How can read the content of the active window?

I am trying to create a bash script that selects the content of the active window, copies the content to the clipboard, and saves the content to a file. This file then gets read by some text editor, and the modification gets pasted back to the active window. My attempt is shown below. At the moment, the part where I do ctrl+a and ctrl+c does not work.

#!/usr/bin/env bash

TMPFILE=$(mktemp).md

if [[ $OSTYPE == "linux-gnu" ]]; then
    xdotool getactivewindow key ctrl+a
    xdotool getactivewindow key ctrl+c
    xclip -selection clipboard -o > $TMPFILE
    urxvt -fn "xft:Iosevka Term:pixelsize=24" -geometry 60x10 -e vim -u ~/.config/vim/vimrc -c 'startinsert' $TMPFILE
    cat $TMPFILE | xclip -selection clipboard
    xdotool key ctrl+v
fi