/**
 * Pure helpers for the Simulator Setup page, split out so they can be unit tested
 * without pulling the route's server-only imports into the test.
 */

import type {
  BaseEloKey,
  ResolvedRating,
  ResolvedSourceElo,
} from "~/services/simulations/input-policy";

/**
 * Short badge text for how a participant's Elo or rating was produced, or null for a
 * directly entered one — the unremarkable case, which needs no badge.
 *
 * The preview table needs this because a generated value is deliberately hidden from
 * `getParticipantSimulatorInputs`, so without the resolved value plus this label the
 * row reads as "nothing saved" and a projection losing to a raw Elo is invisible.
 *
 * Every remaining method is a missing-input fallback (`fallbackElo`,
 * `fallbackRating`, `averageKnown`, `worstKnownMinus`, `block`), which all read the
 * same way to an admin: this participant had nothing usable of its own.
 */
export function resolvedInputMethodLabel(
  method: ResolvedSourceElo["method"] | ResolvedRating["method"]
): string | null {
  switch (method) {
    case "direct":
      return null;
    case "projectedWins":
    case "projectedTablePoints":
      return "from projections";
    case "sourceOdds":
      return "from futures";
    case "blend":
      return "blended";
    default:
      return "fallback";
  }
}

/**
 * Method flag for a bulk-input row that carries a projection instead of an Elo, or
 * undefined when the row says nothing about how its Elo was produced.
 *
 * A row supplying a projection but no explicit Elo means "derive the Elo from this
 * projection". Stamping the flag marks whatever Elo is already stored as generated,
 * so `getParticipantSimulatorInputs` hides it and `resolveSourceElos` re-derives
 * from the projection — without it, the non-destructive upsert leaves a stale
 * hand-entered Elo in place, and that Elo wins the `baseEloPriority` race so the
 * projection is written to the database and then ignored on every run.
 *
 * Returning undefined (rather than an empty object) matters: the upsert only
 * preserves existing metadata, and clears a stale flag for a fresh direct Elo, when
 * the incoming metadata is null.
 */
export function projectionMethodMetadata(
  sourceElo: number | undefined,
  projectedWins: number | undefined,
  projectedTablePoints: number | undefined
): Record<string, unknown> | undefined {
  if (sourceElo !== undefined) return undefined;
  if (projectedWins !== undefined) return { sourceEloMethod: "projectedWins" };
  if (projectedTablePoints !== undefined) return { sourceEloMethod: "projectedTablePoints" };
  return undefined;
}

/**
 * Translate the Base Elo Source select into a full `baseEloPriority` list. Only the
 * head of the list is user-facing (raw Elo vs. projections); the remaining keys keep
 * their existing relative order so a season that already has a custom ordering is
 * not silently flattened.
 */
export function parseBaseEloPriorityChoice(
  value: FormDataEntryValue | null,
  current: BaseEloKey[]
): BaseEloKey[] {
  // The select only renders for simulators that can derive Elo from a projection.
  // When it was not on the form there is no choice to apply, so keep what is stored
  // rather than silently rewriting the season's ordering.
  if (value === null) return current;
  const projections = current.filter((key) => key !== "sourceElo");
  return value === "projectionsFirst"
    ? [...projections, "sourceElo"]
    : ["sourceElo", ...projections];
}