[HELP!]Program still executable but the logic messed up

[silentkill89]

I want to rite a Linux shell script that takes two arguments. These arguments can be files or directories. If two files are supplied, check if they have the same content and print a success or failure outcome. If first argument is a file and the other is a directory, check if files exist in directory and copy it if it is a newer version. If it does not exist, create a link in target directory. If first argument is a directory and second argument is a file, I will be prompted to choose whether to archive content of directory to file or extract archive from file to directory. If two arguments are directories, copy all files in first directory to second directory. Also, I have to make sure that newer versions of files only are copied and report on each file when it is not the case. And also all error should be handle by error checking.

So far im not sure what i did is rite, some logic error occured in my program although it doesn have any error
code:

if [ $# -ne 2 ]
then
echo "Error:$0 does not have valid input."
echo "Please enter 2 valid input."
fi

if test -f $1 && test -f $2
then
d=$(diff $1 $2)
if [ -z $d ]
then
echo "File is same"
else
echo "File is different"
fi
fi

if test -f $1 && test -d $2
then
find $2 -name $1 -print
cp $1 $2
echo "1 file copied."
else
ln $2 $1
echo "Link created."
fi

if test -d $1 && test -f $2
then
read "Choose Y to archive content of directory to file or N to extract archive from file to directory: " r1
if $r1 = Y || $r1 = y
then
tar -cvf $2.tar $1
echo"Archive directory success."
elif
$r1 = N || $r1 = n
then
tar -xvf $2.tar -C $1
echo" Extract archive success."
fi
fi

if test -d $1 && test -f $2
then
cp $1 $2
echo"All files copied."
fi

The first condition is ok which take 2 files as arguments and gave me what i want. but not the 2nd condition. The

ln $2 $1
echo "Link created."

does not display even i met the condition. This same goes the 3rd condition. I knw it's difficult to understand and help with tis program. But at least try to give me some tips so i knw how far im going now.