"""风控通知记录 Service。

本阶段只创建通知记录和提供分页查询，不执行 SMTP 外发。
"""

from __future__ import annotations

from datetime import UTC, datetime
from typing import Any
from uuid import uuid4

from sqlalchemy.ext.asyncio import AsyncSession

from app.api.schemas.risk import RiskNotificationPageQuery
from app.core.contracts import RequestContext
from app.core.risk_cursor import decode_offset_cursor
from app.core.timeutil import from_local
from app.model.fund import FundRiskAlert, FundRiskNotification
from app.repository.fund_query_repository import PageRequest
from app.repository.risk_repository import RiskRepository
from app.service.authorization_service import AuthorizationService
from app.service.risk_query_service import RiskQueryService, scope_from_context


class RiskNotificationService:
    def __init__(self, session: AsyncSession) -> None:
        self.session = session

    async def list_notifications(
        self,
        context: RequestContext,
        query: RiskNotificationPageQuery,
    ) -> dict[str, Any]:
        await AuthorizationService.require(context, "risk:alert:read")
        binding = RiskQueryService._binding(context, query, "/notifications")
        page = await RiskRepository(
            self.session,
            scope=scope_from_context(context),
        ).list_notifications(
            keyword=query.keyword,
            send_status=query.send_status,
            start_time=from_local(query.start_time) if query.start_time else None,
            end_time=from_local(query.end_time) if query.end_time else None,
            page=PageRequest(
                limit=query.limit,
                offset=decode_offset_cursor(query.cursor, binding=binding),
            ),
        )
        return RiskQueryService._page(page, binding=binding)

    def create_in_app(
        self,
        alert: FundRiskAlert,
        *,
        receiver_user_id: int | None,
        title: str,
        content: str,
    ) -> FundRiskNotification:
        notification = self._build(
            alert=alert,
            channel="站内提醒",
            receiver_user_id=receiver_user_id,
            receiver_email=None,
            title=title,
            content=content,
            send_status="已发送",
            sent_at=_now(),
            fail_reason=None,
        )
        self.session.add(notification)
        return notification

    def create_mail_record(
        self,
        alert: FundRiskAlert,
        *,
        receiver_email: str,
        title: str,
        content: str,
        mail_enabled: bool = False,
    ) -> FundRiskNotification:
        notification = self._build(
            alert=alert,
            channel="邮件",
            receiver_user_id=None,
            receiver_email=receiver_email,
            title=title,
            content=content,
            send_status="待发送" if mail_enabled else "未启用",
            sent_at=None,
            fail_reason=None if mail_enabled else "邮件发送功能未启用",
        )
        self.session.add(notification)
        return notification

    def mark_mail_sent(self, notification: FundRiskNotification) -> None:
        """邮件发送成功后回写通知状态。"""
        notification.send_status = "已发送"
        notification.sent_at = _now()
        notification.fail_reason = None

    def mark_mail_failed(
        self,
        notification: FundRiskNotification,
        reason: str,
    ) -> None:
        """邮件发送失败后保留通知记录并记录安全失败原因。"""
        notification.send_status = "发送失败"
        notification.sent_at = None
        notification.fail_reason = reason.strip()[:500] or "邮件发送失败"

    def create_high_risk_records(
        self,
        alerts: list[FundRiskAlert],
        *,
        receiver_user_id: int | None = None,
        receiver_email: str | None = None,
        mail_enabled: bool = False,
    ) -> list[FundRiskNotification]:
        notifications: list[FundRiskNotification] = []
        for alert in alerts:
            if alert.alert_level != "高":
                continue
            title = f"高风险预警：{alert.alert_type}"
            notifications.append(self.create_in_app(
                alert,
                receiver_user_id=receiver_user_id,
                title=title,
                content=alert.evidence_summary,
            ))
            if receiver_email:
                notifications.append(self.create_mail_record(
                    alert,
                    receiver_email=receiver_email,
                    title=title,
                    content=alert.evidence_summary,
                    mail_enabled=mail_enabled,
                ))
        return notifications

    @staticmethod
    def _build(
        *,
        alert: FundRiskAlert,
        channel: str,
        receiver_user_id: int | None,
        receiver_email: str | None,
        title: str,
        content: str,
        send_status: str,
        sent_at: datetime | None,
        fail_reason: str | None,
    ) -> FundRiskNotification:
        referenced_content = (
            content
            if f"预警编号：{alert.alert_no}" in content
            else f"预警编号：{alert.alert_no}；{content}"
        )
        return FundRiskNotification(
            id=_new_notification_id(),
            notification_no=f"N{uuid4().hex[:12].upper()}",
            alert_id=alert.id,
            channel=channel,
            receiver_user_id=receiver_user_id,
            receiver_email=receiver_email,
            title=title,
            content=referenced_content,
            send_status=send_status,
            sent_at=sent_at,
            fail_reason=fail_reason,
            created_at=_now(),
        )


def _new_notification_id() -> int:
    return uuid4().int & ((1 << 63) - 1) or 1


def _now() -> datetime:
    return datetime.now(UTC).replace(tzinfo=None)