#[macro_use]
extern crate quote;

fn main() {
    let out_dir = std::env::var("OUT_DIR").unwrap();
    let dest_path = std::path::Path::new(&out_dir).join("maps.inner.rs");

    let out = (1..=32)
        .into_iter()
        .chain(vec![48, 64])
        .map(|i| {
            let tup_ty = (0..i).into_iter().map(|_| quote!(Option<T>)).collect::<Vec<_>>();
            let nones = (0..i).into_iter().map(|_| quote!(None)).collect::<Vec<_>>();
            let name = format_ident!("Map{}", i as u32);

            let doc_note = format!(
                "Container for a `map` with {} {}",
                i,
                if i == 1 { "field" } else { "fields" }
            );

            quote! {
                #[doc = #doc_note]
                pub struct #name<K: ?Sized, T> {
                    pub tup: (#(#tup_ty,)*),
                    key: std::marker::PhantomData<fn() -> K>
                }

                impl<K: ?Sized, T> Default for #name<K, T> {
                    fn default() -> Self {
                        #name {
                            tup: (#(#nones,)*),
                            key: std::marker::PhantomData
                        }
                    }
                }
            }
        })
        .collect::<Vec<_>>();

    std::fs::write(dest_path, quote!(#(#out)*).to_string()).unwrap();
}