messages.py

from dirlock import DirLock

# import ledsign.newline, ledsign.EOM
import pickle


def initialize(filename="/var/tmp/led-messages"):
    """Sets up a new file with a messagelist in it."""
    m = MessageList()
    with DirLock("/tmp/messages.lock"):
        with open(filename, "w") as f:
            pickle.dump(m, f)


def setmsg(name, msg, filename="/var/tmp/led-messages"):
    """Sets the message named name to msg."""
    with DirLock("/tmp/messages.lock"):
        with open(filename, "r") as f:
            m = pickle.load(f)
        m.set(name, msg)
        updatesign(m)
        with open(filename, "w") as f:
            pickle.dump(m, f)


def remove(name, filename="/var/tmp/led-messages"):
    """Remove the message named name."""
    with DirLock("/tmp/messages.lock"):
        with open(filename, "r") as f:
            m = pickle.load(f)
        m.remove(name)
        updatesign(m)
        with open(filename, "w") as f:
            pickle.dump(m, f)


def list(filename="/var/tmp/led-messages"):
    with DirLock("/tmp/messages.lock"):
        with open(filename, "r") as f:
            m = pickle.load(f)
            for (name, msg) in m:
                print((name + ": " + msg))


def updatesign(msglist):
    print("Updating sign to...")
    print("\\rH".join(msg for (name, msg) in msglist) + "\\r\\r\\r")
    try:
        import socket

        sock = socket.create_connection(("localhost", 41337))
        sock.send("\\rH".join(msg for (name, msg) in msglist) + "\\r\\r\\r")
    finally:
        sock.close()


class MessageList:
    # A message list is basically an ordered dictionary
    def __init__(self):
        self.messagedict = dict()  # Maps names to messages
        self.messageorder = []

    def set(self, name, msg):
        assert set(self.messageorder) == set(self.messagedict.keys())
        if name in list(self.messagedict.keys()):
            self.messagedict[name] = msg
        else:
            self.messagedict[name] = msg
            self.messageorder += [name]

    def get(self, name):
        return self.messagedict[name]

    def remove(self, name):
        assert set(self.messageorder) == set(self.messagedict.keys())
        del self.messagedict[name]
        self.messageorder.remove(name)

    def __iter__(self):
        return ((name, self.messagedict[name]) for name in self.messageorder)