python-voting/voting/voting.py

"""Voting - A Python module for votings on the c-base space-station."""

__AUTHOR__ = 'Brian Wiborg <baccenfutter@c-base.org>'
__LICENSE__ = 'MIT'

from .quorum import Quorum, QuorumKind

from arrow import Arrow, get as arrow_get
from dataclasses import dataclass
from enum import Enum
from typing import Dict, List

import abc
import json.tool


class Vote(Enum):
    """Vote represents a vote by a voter."""
    YES = 0
    NO = 1
    ABSTENTION = 2


class Voting(object):
    title: str
    quorum: Quorum
    voters: List[str]
    start: str
    days: int
    votes: Dict[str, Vote]

    def __init__(self,
                 title: str,
                 quorum: Quorum,
                 voters: List[str],
                 start: str = "",
                 days: int = 7,
                 votes: Dict[str, Vote] = None
    ):
        if len(voters) == 0:
            raise RuntimeError(f"A voting must have at least one voter: {voters}")

        self.title: str = title
        self.quorum: Quorum = quorum if isinstance(quorum, Quorum) else Quorum(**quorum)
        self.voters: List[str] = voters
        self.start: str = start if start else str(Arrow.utcnow())
        self.days: int = days
        self.votes: Dict[str, Vote] = {}

        if votes:
            for voter in votes:
                self.votes[voter] = self.votes[voter] if isinstance(votes[voter], Vote) else Vote[votes[voter]]

    def is_over(self) -> bool:
        return Arrow.utcnow() >= arrow_get(self.start).shift(days=self.days)

    def vote(self, voter: str, vote: Vote) -> None:
        if voter not in self.voters:
            raise ValueError(f"{voter} not in {self.voters}")
        if self.is_over():
            raise RuntimeError(f"Voting has ended! ({self.start} - {arrow_get(self.start).shift(days=self.days)})")
        self.votes[voter] = vote

    def as_dict(self) -> Dict:
        return {
            "title": self.title,
            "quorum": self.quorum.as_dict(),
            "voters": self.voters,
            "start": str(self.start),
            "days": self.days,
            "votes": {k: v.name for (k, v) in self.votes.items()}
        }

    def dumps(self) -> str:
        return json.dumps(self.as_dict())

    @classmethod
    def loads(cls, data: Dict):
        return cls(**json.loads(data))


@dataclass
class Result:
    voting: Voting

    @abc.abstractmethod
    def result(self) -> Dict:
        return {
            "state": self.outcome(),
            "voting": self.voting.as_dict(),
            "votes": self.votes(),
            "quorum_reached": self.quorum_reached(),
        }

    @abc.abstractmethod
    def outcome(self) -> str:
        if not self.has_ended():
            return "LAUFEND"
        else:
            return "ANGENOMMEN" if self.votes()[Vote.YES.name] > self.votes()[Vote.NO.name] and self.quorum_reached() else "ABGELEHNT"

    def has_ended(self) -> bool:
        end_at = arrow_get(self.voting.start).shift(days=self.voting.days)
        return Arrow.utcnow() >= end_at

    def votes(self) -> Dict:
        return {
            Vote.YES.name: len([vote for vote in self.voting.votes if self.voting.votes[vote] == Vote.YES]),
            Vote.NO.name: len([vote for vote in self.voting.votes if self.voting.votes[vote] == Vote.NO]),
            Vote.ABSTENTION.name: len([vote for vote in self.voting.votes if self.voting.votes[vote] == Vote.ABSTENTION]),
        }

    def quorum_reached(self) -> bool:
        if self.voting.quorum.kind == QuorumKind.NONE:
            return True
        elif self.voting.quorum.kind == QuorumKind.ABSOLUTE:
            return sum(self.votes().values()) >= self.voting.quorum.value
        elif self.voting.quorum.kind == QuorumKind.PERCENT:
            return sum(self.votes().values()) * 100 / len(self.voting.voters) >= self.voting.quorum.value
        else:
            raise RuntimeError("BUG: This code should never be reached!")