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::sidebar::{Sidebar, SidebarEntry};
use gpui_native_theme::Theme;

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

struct Harness {
    selected: Option<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(
            Sidebar::new("test-sidebar")
                .selected(self.selected)
                .on_change(move |next, _, cx| {
                    changes.borrow_mut().push(next);
                    view.update(cx, |harness, cx| {
                        harness.selected = next;
                        cx.notify();
                    });
                })
                .entries(|_, _| {
                    vec![
                        SidebarEntry::header("Favorites"),          // 0: never selectable
                        SidebarEntry::row("Documents"),             // 1
                        SidebarEntry::row("Locked").disabled(true), // 2
                        SidebarEntry::header("Locations"),          // 3: never selectable
                        SidebarEntry::row("Trash"),                 // 4
                    ]
                }),
        )
    }
}

/// Entries stack from the top-left: the header band (~32 px) then ~34 px row
/// bands, so clicks at `(50, 16)` hit the header, `(50, 48)` Documents,
/// `(50, 82)` Locked, `(50, 116)` the second header, `(50, 150)` Trash.
fn sidebar_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: None,
        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 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_sidebar_the_keyboard() {
    let (_cx, mut visual, changes) = sidebar_window();

    // The header band is not a row: clicking it reports nothing.
    click(&mut visual, point(px(50.), px(16.)));
    draw(&mut visual);
    assert!(changes.borrow().is_empty());

    click(&mut visual, point(px(50.), px(48.)));
    assert_eq!(*changes.borrow(), vec![Some(1)]);

    // The click focused the sidebar; the arrows move from here.
    visual.simulate_keystrokes("down");
    draw(&mut visual);
    assert_eq!(*changes.borrow(), vec![Some(1), Some(4)]);
}

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

    click(&mut visual, point(px(50.), px(82.)));
    draw(&mut visual);
    assert!(changes.borrow().is_empty());
}

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

    click(&mut visual, point(px(50.), px(48.))); // Documents, focuses
    visual.simulate_keystrokes("down"); // over Locked → Trash
    visual.simulate_keystrokes("down"); // over the second header; no wrap
    draw(&mut visual);
    assert_eq!(*changes.borrow(), vec![Some(1), Some(4)]);

    visual.simulate_keystrokes("up"); // over Locked → Documents
    visual.simulate_keystrokes("end"); // last selectable row
    visual.simulate_keystrokes("home"); // first selectable row
    draw(&mut visual);
    assert_eq!(
        *changes.borrow(),
        vec![Some(1), Some(4), Some(1), Some(4), Some(1)]
    );
}