pactivate

#   pactivate version 0.5.0   https://github.com/cynic-net/pactivate

[ -n "$BASH_VERSION" ] || { echo 1>&2 "source (.) this with Bash."; exit 9; }
#   https://stackoverflow.com/a/28776166/107294
(return 0 2>/dev/null) \
    || { echo 1>&2 "source (.) pactivate with Bash."; exit 9; }

__pa_cleanup() {
    unset __pa_cleanup __pa_echo \
        __pa_builddir __pa_quiet __pa_python __pa_python_deref __pa_pyver \
        __pa_bootdir __pa_basedir __pa_requirements
}
__pa_echo() { [[ -n $__pa_quiet ]] || echo "$@"; }

__pa_basedir=$(cd "$(dirname "$BASH_SOURCE")" && pwd -P)
__pa_builddir=
__pa_quiet=
while [[ $# -gt 0 ]]; do case "$1" in
    -b) shift; __pa_builddir="$1"; shift;;
    -B) shift; __pa_basedir="$1"; shift;;
    -q) shift; __pa_quiet=-q;;
    *)  echo 1>&2 "pactivate: unknown argument: $1"; __pa_cleanup; return 2;;
esac; done;

if [[ -e $__pa_basedir/.python || -L $__pa_basedir/.python ]]; then
    #   Even if it's a dangling link (-e fails) we use it so that the
    #   user sees the error.
    __pa_python=$__pa_basedir/.python
else
    #   We test `py` only in Windows/MINGW because the Unix `py` program
    #   (from the pythonpy package) is a different thing we never want to use.
    for __pa_python in ${MSYSTEM:+py} python3 python PYTHON_NOT_FOUND; do
        "$__pa_python" --version >/dev/null 2>&1 && break
    done
fi
"$__pa_python" --version >/dev/null 2>&1 || {
    [[ -L $__pa_python ]] \
        && echo "$__pa_python -> $(readlink "$__pa_python")"
    $__pa_python --version || true      # Display the suppressed error message
    echo 1>&2 "pactivate: bad python interpreter"
    __pa_cleanup; return 3
}
#   $__pa_pyver is empty for "modern" versions of Python (i.e., those that
#   can use the current get-pip.py, 3.7 and above) and otherwise is the
#   major.minor revision number, suitable for use in the URL to download
#   an alternate version of get-pip.py.
__pa_pyver=$("$__pa_python" -c '
#   Reminder: this script must be compatible with Python 2 syntax.
import sys
M, m = sys.version_info[0], sys.version_info[1]     # Major, minor
if (M < 3 or (M == 3 and m < 7)):
    print("{}.{}".format(M, m))
')

__pa_requirements="$__pa_basedir/requirements.txt"

[[ -z $__pa_builddir ]] && __pa_builddir=$(cd "$__pa_basedir" && pwd -P)/.build

__pa_bootdir="$__pa_builddir/bootstrap/pactivate${__pa_pyver}"
mkdir -p "$__pa_bootdir"    # also ensures that $__pa_builddir exists

[[ -x $__pa_bootdir/bin/pip ]] || {
    echo "----- Installing bootstrap pip (ver=${__pa_pyver:-latest})"
    #   Debian-based systems do not incude distutils in the standard
    #   python3 package; check that it's available and, if not, print a
    #   more informative message than the ModuleNotFoundError.
    "$__pa_python" -c '
import sys
M, m = sys.version_info[0], sys.version_info[1]         # Major, minor
if (M < 3 or (M == 3 and m < 11)): import distutils.cmd # deprecated ≥3.11
        ' || {
        echo 1>&2 \
            "Cannot import 'distuils.cmd'; apt-get install python3-distutils?"
        return 3
    }
    #   get-pip.py produces spurious upgrade notices on older Python versions
    #   such as 3.6 or 2.7; --disable-pip-version-check suppresses these.
    curl --retry 3 --connect-timeout 10 '-#' ${__pa_quiet:+--silent} \
        "https://bootstrap.pypa.io/pip/$__pa_pyver/get-pip.py" \
        | "$__pa_python" - \
            $__pa_quiet -t "$__pa_bootdir" --disable-pip-version-check \
        || return $?
    PYTHONPATH="$__pa_bootdir" "$__pa_bootdir/bin/pip" --version
}

[[ -d $__pa_bootdir/virtualenv/ ]] || {
    echo '----- Installing bootstrap virtualenv'
    #   This install produces spurious "bootstrap/.../bin already exists"
    #   messages; --upgrade suppresses these. However, --upgrade also seems
    #   to entirely remove the bin/ directory, so we "re-install" pip
    #   (which will not re-download it) to restore bin/pip as well.
    PYTHONPATH="$__pa_bootdir" "$__pa_bootdir/bin/pip" \
        $__pa_quiet install --upgrade -t "$__pa_bootdir" pip virtualenv
}

[[ -d $__pa_builddir/virtualenv/ ]] || {
    echo '----- Building virtualenv'
    echo -n "Using $__pa_python"
    if [[ -L $__pa_python ]]; then
        #   MacOS readlink has no -f option, so we must do this the hard
        #   way. Fortunately we already know that the binary exists and is
        #   a Python interpreter.
        __pa_python_deref=$(readlink "$__pa_python")
        __pa_python_deref=$(cd "$__pa_basedir" \
            && cd $(dirname "$__pa_python_deref") \
            && pwd -P)/$(basename "$__pa_python_deref")
        echo " -> $__pa_python_deref"
    else
        __pa_python_deref="$__pa_python"
        echo
    fi
    echo -n "Version: " && "$__pa_python" --version
    PYTHONPATH="$__pa_bootdir" "$__pa_python_deref" -s -m virtualenv \
        $__pa_quiet --prompt $(basename "$__pa_basedir") \
        "$__pa_builddir/virtualenv/" \
    && [[ -f "$__pa_requirements" ]] \
    && "$__pa_builddir/virtualenv/bin/pip" \
        install $__pa_quiet -r "$__pa_requirements"
}

cmp -s $(type -p "$__pa_python") "$__pa_builddir/virtualenv/bin/python" || (
    echo 1>&2 "WARNING:" \
        virtualenv/bin/python \
        "($("$__pa_builddir"/virtualenv/bin/python --version 2>&1))" \
        "is not $__pa_python" \
        "($("$__pa_python" --version 2>&1))" \
    )

. "$__pa_builddir"/virtualenv/*/activate
__pa_cleanup