#! /usr/bin/env bash

ASM_PATH="src/"
TARGET_PATH="target"
TMP_PATH="$TARGET_PATH/temp/"
OBJ_PATH="$TMP_PATH"
LINK_SCRIPT_PATH="src/"
GRUB_CFG_PATH="src/grub.cfg"
ARCH="x86_64"
TARGET="$ARCH-uff"
RUST_BIN="$TARGET_PATH/$TARGET/debug/libkernel.a"
QUEMU="qemu-system-x86_64 -cdrom $TARGET_PATH/uff.iso"

cleanup_target() {
    rm -f $TARGET_PATH/uff.iso &> /dev/null
    rm -rf $TARGET_PATH/kernel.bin

    cleanup_temp
}

create_target() {
    mkdir $TARGET_PATH &> /dev/null
    mkdir $TMP_PATH &> /dev/null
}

cleanup_temp() {
    rm -f $TMP_PATH/* &> /dev/null
}

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

build_kernel_elf() {
    create_target
    for f in $ASM_PATH/*.asm; do
        nasm -felf64 "$f" -o $OBJ_PATH/"$(basename -s .asm $f)".o
    done
    ld -n -o $TARGET_PATH/kernel.bin -gc-sections -T $LINK_SCRIPT_PATH/linker.ld $OBJ_PATH/*.o $RUST_BIN
    cleanup_temp
}

build_kernel_iso() {
    if test ! -e $TARGET_PATH/kernel.bin; then
        build_kernel_elf
    fi
    create_target
    mkdir $TMP_PATH/isofiles &> /dev/null
    mkdir $TMP_PATH/isofiles/boot &> /dev/null
    mkdir $TMP_PATH/isofiles/boot/grub &> /dev/null
    cp $TARGET_PATH/kernel.bin $TMP_PATH/isofiles/boot &> /dev/null
    cp $GRUB_CFG_PATH $TMP_PATH/isofiles/boot/grub/grub.cfg &> /dev/null
    grub-mkrescue -d /usr/lib/grub/i386-pc -o $TARGET_PATH/uff.iso $TMP_PATH/isofiles
    cleanup_temp
}

build_init() {
    create_target
}

build_launch() {
    $QUEMU
}

build_launch_serial() {
    $QUEMU -device isa-debug-exit,iobase=0xf4,iosize=0x04 -serial stdio #-display none
}

build_run() {
    if test ! -e $TARGET_PATH/uff.iso; then
        build_kernel_iso
    fi
    build_launch
}

build_clean() {
    cleanup_target
}

build_build() {
    cargo xbuild
    cleanup_target
    build_run
}
build_tests() {
    cargo xbuild --features testing
    cleanup_target
    build_kernel_iso
    build_launch_serial
}

build_all() {
    build_kernel_elf
}

not_exec=true

for arg in "$@"; do
    case "$arg" in
        "kernel-elf") build_kernel_elf;;
        "kernel-iso") build_kernel_iso;;
        "init") build_init;;
        "launch") build_launch;;
        "run") build_run;;
        "clean") build_clean;;
        "build") build_build;;
        "test") build_tests;;
        "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 "  launch                    launch iso in qemu"
    echo "  run                       creates iso if necessary and runs it in qemu"
    echo "  test                      runs tests in qemu"
    echo
    echo "  kernel-elf                build the kernel-elf"
    echo "  kernel-iso                build the kernel-elf if necessary and the kernel-iso"
    echo "  build                     build the kernel-iso with rust binaries"
    echo "  all                       build kernel"
}

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