43 lines
1.5 KiB
Python
43 lines
1.5 KiB
Python
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import json
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import struct
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class Message:
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"""
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Data carrier for messages. Before a Message may be sent over the network, it must be encoded using the
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`encode_message` function
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"""
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def __init__(self, buffer: bytes) -> None:
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# The byte layout of the structure is a buffer of JSON data preceded by a 2-byte header that specifies how long
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# it is.
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message_length_size = 2
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message_length = struct.unpack(">H", buffer[0:message_length_size])[0]
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message = json.loads(buffer[message_length_size:(message_length_size + message_length)])
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self.author = message["author"]
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self.body = message["body"]
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def as_command(self) -> str:
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"""
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Attempts to extract a command from the message.
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:return: Contents of the command without the command character or an empty string if `self` is not a command.
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"""
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return (self.body[1:] if self.body.startswith("/") else "")
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def encode_message(author: str, body: str) -> bytes:
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"""
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Encodes a message in the Chattle protocol format for transporting over a network connection.
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:param author: Screen name of the user that the message originated from
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:param body: Content of the message. Note that any trailing whitespace characters are stripped.
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:return: An encoded byte buffer of the message that can be decoded by creating a `Message` instance from it.
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"""
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message = json.dumps({
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"author": author,
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"body": body.strip(),
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}).encode("utf-8")
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return (struct.pack(">H", len(message)) + message)
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