add num_sms, check for SIM or modem storage

Author: brentru

adafruit_fona/adafruit_fona.py

@@ -69,6 +69,10 @@
 
 FONA_MAX_SOCKETS = const(6)
 
+# FONA SMS storage methods
+FONA_SMS_STORAGE_SIM = b"\"SM\""
+FONA_SMS_STORAGE_INTERNAL = b"\"SM\""
+
 # pylint: enable=bad-whitespace
 
 # pylint: disable=too-many-instance-attributes, too-many-public-methods
@@ -528,17 +532,27 @@ def send_sms(self, phone_number, message):
         return True
 
     @property
-    def num_sms(self):
-        """Returns the number of SMS messages stored in memory, False otherwise.
+    def num_sms(self, sim_storage=True):
+        """Returns the number of SMS messages stored in memory, False if none stored.
+
+        :param bool sim_storage: SMS storage on the SIM, otherwise internal storage on FONA chip.
         """
         # text mode
         if not self._send_check_reply(b"AT+CMGF=1", reply=REPLY_OK):
             return False
-        
+
         # ask how many SMS are stored
-        self._send_parse_reply(b"AT+CPMS?", b"\"SM_P\"" + b",")
-        print("Reply: ", self._buf)
-        # TODO 
+        if sim_storage:
+            if self._send_parse_reply(b"AT+CPMS?", FONA_SMS_STORAGE_SIM + b",", idx=1):
+                return self._buf
+        else:
+            if self._send_parse_reply(b"AT+CPMS?", FONA_SMS_STORAGE_INTERNAL + b",", idx=1):
+                return self._buf
+        if self._send_parse_reply(b"AT+CPMS?", b"\"SM\",", idx=1):
+            return self._buf
+        if self._send_parse_reply(b"AT+CPMS?", b"\"SM_P\",", idx=1):
+            return self._buf
+        return False
 
     def read_sms(self, sms_slot=None):
         """Reads SMS messages from FONA device.
@@ -552,21 +566,29 @@ def read_sms(self, sms_slot=None):
 
         if not self._send_check_reply(b"AT+CSDH=1", reply=REPLY_OK):
             return False
-        
-        sms_length = 0
 
-        if sms_slot is None:
-            self.uart_write(b"AT+CMGL=\"ALL\"" + b"\r\n")
-            self._read_line()
-            self._read_line()
-            self._read_line()
-            self._read_line()
-            return True
+        # TODO: Add this back
+        #if sms_slot is None:
+        #    self.uart_write(b"AT+CMGL=\"ALL\"" + b"\r\n")
+        #    self._read_line()
+        #    return True
 
         self.uart_write(b"AT+CMGR=" + str(sms_slot).encode() + b"\r\n")
-        self._read_line()
-        return True
-    
+        self._read_line(1000)
+
+        # get sms length
+        if not self._parse_reply(b"+CMGR:", idx=11):
+            return False
+        sms_len = self._buf
+        # rsize shared buf
+        self._buf = bytearray(sms_len)
+        # read into buffer
+        self._uart.readinto(self._buf)
+        # discard unread chars in buffer
+        self._uart.reset_input_buffer()
+
+
+        return bytes(self._buf).decode()
 
 
     ### Socket API (TCP, UDP) ###