configure

#!/bin/sh

export PATH="$PATH:$HOME/.cargo/bin"

NOT_CRAN=${NOT_CRAN:-"false"}

LIBR_POLARS_BUILD=${LIBR_POLARS_BUILD:-""}
# Passed to the --feture flag of cargo build
FEATURES=${LIBR_POLARS_FEATURES:-""}

# Detect if this is on R-universe.
MY_UNIVERSE=${MY_UNIVERSE:-""}

LIBNAME="libr_polars.a"
LIBR_POLARS_DEFAULT_PATH="$(pwd)/tools/${LIBNAME}"
LIBR_POLARS_PATH=${LIBR_POLARS_PATH:-${LIBR_POLARS_DEFAULT_PATH}}

check_cargo() {
  if [ ! "$(command -v cargo)" ]; then
    cat <<EOF
------------------------- [RUST NOT FOUND] -------------------------
The 'cargo' command was not found on the PATH. Please install rustc
from: https://www.rust-lang.org/tools/install

Alternatively, you may install cargo from your OS package manager:
  - Debian/Ubuntu: apt-get install cargo
  - Fedora/CentOS: dnf install cargo
  - macOS: brew install rustc
--------------------------------------------------------------------
EOF
    exit 1
  else
    cat <<EOF
--------------------------- [RUST FOUND] ---------------------------
$(cargo -V)

$(rustc -vV)
--------------------------------------------------------------------
EOF
  fi
}

check_rustup() {
  if [ "$(command -v rustup)" ]; then
    root_dir="$(pwd)"
    # Change to the src directory to detect rust-toolchain.toml
    cd "${root_dir}/src" || true
    cat <<EOF
-------------------------- [RUSTUP FOUND] --------------------------
$(rustup show)
--------------------------------------------------------------------
EOF
    cd "${root_dir}" || true
  else
    cat <<EOF
------------------------ [RUSTUP NOT FOUND] ------------------------
The 'rustup' command was not found on the PATH.
--------------------------------------------------------------------
EOF
  fi
}

check_emscripten() {
  if [ "$(uname)" = "Emscripten" ]; then
    cat <<EOF
-------------------- [NIGHTLY TOOLCHAIN NEEDED] --------------------
It seems that building for Emscripten.
'polars' requires a very recent Rust nightly toolchain.
So using the rust-toolchain.toml file to set the toolchain.
--------------------------------------------------------------------
EOF
    export TARGET="wasm32-unknown-emscripten"
    # Set these for to use the project specific nightly toolchain
    NOT_CRAN="true"
    FEATURES="${FEATURES:-"nightly"}"
  fi
}

check_bin_lib() {
  if [ "${NOT_CRAN}" = "true" ] && [ -z "${LIBR_POLARS_BUILD}" ]; then
    LIBR_POLARS_BUILD="false"
  fi

  # On R-universe, we try to download the pre-built binary from GitHub releases.
  if [ -n "${MY_UNIVERSE}" ] && [ -z "${LIBR_POLARS_BUILD}" ]; then
    cat <<EOF
--------------------- [SETTING FOR R-UNIVERSE] ---------------------
It seems that this is on R-universe <${MY_UNIVERSE}>.
Trying to download pre-built binary.
--------------------------------------------------------------------
EOF
    LIBR_POLARS_BUILD="false"
  fi

  if [ "${LIBR_POLARS_BUILD}" = "false" ]; then
    if [ -f "tools/lib-sums.tsv" ] && [ ! -f "${LIBR_POLARS_PATH}" ]; then
      cat <<EOF
---------------- [TRY TO DOWNLOAD PRE-BUILT BINARY] ----------------
The library was not found at <${LIBR_POLARS_PATH}>.
Trying to download pre-built binary from the Internet...
--------------------------------------------------------------------
EOF
      "${R_HOME}/bin${R_ARCH_BIN}/Rscript" "tools/prep-lib.R" && echo "Done!" ||
        echo "Failed to download pre-built binary."
    fi

    if [ -f "${LIBR_POLARS_PATH}" ] && [ "${LIBR_POLARS_PATH}" != "${LIBR_POLARS_DEFAULT_PATH}" ]; then
      cat <<EOF
------------------------- [COPYING BINARY] -------------------------
Copying <${LIBR_POLARS_PATH}> to <${LIBR_POLARS_DEFAULT_PATH}>.
--------------------------------------------------------------------
EOF
      mkdir -p "$(dirname "${LIBR_POLARS_DEFAULT_PATH}")"
      cp "${LIBR_POLARS_PATH}" "${LIBR_POLARS_DEFAULT_PATH}" && echo "Done!" || echo "Failed to copy binary."
    fi

    if [ -f "${LIBR_POLARS_DEFAULT_PATH}" ]; then
      cat <<EOF
---------------------- [LIBRARY BINARY FOUND] ----------------------
The library was found at <${LIBR_POLARS_DEFAULT_PATH}>. No need to build it.

Note: rustc version: $(command -v rustc >/dev/null && rustc -V || echo "Not found")
--------------------------------------------------------------------
EOF
      export TARGET=""
      generate_makevars
    fi
    cat <<EOF
-------------------- [LIBRARY BINARY NOT FOUND] --------------------
The library was not found at <${LIBR_POLARS_PATH}>.
Falling back to building from source.
--------------------------------------------------------------------
EOF
  fi
}

generate_makevars() {
  for suffix in "" ".win"; do
    makefile="src/Makevars${suffix}"
    sed \
      -e "s|@TARGET@|${TARGET}|" \
      -e "s|@PROFILE@|${PROFILE}|" \
      -e "s|@FEATURES@|${FEATURES}|" \
      "$makefile.in" >"$makefile"
  done

  exit 0
}

copy_rust_toolchain_toml() {
  # The file for setting the toolchain is included in the src/rust directory, which is the root directory of the Rust package.
  # However, this is ignored during the R package build because the cargo build command is executed in the src directory.
  # This ignored behavior is actually desirable to avoid unexpected file downloads on the user's computer,
  # but in CI environments or when the user opts in, the rust-toolchain.toml file is copied to src/rust
  # so that it can be recognized during the R package build.
  path_from="$(pwd)/src/rust/rust-toolchain.toml"
  path_to="$(pwd)/src/rust-toolchain.toml"

  cat <<EOF
------------------ [RUST TOOLCHAIN CONFIGURATION] ------------------
The Rust toolchain file was found at <${path_from}>.
Copying it to <${path_to}>.
--------------------------------------------------------------------
EOF
  cp "${path_from}" "${path_to}" && echo "Done!" ||
    echo "Failed to copy ${path_from} to ${path_to}."
}

check_feature() {
  cat <<EOF
------------------------- [FEATURES CHECK] -------------------------
Selected features: '${FEATURES}'
--------------------------------------------------------------------
EOF
  # TODO: needs documented, and maybe also use on R-universe?
  if echo "${FEATURES}" | grep -q nightly && [ "${NOT_CRAN}" = "true" ]; then
    cat <<EOF
-------------------- [NIGHTLY TOOLCHAIN NEEDED] --------------------
The 'nightly' feature requires a specific version of the Rust nightly toolchain.
So using the rust-toolchain.toml file to set the toolchain.
--------------------------------------------------------------------
EOF
    copy_rust_toolchain_toml

    # Try to add the target
    root_dir="$(pwd)"
    cd "${root_dir}/src" || true
    rustup target add "${TARGET}" || echo "Failed to add target ${TARGET}."

    # For Emscripten build, the rust-src is needed for to include the stdlib to reduce the size of the binary.
    if [ "${TARGET}" = "wasm32-unknown-emscripten" ]; then
      rustup component add rust-src || echo "Failed to add rust-src."
    fi
    cd "${root_dir}" || true
  fi
}

# catch DEBUG envvar, which is passed from pkgbuild::compile_dll()
if [ "${DEBUG}" = "true" ]; then
  PROFILE=dev
else
  PROFILE=release
fi

check_emscripten
check_bin_lib
check_cargo

# This needs rustc to be installed
TARGET="${TARGET:-$(rustc -vV | grep host | cut -d' ' -f2)}"

# They need the TARGET to be set
check_feature
check_rustup

generate_makevars