#!/env/bash

function pyenv () {
    usage="Custom Python virtualenv manager
sivenv [list, delete, load, new] [VENV]
Commands:
  list                List existing virtualenvs (alias: 'ls')
  load VENV           Activate the virtualenv named VENV (alias: 'source')
  new VENV [VERSION]  Create and load a new virtualenv named VENV. Optionally VERSION
                      can be a python version to use for creating the venv. Note that
                      only python3 versions are supported.
  delete VENV         Delete the virtualenv named VENV (alias: 'rm')";

    if [ $# -eq 0 ]; then
        echo "Error: no command specified" >&2;
        echo "$usage";
        return 1;
    fi;

    case $1 in
        "-h"| "--help")
            echo "$usage";
            return 0;;
        "ls"| "list")
            lsvenv "$VIRTUALENV_DIR";;
        "rm"| "delete")
            if [ $# -ne 2 ]; then
                echo "Error: no virtualenv specified" >&2;
                return 1;
            fi;
            rm --recursive --force "${VIRTUALENV_DIR:?}/$2";;
        "source" | "load")
            if [ $# -ne 2 ]; then
                echo "Error: no virtualenv specified" >&2;
                return 1;
            fi;
            # shellcheck source=/dev/null
            source "$VIRTUALENV_DIR/$2/bin/activate";;
        "new")
            if [ $# -lt 2 ]; then
                echo "Error: no virtualenv specified" >&2;
                return 1;
            fi;
            if [ $# -eq 3 ]; then
                version="$3";
            else
                version="3";
            fi
            if ! command -v "python$version" &>/dev/null; then
                echo "Error: no interpreter found for python version '$version'" >&2;
                return 2;
            fi

            if python$version -m venv "$VIRTUALENV_DIR/$2"; then
                echo "New virtualenv '$2' created using $(command -v python$version)" >&2;
                # shellcheck source=/dev/null
                source "$VIRTUALENV_DIR/$2/bin/activate"
            else
                return $?;
            fi;;
        *)
            echo "Error: unknown command '$1'" >&2;
            echo "$usage";
            return 1;;
    esac
}

function lsvenv () {
    venvs=()
    for item in /usr/bin/ls -d "$1"/*/; do
        if stat "${item}/bin/activate" &>/dev/null; then
          venvs+=("$(basename "$item")");
        fi
    done
    echo "${venvs[*]}"
}