#!/usr/bin/sh

remove_target() {
    rm -rf target &> /dev/null
}

create_target() {
    mkdir target &> /dev/null
    mkdir target/temp &> /dev/null
}

cleanup_temp() {
    rm -f target/temp/* &> /dev/null
}

# ---------------------------------------------------

build_kernel() {
    create_target
    nasm -felf64 multiboot_header.asm -o target/temp/multiboot_header.o
    nasm -felf64 boot.asm -o target/temp/boot.o
    ld -n -o target/kernel.bin -T linker.ld target/temp/*.o
    cleanup_temp
}

build_init() {
    create_target
}

build_clean() {
    remove_target
}

build_all() {
    build_kernel
}

not_exec=true

for arg in "$@"; do
    case "$arg" in
        "kernel") build_kernel;;
        "init") build_init;;
        "clean") build_clean;;
        "all") build_all;;
        *)
            echo "warn: ignoring unknown option '$arg'"
            continue;;
    esac
    not_exec=false
    break
done

print_help() {
    echo "usage: $0 option"
    echo "options: "
    echo "  init          initialise directory"
    echo "  clean         cleanup binaries"
    echo
    echo "  kernel        build the kernel"
    echo "  all           build kernel"
}

if $not_exec; then
    echo "error: please specify an argument"
    echo
    print_help
    exit -1
fi