Help with drawing this diagram Tikz or any useful code to be rendered in latex

    documentclass{article}
usepackage{tikz}
usetikzlibrary{positioning}
begin{document}
    begin{tikzpicture}
        draw (0,0)-|(3,5)-|node[pos=.25, fill=white](x){huge X}(0,0);
                draw (6,0)-|(9,5)-|node[pos=.25, fill=white](y){huge Y}(6,0);
                node[below=of x, circle, fill, draw, inner sep=2pt, label=left:xtextsubscript{2}] (x2) {};
                node[below=2cm of x2, circle, fill, draw, inner sep=2pt, label=left:xtextsubscript{1}] (x1){};
                node[below=of y, circle, fill, draw, inner sep=2pt, label=right:ytextsubscript{2}] (y2) {};
                node[below=2cm of y2, circle, fill, draw, inner sep=2pt, label=right:ytextsubscript{1}] (y1){};
                draw(x2)--node[left, pos=0.5](){a}(x1)--node[below,pos=0.5](){b}(y1)--node[right,pos=0.5](){c}(y2);
    end{tikzpicture}
end{document}