don't decode if decoding unneeded

gpgmymail

@@ -57,11 +57,27 @@ def decode_email(message: email.message.Message) -> email.message.Message:
 
     :param message: email.message.Message to be decoded
     :return: decoded email.message.Message"""
+    def decoded_bytes_to_return_value(decoded_bytes: bytes) -> email.message.Message:
+        """
+        if at any point you want to return, return a call of this function and
+        pass decoded_bytes
+
+        :param decoded_bytes: an email as an ASCII byte array; this should be
+                              stored in decoded_bytes
+        :return: the expected return value of decode_email
+        """
+        # if i do message_from_bytes it bizarrely changes it back to base64?
+        # utf-8 has encoding issues so do latin1
+        return email.message_from_string(decoded_bytes.decode("latin1"))
+
     # this is a kinda hacky way to do this by manipulating the message as a
     # string but i couldn't get it to work any other way
-    # decoding needed:
-    # as_string() gives us str, encode() gives us bytes
     decoded_bytes = message.as_bytes()
+    # if email doesn't need decoding
+    has_quopri = b'Content-Transfer-Encoding: quoted-printable' in decoded_bytes
+    has_base64 = b'Content-Transfer-Encoding: base64' in decoded_bytes
+    if not (has_quopri or has_base64):
+        return message
     decoded_bytes = quopri.decodestring(decoded_bytes)
 
     # replace any instances of the Content-Transfer-Encoding header
@@ -71,6 +87,10 @@ def decode_email(message: email.message.Message) -> email.message.Message:
         b'Content-Transfer-Encoding: 7bit'
     )
 
+    # now exit if there's no base64 as i think that's the most fucky
+    if not has_base64:
+        return decoded_bytes_to_return_value(decoded_bytes)
+
     # REALLY hacky but i had issues with the more sensible ways to do this.
     # iterates through a Message object to find CTEs of base64
     # gets the b64 payload and the decoded payload
@@ -142,9 +162,7 @@ def decode_email(message: email.message.Message) -> email.message.Message:
         b'Content-Transfer-Encoding: 7bit'
     )
     
-    # if i do message_from_bytes it bizarrely changes it back to base64?
-    # utf-8 has encoding issues so do latin1
-    return email.message_from_string(decoded_bytes.decode("latin1"))
+    return decoded_bytes_to_return_value(decoded_bytes)
 
 def encrypt(
         message: email.message.Message,