import json


class SafetyContract:
    def __init__(self, name=None, pre=None, post=None, budgets=None, collision_rules=None, trust_policy=None):
        self.name = name
        self.pre = pre
        self.post = post
        self.budgets = budgets or {}
        self.collision_rules = collision_rules or []
        self.trust_policy = trust_policy or {}


def parse_safety_contract_from_json(text: str) -> SafetyContract:
    data = json.loads(text)
    return SafetyContract(
        name=data.get("name"),
        pre=data.get("pre"),
        post=data.get("post"),
        budgets=data.get("budgets", {}),
        collision_rules=data.get("collision_rules", []),
        trust_policy=data.get("trust_policy", {}),
    )