PythonRecipe

# PythonRecipe — standard recipe for Python packages (bits-recipe-tools)
#
# Uses pip to install into an isolated prefix, then patches shebangs for
# relocatability.  Mirrors the install pattern used by lcgcmake's
# pyexternals/CMakeLists.txt (pip install --no-deps --root=/ --prefix=...).
#
# Variables exported by this file (available to recipe overrides):
#
#   PYTHON_EXE          full path to the python3 interpreter
#   PYTHON_MAJOR_MINOR  e.g. "3.12"
#   SITE_PACKAGES       $INSTALLROOT/lib/python3.12/site-packages
#
# Requirement: Python must be in the recipe's `requires:` list so that
# Python_ROOT is set in the environment before this file is sourced.

# bits' init.sh exports _ROOT vars using the package: field name verbatim
# (e.g. Python_ROOT for "package: Python").  Module files now generate uppercase
# names (PYTHON_ROOT) but Python itself may not have been rebuilt yet, so we
# fall back to the mixed-case form that bits always provides.
_PYTHON_ROOT="${PYTHON_ROOT:-${Python_ROOT}}"
PYTHON_EXE="${_PYTHON_ROOT}/bin/python3"
PYTHON_MAJOR_MINOR=$(${PYTHON_EXE} -c 'import sys; print("%d.%d" % sys.version_info[:2])')
SITE_PACKAGES="${INSTALLROOT}/lib/python${PYTHON_MAJOR_MINOR}/site-packages"

# Build PYTHONPATH from every dependency that installed Python modules.
# bits sets *_ROOT for each dep via init.sh sourcing; we add any whose
# lib/pythonX.Y/site-packages directory actually exists.
# The regex accepts both mixed-case names from bits init.sh (e.g. meson_python_ROOT,
# Python_ROOT) and uppercase names from new-style module files (MESON_PYTHON_ROOT).
for _root_var in $(env | grep -E '^[A-Za-z][A-Za-z0-9_]*_ROOT=' | cut -d= -f1 | sort -u); do
  _root_val="${!_root_var}"
  _sp="${_root_val}/lib/python${PYTHON_MAJOR_MINOR}/site-packages"
  [ -d "${_sp}" ] || continue
  export PYTHONPATH="${_sp}${PYTHONPATH:+:${PYTHONPATH}}"
done
unset _root_var _root_val _sp

function Prepare() {
  rsync -av --delete --exclude '**/.git' --delete-excluded "${SOURCEDIR}"/ ./
}

function Configure() { true; }
function Make()      { true; }

function MakeInstall() {
  mkdir -p "${SITE_PACKAGES}"
  # --no-deps             deps are managed by bits, not pip
  # --no-build-isolation  use already-installed build tools (setuptools, etc.)
  # --ignore-installed    don't try to uninstall system packages before installing;
  #                       avoids "Permission denied" when a system copy exists
  # --root=/ --prefix=    install directly into our package tree; no staging dir
  "${PYTHON_EXE}" -m pip install \
    --no-deps --no-build-isolation --ignore-installed \
    --root=/ --prefix="${INSTALLROOT}" .
}

function UnitTest() {
  true
}

function PostInstall() {
  # Replace hardcoded python paths in installed scripts with #!/usr/bin/env python3.
  # Mirrors lcgcmake's pyexternals/Python_postinstall.sh.
  for _f in "${INSTALLROOT}/bin/"*; do
    [ -f "${_f}" ] || continue
    head -n1 "${_f}" | grep -q "/python" || continue
    sed -i.bak "1s|.*|#!/usr/bin/env python3|" "${_f}"
    rm -f "${_f}.bak"
  done
  unset _f
}

function Clean() { true; }

. ${BITS_RECIPE_TOOLS_ROOT}/ModuleRecipe
. ${BITS_RECIPE_TOOLS_ROOT}/PreloadRecipe

function Run() {
  local rc=0
  case $1 in
    Prepare) Prepare ;;
    Build)   Configure && Make && UnitTest && MakeInstall && MakeModule && PostInstall && Preload && Clean ;;
    *)       Prepare && Configure && Make && UnitTest && MakeInstall && MakeModule && PostInstall && Preload && Clean ;;
  esac || rc=$?
  return $rc
}