//! Muestra los **tipos de techo** (plano, tejas, zinc, pizarra, paja) sobre la misma
//! habitación, en un montaje horizontal. `Cutaway::none` → techo entero.
//!
//! `cargo run -p llimphi-voxel --example roof_demo --release` → `/tmp/roof.png`

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

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

const TILE: u32 = 300;
const H: u32 = 340;
const FMT: wgpu::TextureFormat = wgpu::TextureFormat::Rgba8Unorm;

fn main() {
    let tipos = TechoTipo::ALL;
    let cols = tipos.len() as u32;
    let hal = pollster::block_on(Hal::new(None)).expect("hal");
    let mut renderer = Renderer::new(&hal).expect("renderer");
    let mut scene = Scene3d::new();

    let dim = [28u32, 40, 24];
    let mut montage = vec![0u8; (TILE * cols * H * 4) as usize];

    for (i, &techo) in tipos.iter().enumerate() {
        let mut it = Interior::nuevo(1, "sala");
        it.ancho = 22;
        it.fondo = 18;
        it.techo = techo;
        let grid = it.build_grid(dim, Cutaway::none());

        let mut vr = VoxelRenderer::new(&hal.device, &hal.queue, FMT, &grid);
        vr.sun_dir = [0.4, 0.62, 0.5];
        vr.atmosphere = Atmosphere {
            sky_zenith: [96, 140, 200],
            sky_horizon: [206, 220, 234],
            fog_density: 0.0,
            god_rays: 0.0,
        };
        let half = Vec3::new(dim[0] as f32, dim[1] as f32, dim[2] as f32) * 0.5;
        // Mirar desde arriba y al costado → se ve la forma del techo.
        let look = Vec3::new(it.ancho as f32 * 0.5, 8.0, it.fondo as f32 * 0.5) - half;
        let camera = Camera3d::orbit(look, 32_f32.to_radians(), 30_f32.to_radians(), dim[0] as f32 * 1.15);

        let px = render(&hal, &mut renderer, &mut scene, &mut vr, &camera);
        // Copiar el tile a su columna del montaje.
        let x0 = i as u32 * TILE;
        for y in 0..H {
            for x in 0..TILE {
                let src = ((y * TILE + x) * 4) as usize;
                let dst = ((y * TILE * cols + x0 + x) * 4) as usize;
                montage[dst..dst + 4].copy_from_slice(&px[src..src + 4]);
            }
        }
        eprintln!("techo {}", techo.label());
    }
    write_png(&montage, TILE * cols, H, "/tmp/roof.png");
    eprintln!("escrito /tmp/roof.png — {cols} tipos de techo");
}

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: TILE, 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, TILE, H, Color::from_rgba8(12, 14, 20, 255))
        .expect("base");
    let mut enc = hal
        .device
        .create_command_encoder(&wgpu::CommandEncoderDescriptor { label: Some("roof") });
    scene.render(&hal.device, &hal.queue, &mut enc, &view, (TILE, 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 = (TILE * 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: TILE, 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((TILE * 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], w: u32, h: u32, 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();
}