use std::env;

fn main() {
    let target_arch = env::var("CARGO_CFG_TARGET_ARCH").unwrap();
    let disable_simd128 = read_env("LIBCRUX_DISABLE_SIMD128");
    let disable_simd256 = read_env("LIBCRUX_DISABLE_SIMD256");

    // Force a simd build. Make sure you know what you're doing.
    let enable_simd128 = read_env("LIBCRUX_ENABLE_SIMD128");
    let enable_simd256 = read_env("LIBCRUX_ENABLE_SIMD256");

    let simd128_possible = target_arch == "aarch64";
    if (simd128_possible || enable_simd128) && !disable_simd128 {
        // We enable simd128 on all aarch64 builds.
        println!("cargo:rustc-cfg=feature=\"simd128\"");
    }
    let simd126_possible = target_arch == "x86_64";
    if (simd126_possible || enable_simd256) && !disable_simd256 {
        // We enable simd256 on all x86_64 builds.
        // Note that this doesn't mean the required CPU features are available.
        // But the compiler will support them and the runtime checks ensure that
        // it's only used when available.
        //
        // We don't enable this on x86 because it seems to generate invalid code.
        println!("cargo:rustc-cfg=feature=\"simd256\"");
    }
}

fn read_env(key: &str) -> bool {
    match env::var(key) {
        Ok(s) => s == "1" || s == "y" || s == "Y",
        Err(_) => false,
    }
}