//! Pantallazo headless del `llimphi-widget-button` para VER el relieve nuevo
//! (sombra + borde hairline + sheen + specular) en varios themes claros y
//! oscuros, sin levantar ventana.
//!
//! `cargo run -p llimphi-compositor --example pantallazo_button --release -- [out.png]`

use std::fs::File;
use std::io::BufWriter;

use llimphi_compositor::{measure_text_node, mount, paint, View};
use llimphi_hal::{wgpu, Hal};
use llimphi_layout::taffy;
use llimphi_layout::taffy::prelude::{length, percent, FlexDirection, Size, Style};
use llimphi_layout::taffy::{AlignItems, JustifyContent, Rect};
use llimphi_layout::LayoutTree;
use llimphi_raster::peniko::Color;
use llimphi_raster::{vello, Renderer};
use llimphi_text::{Alignment, Typesetter};
use llimphi_widget_button::{button_styled, ButtonPalette};

const W: u32 = 1120;
const H: u32 = 620;
const FMT: wgpu::TextureFormat = wgpu::TextureFormat::Rgba8Unorm;

fn mix(a: Color, b: Color, t: f32) -> Color {
    let (ca, cb) = (a.components, b.components);
    Color {
        components: [
            ca[0] + (cb[0] - ca[0]) * t,
            ca[1] + (cb[1] - ca[1]) * t,
            ca[2] + (cb[2] - ca[2]) * t,
            ca[3],
        ],
        ..a
    }
}

/// Un botón de ancho fijo dentro de una caja (button_view es 100% de ancho).
fn chip(label: &str, pal: &ButtonPalette) -> View<()> {
    let inner = button_styled(
        label,
        Style {
            size: Size { width: percent(1.0_f32), height: length(34.0_f32) },
            padding: Rect { left: length(14.0_f32), right: length(14.0_f32), top: length(0.0_f32), bottom: length(0.0_f32) },
            align_items: Some(AlignItems::CENTER),
            justify_content: Some(JustifyContent::CENTER),
            ..Default::default()
        },
        Alignment::Center,
        pal,
        (),
    );
    View::<()>::new(Style {
        size: Size { width: length(150.0_f32), height: length(34.0_f32) },
        ..Default::default()
    })
    .children(vec![inner])
}

/// Fila de una demo por theme: fondo bg_app + nombre + 3 botones
/// (default · hover-preview · primario accent).
fn fila_theme(nombre: &str) -> View<()> {
    let theme = llimphi_theme::Theme::by_name(nombre).expect("theme");
    let default_pal = ButtonPalette::from_theme(&theme);
    // Preview del estado hover: una paleta cuyo bg es el bg_button_hover.
    let mut hover_pal = default_pal;
    hover_pal.bg = theme.bg_button_hover;
    // Primario: fondo = accent, texto que contraste, radio un toque mayor.
    let white = Color::from_rgba8(255, 255, 255, 255);
    let black = Color::from_rgba8(0, 0, 0, 255);
    let lum = {
        let k = theme.accent.components;
        0.2126 * k[0] + 0.7152 * k[1] + 0.0722 * k[2]
    };
    let primary_pal = ButtonPalette {
        bg: theme.accent,
        bg_hover: mix(theme.accent, white, 0.12),
        fg: if lum < 0.55 { white } else { black },
        radius: 7.0,
    };

    let etiqueta = View::<()>::new(Style {
        size: Size { width: length(120.0_f32), height: length(34.0_f32) },
        align_items: Some(AlignItems::CENTER),
        ..Default::default()
    })
    .text_aligned(nombre.to_string(), 13.0, theme.fg_muted, Alignment::Start);

    View::<()>::new(Style {
        size: Size { width: percent(1.0_f32), height: length(72.0_f32) },
        flex_direction: FlexDirection::Row,
        align_items: Some(AlignItems::CENTER),
        gap: Size { width: length(16.0_f32), height: length(0.0_f32) },
        padding: Rect { left: length(24.0_f32), right: length(24.0_f32), top: length(0.0_f32), bottom: length(0.0_f32) },
        ..Default::default()
    })
    .fill(theme.bg_app)
    .children(vec![
        etiqueta,
        chip("Guardar", &default_pal),
        chip("Guardar", &hover_pal),
        chip("Aceptar", &primary_pal),
    ])
}

fn main() {
    let out = std::env::args().nth(1).unwrap_or_else(|| "pantallazo_button.png".to_string());
    let temas = ["Dark", "Light", "Tawa", "macOS", "Sunset", "Breeze", "Print", "Aurora"];
    let filas: Vec<View<()>> = temas.iter().map(|t| fila_theme(t)).collect();

    let root = View::<()>::new(Style {
        size: Size { width: percent(1.0_f32), height: percent(1.0_f32) },
        flex_direction: FlexDirection::Column,
        ..Default::default()
    })
    .fill(Color::from_rgba8(20, 20, 24, 255))
    .children(filas);

    let mut layout = LayoutTree::new();
    let mounted = mount(&mut layout, root);
    let mut ts = Typesetter::new();
    let computed = {
        let tmap = &mounted.text_measures;
        layout
            .compute_with_measure(mounted.root, (W as f32, H as f32), |nid, known, avail| {
                match tmap.get(&nid) {
                    Some(tm) => measure_text_node(&mut ts, tm, known, avail),
                    None => taffy::Size::ZERO,
                }
            })
            .expect("layout")
    };
    let mut scene = vello::Scene::new();
    paint(&mut scene, &mounted, &computed, &mut ts, None, None);

    let hal = pollster::block_on(Hal::new(None)).expect("hal");
    let mut renderer = Renderer::new(&hal).expect("renderer");
    let target = hal.device.create_texture(&wgpu::TextureDescriptor {
        label: Some("pantallazo-button"),
        size: wgpu::Extent3d { width: W, height: H, depth_or_array_layers: 1 },
        mip_level_count: 1,
        sample_count: 1,
        dimension: wgpu::TextureDimension::D2,
        format: FMT,
        usage: wgpu::TextureUsages::STORAGE_BINDING
            | wgpu::TextureUsages::RENDER_ATTACHMENT
            | wgpu::TextureUsages::COPY_SRC,
        view_formats: &[],
    });
    let view = target.create_view(&wgpu::TextureViewDescriptor::default());
    renderer
        .render_to_view(&hal, &scene, &view, W, H, Color::from_rgba8(20, 20, 24, 255))
        .expect("render_to_view");
    write_png(&hal, &target, &out);
    eprintln!("pantallazo_button: escrito {out} ({W}x{H})");
}

fn write_png(hal: &Hal, target: &wgpu::Texture, path: &str) {
    let unpadded = (W * 4) as usize;
    let align = wgpu::COPY_BYTES_PER_ROW_ALIGNMENT as usize;
    let padded = unpadded.div_ceil(align) * align;
    let buf = hal.device.create_buffer(&wgpu::BufferDescriptor {
        label: Some("readback"),
        size: (padded * H as usize) as u64,
        usage: wgpu::BufferUsages::MAP_READ | wgpu::BufferUsages::COPY_DST,
        mapped_at_creation: false,
    });
    let mut enc = hal
        .device
        .create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });
    enc.copy_texture_to_buffer(
        wgpu::TexelCopyTextureInfo {
            texture: target,
            mip_level: 0,
            origin: wgpu::Origin3d::ZERO,
            aspect: wgpu::TextureAspect::All,
        },
        wgpu::TexelCopyBufferInfo {
            buffer: &buf,
            layout: wgpu::TexelCopyBufferLayout {
                offset: 0,
                bytes_per_row: Some(padded as u32),
                rows_per_image: Some(H),
            },
        },
        wgpu::Extent3d { width: W, height: H, depth_or_array_layers: 1 },
    );
    hal.queue.submit(std::iter::once(enc.finish()));
    let slice = buf.slice(..);
    let (tx, rx) = std::sync::mpsc::channel();
    slice.map_async(wgpu::MapMode::Read, move |r| {
        let _ = tx.send(r);
    });
    let _ = hal.device.poll(wgpu::PollType::wait_indefinitely());
    rx.recv().unwrap().unwrap();
    let data = slice.get_mapped_range();
    let mut pixels = Vec::with_capacity((W * H * 4) as usize);
    for row in 0..H as usize {
        let s = row * padded;
        pixels.extend_from_slice(&data[s..s + unpadded]);
    }
    drop(data);
    buf.unmap();
    let file = File::create(path).expect("png");
    let mut enc = png::Encoder::new(BufWriter::new(file), W, H);
    enc.set_color(png::ColorType::Rgba);
    enc.set_depth(png::BitDepth::Eight);
    let mut w = enc.write_header().unwrap();
    w.write_image_data(&pixels).unwrap();
}