use anyhow::{Context, Result};
use enkou_shaders::Coefficients2;
use enkou_shaders::camera::Camera;
use enkou_shaders::chaos_game::ChaosGame;
use enkou_shaders::transform::Transform;
use enkou_shaders::variation::Variation;
use glam::{Affine2, UVec2, Vec2, uvec2, vec2};
use image::{GrayImage, Luma};
use rand::SeedableRng;
use rand_xoshiro::Xoshiro256StarStar;
use std::mem;
use std::process::Command;
use tempfile::NamedTempFile;

const ITERATIONS_DISCARD: usize = 20;
const ITERATIONS: usize = 50_000;
const IMAGE_DIMENSION: UVec2 = uvec2(600, 600);

pub fn main() -> Result<()> {
    let mut rng = Xoshiro256StarStar::from_seed([4u8; 32]);

    let transforms = [
        {
            // F_0: (x / 2, y / 2)
            let coefficients = Affine2::from_coefficients(0.5, 0.0, 0.0, 0.0, 0.5, 0.0);
            Transform::new(coefficients, Affine2::IDENTITY, uvec2(0, 1), vec2(0.0, 1.0))
        },
        {
            // F_1: ((x + 1) / 2, y / 2)
            let coefficients = Affine2::from_coefficients(0.5, 0.0, 0.5, 0.0, 0.5, 0.0);
            Transform::new(coefficients, Affine2::IDENTITY, uvec2(0, 1), vec2(0.0, 1.0))
        },
        {
            // F_2: (x / 2, (y + 1) / 2)
            let coefficients = Affine2::from_coefficients(0.5, 0.0, 0.0, 0.0, 0.5, 0.5);
            Transform::new(coefficients, Affine2::IDENTITY, uvec2(0, 1), vec2(0.0, 1.0))
        },
    ];

    let weights = [1.0 / 3.0, 1.0 / 3.0, 1.0 / 3.0];

    let variations = [Variation::IDENTITY];

    // The gasket is defined on the range [0, 1] for both X and Y
    let camera = Camera::new(
        IMAGE_DIMENSION,
        Vec2::ONE * 0.5,
        0.0,
        Vec2::ZERO,
        IMAGE_DIMENSION.as_vec2(),
    );

    let mut image = GrayImage::new(IMAGE_DIMENSION.x, IMAGE_DIMENSION.y);

    let chaos_game = ChaosGame::new(&mut rng, &transforms, &weights, &variations);

    chaos_game
        .skip(ITERATIONS_DISCARD)
        .take(ITERATIONS)
        .filter_map(|(point_ifs, _)| camera.transform_point_to_image(point_ifs))
        .for_each(|point_pixel| image.put_pixel(point_pixel.x, point_pixel.y, Luma([255])));

    let temp = NamedTempFile::with_suffix(".png").context("Unable to create file for image")?;
    image.save(temp.path()).context("Unable to save image")?;

    let open_program: &str = cfg_select! {
        unix => "xdg-open",
        _ => panic!("No available program to open images")
    };

    Command::new(open_program)
        .arg(temp.path())
        .spawn()?
        .wait()?;

    // In case the image viewer forks and gives control back prior to reading the file,
    // drop it and don't run the destructor
    mem::forget(temp);

    Ok(())
}