"""GSM gateway SMS provider (M5 — written now, live-tested with hardware later).

Targets GoIP/Yeastar-class multi-SIM gateways with an HTTP SMS API (§17.3).
The default request shape matches the GoIP family:

    GET http://<gw>/default/en_US/send.html?u=<user>&p=<pass>&l=<line>&n=<msisdn>&m=<text>

Each tenant sends through its own SIM: the line number comes from
phone_numbers.gateway_port (assigned in the super-admin panel). The exact
gateway model is an open question (§17.3) — everything model-specific is
isolated in `_build_request` / `_check_response` so a different vendor is a
small patch, and HARDWARE_TESTING.md walks through live verification.
"""

from __future__ import annotations

import logging
import uuid

import httpx
from sqlalchemy import select

from gogo.config import get_settings
from gogo.db import get_sessionmaker
from gogo.models import PhoneNumber

log = logging.getLogger("gogo.sms.gateway")


class GatewayError(Exception):
    pass


class GsmGatewaySmsProvider:
    # test hook (same pattern as PartnerApiProvider)
    client_factory = staticmethod(lambda timeout: httpx.AsyncClient(timeout=timeout))

    async def send(self, tenant_id: uuid.UUID, to_msisdn: str, body: str) -> None:
        line = await self._line_for_tenant(tenant_id)
        url, params = self._build_request(line, to_msisdn, body)
        async with self.client_factory(timeout=15) as client:
            resp = await client.get(url, params=params)
        self._check_response(resp)
        log.info("SMS sent via gateway line %s to %s", line, to_msisdn)

    async def _line_for_tenant(self, tenant_id: uuid.UUID) -> int:
        async with get_sessionmaker()() as session:
            number = (
                await session.execute(
                    select(PhoneNumber).where(PhoneNumber.tenant_id == tenant_id)
                )
            ).scalar_one_or_none()
        if number is None or number.gateway_port is None:
            raise GatewayError(f"tenant {tenant_id} has no SIM/gateway port assigned")
        return number.gateway_port

    def _build_request(self, line: int, to_msisdn: str, body: str) -> tuple[str, dict]:
        s = get_settings()
        if not s.gsm_gateway_url:
            raise GatewayError("GOGO_GSM_GATEWAY_URL is not configured")
        url = s.gsm_gateway_url.rstrip("/") + "/default/en_US/send.html"
        return url, {
            "u": s.gsm_gateway_user,
            "p": s.gsm_gateway_password,
            "l": str(line),
            "n": to_msisdn.lstrip("+"),
            "m": body,
        }

    def _check_response(self, resp: httpx.Response) -> None:
        if resp.status_code != 200:
            raise GatewayError(f"gateway returned HTTP {resp.status_code}")
        text = resp.text.lower()
        if "error" in text or "fail" in text:
            raise GatewayError(f"gateway rejected SMS: {resp.text[:200]}")