use iris::prelude::*;
use winit::{dpi::LogicalSize, window::WindowAttributes};

fn main() {
    DefaultApp::<State>::run();
}

#[derive(DefaultUiState)]
struct State {
    ui_state: DefaultUiState,
}

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) -> image::DynamicImage {
    let hue = ((i * 47) % 255) as u8;
    image::RgbaImage::from_pixel(48, 48, 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))
            .wrap(true)
            .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))
            .wrap(true)
            .color(text_color)
            .pad(dp(8.0))
            .background(rect(tint))
            .add_strong(rsc)
            .any()
    }
}

impl DefaultAppState for State {
    fn window_attributes() -> WindowAttributes {
        WindowAttributes::default().with_inner_size(LogicalSize::new(420.0, 900.0))
    }

    fn new(
        mut ui_state: DefaultUiState,
        rsc: &mut DefaultRsc<Self>,
        _: Proxy<Self::Event>,
    ) -> Self {
        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(root.any());

        Self { ui_state }
    }
}