import { CityName } from "../utils/types";
import { STATS_MAX_TIME_MS, UNCLASSIFIED } from "./tickets.constants";
import { getTicketsCollection } from "./tickets.getters";
import type { TicketStatsDateRange } from "./tickets.types";

const effectiveSubjectIdExpr = {
  $ifNull: [
    "$externalCallFields.event_subject_id",
    {
      $ifNull: [
        "$externalCallFields.event_sub_subject_id",
        "$externalCallFields.event_sub_subject_id2",
      ],
    },
  ],
};

const departmentsSubjectsLookup = (cityName: CityName) => ({
  $lookup: {
    from: "departmentsSubjects",
    let: { sid: "$effectiveSubjectId", c: cityName },
    pipeline: [
      {
        $match: {
          $expr: {
            $and: [
              { $eq: ["$cityName", "$$c"] },
              {
                $or: [
                  { $eq: ["$subject_id", { $ifNull: ["$$sid", ""] }] },
                  { $eq: ["$sub_subject_id", { $ifNull: ["$$sid", ""] }] },
                  { $eq: ["$sub_subject_id2", { $ifNull: ["$$sid", ""] }] },
                ],
              },
            ],
          },
        },
      },
      { $limit: 1 },
    ],
    as: "subj",
  },
});

const subjectLabelExpr = {
  $cond: {
    if: { $gt: [{ $size: "$subj" }, 0] },
    then: {
      $ifNull: [{ $arrayElemAt: ["$subj.subjectName", 0] }, UNCLASSIFIED],
    },
    else: UNCLASSIFIED,
  },
};

const ticketDateMatch = (dateRange: TicketStatsDateRange) => ({
  createdAt: { $gte: dateRange.from, $lte: dateRange.to },
});

/** Legacy draft detection for tickets created before isDraft existed. */
export const isDraftSubjectIdExpr = {
  $or: [
    { $eq: [{ $type: "$externalCallFields.event_subject_id" }, "missing"] },
    { $eq: ["$externalCallFields.event_subject_id", null] },
    {
      $regexMatch: {
        input: { $ifNull: ["$externalCallFields.event_subject_id", ""] },
        regex: /^\s*$/,
      },
    },
  ],
};

/**
 * Draft when isDraft is true, not draft when isDraft is false,
 * otherwise fall back to legacy subject-id heuristic for older tickets.
 */
export const isDraftTicketExpr = {
  $or: [
    { $eq: ["$isDraft", true] },
    {
      $and: [{ $ne: ["$isDraft", false] }, isDraftSubjectIdExpr],
    },
  ],
};

export const ticketsWithCallSidMatch = (
  cityName: CityName,
  dateRange: TicketStatsDateRange,
) => ({
  cityName,
  callSid: { $exists: true, $nin: [null, ""] },
  ...ticketDateMatch(dateRange),
});

export const subjectResolutionStages = (
  cityName: CityName,
): Record<string, unknown>[] => [
  { $addFields: { effectiveSubjectId: effectiveSubjectIdExpr } },
  departmentsSubjectsLookup(cityName),
  { $addFields: { subject: subjectLabelExpr } },
];

export const runTicketStatsAggregate = async <T>(
  pipeline: Record<string, unknown>[],
): Promise<T[]> => {
  const rows = await getTicketsCollection()
    .aggregate(pipeline, { maxTimeMS: STATS_MAX_TIME_MS })
    .toArray();
  return rows as T[];
};