"""Usage metering (§12): agent voice minutes per tenant per month.

Human-answered ring-group time and chat do NOT count toward voice minutes.
Soft limits: 80% → owner email + dashboard banner; 100% → super-admin alert,
agent keeps answering (hard cutoff only via tenant flag, default off).
"""

from __future__ import annotations

import logging
import uuid
from datetime import UTC, datetime

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from gogo.models import Tenant, UsageCounter

log = logging.getLogger("gogo.metering")


def current_month(at: datetime | None = None) -> str:
    at = at or datetime.now(UTC)
    return f"{at.year:04d}-{at.month:02d}"


async def get_counter(
    session: AsyncSession, tenant_id: uuid.UUID, month: str | None = None
) -> UsageCounter:
    month = month or current_month()
    counter = (
        await session.execute(
            select(UsageCounter).where(
                UsageCounter.tenant_id == tenant_id, UsageCounter.month == month
            )
        )
    ).scalar_one_or_none()
    if counter is None:
        counter = UsageCounter(tenant_id=tenant_id, month=month)
        session.add(counter)
        await session.flush()
    return counter


async def record_agent_call(
    session: AsyncSession, tenant: Tenant, agent_seconds: int
) -> None:
    """Meter one agent-handled call and fire soft-limit warnings (§12)."""
    counter = await get_counter(session, tenant.id)
    counter.agent_seconds += max(0, agent_seconds)
    counter.calls += 1

    included_s = tenant.included_minutes * 60
    if included_s <= 0:
        return
    used = counter.agent_seconds
    if used >= included_s and not counter.warned_100:
        counter.warned_100 = True
        log.warning(
            "tenant %s exceeded included minutes (%d/%d min) — super-admin alert",
            tenant.slug, used // 60, tenant.included_minutes,
        )
        await _send_warning(session, tenant, used // 60, 100)
        await _alert_admin(tenant, used // 60)
    elif used >= included_s * 0.8 and not counter.warned_80:
        counter.warned_80 = True
        await _send_warning(session, tenant, used // 60, 80)


async def _send_warning(session: AsyncSession, tenant: Tenant, used_minutes: int, pct: int):
    from gogo.proposals.email import send_usage_warning_email

    try:
        await send_usage_warning_email(session, tenant, used_minutes, pct)
    except Exception:  # noqa: BLE001 — metering must never break call handling
        log.exception("usage warning email failed (tenant %s)", tenant.slug)


async def _alert_admin(tenant: Tenant, used_minutes: int) -> None:
    """100% soft-limit hit → alert the super-admin for an upsell conversation (§12)."""
    from gogo.config import get_settings
    from gogo.email import EmailMessage, send_email

    to = get_settings().admin_alert_email
    if not to:
        return
    try:
        await send_email(
            EmailMessage(
                [to],
                f"[Gogo] {tenant.name} prešao 100% minuta ({used_minutes} min)",
                f"Salon {tenant.name} ({tenant.slug}) je prešao uključene minute "
                f"({used_minutes}/{tenant.included_minutes}). Asistent i dalje odgovara "
                "(hard cutoff je isključen) — vrijeme za razgovor o većem paketu.",
            )
        )
    except Exception:  # noqa: BLE001
        log.exception("admin alert email failed")


async def record_sms(session: AsyncSession, tenant_id: uuid.UUID) -> None:
    counter = await get_counter(session, tenant_id)
    counter.sms_sent += 1


async def record_chat_session(session: AsyncSession, tenant_id: uuid.UUID) -> None:
    counter = await get_counter(session, tenant_id)
    counter.chat_sessions += 1


async def usage_summary(session: AsyncSession, tenant: Tenant) -> dict:
    """For the dashboard usage bar (§10) and super-admin overview (§11)."""
    counter = await get_counter(session, tenant.id)
    used_min = counter.agent_seconds // 60
    included = tenant.included_minutes
    pct = min(100, round(used_min * 100 / included)) if included else 0
    return {
        "month": counter.month,
        "used_minutes": used_min,
        "included_minutes": included,
        "pct": pct,
        "calls": counter.calls,
        "sms_sent": counter.sms_sent,
        "chat_sessions": counter.chat_sessions,
        "over_80": bool(included) and used_min >= included * 0.8,
        "over_100": bool(included) and used_min >= included,
    }