activate

#https://unix.stackexchange.com/a/153061
VIRTUALIZE_SOURCED_NAME="${_:-$BASH_SOURCE}"  # must do this first because of $_ ambiguity

if [ "${BASH_SOURCE-}" = "$0" ]; then
    echo "You must source this script: \$ source $0" >&2
    exit 33
fi

if [[ $VIRTUALIZE_ROOT && ! $VIRTUALIZE_ACTIVATING ]]; then
    echo "virtualizer is active, not activating" $VIRTUALIZE_SOURCED_NAME
    unset VIRTUALIZE_SOURCED_NAME
    return
fi

if [[ $VIRTUALIZE_PYENV_DIR ]]; then
    echo "This shell is already virtualized for $VIRTUALIZE_PYENV_DIR, type 'unactivate' to undo"
    return
fi

VIRTUALIZE_PYENV_DIR=$( cd -- "$( dirname -- "${VIRTUALIZE_SOURCED_NAME}" )" &> /dev/null && pwd )

VIRTUALIZE_PYENV_ORIG_PYENV_ROOT="$PYENV_ROOT"
VIRTUALIZE_PYENV_ORIG_PATH="$PATH"
export PYENV_ROOT="$VIRTUALIZE_PYENV_DIR/pyenv"
export PATH="$PYENV_ROOT/bin:$PATH"
eval "$(pyenv init - --no-rehash)"

function unactivate_pyenv() {
    if [[ $VIRTUALIZE_PYENV_ORIG_PYENV_ROOT ]]; then
        PYENV_ROOT="$VIRTUALIZE_PYENV_ORIG_PYENV_ROOT"
    else
        unset PYENV_ROOT
    fi
    PATH="$VIRTUALIZE_PYENV_ORIG_PATH"
    unset VIRTUALIZE_PYENV_ORIG_PYENV_ROOT
    unset VIRTUALIZE_PYENV_ORIG_PATH
    unset VIRTUALIZE_SOURCED_NAME
    unset VIRTUALIZE_PYENV_INSTALL_DIR
    unset VIRTUALIZE_PYENV_DIR
}

# stop here if called on behalf of virtualize
if [[ $VIRTUALIZE_ACTIVATING ]]; then
    # let virtualized deal with customizing the prompt
    return
fi

###
### standalone mode only from here on
###

VIRTUALIZE_ROOT=$VIRTUALIZE_PYENV_DIR  # prevents autoactivating

function unactivate() {
    local virtualize_pyenv_dir="$VIRTUALIZE_PYENV_DIR"
    unactivate_pyenv
    unset -f unactivate_pyenv
    PS1="$VIRTUALIZE_PYENV_ORIG_PS1"
    unset VIRTUALIZE_PYENV_ORIG_PS1
    unset VIRTUALIZE_PYENV_ACTIVE_VERSION
    unset VIRTUALIZE_PYENV_DISPLAY
    unset VIRTUALIZE_ROOT
    unset -f unactivate
    echo "unactivated $virtualize_pyenv_dir"
}

#VIRTUALIZE_PYENV_ORIG_PS1="$PS1"
VIRTUALIZE_PYENV_ACTIVE_VERSION=$( $PYENV_ROOT/bin/pyenv version 2>&1 | head -1 | cut -d" " -f2 )
VIRTUALIZE_PYENV_DISPLAY="$(echo $VIRTUALIZE_PYENV_DIR | sed 's%^$HOME/%%' | sed 's/\//·/g') $VIRTUALIZE_PYENV_ACTIVE_VERSION"
if [[ $ZSH_VERSION ]]; then
   PS1="[$VIRTUALIZE_PYENV_DISPLAY]$PS1"
else  # for bash (and others?)
   PS1="[$VIRTUALIZE_PYENV_DISPLAY]\n$PS1"
fi

echo "pyenv activated for $VIRTUALIZE_PYENV_DIR"
echo "type 'unactivate' to undo"