from __future__ import annotations

import asyncio
import hashlib
import hmac
import json
import logging
from dataclasses import dataclass
from typing import Any, Optional

import aiohttp
from sqlalchemy.ext.asyncio import AsyncSession

from app.database.crud.webhook import (
    get_active_webhooks_for_event,
    record_webhook_delivery,
    update_webhook_stats,
)

logger = logging.getLogger(__name__)


@dataclass
class DeliveryResult:
    """Результат доставки webhook."""

    webhook: Any
    event_type: str
    payload: dict[str, Any]
    status: str
    response_status: Optional[int] = None
    response_body: Optional[str] = None
    error_message: Optional[str] = None


class WebhookService:
    """Сервис для отправки webhooks."""

    def __init__(self) -> None:
        self._session: Optional[aiohttp.ClientSession] = None

    async def _get_session(self) -> aiohttp.ClientSession:
        """Получить или создать HTTP сессию."""
        if self._session is None or self._session.closed:
            timeout = aiohttp.ClientTimeout(total=10, connect=5)
            self._session = aiohttp.ClientSession(timeout=timeout)
        return self._session

    async def close(self) -> None:
        """Закрыть HTTP сессию."""
        if self._session and not self._session.closed:
            await self._session.close()

    def _sign_payload(self, payload: str, secret: str) -> str:
        """Подписать payload с помощью секрета."""
        return hmac.new(
            secret.encode("utf-8"),
            payload.encode("utf-8"),
            hashlib.sha256,
        ).hexdigest()

    async def send_webhook(
        self,
        db: AsyncSession,
        event_type: str,
        payload: dict[str, Any],
    ) -> None:
        """Отправить webhook для события."""
        webhooks = await get_active_webhooks_for_event(db, event_type)

        if not webhooks:
            logger.debug("No active webhooks for event type: %s", event_type)
            return

        # Выполняем HTTP запросы параллельно (без операций с БД)
        tasks = [
            self._deliver_webhook_http(webhook, event_type, payload)
            for webhook in webhooks
        ]
        results = await asyncio.gather(*tasks, return_exceptions=True)

        # Записываем результаты в БД последовательно (избегаем concurrent session access)
        for result in results:
            if isinstance(result, Exception):
                logger.exception("Unexpected error during webhook delivery: %s", result)
                continue
            if isinstance(result, DeliveryResult):
                await self._record_result(db, result)

    async def _deliver_webhook_http(
        self,
        webhook: Any,
        event_type: str,
        payload: dict[str, Any],
    ) -> DeliveryResult:
        """Выполнить HTTP доставку webhook (без операций с БД)."""
        payload_json = json.dumps(payload, default=str, ensure_ascii=False)
        headers = {
            "Content-Type": "application/json",
            "X-Webhook-Event": event_type,
            "X-Webhook-Id": str(webhook.id),
        }

        # Добавляем подпись, если есть секрет
        if webhook.secret:
            signature = self._sign_payload(payload_json, webhook.secret)
            headers["X-Webhook-Signature"] = f"sha256={signature}"

        try:
            session = await self._get_session()
            async with session.post(
                webhook.url,
                data=payload_json,
                headers=headers,
            ) as response:
                response_body = await response.text()
                # Ограничиваем размер ответа для хранения
                if len(response_body) > 1000:
                    response_body = response_body[:1000] + "... (truncated)"

                status = "success" if 200 <= response.status < 300 else "failed"
                error_message = None
                if status == "failed":
                    error_message = f"HTTP {response.status}: {response_body[:500]}"

                return DeliveryResult(
                    webhook=webhook,
                    event_type=event_type,
                    payload=payload,
                    status=status,
                    response_status=response.status,
                    response_body=response_body,
                    error_message=error_message,
                )

        except asyncio.TimeoutError:
            return DeliveryResult(
                webhook=webhook,
                event_type=event_type,
                payload=payload,
                status="failed",
                error_message="Request timeout",
            )

        except Exception as error:
            return DeliveryResult(
                webhook=webhook,
                event_type=event_type,
                payload=payload,
                status="failed",
                error_message=str(error),
            )

    async def _record_result(self, db: AsyncSession, result: DeliveryResult) -> None:
        """Записать результат доставки в БД (последовательно)."""
        try:
            await record_webhook_delivery(
                db,
                webhook_id=result.webhook.id,
                event_type=result.event_type,
                payload=result.payload,
                status=result.status,
                response_status=result.response_status,
                response_body=result.response_body,
                error_message=result.error_message,
            )

            await update_webhook_stats(db, result.webhook, result.status == "success")

            if result.status == "success":
                logger.info(
                    "Webhook %s delivered successfully to %s",
                    result.webhook.id,
                    result.webhook.url,
                )
            else:
                logger.warning(
                    "Webhook %s delivery failed: %s",
                    result.webhook.id,
                    result.error_message,
                )
        except Exception as error:
            logger.exception(
                "Failed to record webhook delivery result for %s: %s",
                result.webhook.id,
                error,
            )


# Глобальный экземпляр сервиса
webhook_service = WebhookService()