import logging
from typing import Callable

logger = logging.getLogger("qkernel.policy")


class PolicyContext:
    def __init__(self):
        self.allowed: bool = True
        self.route_override: str | None = None
        self.priority_boost: int = 0
        self.tags: list[str] = []


class PolicyRule:
    def __init__(
        self,
        name: str,
        condition: Callable[[dict], bool],
        action: Callable[[dict, PolicyContext], PolicyContext],
    ):
        self.name = name
        self.condition = condition
        self.action = action


class PolicyEngine:
    def __init__(self):
        self._rules: list[PolicyRule] = []

    def add_rule(self, rule: PolicyRule) -> None:
        self._rules.append(rule)

    def evaluate(self, event: dict) -> PolicyContext:
        ctx = PolicyContext()
        for rule in self._rules:
            if rule.condition(event):
                logger.debug("Policy rule '%s' triggered", rule.name)
                ctx = rule.action(event, ctx)
        return ctx

    def add_default_rules(self) -> None:
        self.add_rule(PolicyRule(
            name="block_anonymous",
            condition=lambda e: e.get("user_id", "anonymous") == "anonymous",
            action=lambda e, ctx: setattr(ctx, "allowed", False) or ctx,
        ))
        block_anon_rule = PolicyRule(
            name="block_anonymous_message",
            condition=lambda e: e.get("user_id", "anonymous") == "anonymous"
            and bool(e.get("message", "").strip()),
            action=lambda e, ctx: setattr(ctx, "allowed", False) or ctx,
        )
        self.add_rule(block_anon_rule)

        chat_boost = PolicyRule(
            name="boost_chat",
            condition=lambda e: e.get("type") == "chat",
            action=lambda e, ctx: setattr(ctx, "priority_boost", 5) or ctx,
        )
        self.add_rule(chat_boost)

        long_message = PolicyRule(
            name="long_message_route",
            condition=lambda e: len(e.get("message", "")) > 500,
            action=lambda e, ctx: setattr(ctx, "route_override", "brain") or ctx,
        )
        self.add_rule(long_message)