//! **Fauna (seres) procedural**: los 16 animales del catálogo [`Bicho`] en una
//! grilla, sobre pasto. `cargo run -p llimphi-voxel --example fauna_demo --release`
//! → `/tmp/fauna.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::{stamp_bicho, Bicho, Material};

const W: u32 = 1280;
const H: u32 = 720;
const FMT: wgpu::TextureFormat = wgpu::TextureFormat::Rgba8Unorm;

fn main() {
    let bichos = Bicho::ALL;
    let cols = 4i32;
    let step = 10i32;
    let margin = 8i32;
    let rows = (bichos.len() as i32 + cols - 1) / cols;
    let dim = [
        (cols * step + 2 * margin) as u32,
        24,
        (rows * step + 2 * margin) as u32,
    ];
    let mut g = VoxelGrid::new(dim);

    // Suelo de pasto con leve grano.
    for x in 0..dim[0] {
        for z in 0..dim[2] {
            let c = Material::Grass.color();
            let t = ((x * 3 + z * 5) % 9) as i32 - 4;
            let sh = |v: u8| (v as i32 + t).clamp(0, 255) as u8;
            g.set(x, 0, z, [sh(c[0]), sh(c[1]), sh(c[2])]);
        }
    }

    for (i, &bicho) in bichos.iter().enumerate() {
        let cx = i as i32 % cols;
        let cz = i as i32 / cols;
        let x = margin + cx * step + step / 2;
        let z = margin + cz * step + step / 2;
        stamp_bicho(&mut g, bicho, x as u32, 1, z as u32, 0);
        eprintln!("{}: {}", i, bicho.label());
    }

    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, &g);
    vr.sun_dir = [0.42, 0.62, 0.5];
    vr.atmosphere = Atmosphere {
        sky_zenith: [96, 146, 210],
        sky_horizon: [210, 224, 238],
        fog_density: 0.15 / dim[0] as f32,
        god_rays: 0.0,
    };
    let half = Vec3::new(dim[0] as f32, dim[1] as f32, dim[2] as f32) * 0.5;
    let look = Vec3::new(dim[0] as f32 * 0.5, 3.0, dim[2] as f32 * 0.5) - half;
    let camera = Camera3d::orbit(look, 22_f32.to_radians(), 24_f32.to_radians(), dim[0].max(dim[2]) as f32 * 0.82);

    let mut scene = Scene3d::new();
    let pixels = render(&hal, &mut renderer, &mut scene, &mut vr, &camera);
    write_png(&pixels, "/tmp/fauna.png");
    eprintln!("escrito /tmp/fauna.png — {} seres", bichos.len());
}

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("fauna") });
    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 s = row * padded;
        pixels.extend_from_slice(&data[s..s + 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();
}