/**
 * Shared helpers for "shared major" simulators (CS2, tennis).
 *
 * A major (a real tournament) can be linked to several sports_season windows.
 * The bracket/stage structure is built and scored once on the PRIMARY window;
 * sibling windows hold no structure of their own. When simulating a sibling, the
 * simulator must read the structure from the primary and translate the primary
 * window's season_participant ids into the local window's ids via the shared
 * canonical participant. These helpers centralise that resolution + translation.
 */

import { getPrimaryEventForTournament } from "~/models/scoring-event";
import { findParticipantsBySportsSeasonId } from "~/models/season-participant";

/** Maps a participant id from one window to another (or passes it through). */
export type IdTranslator = (id: string | null) => string | null;

/** Identity translation — used when structure lives in the event's own window. */
export const IDENTITY_TR: IdTranslator = (id) => id;

/**
 * Build a translator that maps a PRIMARY window's season_participant id to the
 * equivalent id in a LOCAL (sibling) window, bridging via the shared canonical
 * participant. Ids that can't be bridged (no canonical link, or no local
 * counterpart) pass through unchanged so structure is never silently dropped.
 */
export function buildSpTranslator(
  primaryParticipants: Array<{ id: string; participantId: string | null }>,
  localParticipants: Array<{ id: string; participantId: string | null }>
): IdTranslator {
  const primaryToCanonical = new Map(
    primaryParticipants
      .filter((p) => p.participantId)
      .map((p) => [p.id, p.participantId as string])
  );
  const canonicalToLocal = new Map(
    localParticipants
      .filter((p) => p.participantId)
      .map((p) => [p.participantId as string, p.id])
  );
  return (id: string | null): string | null => {
    if (!id) return id;
    const canonical = primaryToCanonical.get(id);
    if (!canonical) return id;
    return canonicalToLocal.get(canonical) ?? id;
  };
}

export interface StructureSource {
  /** Event id whose bracket/stage rows hold this event's structure. */
  sourceId: string;
  /** Translate the source window's participant ids into the local window's. */
  tr: IdTranslator;
}

/**
 * Resolve where an event's bracket/stage structure lives and how to map its
 * participant ids into the local window. For a primary/standalone/non-linked
 * event this is the event itself with identity translation. For a sibling
 * (tournament-linked, non-primary) event, the structure is the primary event and
 * ids are translated primary→local.
 *
 * `translatorCache` is keyed by primary sports_season id so a window's majors
 * (whose primaries may live in different windows) each build their translator
 * once.
 */
export async function resolveStructureSource(
  event: { id: string; tournamentId: string | null; isPrimary: boolean },
  localParticipants: Array<{ id: string; participantId: string | null }>,
  translatorCache: Map<string, IdTranslator>
): Promise<StructureSource> {
  if (!event.tournamentId || event.isPrimary) {
    return { sourceId: event.id, tr: IDENTITY_TR };
  }
  const primary = await getPrimaryEventForTournament(event.tournamentId);
  if (!primary || primary.id === event.id) {
    return { sourceId: event.id, tr: IDENTITY_TR };
  }
  let tr = translatorCache.get(primary.sportsSeasonId);
  if (!tr) {
    const primaryParticipants = await findParticipantsBySportsSeasonId(
      primary.sportsSeasonId
    );
    tr = buildSpTranslator(primaryParticipants, localParticipants);
    translatorCache.set(primary.sportsSeasonId, tr);
  }
  return { sourceId: primary.id, tr };
}