//! Scrolling moves content and stops at its ends.

use iris::harness::{Harness, assert_corners};
use iris::prelude::*;

#[test]
fn scrollable_enables_a_region_node_but_raw_scroll_does_not() {
    let mut h = Harness::new((100, 100));
    let default_child = ().add(&mut h.rsc);
    let _default = default_child.scrollable().add(&mut h.rsc);
    assert!(h.rsc.widgets().is_region_node(default_child));
    h.rsc.widgets_mut().set_region_node(default_child, false);
    assert!(!h.rsc.widgets().is_region_node(default_child));

    let raw_child = ().add(&mut h.rsc);
    let _raw = Scroll::new(raw_child.add_strong(&mut h.rsc), Axis::Y).add(&mut h.rsc);
    assert!(!h.rsc.widgets().is_region_node(raw_child));

    let explicit = ().region_node().add(&mut h.rsc);
    assert!(h.rsc.widgets().is_region_node(explicit));
}

#[test]
fn a_scrollable_child_can_drop_its_region_node() {
    let mut h = Harness::new((400, 200));
    let top = rect(Color::RED).height(200).add(&mut h.rsc);
    let bottom = rect(Color::BLUE).height(200).add(&mut h.rsc);
    let content = (top, bottom).span(Dir::DOWN).add(&mut h.rsc);
    h.set_root(content.scrollable());
    h.rsc.widgets_mut().set_region_node(content, false);
    h.frame();

    h.move_to((200, 100));
    h.scroll((0, 1));
    h.frame();

    assert!(!h.rsc.widgets().is_region_node(content));
    assert_corners!(h, top, (0, -150), (400, 50));
}

#[test]
fn a_wheel_scrolls_the_content_and_stops_at_its_end() {
    let mut h = Harness::new((400, 200));
    // Twice the window's height, so there is 200 to scroll.
    let top = rect(Color::RED).height(200).add(&mut h.rsc);
    let bottom = rect(Color::BLUE).height(200).add(&mut h.rsc);
    h.set_root((top, bottom).span(Dir::DOWN).scrollable());
    h.move_to((200, 100));

    // `Scroll` starts snapped to the end.
    assert_corners!(h, top, (0, -200), (400, 0));

    // The handler scales a wheel line by 50.
    h.scroll((0, 1));
    h.frame();
    assert_corners!(h, top, (0, -150), (400, 50));

    h.scroll((0, 10));
    h.frame();
    assert_corners!(h, top, (0, 0), (400, 200));
}

/// A widget that clips to its box may not report more than the box: its
/// parent would place the part it cut off, and the framework would put a
/// drawing longer than its box somewhere. `Masked` is the second of these
/// after `Scroll`, and the assertion in `draw_at` is what says so.
#[test]
#[should_panic = "clips to"]
fn a_clipping_widget_reporting_more_than_its_box_is_caught() {
    struct Clipper(StrongWidget);

    impl Widget for Clipper {
        fn draw(&mut self, painter: &mut Painter) -> Size {
            painter.set_mask(painter.region());
            painter.widget(&self.0).size()
        }
    }

    let mut h = Harness::new((100, 100));
    let tall = rect(Color::RED).height(400).add_strong(&mut h.rsc);
    let clipper = Clipper(tall).add(&mut h.rsc);
    h.set_root(clipper);
    h.frame();
}