configure

#!/bin/sh
# configure — auto-detect CUDA for RcppML
#
# This script is run by R CMD INSTALL before compiling the package.
# It detects optional dependencies (CUDA) and generates:
#   1. src/Makevars      — compiler flags for the R package build
#   2. inst/build_config — capability summary for R-side runtime detection
#
# The GPU shared library (RcppML_gpu.so) is NOT built here — it requires
# a separate `make -f src/Makefile.gpu` step (see PRODUCTION_STATUS.md §6).
# This script merely records the CUDA location so R can find it.

echo "=== Configuring RcppML ==="

# ---- Detect CUDA ----
CUDA_FOUND="no"
NVCC_PATH=""
CUDA_VERSION=""
CUDA_HOME_DETECTED=""

if [ -n "$CUDA_HOME" ]; then
  CUDA_HOME_DETECTED="$CUDA_HOME"
elif command -v nvcc >/dev/null 2>&1; then
  CUDA_HOME_DETECTED=$(dirname $(dirname $(command -v nvcc)))
fi

if [ -n "$CUDA_HOME_DETECTED" ] && [ -x "$CUDA_HOME_DETECTED/bin/nvcc" ]; then
  CUDA_FOUND="yes"
  NVCC_PATH="$CUDA_HOME_DETECTED/bin/nvcc"
  CUDA_VERSION=$("$NVCC_PATH" --version 2>/dev/null | grep "release" | sed 's/.*release \([0-9.]*\).*/\1/')
  echo "  CUDA: found (nvcc: $NVCC_PATH, version: $CUDA_VERSION)"
else
  echo "  CUDA: not found (GPU features will be unavailable)"
fi

# ---- Detect GPU architecture ----
GPU_ARCH=""
if [ "$CUDA_FOUND" = "yes" ] && command -v nvidia-smi >/dev/null 2>&1; then
  GPU_ARCH=$(nvidia-smi --query-gpu=compute_cap --format=csv,noheader 2>/dev/null | head -1 | tr -d '.')
  if [ -n "$GPU_ARCH" ]; then
    echo "  GPU architecture: sm_$GPU_ARCH"
  fi
fi

# ---- Detect OpenMP ----
# OpenMP detection is handled by R's $(SHLIB_OPENMP_CXXFLAGS)
# We just record whether it's likely available
OMP_FOUND="unknown"
if [ -n "$SHLIB_OPENMP_CXXFLAGS" ]; then
  OMP_FOUND="yes"
fi

# ---- Generate src/Makevars ----
echo "  Generating src/Makevars..."

if [ -f src/Makevars.in ]; then
  sed \
    -e "s|@CUDA_FOUND@|${CUDA_FOUND}|g" \
    -e "s|@CUDA_HOME@|${CUDA_HOME_DETECTED}|g" \
    src/Makevars.in > src/Makevars
else
  echo "  Warning: src/Makevars.in not found, using existing src/Makevars"
fi

# ---- Write build config for R runtime ----
mkdir -p inst
cat > inst/build_config << EOF
# Auto-generated by configure — do not edit
cuda_found=${CUDA_FOUND}
cuda_version=${CUDA_VERSION}
cuda_home=${CUDA_HOME_DETECTED}
nvcc_path=${NVCC_PATH}
gpu_arch=${GPU_ARCH}
build_date=$(date -u +%Y-%m-%dT%H:%M:%SZ 2>/dev/null || date)
EOF

echo "=== Configuration complete ==="