function venv -d "Manipulate Python virtual environments (venv)"

    if test (count $argv) -eq 0
        echo "usage: venv [list | deactivate | activate VENV]"
        return 1
    end

    if test $argv[1] = "list" -o $argv[1] = "l"
        ls -1 --color=no $WORKON_HOME
    else if test $argv[1] = "deactivate" -o $argv[1] = "d"
        type -q deactivate; and deactivate
    else if test $argv[1] = "activate" -o $argv[1] = "a"
        source $WORKON_HOME/{$argv[2]}/bin/activate.fish
    else
        return 1
    end
    return 0
end

# see http://fishshell.com/docs/current/completions.html

# disable file completions
complete -c venv -f

# subcommand completion
set -l commands list deactivate activate
complete -c venv -n "not __fish_seen_subcommand_from $commands" -a "$commands"

# activate completion
complete -c venv -n "__fish_seen_subcommand_from activate" \
    -a "(ls $WORKON_HOME)"