//! Catálogo de la **nueva tanda de materiales de terreno**: una fila de bloques,
//! cada uno de un material (tierra, arcilla, grava, arenisca, basalto, granito,
//! mármol, hielo, lava, musgo) con su color + un jitter de grano por vóxel.
//!
//! `cargo run -p llimphi-voxel --example materials_demo --release` → `/tmp/materials.png`

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

use llimphi_3d::glam::Vec3;
use llimphi_3d::{Atmosphere, Camera3d, Scene3d, VoxelGrid, VoxelRenderer};
use llimphi_hal::{wgpu, Hal};
use llimphi_raster::peniko::Color;
use llimphi_raster::{vello, Renderer};
use llimphi_voxel::Material;

const W: u32 = 1280;
const H: u32 = 480;
const FMT: wgpu::TextureFormat = wgpu::TextureFormat::Rgba8Unorm;

// Hash barato para el jitter de grano (mismo espíritu que worldgen::grained).
fn jitter(base: [u8; 3], x: i32, y: i32, z: i32, grain: f32) -> [u8; 3] {
    let mut h = (x as u32)
        .wrapping_mul(0x9E37_79B9)
        .wrapping_add((y as u32).wrapping_mul(0x85EB_CA77))
        .wrapping_add((z as u32).wrapping_mul(0xC2B2_AE35));
    h ^= h >> 15;
    h = h.wrapping_mul(0x2C1B_3C6D);
    h ^= h >> 13;
    let r = (h & 0xFF) as f32 / 255.0;
    let f = 1.0 + (r - 0.5) * 2.0 * grain * 0.22;
    let c = |v: u8| (v as f32 * f).clamp(0.0, 255.0) as u8;
    [c(base[0]), c(base[1]), c(base[2])]
}

fn main() {
    let fila = [
        Material::Tierra,
        Material::Arcilla,
        Material::Grava,
        Material::Arenisca,
        Material::Basalto,
        Material::Granito,
        Material::Marmol,
        Material::Hielo,
        Material::Lava,
        Material::Musgo,
    ];
    let s: i32 = 7; // lado del bloque
    let gap: i32 = 3;
    let step = s + gap;
    let margin = 4;
    let dim = [
        (fila.len() as i32 * step + 2 * margin) as u32,
        (s + 8) as u32,
        (s + 8) as u32,
    ];
    let mut grid = VoxelGrid::new(dim);
    let cz = dim[2] as i32 / 2;
    for (i, mat) in fila.iter().enumerate() {
        let col = mat.color();
        let grain = mat.grain();
        let x0 = margin + i as i32 * step;
        for dx in 0..s {
            for dy in 0..s {
                for dz in 0..s {
                    let (x, y, z) = (x0 + dx, 1 + dy, cz - s / 2 + dz);
                    grid.set(x as u32, y as u32, z as u32, jitter(col, x, y, z, grain));
                }
            }
        }
        eprintln!("{:>9}: color {:?} grano {:.2}", mat.label(), col, grain);
    }

    let hal = pollster::block_on(Hal::new(None)).expect("hal");
    let mut renderer = Renderer::new(&hal).expect("renderer");
    let mut vr = VoxelRenderer::new(&hal.device, &hal.queue, FMT, &grid);
    vr.sun_dir = [0.35, 0.72, 0.55];
    vr.atmosphere = Atmosphere {
        sky_zenith: [92, 120, 168],
        sky_horizon: [196, 208, 222],
        fog_density: 0.0,
        god_rays: 0.0,
    };
    let camera = Camera3d::orbit(
        Vec3::new(0.0, s as f32 * 0.3, 0.0),
        10_f32.to_radians(),
        24_f32.to_radians(),
        dim[0] as f32 * 0.7,
    );
    let mut scene = Scene3d::new();
    let pixels = render(&hal, &mut renderer, &mut scene, &mut vr, &camera);
    write_png(&pixels, "/tmp/materials.png");
    eprintln!("escrito /tmp/materials.png — nueva tanda de 10 materiales de terreno");
}

fn render(
    hal: &Hal,
    renderer: &mut Renderer,
    scene: &mut Scene3d,
    vr: &mut VoxelRenderer,
    camera: &Camera3d,
) -> Vec<u8> {
    let inter = hal.device.create_texture(&wgpu::TextureDescriptor {
        label: Some("inter"),
        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::TEXTURE_BINDING
            | wgpu::TextureUsages::RENDER_ATTACHMENT
            | wgpu::TextureUsages::COPY_SRC,
        view_formats: &[],
    });
    let view = inter.create_view(&wgpu::TextureViewDescriptor::default());
    renderer
        .render_to_view(hal, &vello::Scene::new(), &view, W, H, Color::from_rgba8(0, 0, 0, 255))
        .expect("base");
    let mut enc = hal
        .device
        .create_command_encoder(&wgpu::CommandEncoderDescriptor { label: Some("materials") });
    scene.render(&hal.device, &hal.queue, &mut enc, &view, (W, H), camera, Some(vr), &[]);
    hal.queue.submit(std::iter::once(enc.finish()));
    let _ = hal.device.poll(wgpu::PollType::wait_indefinitely());
    readback(hal, &inter)
}

fn readback(hal: &Hal, target: &wgpu::Texture) -> Vec<u8> {
    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 srow = row * padded;
        pixels.extend_from_slice(&data[srow..srow + unpadded]);
    }
    drop(data);
    buf.unmap();
    pixels
}

fn write_png(pixels: &[u8], path: &str) {
    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 wtr = enc.write_header().unwrap();
    wtr.write_image_data(pixels).unwrap();
}