#!/usr/bin/bash
COMPILER_DIR="${PWD}/compiler"
DOWNLOAD_DIR="${COMPILER_DIR}/download"
SOURCES_DIR="${COMPILER_DIR}/sources"
BUILD_DIR="${COMPILER_DIR}/build"

GCC_VER=10.2.0
GCC_TAR_FILE="gcc-${GCC_VER}.tar.xz"
GCC_TAR_URL="https://ftp.gnu.org/gnu/gcc/gcc-${GCC_VER}/${GCC_TAR_FILE}"
GCC_SOURCE="${SOURCES_DIR}/gcc-${GCC_VER}"
GCC_BUILD="${BUILD_DIR}/gcc-${GCC_VER}"

BINUTILS_VER=2.36
BINUTILS_TAR_FILE="binutils-${BINUTILS_VER}.tar.xz"
BINUTILS_TAR_URL="https://ftp.gnu.org/gnu/binutils/${BINUTILS_TAR_FILE}"
BINUTILS_SOURCE="${SOURCES_DIR}/binutils-${BINUTILS_VER}"
BINUTILS_BUILD="${BUILD_DIR}/binutils-${BINUTILS_VER}"

TARGET_COMPILER="${COMPILER_DIR}/target"

export MAKEFLAGS="-j$(nproc)"

export PREFIX="${TARGET_COMPILER}"
export TARGET=i686-elf
export PATH="${PREFIX}/bin:${PATH}"

function log() {
  echo "$*"
}

function yes_or_no() {
  while true; do
    read -p "$* [y/n]: " yn
    case $yn in
    [Yy]*) return 0 ;;
    [Nn]*)
      echo "Aborted"
      return 1
      ;;
    esac
  done
}

function download() {
  if [ -f "${DOWNLOAD_DIR}/$2" ]; then
    log "Not downloading $2"
    return 0
  fi
  log "Downloading $2"
  curl -o "${DOWNLOAD_DIR}/$2" "$1"
}

function extract_source() {
  if [ -d "$1" ]; then
    log "already extracted $2, skipping"
    return 0
  fi
  log "Extracting $2"
  tar -C "${SOURCES_DIR}" -xf "${DOWNLOAD_DIR}/$2"
}

function ensure_dir() {
  if [ ! -d "$1" ]; then
    mkdir -p "$1"
  fi
}

# Verify

if [ -d "${COMPILER_DIR}" ]; then
  if ! yes_or_no "Do you want to rebuild?"; then
    exit 1
  fi
fi

# Download sources
ensure_dir "${COMPILER_DIR}"

ensure_dir "${DOWNLOAD_DIR}"
ensure_dir "${TARGET_COMPILER}"
ensure_dir "${BUILD_DIR}"
ensure_dir "${GCC_BUILD}"
ensure_dir "${BINUTILS_BUILD}"

download "${GCC_TAR_URL}" "${GCC_TAR_FILE}"
download "${BINUTILS_TAR_URL}" "${BINUTILS_TAR_FILE}"

extract_source "${GCC_SOURCE}" "${GCC_TAR_FILE}"
extract_source "${BINUTILS_SOURCE}" "${BINUTILS_TAR_FILE}"

# Build
function build_binutils() {
  pushd . || return 1
  cd "${BINUTILS_BUILD}" || return 1
  "${BINUTILS_SOURCE}/configure" --target=${TARGET} --prefix=${PREFIX} --with-sysroot --disable-nls --disable-werror || return 1
  make || return 1
  make install || return 1
  popd || return 1
  return 0
}

function build_gcc() {
  if ! which -- "${TARGET}-as"; then
    log "Could not find ${TARGET}-as!"
    return 1
  fi
  pushd . || return 1
  cd "${GCC_BUILD}" || return 1
  "${GCC_SOURCE}/configure" --target=${TARGET} --prefix=${PREFIX} --disable-nls --enable-languages=c --without-headers || return 1
  make all-gcc || return 1
  make all-target-libgcc || return 1
  make install-gcc || return 1
  make install-target-libgcc || return 1
  popd || return 1
  return 0
}

if ! build_binutils; then
  log "Failed to build binutils!"
  exit 1
fi

if ! build_gcc; then
  log "Failed to build binutils!"
  exit 1
fi