import { pbAdmin } from "@/lib/pocketbase/client";
import { Logger } from "@/lib/logger";
import {
  accumulateActivities,
  accumulateClientErrors,
  accumulateClientEvents,
  buildDayRollups,
  newActivityAccumulator,
  newClientErrorAccumulator,
  newClientEventAccumulator,
  type ActivityRow,
  type ClientErrorRow,
  type ClientEventRow,
} from "./rollup-core";

const logger = new Logger("Telemetry > Rollup");

export const utcDay = (date: Date): string => date.toISOString().slice(0, 10);

const addDays = (dateStr: string, days: number): string => {
  const d = new Date(`${dateStr}T00:00:00.000Z`);
  d.setUTCDate(d.getUTCDate() + days);
  return utcDay(d);
};

const bound = (dateStr: string): string => `${dateStr} 00:00:00.000Z`;

const dayFilter = (dateStr: string): string =>
  `created >= '${bound(dateStr)}' && created < '${bound(addDays(dateStr, 1))}'`;

const distinctPlayersInWindow = async (fromDate: string, toDateExclusive: string): Promise<number> => {
  const players = new Set<string>();
  const filter = `created >= '${bound(fromDate)}' && created < '${bound(toDateExclusive)}'`;

  await pbAdmin.pageCollection<{ player?: string }>("activities", { filter, fields: "player,created" }, (rows) => {
    for (const row of rows) if (row.player) players.add(row.player);
  });
  await pbAdmin.pageCollection<{ player?: string }>("client_events", { filter, fields: "player,created" }, (rows) => {
    for (const row of rows) if (row.player) players.add(row.player);
  });

  return players.size;
};

export const runRollups = async (
  dateStr: string,
  opts: { trailing?: boolean } = {}
): Promise<number> => {
  await pbAdmin.authPromise;

  const activities = newActivityAccumulator();
  const clientEvents = newClientEventAccumulator();
  const clientErrors = newClientErrorAccumulator();

  await pbAdmin.pageCollection<ActivityRow>(
    "activities",
    { filter: dayFilter(dateStr), fields: "name,player,duration,success,error,created" },
    (rows) => accumulateActivities(activities, rows)
  );
  await pbAdmin.pageCollection<ClientEventRow>(
    "client_events",
    { filter: dayFilter(dateStr), fields: "name,player,session_id,route_id,value,created" },
    (rows) => accumulateClientEvents(clientEvents, rows)
  );
  await pbAdmin.pageCollection<ClientErrorRow>(
    "client_errors",
    { filter: dayFilter(dateStr), fields: "group_hash,created" },
    (rows) => accumulateClientErrors(clientErrors, rows)
  );

  // Trailing scans re-read the full 7/30-day windows; hourly at most.
  let wau: number | undefined;
  let mau: number | undefined;
  if (opts.trailing !== false) {
    const nextDay = addDays(dateStr, 1);
    [wau, mau] = await Promise.all([
      distinctPlayersInWindow(addDays(dateStr, -6), nextDay),
      distinctPlayersInWindow(addDays(dateStr, -29), nextDay),
    ]);
  }

  const partial = dateStr >= utcDay(new Date());
  const rollups = buildDayRollups(dateStr, {
    activities,
    clientEvents,
    clientErrors,
    wau,
    mau,
    partial,
  });

  for (const rollup of rollups) {
    await pbAdmin.upsertRollup(rollup);
  }

  logger.info(`Rolled up ${dateStr}: ${rollups.length} metrics${partial ? " (partial)" : ""}`);
  return rollups.length;
};

export const runScheduledRollups = async (
  lastRunDay: string | undefined,
  opts: { trailing?: boolean } = {}
): Promise<string> => {
  const today = utcDay(new Date());
  if (lastRunDay && lastRunDay !== today) {
    await runRollups(lastRunDay, { trailing: true });
  }
  await runRollups(today, opts);
  return today;
};