Python/blockchain/proof_of_stake.py

import random


class Validator:
    def __init__(self, name: str, stake: int) -> None:
        """
        Initializes a new validator with a given name and stake.

        Args:
            name (str): The name of the validator.
            stake (int): The amount of stake the validator has.
        """
        self.name = name
        self.stake = stake


def choose_validator(validators: list[Validator]) -> Validator:
    """
    Selects a validator to create the next block based on the weight of their stake.

    The higher the stake, the greater the chance to be selected.

    Args:
        validators (list[Validator]): A list of Validator objects.

    Returns:
        Validator: The selected validator based on weighted random selection.

    Example:
        >>> validators = [Validator("Alice", 50), Validator("Bob", 30)]
        >>> chosen = choose_validator(validators)
        >>> isinstance(chosen, Validator)
        True
    """
    total_stake = sum(v.stake for v in validators)
    weighted_validators = [(v, v.stake / total_stake) for v in validators]
    selected = random.choices(
        [v[0] for v in weighted_validators], weights=[v[1] for v in weighted_validators]
    )
    return selected[0]