Add client and connection abstractions (#3)

py_ness_232/__init__.py

@@ -0,0 +1,4 @@
+from .client import Client
+from .connection import Connection
+
+__all__ = ['Client', 'Connection']

py_ness_232/client.py

@@ -0,0 +1,35 @@
+from typing import Optional
+
+from .connection import Connection, IP232Connection
+from .event import BaseEvent
+from .packet import CommandType, Packet
+
+
+class Client:
+    def __init__(self,
+                 connection: Optional[Connection] = None,
+                 host: Optional[str] = None,
+                 port: Optional[int] = None):
+        if connection is None:
+            assert host is not None
+            assert port is not None
+            connection = IP232Connection(host, port)
+
+        self.__connection = connection
+
+    def send_command(self, command: str) -> None:
+        packet = Packet.create(
+            command=CommandType.USER_INTERFACE,
+            start=0x83,
+            address=0x00,
+            data=command.encode('ascii'),
+        )
+        return self.__connection.write(packet.encode().encode('ascii'))
+
+    def read_event(self) -> Optional[BaseEvent]:
+        data = self.__connection.read()
+        if data is not None:
+            pkt = Packet.decode(data)
+            return BaseEvent.decode(pkt)
+
+        return None

py_ness_232/connection.py

@@ -0,0 +1,72 @@
+import socket
+from abc import ABC
+from typing import Optional
+
+
+class Connection(ABC):
+    """Represents a connection to a Ness D8X/D16X server"""
+
+    def read(self) -> Optional[bytes]:
+        raise NotImplementedError()
+
+    def write(self, data: bytes) -> None:
+        raise NotImplementedError()
+
+    def close(self) -> None:
+        raise NotImplementedError()
+
+
+class IP232Connection(Connection):
+    """A connection via IP232 with a Ness D8X/D16X server"""
+
+    def __init__(self, host: str, port: int):
+        super().__init__()
+
+        self.__host = host
+        self.__port = port
+        self.__socket: Optional[socket.socket] = None
+
+    def __connect(self) -> None:
+        self.__socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        self.__socket.connect((self.__host, self.__port))
+
+    def read(self) -> Optional[bytes]:
+        if self.__socket is None:
+            self.__connect()
+            assert self.__socket is not None
+
+        data = self.__socket.recv(1024)
+        if data is None:
+            self.close()
+            return None
+
+        data = data.strip()
+        if len(data) == 0:
+            return None
+
+        return data
+
+    def write(self, data: bytes) -> None:
+        if self.__socket is None:
+            self.__connect()
+            assert self.__socket is not None
+
+        self.__socket.send(data)
+
+    def close(self) -> None:
+        if self.__socket is not None:
+            self.__socket.close()
+            self.__socket = None
+
+
+class RS232Connection(Connection):
+    """A connection via RS232 with a Ness D8X/D16X server"""
+
+    def read(self) -> Optional[bytes]:
+        pass
+
+    def write(self, data: bytes) -> None:
+        pass
+
+    def close(self) -> None:
+        pass