report
    visual.simulate_keystrokes("right"); // Two
    visual.simulate_keystrokes("right"); // over the disabled tab → End
    visual.simulate_keystrokes("right"); // last; no wrap
    assert_eq!(*changes.borrow(), vec![1, 3]);

    visual.simulate_keystrokes("left"); // over the disabled tab → Two
    visual.simulate_keystrokes("home"); // One
    visual.simulate_keystrokes("end"); // End
    assert_eq!(*changes.borrow(), vec![1, 3, 1, 0, 3]);
}

#[test]
fn clicking_a_different_tab_reports_once() {
    let (_cx, mut visual, changes) = tabs_window();

    click(&mut visual, point(px(20.), px(12.))); // One: no change, just focus
    click(&mut visual, point(px(62.), px(12.))); // Two
    click(&mut visual, point(px(62.), px(12.))); // Two again: no change
    assert_eq!(*changes.borrow(), vec![1]);
}