#!/usr/bin/env sh

# Find R compilers
CC=`${R_HOME}/bin/R CMD config CC`
CFLAGS=`${R_HOME}/bin/R CMD config CFLAGS`
# compiler and flags to 'cc' file
echo "CC=${CC}" > inst/cc
echo "CFLAGS=${CFLAGS}" >> inst/cc

# gcc compiler info to output #3291
case $CC in gcc*)
  GCCV=`${CC} -dumpfullversion -dumpversion`
  echo "$CC $GCCV"
esac

# Let's keep this simple. If pkg-config is available, use it. Otherwise print
# the helpful message to aid user if compilation does fail. Note 25 of R-exts:
# "[pkg-config] is available on the machines used to produce the CRAN binary packages"
# This script should pass `checkbashisms` for portability; e.g. CRAN's Solaris 10,
# and R-exts note 24 now suggests 'checkbashisms' as we proposed.

msg=0
NOZLIB=1 # if pkg-config is not available then zlib will be disabled for higher chance of compilation success
pkg-config --version > config.log 2>&1
if [ $? -ne 0 ]; then
  echo "*** pkg-config is not installed."
  msg=1
else
  pkg-config --exists zlib
  if [ $? -ne 0 ]; then
    echo "*** pkg-config is installed but 'pkg-config --exists zlib' did not return 0."
    msg=1
  else
    NOZLIB=0
    lib=`pkg-config --libs zlib`
    cflag=`pkg-config --cflags zlib`
    expr -- "$lib" : ".*-lz$" >> config.log  # -- for FreeBSD, #4652
    if [ $? -ne 0 ]; then
      expr -- "$lib" : ".*-lz " >> config.log
      # would use \b in one expr but MacOS does not support \b
      if [ $? -ne 0 ]; then
        echo "*** pkg-config is installed and 'pkg-config --exists zlib' succeeds but"
        echo "*** 'pkg-config --libs zlib' returns '${lib}' which does not include the standard -lz."
        msg=1
      fi
    fi
  fi
fi

if [ $msg -ne 0 ]; then
  echo "*** Compilation will now be attempted and if it works you can ignore this message. In"
  echo "*** particular, this should be the case on Mac where zlib is built in or pkg-config"
  echo "*** is not installed. However, if compilation fails, try 'locate zlib.h zconf.h' and"
  echo "*** ensure the zlib development library is installed :"
  echo "***   deb: zlib1g-dev (Debian, Ubuntu, ...)"
  echo "***   rpm: zlib-devel (Fedora, EPEL, ...)"
  echo "***   There is a zlib in brew for OSX but the built in zlib should work."
  echo "*** Note that zlib is required to compile R itself so you may find the advice in the R-admin"
  echo "*** guide helpful regarding zlib. On Debian/Ubuntu, zlib1g-dev is a dependency of r-base as"
  echo "*** shown by 'apt-cache showsrc r-base | grep ^Build-Depends | grep zlib', and therefore"
  echo "*** 'sudo apt-get build-dep r-base' should be sufficient too."
  echo "*** To silence this message, please ensure that :"
  echo "***   1) 'pkg-config --exists zlib' succeeds (i.e. \$? -eq 0)"
  echo "***   2) 'pkg-config --libs zlib' contains -lz"
  echo "*** Compilation will now be attempted ..."
else
  version=`pkg-config --modversion zlib`
  echo "zlib ${version} is available ok"
fi

# Test if we have a OPENMP compatible compiler
# Aside: ${SHLIB_OPENMP_CFLAGS} does not appear to be defined at this point according to Matt's testing on
# Linux, and R CMD config SHLIB_OPENMP_CFLAGS also returns 'no information for variable'. That's not
# inconsistent with R-exts$1.2.1.1, though, which states it's 'available for use in Makevars' (so not
# necessarily here in configure). Hence use -fopenmp directly for this detection step.
# printf not echo to pass checkbashisms w.r.t. to the \n

cat <<EOF > test-omp.c
#include <omp.h>
int main() {
  return omp_get_num_threads();
}
EOF

detect_openmp () {
  export PKG_CXXFLAGS=""
  if [ "$(uname)" = "Linux" ]; then
    : '
    printf "%s" "* checking if R installation supports OpenMP without any extra hints... "
    if "${R_HOME}/bin/R" CMD SHLIB test-omp.c >> config.log 2>&1; then
      echo "yes"
      export R_OPENMP_ENABLED=1
      return
    else
      echo "no"
    fi


    printf "%s" "* checking if R installation supports openmp with \"-fopenmp\" flag... "
    if ${CC} ${CFLAGS} -fopenmp test-omp.c >> config.log 2>&1; then
      echo "yes"
      export PKG_CFLAGS="${PKG_CFLAGS} -fopenmp"
      export R_OPENMP_ENABLED=1
      return
    else
      echo "no"
    fi
    '
  fi # uname=Linux

  if [ "$(uname)" = "Darwin" ]; then
    export openmapp="-fopenmp"

    # https://mac.r-project.org/openmp
    printf "%s" "* checking if R installation supports OpenMP with \"-Xclang -fopenmp\" ... "

      echo "yes"
      export PKG_CFLAGS="${PKG_CFLAGS} -Xclang -fopenmp"
      export PKG_LIBS="${PKG_LIBS} -lomp"
      export R_OPENMP_ENABLED=1
      export PKG_CXXFLAGS="-Xpreprocessor -fopenmp"
      return

    printf "%s" "* checking if R installation supports OpenMP with \"-fopenmp\" ... "

      echo "yes"
      export PKG_CFLAGS="${PKG_CFLAGS} -fopenmp"
      export R_OPENMP_ENABLED=1
      export PKG_CXXFLAGS="-Xpreprocessor -fopenmp"
      return

    if [ "$(uname -m)" = "arm64" ]; then
      HOMEBREW_PREFIX=/usr/local
    else
      HOMEBREW_PREFIX=/usr/local
    fi

    if [ -e "${HOMEBREW_PREFIX}/opt/libomp" ]; then
      printf "%s" "* checking if libomp installation at ${HOMEBREW_PREFIX}/opt/libomp can be used... 
"
      LIBOMP_INCLUDE="-I${HOMEBREW_PREFIX}/opt/libomp/include -Xclang -fopenmp"
      LIBOMP_LINK="-L${HOMEBREW_PREFIX}/opt/libomp/lib -lomp"
      if ${CC} ${CFLAGS} ${LIBOMP_INCLUDE} ${LIBOMP_LINK} test-omp.c >> config.log 2>&1; then
        echo "yes"
        export PKG_CFLAGS="${PKG_CFLAGS} ${LIBOMP_INCLUDE}"
        export PKG_LIBS="${PKG_LIBS} ${LIBOMP_LINK}"
        export R_OPENMP_ENABLED=1
        return
      else
        echo "no"
      fi
    fi

  fi # uname=Darwin

  # No support for OpenMP available
  export R_OPENMP_ENABLED=0
}

detect_openmp

# Clean up.
rm -f test-omp.* a.out

if [ "${R_OPENMP_ENABLED}" = "0" ]; then
  echo "***"
  echo "*** OpenMP not supported!"
  echo "***   parallelize operations like sorting, grouping, file reading, etc."
  echo "*** Continuing installation without OpenMP support..."
  echo "***"
  sed -e "s|@openmp_cflags@||" src/Makevars.in > src/Makevars
else
  sed -e "s|@openmp_cflags@|\$(SHLIB_OPENMP_CFLAGS)|" src/Makevars.in > src/Makevars
fi

# retain user supplied PKG_ env variables, #4664. See comments in Makevars.in too.
sed -e "s|@PKG_CFLAGS@|$PKG_CFLAGS|" src/Makevars > src/Makevars.tmp && mv src/Makevars.tmp src/Makevars
sed -e "s|@PKG_CXXFLAGS@|$PKG_CXXFLAGS|" src/Makevars > src/Makevars.tmp && mv src/Makevars.tmp src/Makevars
sed -e "s|@PKG_LIBS@|$PKG_LIBS|" src/Makevars > src/Makevars.tmp && mv src/Makevars.tmp src/Makevars

# optional dependency on zlib
if [ "$NOZLIB" = "1" ]; then
  echo "*** Compilation without compression support in fwrite"
  sed -e "s|@zlib_cflags@|-DNOZLIB|" src/Makevars > src/Makevars.tmp && mv src/Makevars.tmp src/Makevars
  sed -e "s|@zlib_libs@||" src/Makevars > src/Makevars.tmp && mv src/Makevars.tmp src/Makevars
else
  sed -e "s|@zlib_cflags@|${cflag}|" src/Makevars > src/Makevars.tmp && mv src/Makevars.tmp src/Makevars
  sed -e "s|@zlib_libs@|${lib}|" src/Makevars > src/Makevars.tmp && mv src/Makevars.tmp src/Makevars
fi

exit 0
