#!/usr/bin/env sh
# MIT License, Copyright (c) 2021 Marvin Borner

set -e

cd "$(dirname "$0")"

MAKE=make
NPROC=nproc
SUDO=sudo
TAGS=ctags

mode="${1}"
no_ask="${2}"

build_cross() {
    if [ ! -d "./cross/" ]; then
        if [ "$no_ask" != "-y" ]; then
            echo -n "Do you want to compile a cross compiler (this can take around 20 minutes)? [yn] "
            read -r answer
            if ! [ "$answer" != "${answer#[Yy]}" ]; then
                echo "The compilation of SegelBoot requires a cross compiler!"
                exit 1
            fi
        fi

        # Create directory
        mkdir -p cross
        cd cross
        DIR=$(pwd)

        # Get sources
        mkdir "${DIR}/src" && cd "${DIR}/src"
        echo "Downloading..."
        curl "https://ftp.gnu.org/gnu/binutils/binutils-2.36.1.tar.gz" >binutils.tar.gz
        tar xzf binutils.tar.gz
        curl "https://ftp.gnu.org/gnu/gcc/gcc-11.1.0/gcc-11.1.0.tar.gz" >gcc.tar.gz
        tar xzf gcc.tar.gz

        # Prepare compiling
        mkdir -p "${DIR}/opt/bin"
        export PREFIX="${DIR}/opt"
        export TARGET=i686-elf
        export PATH="$PREFIX/bin:$PATH"

        # Compile binutils
        mkdir "${DIR}/src/build-binutils" && cd "${DIR}/src/build-binutils"
        ../binutils-2.36.1/configure --target="$TARGET" --prefix="$PREFIX" --with-sysroot --disable-nls --disable-werror
        $MAKE -j $($NPROC)
        $MAKE install

        # Compile GCC
        mkdir "${DIR}/src/build-gcc" && cd "${DIR}/src/build-gcc"
        ../gcc-11.1.0/configure --target="$TARGET" --prefix="$PREFIX" --disable-nls --enable-languages=c --without-headers
        $MAKE -j $($NPROC) all-gcc all-target-libgcc
        $MAKE install-gcc install-target-libgcc

        # Remove sources
        rm -rf "${DIR}/src/"

        cd "${DIR}/.."
    fi
}

# Generate configs for better development experience
generate() {
    ctags -R --exclude=.git --exclude=build --exclude=cross .

    # Compile commands for ALE in Vim
    make --always-make --dry-run |
        grep -wE 'gcc|g\+\+' |
        grep -w '\-c' |
        jq -nR '[inputs|{directory:".", command:., file: match(" [^ ]+$").string[1:]}]' \
            >compile_commands.json
}

build() {
    mkdir -p build/

    # Build
    printf "\nBuilding...\n"
    $MAKE -j $($NPROC)

    # Create disk image
    dd if=/dev/zero of=build/disk.img bs=1k count=32k status=none
    DEV=$($SUDO losetup --find --partscan --show build/disk.img)
    PART="p1"
    $SUDO parted -s "$DEV" mklabel msdos mkpart primary ext2 32k 100% -a minimal set 1 boot on
    $SUDO mke2fs -b 1024 -q "$DEV$PART"

    # Write bootsector but jump over partition table (at 440 to 510)
    $SUDO dd if=build/boot.bin of="$DEV" bs=1 count=440 conv=notrunc status=none
    $SUDO dd if=build/boot.bin of="$DEV" bs=1 skip=510 seek=510 conv=notrunc status=none

    # Mount disk and copy files
    mkdir -p mnt/
    $SUDO mount "$DEV$PART" mnt/
    $SUDO mkdir -p mnt/boot/
    $SUDO cp example/segelboot.cfg mnt/boot/
    $SUDO cp build/examples/* mnt/boot/

    #$SUDO cp -r "$HOME"/code/melvix/disk/* mnt/ || true
    #$SUDO cp -r "$HOME"/code/melvix/build/apps/ mnt/apps/ || true

    $SUDO umount mnt/ || (sync && $SUDO umount mnt/)
    rm -rf mnt/

    $SUDO losetup -d "$DEV"
}

emulate() {
    qemu-system-i386 -enable-kvm -d guest_errors -cpu max -serial stdio -m 256M -vga std -drive file=build/disk.img,format=raw,index=1,media=disk
}

# Always generate updated configurations
generate

if [ "${mode}" = "cross" ]; then
    build_cross
elif [ "${mode}" = "build" ]; then
    build_cross
    $MAKE clean
    build
else
    build_cross
    $MAKE clean
    build
    emulate
fi