use iris::prelude::*;

const ROWS: usize = 800;
const IMAGE_EVERY: usize = 12;

fn row_text(i: usize) -> String {
    const SENTENCE: &str =
        "Iris lays out this row once and moves it on scroll, never re-laying it out. ";
    let repeats = 1 + (i * 7) % 5;
    format!("Message {i}: {}", SENTENCE.repeat(repeats))
}

fn row_image(i: usize) -> iris::image::DynamicImage {
    let hue = ((i * 47) % 255) as u8;
    iris::image::RgbaImage::from_pixel(48, 48, iris::image::Rgba([hue, 128, 255 - hue, 255])).into()
}

fn build_row<Rsc: UiRsc + 'static>(rsc: &mut Rsc, i: usize) -> StrongWidget {
    let tint = if i.is_multiple_of(2) {
        Srgba8::rgb(120, 130, 170)
    } else {
        Srgba8::rgb(70, 80, 140)
    };
    let text_color = PaintId::BLACK;
    if i.is_multiple_of(IMAGE_EVERY) {
        let text = wtext(row_text(i))
            .overflow(TextOverflow::Wrap)
            .color(text_color)
            .add_strong(rsc)
            .any();
        let img = image::<Rsc>(row_image(i))(rsc);
        let img = rsc.widgets_mut().add_strong(img).any();
        let mut span = Span::empty(Dir::DOWN);
        span.push(text);
        span.push(img);
        span.pad(dp(8.0))
            .background(rect(tint))
            .add_strong(rsc)
            .any()
    } else {
        wtext(row_text(i))
            .overflow(TextOverflow::Wrap)
            .color(text_color)
            .pad(dp(8.0))
            .background(rect(tint))
            .add_strong(rsc)
            .any()
    }
}

pub(crate) fn build<Rsc: HasEvents>(rsc: &mut Rsc, ui_state: &mut impl HasRoot<Rsc>) {
    let mut list = LazySpan::new(Dir::DOWN, Pin::End);
    for i in 0..ROWS {
        let row = build_row(rsc, i);
        list.push_back(LazyItem::new(i as u64, row));
    }

    let root = list
        .scrollable()
        .masked()
        .background(rect(PaintId::WHITE))
        .add_strong(rsc);
    ui_state.set_root(rsc, root.any());
}