"""Audit and usage-ledger ports.

``AuditPort`` writes the immutable trail; ``UsageLedgerPort`` is the billing
source of truth. Both are append-only by contract.
"""

from __future__ import annotations

from dataclasses import dataclass, field
from datetime import datetime
from typing import Protocol, runtime_checkable

from app.domain.ai_control.models import RateUnit
from app.domain.audit.models import AuditEvent


@dataclass(slots=True, kw_only=True)
class UsageRecord:
    organization_id: str
    unit: RateUnit
    quantity: float
    unit_price: float = 0.0
    internal_cost_estimate: float = 0.0
    total_price: float = 0.0
    project_id: str | None = None
    user_id: str | None = None
    employee_id: str | None = None
    run_id: str | None = None
    metadata_json: dict = field(default_factory=dict)


@dataclass(slots=True, kw_only=True)
class UsageAggregate:
    unit: RateUnit
    quantity: float = 0.0
    total_price: float = 0.0
    internal_cost_estimate: float = 0.0


@dataclass(slots=True, kw_only=True)
class UsageBreakdown:
    """Grouped totals for the billing dashboard."""

    by_unit: list[UsageAggregate] = field(default_factory=list)
    by_employee: dict[str, float] = field(default_factory=dict)
    by_project: dict[str, float] = field(default_factory=dict)
    total_price: float = 0.0
    total_cost: float = 0.0


@runtime_checkable
class AuditPort(Protocol):
    async def record(self, *, event: AuditEvent) -> AuditEvent: ...

    async def list_for_organization(
        self, *, organization_id: str, limit: int = 100, offset: int = 0
    ) -> list[AuditEvent]: ...


@runtime_checkable
class UsageLedgerPort(Protocol):
    async def record(self, *, usage: UsageRecord) -> None:
        """Append one usage event. Never raises for business reasons — a failed
        ledger write is an infrastructure error and must surface loudly."""
        ...

    async def breakdown(
        self,
        *,
        organization_id: str,
        since: datetime | None = None,
        until: datetime | None = None,
    ) -> UsageBreakdown: ...