Refactored some classes into separate files in lib/

lib/simple_mqtt.py

@@ -0,0 +1,78 @@
+import socket
+import struct
+
+
+class SimpleMQTT:
+    def __init__(self, host, port=1883):
+        self.host = host
+        self.port = port
+        self.sock = None
+
+    def connect(self, client_id, username=None, password=None):
+        addr_info = socket.getaddrinfo(self.host, self.port)
+        addr = addr_info[0][-1]
+        self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        self.sock.connect(addr)
+
+        # Flags: Clean session (bit 1) + optional credentials
+        flags = 0x02
+        if username:
+            flags |= 0x80
+        if password:
+            flags |= 0x40
+
+        # Variable header: Protocol Name (MQTT) + Level (4) + Flags + KeepAlive (60s)
+        var_header = bytearray(
+            [0x00, 0x04, ord("M"), ord("Q"), ord("T"), ord("T"), 0x04, flags, 0x00, 0x3C]
+        )
+
+        payload = bytearray()
+        payload.extend(self._encode_str(client_id))
+        if username:
+            payload.extend(self._encode_str(username))
+        if password:
+            payload.extend(self._encode_str(password))
+
+        body = var_header + payload
+        packet = bytearray([0x10]) + self._encode_len(len(body)) + body
+        self.sock.write(packet)
+
+        # Read CONNACK (4 bytes: 0x20, 0x02, ack_flags, return_code)
+        resp = self.sock.read(4)
+        if not resp or resp[0] != 0x20 or resp[3] != 0x00:
+            code = resp[3] if resp and len(resp) >= 4 else "nil"
+            raise RuntimeError(f"MQTT connection failed: code {code}")
+
+    def publish(self, topic, payload, retain=False):
+        cmd = 0x30 | (0x01 if retain else 0x00)
+        if isinstance(payload, str):
+            payload = payload.encode("utf-8")
+        body = self._encode_str(topic) + payload
+        packet = bytearray([cmd]) + self._encode_len(len(body)) + body
+        self.sock.write(packet)
+
+    def disconnect(self):
+        try:
+            if self.sock:
+                self.sock.write(bytearray([0xE0, 0x00]))
+                self.sock.close()
+        except Exception:
+            pass
+        finally:
+            self.sock = None
+
+    def _encode_str(self, s):
+        raw = s.encode("utf-8")
+        return struct.pack("!H", len(raw)) + raw
+
+    def _encode_len(self, length):
+        encoded = bytearray()
+        while True:
+            digit = length % 128
+            length //= 128
+            if length > 0:
+                digit |= 0x80
+            encoded.append(digit)
+            if length == 0:
+                break
+        return encoded