#!/usr/bin/env sh

mode="${1}"
network="rtl8139"

qemu_with_flags() {
  if [ "${mode}" = "image" ] || [ "${mode}" = "image_debug" ]; then
    # TODO: Find out why kvm install is incredibly slow
    SDL_VIDEO_X11_DGAMOUSE=0 qemu-system-i386 -no-reboot -vga std -smp "$(nproc)" -serial mon:stdio -rtc base=localtime -m 256M -net nic,model=${network},macaddr=42:42:42:42:42:42 -net user "$@"
  else
    SDL_VIDEO_X11_DGAMOUSE=0 qemu-system-i386 -enable-kvm -cpu host -no-reboot -vga std -smp "$(nproc)" -serial stdio -rtc base=localtime -m 256M -net nic,model=${network},macaddr=42:42:42:42:42:42 -net user "$@"
  fi
}

compile_with_flags() {
  if [ "${mode}" = "image" ] || [ "${mode}" = "image_debug" ]; then
    i686-elf-gcc -std=gnu99 -ffreestanding -nostdlib -Wall -Wextra -Wno-unused-parameter -D INSTALL_MELVIX "$@"
  else
    i686-elf-gcc -std=gnu99 -ffreestanding -nostdlib -Wall -Wextra -Wno-unused-parameter "$@"
  fi

}

make_cross() {
  if [ ! -d "./cross/" ]; then
    # Create directory
    mkdir -p cross
    cd cross || exit
    DIR=$(pwd)

    # Get sources
    mkdir "${DIR}/src" && cd "${DIR}/src" || exit
    echo "Downloading..."
    curl -sSL "https://ftp.gnu.org/gnu/binutils/binutils-2.32.tar.xz" | tar xJ
    curl -sSL "https://ftp.gnu.org/gnu/gcc/gcc-9.2.0/gcc-9.2.0.tar.xz" | tar xJ

    # 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" || exit
    ../binutils-2.32/configure --target="$TARGET" --prefix="$PREFIX" --with-sysroot --disable-nls --disable-werror
    make
    make install

    # Compile GCC
    mkdir "${DIR}/src/build-gcc" && cd "${DIR}/src/build-gcc" || exit
    ../gcc-9.2.0/configure --target="$TARGET" --prefix="$PREFIX" --disable-nls --enable-languages=c,c++ --without-headers
    make all-gcc
    make all-target-libgcc
    make install-gcc
    make install-target-libgcc

    cd "${DIR}/.." || exit
  else
    # Should be sourced to take effect
    cd cross || exit
    DIR=$(pwd)
    export PREFIX="${DIR}/opt"
    export TARGET=i686-elf
    export PATH="$PREFIX/bin:$PATH"
    cd ..
  fi
}

make_build() {
  echo "Building..."
  mkdir -p ./build/kernel && mkdir -p ./build/userspace

  # Assemble ASM files
  find ./src/kernel/ -name \*.asm >./build/tmp
  while read -r line; do
    stripped=$(echo "${line}" | sed -r 's/\//_/g')
    stripped=${stripped#??????}
    stripped=${stripped%%???}o
    nasm -f elf ./"${line}" -o ./build/kernel/asm_"${stripped}" || exit
  done <./build/tmp
  rm ./build/tmp

  # Make all kernel C files
  find ./src/kernel/ -name \*.c >./build/tmp
  while read -r line; do
    stripped=$(echo "${line}" | sed -r 's/\//_/g')
    stripped=${stripped#??????}
    stripped=${stripped%%?}o
    compile_with_flags -Os -s -c ./"${line}" -I ./src -D ${network} -o ./build/kernel/"${stripped}" || exit
  done <./build/tmp
  rm ./build/tmp

  # Link kernel ASM and C objects
  compile_with_flags -Os -s ./build/kernel/*.o -T ./src/kernel/linker.ld -I ./src -o ./build/melvix.bin || exit

  # Modules
  # TODO: Find out why no font optimizations cause strange glitches
  compile_with_flags -Os -c ./src/resources/font.c -o ./build/font.o
  i686-elf-objcopy -O binary ./build/font.o ./build/font.bin
  rm ./build/font.o

  # Userspace
  # TODO: Find out why userspace optimizations (-Os) cause fatal errors
  nasm -f elf ./src/userspace/start.asm -o ./build/userspace/start.o || exit
  find ./src/userspace/ -name \*.c >./build/tmp
  while read -r line; do
    stripped=$(echo "${line}" | sed -r 's/\//_/g')
    stripped=${stripped#??????}
    stripped=${stripped%%?}o
    compile_with_flags -O3 -c ./"${line}" -I ./src/userspace -o ./build/userspace/"${stripped}" || exit
  done <./build/tmp
  rm ./build/tmp
  compile_with_flags -O3 ./build/userspace/*.o -T ./src/userspace/linker.ld -I ./src/userspace -o ./build/user.bin || exit

  # Create ISO
  mkdir -p ./iso/boot/
  mv ./build/melvix.bin ./iso/boot/kernel.bin
  nasm ./src/bootloader/cd.asm -f bin -o ./iso/boot/cd.bin || exit
  nasm ./src/bootloader/hdd1.asm -f bin -o ./iso/boot/hdd1.bin || exit
  nasm ./src/bootloader/hdd2.asm -f bin -o ./iso/boot/hdd2.bin || exit
  cp ./build/user.bin ./iso/user.bin || exit
  cp ./build/font.bin ./iso/font.bin || exit
  genisoimage -quiet -input-charset utf-8 -no-emul-boot -b boot/cd.bin -o ./build/melvix.iso ./iso
  head -c 10485760 /dev/zero >./build/hdd10M.img

  printf "Build finshed successfully!\n\n"
}

make_test() {
  qemu_with_flags -cdrom ./build/melvix.iso -drive file=./build/hdd10M.img,format=raw
}

make_debug() {
  qemu_with_flags -s -cdrom ./build/melvix.iso -drive file=./build/hdd10M.img,format=raw
}

make_image_debug() {
  qemu_with_flags -cdrom ./build/melvix.iso -drive file=./build/hdd10M.img,format=raw
  qemu_with_flags -drive file=./build/hdd10M.img,format=raw
}

make_image() {
  start=$(date +%s.%N)
  qemu_with_flags -nographic -cdrom ./build/melvix.iso -drive file=./build/hdd10M.img,format=raw >install.log
  end=$(date +%s.%N)
  cat install.log
  printf "[LOG END]\n\n"
  tail install.log | grep -q "Installation successful!" && echo Booted and installed within "$(echo "$end - $start" | bc -l)" seconds || echo Installation failed!
  rm install.log
}

make_clean() {
  rm -rf ./build ./iso
}

if [ "${mode}" = "cross" ]; then
  make_cross
elif [ "${mode}" = "build" ]; then
  make_cross
  make_clean
  make_build
elif [ "${mode}" = "clean" ]; then
  make_clean
elif [ "${mode}" = "test" ]; then
  make_cross
  make_clean
  make_build
  make_test
elif [ "${mode}" = "debug" ]; then
  make_debug
elif [ "${mode}" = "image_debug" ]; then
  make_cross
  make_clean
  make_build
  make_image_debug
elif [ "${mode}" = "image" ]; then
  make_cross
  make_clean
  make_build
  make_image
else
  echo "Please use the following syntax:"
  echo "./run {cross | build | clean | test | debug | image}"
fi