/**
 * Fitbit Web API exercise-session sync.
 *
 * Reads exercise sessions from the classic `activities/list` endpoint
 * (`afterDate` + ascending offset/limit pagination) and upserts each into the
 * `Workout` table as `source = FITBIT`, keyed on `(userId, source, externalId)`
 * (externalId = the Fitbit `logId`) so a re-fetch overwrites in place.
 *
 * A Fitbit run and the same run via Apple Health (or WHOOP) stay distinct
 * `Workout` rows (different `source`); the read-time `pickCanonicalWorkoutRows`
 * picker collapses the cross-source twin per the user's source ladder (FITBIT is
 * already in the default ladder, ranked just below WHOOP). No ingest-time
 * collapse for a server-owned source pair.
 *
 * The page-walk is bounded (the 150 req/h budget is tight): a small page cap
 * covers the incremental window comfortably; a deep backfill is bounded by the
 * backfill horizon `afterDate`. A per-endpoint 403 soft-skips the resource.
 */
import { fetchActivityList, mapWorkout, readActivityList } from "./client";
import type { FitbitMappedWorkout } from "./client";
import { getValidToken, handleCollectionFetchError } from "./sync-core";
import type { FitbitResourceSyncOptions } from "./sync-core";
import { prisma } from "@/lib/db";
import { emitInsertedWorkoutArrival } from "@/lib/arrivals/workout-emit";
import { annotate, getEvent } from "@/lib/logging/context";
import { resolveUserTimezone } from "@/lib/tz/resolver";

/** Activities per page on the `activities/list` walk. */
const WORKOUT_PAGE_SIZE = 100;
/** Hard ceiling on pages walked per cycle (rate-budget guard). */
const WORKOUT_MAX_PAGES = 12;

export async function syncUserWorkout(
  userId: string,
  opts: FitbitResourceSyncOptions = {},
): Promise<number> {
  const tokenInfo = await getValidToken(userId);
  if (!tokenInfo) return 0;

  // `startTime` on the activities list is offset-less local wall-clock; anchor
  // it to the user's stored zone rather than the process zone.
  const tz = await resolveUserTimezone(userId);

  const afterDate =
    opts.start ?? new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);

  const entries: ReturnType<typeof readActivityList> = [];
  let offset = 0;
  let pages = 0;
  while (pages < WORKOUT_MAX_PAGES) {
    let body: unknown;
    try {
      body = await fetchActivityList(tokenInfo.accessToken, afterDate, {
        limit: WORKOUT_PAGE_SIZE,
        offset,
      });
    } catch (err) {
      return handleCollectionFetchError("fetchExercise", userId, err);
    }
    const page = readActivityList(body);
    entries.push(...page);
    pages += 1;
    if (page.length < WORKOUT_PAGE_SIZE) break;
    offset += WORKOUT_PAGE_SIZE;
  }

  let imported = 0;
  for (const entry of entries) {
    const w: FitbitMappedWorkout | null = mapWorkout(entry, tz);
    if (!w) continue; // no usable time span — not a workout

    const data = {
      sportType: w.sportType,
      startedAt: w.startedAt,
      endedAt: w.endedAt,
      durationSec: w.durationSec,
      totalEnergyKcal: w.totalEnergyKcal,
      totalDistanceM: w.totalDistanceM,
      avgHeartRate: w.avgHeartRate,
      maxHeartRate: w.maxHeartRate,
      minHeartRate: w.minHeartRate,
    };
    try {
      const [inserted] = await prisma.workout.createManyAndReturn({
        data: {
          userId,
          source: "FITBIT",
          externalId: w.externalId,
          ...data,
        },
        skipDuplicates: true,
        select: { id: true, startedAt: true },
      });
      if (inserted) {
        void emitInsertedWorkoutArrival(userId, inserted, "fitbit").catch(
          () => {},
        );
      } else {
        await prisma.workout.update({
          where: {
            userId_source_externalId: {
              userId,
              source: "FITBIT",
              externalId: w.externalId,
            },
          },
          data,
        });
      }
      imported++;
    } catch (err) {
      getEvent()?.addWarning(`fitbit: failed to upsert workout: ${err}`);
    }
  }

  // `markSynced` is owned by the orchestrator (`syncUserFitbit`).
  annotate({ action: { name: "fitbit.workout.sync", details: { imported } } });
  return imported;
}