use std::{
    env,
    io::{self, Write},
    path::PathBuf,
    process::Command,
};

fn build_x86_64() {
    const DEFAULT_8086_AS: &str = "nasm";
    const AP_BOOTSTRAP_S: &str = "src/arch/x86_64/boot/ap_boot.S";

    println!("cargo:rerun-if-changed={}", AP_BOOTSTRAP_S);

    let out_dir = env::var("OUT_DIR").unwrap();
    let assembler = env::var("AS8086").unwrap_or(DEFAULT_8086_AS.to_owned());

    let ap_bootstrap_out = PathBuf::from(out_dir).join("__x86_64_ap_boot.bin");

    // Assemble the code
    let output = Command::new(assembler.as_str())
        .args([
            "-fbin",
            "-o",
            ap_bootstrap_out.to_str().unwrap(),
            AP_BOOTSTRAP_S,
        ])
        .output()
        .unwrap();

    if !output.status.success() {
        io::stderr().write_all(&output.stderr).ok();
        panic!("{}: could not assemble {}", assembler, AP_BOOTSTRAP_S);
    }
}

fn main() {
    let arch = env::var("CARGO_CFG_TARGET_ARCH").unwrap();

    println!("cargo:rerun-if-changed=build.rs");

    match arch.as_str() {
        "x86_64" => build_x86_64(),
        "aarch64" => (),
        _ => panic!("Unknown target arch: {:?}", arch),
    }
}