function path_join(a, b,    x, y) {
    x = a
    y = b

    sub(/\/+$/, "", x)   # remove trailing / from a
    sub(/^\/+/, "", y)   # remove leading / from b

    if (x == "")
        return y
    if (y == "")
        return x

    return x "/" y
}

BEGIN { FS = "," } ;
ARGIND == 1 {
    # requested dirs
    dir=path_join(ENVIRON["HOME"], $1)
    cmd="mkdir -p " dir
    print cmd
    system(cmd)

    next
}

ARGIND == 2 {
    # block for locations
    src=path_join(ENVIRON["PWD"], $1)
    dst=path_join(ENVIRON["HOME"], $2)
    testcmd="test -e " dst
    linkcmd="ln -sf " src " " dst
    diffcmd="diff -ursN " dst " " src
    
    if (system(testcmd) == 0) {
	system("ls -lda " dst)
	printf "Exists, overwrite? y/N/d" # no newline
	getline resp < "/dev/tty"
	while (1) {
	    if (resp == "d" || resp == "D") {
		# dst is exists src is new, order is right
		print "Showing diff to apply (empty is none)"
		system(diffcmd)
		printf "Exists, overwrite? y/N/d" # no newline
		getline resp < "/dev/tty"
		continue
	    } else if (resp == "y" || resp == "Y") {
		print linkcmd
		system(linkcmd)
		break
	    } else if (resp == "n" || resp == "N" || resp == "") {
		print "Skipped"
		break
	    }
	    print "Exists, overwrite? y/N/d"
	    getline resp < "/dev/tty"
	}
    } else {
	print linkcmd
	system(echo linkcmd)
    }
}