"""风控只读查询接口。"""

import json
from collections.abc import AsyncIterator
from datetime import datetime, time
from typing import Any

from fastapi import APIRouter, Depends, File, Path, UploadFile
from sqlalchemy.ext.asyncio import AsyncSession
from starlette.responses import StreamingResponse

from app.api.dependencies.auth import build_request_context
from app.api.dependencies.database import get_session
from app.api.dependencies.rate_limit import enforce_rate_limit
from app.api.schemas.risk import (
    RiskAlertEscalationRequest,
    RiskAlertExclusionRequest,
    RiskAlertPageQuery,
    RiskAlertResolutionRequest,
    RiskDailyReportGenerateRequest,
    RiskDailyReportMailRequest,
    RiskEvidencePageQuery,
    RiskEvidenceSource,
    RiskNotificationPageQuery,
)
from app.core.contracts import RequestContext
from app.infrastructure.db import mysql_scan_lock
from app.service.risk_action_service import RiskActionService
from app.service.risk_daily_report_mail_service import RiskDailyReportMailService
from app.service.risk_daily_report_service import RiskDailyReportService
from app.service.risk_evidence_archive_service import RiskEvidenceArchiveService
from app.service.risk_notification_service import RiskNotificationService
from app.service.risk_query_service import RiskQueryService
from app.service.risk_scan_service import RiskScanBusyError, RiskScanService

router = APIRouter(
    prefix="/api/v1/risk",
    tags=["risk"],
    dependencies=[Depends(enforce_rate_limit)],
)


@router.get("/overview")
async def risk_overview(
    context: RequestContext = Depends(build_request_context),  # noqa: B008
    session: AsyncSession = Depends(get_session),  # noqa: B008
) -> dict[str, object]:
    data = await RiskQueryService(session).overview(context)
    return _envelope(data, context)


@router.get("/alerts")
async def list_risk_alerts(
    query: RiskAlertPageQuery = Depends(),  # noqa: B008
    context: RequestContext = Depends(build_request_context),  # noqa: B008
    session: AsyncSession = Depends(get_session),  # noqa: B008
) -> dict[str, object]:
    data = await RiskQueryService(session).list_alerts(context, query)
    return _list_envelope(data, context)


@router.post("/alerts/scan")
async def scan_risk_alerts(
    context: RequestContext = Depends(build_request_context),  # noqa: B008
    session: AsyncSession = Depends(get_session),  # noqa: B008
) -> dict[str, object]:
    # 手工触发的扫描必须与定时扫描互斥，否则两条路径会同时查不到重复、同时插入。
    # 锁加在**入口层**而不是 `RiskScanService.scan()` 内部：`GET_LOCK` 是连接级的，
    # 而调度器已在它自己的 session 上持锁 —— 被两个入口共用的服务方法若再取同一把锁，
    # 取锁的连接不是持锁的那一个、必然失败，会**把定时扫描自己挡死**。
    async with mysql_scan_lock() as acquired:
        if not acquired:
            raise RiskScanBusyError("规则扫描正在执行，请稍后重试")
        data = await RiskScanService(session).scan(context)
    return _envelope(data, context)


@router.post("/alerts/{alert_no}/acknowledgements")
async def acknowledge_risk_alert(
    alert_no: str = Path(min_length=1, max_length=64, pattern=r"^[A-Za-z0-9_-]+$"),
    context: RequestContext = Depends(build_request_context),  # noqa: B008
    session: AsyncSession = Depends(get_session),  # noqa: B008
) -> dict[str, object]:
    data = await RiskActionService(session).acknowledge(alert_no, context)
    return _envelope(data, context)


@router.post("/alerts/{alert_no}/investigations")
async def investigate_risk_alert(
    alert_no: str = Path(min_length=1, max_length=64, pattern=r"^[A-Za-z0-9_-]+$"),
    context: RequestContext = Depends(build_request_context),  # noqa: B008
    session: AsyncSession = Depends(get_session),  # noqa: B008
) -> dict[str, object]:
    data = await RiskActionService(session).investigate(alert_no, context)
    return _envelope(data, context)


@router.post("/alerts/{alert_no}/exclusions")
async def exclude_risk_alert(
    payload: RiskAlertExclusionRequest,
    alert_no: str = Path(min_length=1, max_length=64, pattern=r"^[A-Za-z0-9_-]+$"),
    context: RequestContext = Depends(build_request_context),  # noqa: B008
    session: AsyncSession = Depends(get_session),  # noqa: B008
) -> dict[str, object]:
    data = await RiskActionService(session).exclude(alert_no, payload.reason, context)
    return _envelope(data, context)


@router.post("/alerts/{alert_no}/resolutions")
async def resolve_risk_alert(
    payload: RiskAlertResolutionRequest,
    alert_no: str = Path(min_length=1, max_length=64, pattern=r"^[A-Za-z0-9_-]+$"),
    context: RequestContext = Depends(build_request_context),  # noqa: B008
    session: AsyncSession = Depends(get_session),  # noqa: B008
) -> dict[str, object]:
    data = await RiskActionService(session).resolve(alert_no, payload.resolution, context)
    return _envelope(data, context)


@router.post("/alerts/{alert_no}/escalations")
async def escalate_risk_alert(
    payload: RiskAlertEscalationRequest,
    alert_no: str = Path(min_length=1, max_length=64, pattern=r"^[A-Za-z0-9_-]+$"),
    context: RequestContext = Depends(build_request_context),  # noqa: B008
    session: AsyncSession = Depends(get_session),  # noqa: B008
) -> dict[str, object]:
    data = await RiskActionService(session).escalate(alert_no, payload.reason, context)
    return _envelope(data, context)


@router.post("/alerts/{alert_no}/evidence")
async def archive_risk_evidence(
    evidence_file: UploadFile = File(...),  # noqa: B008
    alert_no: str = Path(min_length=1, max_length=64, pattern=r"^[A-Za-z0-9_-]+$"),
    context: RequestContext = Depends(build_request_context),  # noqa: B008
    session: AsyncSession = Depends(get_session),  # noqa: B008
) -> dict[str, object]:
    try:
        data = await RiskEvidenceArchiveService(session).archive(alert_no, evidence_file, context)
        return _envelope(data, context)
    finally:
        await evidence_file.close()


@router.get("/alerts/{alert_no}")
async def get_risk_alert(
    alert_no: str = Path(min_length=1, max_length=64, pattern=r"^[A-Za-z0-9_-]+$"),
    context: RequestContext = Depends(build_request_context),  # noqa: B008
    session: AsyncSession = Depends(get_session),  # noqa: B008
) -> dict[str, object]:
    data = await RiskQueryService(session).get_alert_detail(context, alert_no.strip())
    return _envelope(data, context)


@router.get("/evidence/{source}")
async def list_risk_evidence(
    source: RiskEvidenceSource = Path(),  # noqa: B008
    query: RiskEvidencePageQuery = Depends(),  # noqa: B008
    context: RequestContext = Depends(build_request_context),  # noqa: B008
    session: AsyncSession = Depends(get_session),  # noqa: B008
) -> dict[str, object]:
    data = await RiskQueryService(session).list_evidence(context, source, query)
    return _list_envelope(data, context)


@router.get("/notifications")
async def list_risk_notifications(
    query: RiskNotificationPageQuery = Depends(),  # noqa: B008
    context: RequestContext = Depends(build_request_context),  # noqa: B008
    session: AsyncSession = Depends(get_session),  # noqa: B008
) -> dict[str, object]:
    data = await RiskNotificationService(session).list_notifications(context, query)
    return _list_envelope(data, context)


@router.post("/daily-report")
async def generate_risk_daily_report(
    payload: RiskDailyReportGenerateRequest,
    context: RequestContext = Depends(build_request_context),  # noqa: B008
    session: AsyncSession = Depends(get_session),  # noqa: B008
) -> dict[str, object]:
    report_time = (
        datetime.combine(payload.report_date, time.min)
        if payload.report_date is not None
        else None
    )
    data = await RiskDailyReportService(session).generate(context, report_time)
    return _envelope(data, context)


@router.post("/daily-report/stream")
async def stream_risk_daily_report(
    payload: RiskDailyReportGenerateRequest,
    context: RequestContext = Depends(build_request_context),  # noqa: B008
    session: AsyncSession = Depends(get_session),  # noqa: B008
) -> StreamingResponse:
    report_time = (
        datetime.combine(payload.report_date, time.min)
        if payload.report_date is not None
        else None
    )

    async def events() -> AsyncIterator[str]:
        async for event in RiskDailyReportService(session).stream(context, report_time):
            event_type = str(event.get("type", "message"))
            payload = json.dumps(event, ensure_ascii=False, default=str)
            yield f"event: {event_type}\ndata: {payload}\n\n"

    return StreamingResponse(
        events(),
        media_type="text/event-stream",
        headers={"Cache-Control": "no-cache", "X-Accel-Buffering": "no"},
    )


@router.post("/daily-report/mail")
async def send_risk_daily_report_mail(
    payload: RiskDailyReportMailRequest,
    context: RequestContext = Depends(build_request_context),  # noqa: B008
) -> dict[str, object]:
    data = await RiskDailyReportMailService().send(
        payload.recipients,
        payload.subject,
        payload.content,
        context=context,
    )
    return _envelope(data, context)


def _envelope(data: object, context: RequestContext) -> dict[str, object]:
    return {
        "data": data,
        "meta": {"trace_id": context.trace_id},
    }


def _list_envelope(page: dict[str, Any], context: RequestContext) -> dict[str, object]:
    """列表资源的信封（docs/05 §3.3）。

    §3.3 的列表样例是 `data` 为**纯数组**、游标与 `has_more` 放在 `meta` 里，并且明确
    「业务接口不得增加其他顶层字段」。而 `RiskQueryService._page` 返回的是
    `{items, next_cursor, has_more}` —— 整体塞进 `data` 后，游标跑进了**业务数据**里、
    `meta` 只剩 trace_id，两处都不符合契约。

    这里统一拆包；service 侧不必改（它继续返回那个内部结构，只是不再直接当 `data` 用）。
    """
    return {
        "data": page.get("items") or [],
        "meta": {
            "trace_id": context.trace_id,
            "next_cursor": page.get("next_cursor"),
            "has_more": bool(page.get("has_more")),
        },
    }