import { parseAdminAuth } from "@/lib/api/admin-auth-context";
import { prisma } from "@/lib/prisma";
import { fail, ok } from "@/lib/response";
import { AuthError } from "@/modules/auth/errors";
import { requirePermission } from "@/modules/auth/rbac";
import { serializeAlert } from "@/modules/alert/serializer";
import type { AlertStatus, AlertType } from "@/modules/alert/types";

const VALID_ALERT_TYPES: readonly AlertType[] = [
  "PRICE_DEVIATION",
  "STALE_FALLBACK",
  "RPA_FAILED",
  "RPA_CAPTCHA",
  "STRUCT_CHANGE",
  "SESSION_EXPIRED",
  "SECURITY",
  "MANUAL_FALLBACK",
];

const VALID_ALERT_STATUSES: readonly AlertStatus[] = ["open", "resolved"];

function parsePagination(searchParams: URLSearchParams): {
  page: number;
  size: number;
} | null {
  const pageRaw = searchParams.get("page");
  const sizeRaw = searchParams.get("size");

  if (!pageRaw || !sizeRaw) {
    return null;
  }

  const page = Number(pageRaw);
  const size = Number(sizeRaw);

  if (
    !Number.isInteger(page) ||
    !Number.isInteger(size) ||
    page < 1 ||
    size < 1 ||
    size > 100
  ) {
    return null;
  }

  return { page, size };
}

function parseFilters(searchParams: URLSearchParams): {
  type?: AlertType;
  status?: AlertStatus;
} | { error: string } {
  const typeRaw = searchParams.get("type");
  const statusRaw = searchParams.get("status");

  if (typeRaw && !VALID_ALERT_TYPES.includes(typeRaw as AlertType)) {
    return { error: "无效的预警类型" };
  }

  if (statusRaw && !VALID_ALERT_STATUSES.includes(statusRaw as AlertStatus)) {
    return { error: "无效的预警状态" };
  }

  return {
    type: typeRaw ? (typeRaw as AlertType) : undefined,
    status: statusRaw ? (statusRaw as AlertStatus) : undefined,
  };
}

/** GET /api/alerts — 预警列表（task-056） */
export async function GET(request: Request) {
  let auth;
  try {
    auth = parseAdminAuth(request);
    requirePermission(auth, "alert:read");
  } catch (error) {
    if (error instanceof AuthError) {
      return fail(error.code, error.message, error.httpStatus);
    }
    throw error;
  }

  void auth;

  const searchParams = new URL(request.url).searchParams;
  const pagination = parsePagination(searchParams);
  if (!pagination) {
    return fail("VALIDATION_FAILED", "请提供有效的 page 和 size 参数", 400);
  }

  const filters = parseFilters(searchParams);
  if ("error" in filters) {
    return fail("VALIDATION_FAILED", filters.error, 400);
  }

  const where = {
    ...(filters.type ? { alertType: filters.type } : {}),
    ...(filters.status ? { status: filters.status } : {}),
  };

  const { page, size } = pagination;

  const [total, records] = await Promise.all([
    prisma.alertLog.count({ where }),
    prisma.alertLog.findMany({
      where,
      orderBy: { createdAt: "desc" },
      skip: (page - 1) * size,
      take: size,
    }),
  ]);

  return ok({
    list: records.map(serializeAlert),
    total,
    page,
    size,
  });
}