use std::{env, fs, path::Path};

fn main() {
   let out_dir = env::var_os("OUT_DIR").unwrap();
   let dest_path = Path::new(&out_dir).join("concat.rs");

   let combinations = [
      (1, 8),
      (1, 9),
      (2, 1),
      (2, 2),
      (4, 3),
      (16, 7),
      (23, 8),
      (31, 9),
      (40, 9),
      (49, 9),
      (58, 10),
      (68, 10),
      (78, 1),
      (79, 9),
      (88, 9),
      (97, 9),
      (106, 9),
      (115, 9),
   ];

   let mut code = String::new();
   for (i, j) in combinations {
      code += &format!(
         "pub const fn concat_{i}_{j}(a: [u8; {i}], b: [u8; {j}]) -> [u8; {i} + {j}] {{
                    [{a}, {b}]
                }}",
         i = i,
         j = j,
         a = (0..i)
            .map(|idx| format!("a[{idx}]"))
            .collect::<Vec<_>>()
            .join(","),
         b = (0..j)
            .map(|idx| format!("b[{idx}]"))
            .collect::<Vec<_>>()
            .join(","),
      );
   }

   fs::write(dest_path, code).unwrap();
   println!("cargo:rerun-if-changed=build.rs");

   let version_major: u16 = env!("CARGO_PKG_VERSION_MAJOR").parse().unwrap();
   let version_minor: u16 = env!("CARGO_PKG_VERSION_MINOR").parse().unwrap();
   let version_patch: u16 = env!("CARGO_PKG_VERSION_PATCH").parse().unwrap();
   let pre_release: bool = !env!("CARGO_PKG_VERSION_PRE").is_empty();

   fs::write(
      Path::new(&out_dir).join("version_info.rs"),
      format!(
         "
            pub const VERSION_MAJOR: u16 = {version_major};
            pub const VERSION_MINOR: u16 = {version_minor};
            pub const VERSION_PATCH: u16 = {version_patch};
            pub const VERSION_PRE: bool = {pre_release};
            "
      ),
   )
      .unwrap();
   println!("cargo:rerun-if-changed=Cargo.toml");
}