activate

[ -n "$BASH_SOURCE" ] \
    || { echo 1>&2 "source (.) this with Bash."; exit 2; }
__activate_quiet=
[[ $1 = -q ]] && { shift; __activate_quiet=-q; }
(
    basedir=$(cd "$(dirname "$BASH_SOURCE")" && pwd -P)
    cd "$basedir"
    [ -d .build/virtualenv ] || {
        py='python3'; $py -m pip --version >/dev/null 2>&1 || py='python'

        echo 'Bootstrapping virtualenv'
        bsdir=".build/virtualenv-bootstrap"
        deb_nouser=--system     # Must turn off --user on Debian
        $py -m pip install $deb_nouser >/dev/null 2>&1 || deb_nouser=
        $py -m pip $__activate_quiet $__activate_quiet install $deb_nouser \
            -b "$bsdir/build" -t "$bsdir/target" virtualenv

        echo 'Building virtualenv...'
        $py $bsdir/target/virtualenv.py --prompt="($(basename "$basedir")) " \
            $__activate_quiet .build/virtualenv "$@" \
        && . .build/virtualenv/*/activate \
        && pip install $__activate_quiet -r requirements.txt
    }
) \
&& . "$(dirname "$BASH_SOURCE")"/.build/virtualenv/*/activate