"""SchedulingProvider interface (§8) and per-tenant provider resolution.

Adding a third provider = one new module registering itself here. No changes
to the agent, tools, or proposal engine are needed.
"""

from __future__ import annotations

from datetime import date
from typing import Protocol, runtime_checkable

from sqlalchemy.ext.asyncio import AsyncSession

from gogo.domain import BookingRequestData, DeliveryResult, ServiceInfo, Slot
from gogo.models import ProviderConfig, Tenant


@runtime_checkable
class SchedulingProvider(Protocol):
    """Availability lookup + proposal delivery for one tenant."""

    async def get_services(self) -> list[ServiceInfo] | None:
        """Optional catalog sync; None = provider has no catalog."""
        ...

    async def get_availability(
        self, service_id: str, date_from: date, date_to: date, home_visit: bool = False
    ) -> list[Slot]:
        """Ready-to-offer free slots. The agent picks up to 3."""
        ...

    async def deliver_request(self, booking_request: BookingRequestData) -> DeliveryResult:
        """Deliver the proposal to the owner (email / partner push).

        Outcome is signaled back via webhook/polling (partner) or the owner's
        email/dashboard actions (google_calendar, mock).
        """
        ...


_REGISTRY: dict[str, type] = {}


def register_provider(name: str):
    def deco(cls):
        _REGISTRY[name] = cls
        return cls

    return deco


async def get_provider(session: AsyncSession, tenant: Tenant) -> SchedulingProvider:
    """Instantiate the tenant's configured provider."""
    # Imports here to avoid circulars; modules self-register on import.
    from gogo.scheduling import google_calendar, mock, partner_api  # noqa: F401

    cls = _REGISTRY.get(tenant.scheduling_provider)
    if cls is None:
        raise ValueError(f"Unknown scheduling provider: {tenant.scheduling_provider}")
    config = await _load_config(session, tenant)
    return cls(session=session, tenant=tenant, config=config)


async def _load_config(session: AsyncSession, tenant: Tenant) -> dict:
    from sqlalchemy import select

    row = (
        await session.execute(
            select(ProviderConfig).where(ProviderConfig.tenant_id == tenant.id)
        )
    ).scalar_one_or_none()
    return row.config if row else {}