//! Input across layers: what stops at a layer, what passes through it, and
//! where hovering stops.

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

use iris::harness::Harness;
use iris::prelude::*;

const WINDOW: f32 = 100.0;

/// Every sense that has fired on one widget since it was last read.
#[derive(Default, Clone)]
struct Fired(Rc<RefCell<Vec<CursorSense>>>);

impl Fired {
    fn take(&self) -> Vec<CursorSense> {
        std::mem::take(&mut self.0.borrow_mut())
    }
}

/// A widget filling whatever it is given, recording the senses it is sent.
fn listener(h: &mut Harness, senses: impl Into<CursorSenses>) -> (WeakWidget<Rect>, Fired) {
    let fired = Fired::default();
    let record = fired.clone();
    let id = rect(Color::WHITE)
        .on(senses.into(), move |ctx, _| {
            record.0.borrow_mut().push(ctx.data.sense)
        })
        .add(&mut h.rsc);
    (id, fired)
}

/// A widget with no senses of its own, to leave a gap beside one that has.
fn blank(h: &mut Harness) -> WeakWidget<Rect> {
    rect(Color::WHITE).add(&mut h.rsc)
}

fn harness() -> Harness {
    Harness::new((WINDOW, WINDOW))
}

#[test]
fn hover_stops_at_the_topmost_widget() {
    let mut h = harness();
    let (bottom, bottom_hover) = listener(&mut h, CursorSense::HoverStart);
    let (middle, middle_hover) = listener(&mut h, CursorSense::HoverStart);
    let (top, top_hover) = listener(&mut h, CursorSense::HoverStart);
    h.set_root((bottom, middle, top).stack());

    h.move_to((50, 50));

    assert_eq!(top_hover.take(), [CursorSense::HoverStart]);
    assert_eq!(
        middle_hover.take(),
        [],
        "hover is not shared with a layer below"
    );
    assert_eq!(bottom_hover.take(), []);
}

#[test]
fn a_scroll_passes_through_every_widget_that_does_not_want_it() {
    let mut h = harness();
    let (list, scrolled) = listener(&mut h, CursorSense::Scroll);
    let (button, clicked) = listener(&mut h, CursorSense::click());
    let (overlay, overlay_clicked) = listener(&mut h, CursorSense::click());
    h.set_root((list, button, overlay).stack());

    h.move_to((50, 50));
    h.scroll((0, 10));

    assert_eq!(
        scrolled.take(),
        [CursorSense::Scroll],
        "two layers of click-only widgets do not stop a scroll"
    );
    assert_eq!(clicked.take(), []);
    assert_eq!(overlay_clicked.take(), []);
}

#[test]
fn hovering_a_button_above_does_not_stop_a_later_scroll() {
    let mut h = harness();
    let (list, scrolled) = listener(&mut h, CursorSense::Scroll);
    let (button, _clicked) = listener(&mut h, CursorSense::click());
    h.set_root((list, button).stack());

    // The hover arrives in its own frame, as a window delivers it.
    h.move_to((50, 50));
    assert_eq!(scrolled.take(), []);

    h.scroll((0, 10));
    assert_eq!(
        scrolled.take(),
        [CursorSense::Scroll],
        "a hover already resting on the button must not consume the wheel"
    );
}

#[test]
fn only_the_topmost_listener_takes_a_press() {
    let mut h = harness();
    let (below, below_clicked) = listener(&mut h, CursorSense::click());
    let (above, above_clicked) = listener(&mut h, CursorSense::click());
    h.set_root((below, above).stack());

    h.click((50, 50));

    assert_eq!(above_clicked.take(), [CursorSense::click()]);
    assert_eq!(below_clicked.take(), [], "one press goes to one widget");
}

#[test]
fn a_press_beside_the_button_reaches_the_layer_below() {
    let mut h = harness();
    let (list, list_clicked) = listener(&mut h, CursorSense::click());
    // The row above the list covers it, but only its left half is the button.
    let (button, button_clicked) = listener(&mut h, CursorSense::click());
    let row = (button, blank(&mut h)).span(Dir::RIGHT).add(&mut h.rsc);
    h.set_root((list, row).stack());

    h.click((20, 50));
    assert_eq!(button_clicked.take(), [CursorSense::click()]);
    assert_eq!(list_clicked.take(), []);

    h.click((80, 50));
    assert_eq!(button_clicked.take(), [], "the cursor is not on the button");
    assert_eq!(
        list_clicked.take(),
        [CursorSense::click()],
        "a press beside the button belongs to what is under it"
    );
}

#[test]
fn leaving_a_widget_still_ends_its_hover() {
    let mut h = harness();
    let (widget, hover) = listener(&mut h, CursorSense::HoverStart | CursorSense::HoverEnd);
    h.set_root(widget);

    h.move_to((50, 50));
    assert_eq!(hover.take(), [CursorSense::HoverStart]);

    h.leave();
    assert_eq!(hover.take(), [CursorSense::HoverEnd]);
}

#[test]
fn leaving_a_widget_does_not_block_the_layer_below() {
    let mut h = harness();
    let (below, below_hover) = listener(&mut h, CursorSense::HoverStart);
    // Only the left half of the layer above is a widget, so the cursor can
    // leave it without leaving the one underneath.
    let (above, above_hover) = listener(&mut h, CursorSense::HoverStart | CursorSense::HoverEnd);
    let row = (above, blank(&mut h)).span(Dir::RIGHT).add(&mut h.rsc);
    h.set_root((below, row).stack());

    h.move_to((20, 50));
    assert_eq!(above_hover.take(), [CursorSense::HoverStart]);
    assert_eq!(below_hover.take(), [], "the layer above is over it");

    h.move_to((80, 50));
    assert_eq!(above_hover.take(), [CursorSense::HoverEnd]);
    assert_eq!(
        below_hover.take(),
        [CursorSense::HoverStart],
        "ending a hover above must not stop the hover below"
    );
}

#[test]
fn covering_a_widget_ends_its_hover() {
    let mut h = harness();
    let (below, below_hover) = listener(&mut h, CursorSense::HoverStart | CursorSense::HoverEnd);
    let (above, above_hover) = listener(&mut h, CursorSense::HoverStart);
    let row = (above, blank(&mut h)).span(Dir::RIGHT).add(&mut h.rsc);
    h.set_root((below, row).stack());

    h.move_to((80, 50));
    assert_eq!(below_hover.take(), [CursorSense::HoverStart]);

    h.move_to((20, 50));
    assert_eq!(above_hover.take(), [CursorSense::HoverStart]);
    assert_eq!(
        below_hover.take(),
        [CursorSense::HoverEnd],
        "a widget covered by one that took the input is no longer hovered"
    );

    h.move_to((80, 50));
    assert_eq!(
        below_hover.take(),
        [CursorSense::HoverStart],
        "uncovering it hovers it again"
    );
}

#[test]
fn hover_starts_and_ends_once_each() {
    let mut h = harness();
    // Only the left half is the widget, so the cursor can leave it without
    // leaving the window.
    let (widget, hover) = listener(&mut h, CursorSense::HoverStart | CursorSense::HoverEnd);
    let row = (widget, blank(&mut h)).span(Dir::RIGHT).add(&mut h.rsc);
    h.set_root(row);

    h.move_to((20, 50));
    assert_eq!(hover.take(), [CursorSense::HoverStart]);

    h.move_to((30, 50));
    assert_eq!(hover.take(), [], "staying inside is not a second start");

    h.move_to((80, 50));
    assert_eq!(hover.take(), [CursorSense::HoverEnd]);

    h.move_to((90, 50));
    assert_eq!(hover.take(), [], "an ended hover does not end again");

    h.move_to((20, 50));
    assert_eq!(
        hover.take(),
        [CursorSense::HoverStart],
        "re-entering starts it"
    );
}