import type { ProvisionableUser } from 'officerdb';
import { listJellyfinAccounts } from '../db';
import { listJellyfinUsers } from './provision';
import { normalize, type JellyfinUser } from './reconcile';
import { getProvisionableUsers, hasProvisionableUsers } from './user-list';
import type { UpstreamTarget } from './upstream';

// Who exists on each side, and which pairs are the same person.
//
// Read-only, and deliberately no part of provisioning: this answers "what is true now", where
// `planReconcile` answers "what would happen if we ran". They share `normalize` so the screen cannot
// disagree with the matching rule about whether `Diogo` and `diogo` are one person — a settings page that
// showed them as two would be lying about what the next connection will do.
//
// The join is by the LINK ROW where one exists, and by the folded name where one does not. That ordering
// matters: a recorded pairing is a fact, and a name that happens to match is only a candidate.

export type AccountPair = {
  officer: { id: number; username: string | null; name: string | null; role: string } | null;
  jellyfin: { id: string; name: string } | null;
  /** A row in `jellyfin_accounts` says these two are the same person. */
  linked: boolean;
  /** The Jellyfin account existed before Officer knew about it. Never deleted on deprovision. */
  adopted: boolean;
  /** Names match but nothing is recorded — what connecting would adopt. */
  matchable: boolean;
};

export type AccountView =
  | { known: false; reason: string }
  | { known: true; pairs: AccountPair[]; counts: { linked: number; officerOnly: number; jellyfinOnly: number } };

const officerOf = (u: ProvisionableUser) => ({ id: u.id, username: u.username, name: u.name, role: u.role });

/**
 * Build the view for one server.
 *
 * `known: false` when the platform has not sent the account list. That is not the same as "no users" and
 * the screen must not render it as an empty table — it means this plugin is not entitled to the list or
 * the push has not arrived, and showing "0 Officer accounts" would read as a fact about the server.
 */
export async function buildAccountView(cfg: UpstreamTarget, serverId: number): Promise<AccountView> {
  if (!hasProvisionableUsers()) {
    return { known: false, reason: 'the platform has not sent the account list yet' };
  }

  const officer = getProvisionableUsers();
  const jellyfin: JellyfinUser[] = await listJellyfinUsers(cfg);
  const links = await listJellyfinAccounts(serverId);

  const linkByUserId = new Map(links.map((l) => [l.userId, l]));
  const jellyfinById = new Map(jellyfin.map((j) => [j.Id, j]));
  const jellyfinByName = new Map(jellyfin.map((j) => [normalize(j.Name), j]));
  const claimed = new Set<string>();

  const pairs: AccountPair[] = [];

  for (const user of officer) {
    const link = linkByUserId.get(user.id);
    const byName = user.username ? jellyfinByName.get(normalize(user.username)) : undefined;

    if (link) {
      // The linked account can be GONE — deleted in Jellyfin's own UI. Reported as an Officer account with
      // no Jellyfin side rather than quietly re-matching it by name, because those are different events
      // and only one of them is somebody's account disappearing.
      const live = jellyfinById.get(link.jellyfinUserId);
      if (live) claimed.add(live.Id);
      pairs.push({
        officer: officerOf(user),
        jellyfin: live ? { id: live.Id, name: live.Name } : null,
        linked: true,
        adopted: link.adopted,
        matchable: false,
      });
      continue;
    }

    if (byName && !claimed.has(byName.Id)) {
      claimed.add(byName.Id);
      pairs.push({
        officer: officerOf(user),
        jellyfin: { id: byName.Id, name: byName.Name },
        linked: false,
        adopted: false,
        matchable: true,
      });
      continue;
    }

    pairs.push({ officer: officerOf(user), jellyfin: null, linked: false, adopted: false, matchable: false });
  }

  for (const j of jellyfin) {
    if (claimed.has(j.Id)) continue;
    pairs.push({
      officer: null,
      jellyfin: { id: j.Id, name: j.Name },
      linked: false,
      adopted: false,
      matchable: false,
    });
  }

  return {
    known: true,
    pairs,
    counts: {
      linked: pairs.filter((p) => p.linked).length,
      officerOnly: pairs.filter((p) => p.officer && !p.jellyfin).length,
      jellyfinOnly: pairs.filter((p) => !p.officer).length,
    },
  };
}