use hdf5::filters::blosc_set_nthreads;
use hdf5::{File, H5Type, Result};
use ndarray::{arr2, s};

#[derive(H5Type, Clone, PartialEq, Debug)] // register with HDF5
#[repr(u8)]
pub enum Color {
    R = 1,
    G = 2,
    B = 3,
}

#[derive(H5Type, Clone, PartialEq, Debug)] // register with HDF5
#[repr(C)]
pub struct Pixel {
    xy: (i64, i64),
    color: Color,
}

impl Pixel {
    pub fn new(x: i64, y: i64, color: Color) -> Self {
        Self { xy: (x, y), color }
    }
}

fn write_hdf5() -> Result<()> {
    use Color::*;
    let file = File::create("pixels.h5")?; // open for writing
    let group = file.create_group("dir")?; // create a group
    blosc_set_nthreads(2); // set number of blosc threads
    let builder = group.new_dataset_builder();
    let builder = builder.blosc_zstd(9, true); // zstd + shuffle
    let ds = builder
        .with_data(&arr2(&[
            // write a 2-D array of data
            [Pixel::new(1, 2, R), Pixel::new(2, 3, B)],
            [Pixel::new(3, 4, G), Pixel::new(4, 5, R)],
            [Pixel::new(5, 6, B), Pixel::new(6, 7, G)],
        ]))
        // finalize and write the dataset
        .create("pixels")?;
    // create an attr with fixed shape but don't write the data
    let attr = ds.new_attr::<Color>().shape([3]).create("colors")?;
    // write the attr data
    attr.write(&[R, G, B])?;
    Ok(())
}

fn read_hdf5() -> Result<()> {
    use Color::*;
    let file = File::open("pixels.h5")?; // open for reading
    let ds = file.dataset("dir/pixels")?; // open the dataset
    assert_eq!(
        // read a slice of the 2-D dataset and verify it
        ds.read_slice::<Pixel, _, _>(s![1.., ..])?,
        arr2(&[
            [Pixel::new(3, 4, G), Pixel::new(4, 5, R)],
            [Pixel::new(5, 6, B), Pixel::new(6, 7, G)],
        ])
    );
    let attr = ds.attr("colors")?; // open the attribute
    assert_eq!(attr.read_1d::<Color>()?.as_slice().unwrap(), &[R, G, B]);
    Ok(())
}

fn main() -> Result<()> {
    write_hdf5()?;
    read_hdf5()?;
    Ok(())
}
