#!/usr/bin/env bash

usage() {
  cat << EOF
Usage: $(basename "$0") [COMMAND]

Commands:
  build         Build the kernel (default)
  menuconfig    Run menuconfig and save customizations
  repack        Repack stock boot image with custom kernel
  download      Download latest LineageOS boot image
  help          Show this help message

Examples:
  $(basename "$0")              # Build the kernel
  $(basename "$0") build        # Build the kernel
  $(basename "$0") menuconfig   # Configure kernel interactively
  $(basename "$0") repack       # Repack stock_boot.img with new kernel (auto-downloads if missing)
  $(basename "$0") download     # Download latest LineageOS boot.img for dodge
EOF
  exit 0
}

set_basedir() {
  BASEDIR=$(realpath "$(dirname -- "$(realpath -- "${BASH_SOURCE[0]}")")/..")
}

ensure_repo_initialized() {
  if [ ! -d "$BASEDIR/.repo" ]; then
    echo ".dir missing, initializing..."
    pushd "$BASEDIR" > /dev/null
    repo init -u "$BASEDIR/meta" --git-lfs
    repo sync
    popd > /dev/null
  fi
}

download_magisk() {
  if [ ! -d "$BASEDIR/prebuilts/magisk" ]; then
    echo "Magisk binaries missing, downloading..."
    mkdir -p "$BASEDIR/prebuilts/magisk"
    pushd "$BASEDIR/prebuilts/magisk" > /dev/null
    wget "https://github.com/topjohnwu/Magisk/releases/download/v29.0/Magisk-v29.0.apk" || curl -OL "https://github.com/topjohnwu/Magisk/releases/download/v29.0/Magisk-v29.0.apk"
    unzip "Magisk-v29.0.apk"
    popd > /dev/null
  fi
}

setup_toolchain_vars() {
  GCCDIR="$BASEDIR/prebuilts/gcc/linux-x86/aarch64/aarch64-linux-android-4.9"
  GCCDIR32="$BASEDIR/prebuilts/gcc/linux-x86/arm/arm-linux-androideabi-4.9"
  CLANGDIR="$BASEDIR/prebuilts/clang/host/linux-x86/clang-r547379"
  KERNELBUILDTOOLS="$BASEDIR/prebuilts/kernel-build-tools/linux-x86"

  MAKEOPTS=(
    O="$BASEDIR/work"
    ARCH=arm64
    PATH="$CLANGDIR/bin:$GCCDIR/bin:$KERNELBUILDTOOLS/bin:$PATH"
    LD_LIBRARY_PATH="$CLANGDIR/lib"
    LLVM=1
    CROSS_COMPILE="$GCCDIR/bin/aarch64-linux-android-"
    CROSS_COMPILE_ARM32="$GCCDIR32/bin/arm-linux-androideabi-"
    CLANG_TRIPLE=aarch64-linux-gnu-
  )
}

prepare_kernel_source() {
  echo "Preparing source..."
  pushd "$BASEDIR/kernel/oneplus/sm8750" > /dev/null

  git reset --hard
  git clean -fd
  ln -s "${BASEDIR}/external/SukiSU-Ultra" "KernelSU"
  ln -s "${BASEDIR}/external/SukiSU-Ultra/kernel" "drivers/kernelsu"

  popd > /dev/null
}

add_sukisu() {
  pushd "$BASEDIR/kernel/oneplus/sm8750" > /dev/null

  MOD=false
  grep -q "kernelsu" "drivers/Makefile" || printf "\nobj-\$(CONFIG_KSU) += kernelsu/\n" >> "drivers/Makefile" || echo "[+] Modified Makefile."
  grep -q "source \"drivers/kernelsu/Kconfig\"" "drivers/Kconfig" || sed -i "/endmenu/i\source \"drivers/kernelsu/Kconfig\"" "drivers/Kconfig" && echo "[+] Modified Kconfig."

  popd > /dev/null
}

add_susfs() {
  pushd "$BASEDIR/kernel/oneplus/sm8750" > /dev/null

  cp "${BASEDIR}/external/susfs4ksu/kernel_patches/fs/"* "fs/"
  cp "${BASEDIR}/external/susfs4ksu/kernel_patches/include/linux/"* "include/linux/"
  patch --fuzz=3 -p1 < "${BASEDIR}/external/susfs4ksu/kernel_patches/50_add_susfs_in_gki-android15-6.6.patch"

  popd > /dev/null
}

configure_kernel() {
  pushd "$BASEDIR/kernel/oneplus/sm8750" > /dev/null

  mkdir -p "$BASEDIR/out"
  mkdir -p "$BASEDIR/work"

  make ${MAKEOPTS[@]} mrproper
  make ${MAKEOPTS[@]} gki_defconfig

  scripts/kconfig/merge_config.sh -m -O "$BASEDIR/work" \
    "$BASEDIR/work/.config" \
    arch/arm64/configs/vendor/sun_perf.config \
    arch/arm64/configs/vendor/oplus/sun_perf.config

  if [ -e "${BASEDIR}/.config" ]; then
    echo "Adding custom configuration..."
    scripts/kconfig/merge_config.sh -m -O "${BASEDIR}/work" \
      "${BASEDIR}/work/.config" \
      "${BASEDIR}/.config"
  fi

  echo "CONFIG_DODGE_DTB=y" >> "$BASEDIR/work/.config"
  echo "CONFIG_OPLUS_DEVICE_DTBS=y" >> "$BASEDIR/work/.config"
  echo "CONFIG_COMPAT=y" >> "$BASEDIR/work/.config"
  echo "CONFIG_COMPAT_VDSO=y" >> "$BASEDIR/work/.config"

  make ${MAKEOPTS[@]} olddefconfig

  popd > /dev/null
}

build_kernel() {
  pushd "$BASEDIR/kernel/oneplus/sm8750" > /dev/null

  make ${MAKEOPTS[@]} \
    KCFLAGS="-Wno-error=frame-larger-than=" \
    -j$(nproc) 2>&1 | tee "$BASEDIR/work/build.log"

  popd > /dev/null
}

prepare_anykernel() {
  echo "Preparing AnyKernel3 package..."
  rm -rf "${BASEDIR}/work/AnyKernel3"
  mkdir -p "${BASEDIR}/work/AnyKernel3"
  cp -ra "${BASEDIR}/external/AnyKernel3/"* "${BASEDIR}/work/AnyKernel3/"
  cp "${BASEDIR}/meta/anykernel.sh" "${BASEDIR}/work/AnyKernel3/anykernel.sh"
  cp "${BASEDIR}/prebuilts/magisk/lib/arm64-v8a/libbusybox.so" "${BASEDIR}/work/AnyKernel3/tools/busybox"
  cp "${BASEDIR}/prebuilts/magisk/lib/arm64-v8a/libmagiskboot.so" "${BASEDIR}/work/AnyKernel3/tools/magiskboot"
  chmod +x "${BASEDIR}/work/AnyKernel3/tools/"*

  echo "Copying kernel Image..."
  cp "${BASEDIR}/work/arch/arm64/boot/Image" "${BASEDIR}/work/AnyKernel3/"
}

create_flashable_zip() {
  echo "Creating flashable zip..."
  KERNEL_VERSION=$(cat "${BASEDIR}/kernel/oneplus/sm8750/include/config/kernel.release" 2>/dev/null || echo "unknown")
  OUTPUT_ZIP="${BASEDIR}/out/LiteKernel-${KERNEL_VERSION}-$(date +%Y%m%d-%H%M%S).zip"

  pushd "${BASEDIR}/work/AnyKernel3" > /dev/null
  zip -r9 "${OUTPUT_ZIP}" * -x .git README.md .gitignore ./*.zip
  popd > /dev/null

  echo "Build complete!"
  echo "Flashable zip: ${OUTPUT_ZIP}"
}

run_menuconfig() {
  set_basedir
  setup_toolchain_vars

  mkdir -p "$BASEDIR/out"
  mkdir -p "$BASEDIR/work"

  pushd "$BASEDIR/kernel/oneplus/sm8750" > /dev/null

  echo "Generating base configuration..."
  make ${MAKEOPTS[@]} mrproper
  make ${MAKEOPTS[@]} gki_defconfig

  scripts/kconfig/merge_config.sh -m -O "$BASEDIR/work" \
    "$BASEDIR/work/.config" \
    arch/arm64/configs/vendor/sun_perf.config \
    arch/arm64/configs/vendor/oplus/sun_perf.config

  make ${MAKEOPTS[@]} olddefconfig
  cp "$BASEDIR/work/.config" "$BASEDIR/work/.config.base"

  if [ -e "${BASEDIR}/.config" ]; then
    echo "Merging existing custom configuration..."
    scripts/kconfig/merge_config.sh -m -O "${BASEDIR}/work" \
      "${BASEDIR}/work/.config" \
      "${BASEDIR}/.config"
    make ${MAKEOPTS[@]} olddefconfig
  fi

  make ${MAKEOPTS[@]} menuconfig

  extract_custom_config

  popd > /dev/null
}

extract_custom_config() {
  echo "Extracting custom configuration differences..."

  if [ ! -f "$BASEDIR/work/.config.base" ]; then
    echo "Warning: No base config found for comparison"
    return
  fi

  > "$BASEDIR/.config"

  declare -A base_configs
  declare -A current_configs

  while IFS= read -r line; do
    if [[ "$line" =~ ^CONFIG_([^=]+)= ]]; then
      config_name="${BASH_REMATCH[1]}"
      base_configs["$config_name"]="$line"
    elif [[ "$line" =~ ^#\ (CONFIG_[^\ ]+)\ is\ not\ set ]]; then
      config_name="${BASH_REMATCH[1]#CONFIG_}"
      base_configs["$config_name"]="$line"
    fi
  done < "$BASEDIR/work/.config.base"

  while IFS= read -r line; do
    if [[ "$line" =~ ^CONFIG_([^=]+)= ]]; then
      config_name="${BASH_REMATCH[1]}"
      current_configs["$config_name"]="$line"
    elif [[ "$line" =~ ^#\ (CONFIG_[^\ ]+)\ is\ not\ set ]]; then
      config_name="${BASH_REMATCH[1]#CONFIG_}"
      current_configs["$config_name"]="$line"
    fi
  done < "$BASEDIR/work/.config"

  for config_name in "${!current_configs[@]}"; do
    if [[ "${base_configs[$config_name]}" != "${current_configs[$config_name]}" ]]; then
      echo "${current_configs[$config_name]}" >> "$BASEDIR/.config"
    fi
  done

  if [ -s "$BASEDIR/.config" ]; then
    sort -o "$BASEDIR/.config" "$BASEDIR/.config"
    echo ""
    echo "Custom configuration saved to: $BASEDIR/.config"
    echo "Changes from base configuration:"
    cat "$BASEDIR/.config"
    echo ""
  else
    echo "No configuration changes from base detected."
    rm -f "$BASEDIR/.config"
  fi
}

download_lineageos_boot() {
  set_basedir

  echo "Fetching latest LineageOS build information for dodge..."

  if ! command -v python3 &> /dev/null; then
    echo "Error: python3 is required but not found"
    return 1
  fi

  BOOT_URL=$(curl -s "https://download.lineageos.org/api/v2/devices/dodge/builds" | python3 -c 'import sys,json;d=json.load(sys.stdin);boot=[f for f in d[0]["files"] if f["filename"]=="boot.img"][0];print(boot["url"])' 2>/dev/null)

  if [ -z "$BOOT_URL" ]; then
    echo "Error: Failed to fetch boot.img URL from LineageOS API"
    return 1
  fi

  echo "Found boot.img URL: $BOOT_URL"
  echo "Downloading boot.img..."

  wget -O "${BASEDIR}/stock_boot.img" "$BOOT_URL" || curl -L -o "${BASEDIR}/stock_boot.img" "$BOOT_URL"

  if [ ! -f "${BASEDIR}/stock_boot.img" ]; then
    echo "Error: Failed to download boot.img"
    return 1
  fi

  echo "Boot image saved to: ${BASEDIR}/stock_boot.img"
}

repack_boot_image() {
  set_basedir
  download_magisk

  if [ ! -f "${BASEDIR}/stock_boot.img" ]; then
    echo "stock_boot.img not found, attempting to download from LineageOS..."
    download_lineageos_boot || return 1
  fi

  if [ ! -f "${BASEDIR}/work/arch/arm64/boot/Image" ]; then
    echo "Error: Kernel Image not found at ${BASEDIR}/work/arch/arm64/boot/Image"
    echo "Please build the kernel first using: $(basename "$0") build"
    return 1
  fi

  MAGISKBOOT="${BASEDIR}/prebuilts/magisk/lib/x86_64/libmagiskboot.so"
  chmod +x "${MAGISKBOOT}"

  echo "Repacking boot image..."
  rm -rf "${BASEDIR}/out/repack"
  mkdir -p "${BASEDIR}/out/repack"
  pushd "${BASEDIR}/out/repack" > /dev/null

  ${MAGISKBOOT} unpack "${BASEDIR}/stock_boot.img"
  cp "${BASEDIR}/work/arch/arm64/boot/Image" kernel
  ${MAGISKBOOT} repack "${BASEDIR}/stock_boot.img" "${BASEDIR}/out/new_boot.img"

  popd > /dev/null

  echo ""
  echo "Boot image repacked successfully!"
  echo "Output: ${BASEDIR}/out/new_boot.img"
}

build() {
  set_basedir
  ensure_repo_initialized
  download_magisk
  setup_toolchain_vars
  prepare_kernel_source
  add_sukisu
  add_susfs
  configure_kernel
  build_kernel
  prepare_anykernel
  create_flashable_zip
}

main() {
  local command="${1:-build}"

  case "$command" in
    build)
      build
      ;;
    menuconfig)
      run_menuconfig
      ;;
    repack)
      repack_boot_image
      ;;
    download)
      download_lineageos_boot
      ;;
    help|--help|-h)
      usage
      ;;
    *)
      echo "Error: Unknown command '$command'"
      echo ""
      usage
      ;;
  esac
}

main "$@"