from __future__ import annotations

from dataclasses import dataclass, field
from typing import Any

from .models import AgentCandidateAct, Decision


@dataclass
class PolicyEngine:
    """
    Minimal synthetic policy layer for reference tests.

    The policy engine does not determine legal compliance. It enforces
    caller-supplied constraints.
    """
    allowed_email_recipients: set[str] = field(default_factory=set)
    allowed_financial_beneficiaries: set[str] = field(default_factory=set)
    allowed_destinations: set[str] = field(default_factory=set)

    def validate(self, act: AgentCandidateAct, live_args: dict[str, Any]) -> Decision:
        if self.allowed_destinations and act.destination not in self.allowed_destinations:
            return Decision(False, "EF_DESTINATION_POLICY_DENY", "Destination is not allowed.")

        if act.consequence_class == "COMMUNICATION":
            recipient = live_args.get("to")
            if act.provenance in {"retrieval", "tool", "unknown"}:
                return Decision(
                    False,
                    "EF_INSTRUCTION_PROVENANCE_FAILURE",
                    "High-consequence communication is not authorized from this provenance.",
                )
            if recipient is not None and self.allowed_email_recipients:
                if recipient not in self.allowed_email_recipients:
                    return Decision(
                        False,
                        "EF_RECIPIENT_POLICY_DENY",
                        "Recipient is outside configured authorization.",
                    )

        if act.consequence_class == "FINANCIAL":
            beneficiary = live_args.get("beneficiary")
            if self.allowed_financial_beneficiaries:
                if beneficiary not in self.allowed_financial_beneficiaries:
                    return Decision(
                        False,
                        "EF_BENEFICIARY_POLICY_DENY",
                        "Beneficiary is outside configured authorization.",
                    )

        return Decision(True, "EF_POLICY_ALLOW", "Configured policy predicates passed.")