70 lines
2.3 KiB
Python
70 lines
2.3 KiB
Python
import hashlib
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from datetime import datetime
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class Event(object):
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"""
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Class that represents something that modifies the state of the system
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"""
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def __init__(self, message="", user_id="", date=None, parents=None):
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self.user_id: str = user_id # id of the user that triggers the modification
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self.date: datetime | None = date or datetime.now() # when
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self.message: str = message # user input or whatever that modifies the system
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self.parents: list[str] = parents # digest(s) of the parent(s) of this event
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self._digest: str | None = None # digest of the event
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def __str__(self):
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return f"{self.date.strftime('%d/%m/%Y %H:%M:%S')} {self.message}"
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def __repr__(self):
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return f"{self.get_digest()[:12]} {self.message}"
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def get_digest(self):
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"""
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Returns the digest of the event
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:return: sha256 of the event
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"""
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if self._digest:
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return self._digest
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if self.user_id == "":
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# only possible during the unit test
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# We use this little trick to speed up the unit test
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self._digest = self.message[6:] if self.message.startswith("TEST::") else "xxx"
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return self._digest
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if not isinstance(self.message, str):
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raise NotImplementedError(f"message={self.message}")
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to_hash = f"Event:{self.user_id}{self.date}{self.message}{self.parents}".encode("utf-8")
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self._digest = hashlib.sha256(to_hash).hexdigest()
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return self._digest
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def to_dict(self):
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return self.__dict__
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def from_dict(self, as_dict):
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self.user_id = as_dict["user_id"]
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self.date = datetime.fromisoformat(as_dict["date"])
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self.message = as_dict["message"]
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self.parents = as_dict["parents"]
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self._digest = as_dict["_digest"] # freeze the digest
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def __eq__(self, other):
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if id(self) == id(other):
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return True
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if isinstance(other, Event):
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return (self.user_id == other.user_id and
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self.date == other.date and
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self.message == other.message and
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self.parents == other.parents)
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return False
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def __hash__(self):
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return hash(self.get_digest())
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