/**
 * Server-facing candidate plateau helpers. These numbers are for Agent
 * projection only; they never grant exact-minute confirmation.
 */

import { RECTIFICATION_POLICY } from "../../rectification-policy.ts";

export function timeToMinutes(value: string): number | null {
  const match = /^(?:[01]\d|2[0-3]):([0-5]\d)$/.exec(value);
  if (!match) return null;
  const hours = Number(value.slice(0, 2));
  const minutes = Number(match[1]);
  return hours * 60 + minutes;
}

/**
 * Width of the indistinguishable top cluster, in minutes.
 * Uses the engine's tied_minute_count and the inclusive span of public times.
 */
export function indistinguishableWidthMinutes(
  candidates: readonly Readonly<{
    time: string;
    rank: number;
    tiedMinuteCount: number;
  }>[],
): number {
  if (candidates.length === 0) return 0;
  const ranked = [...candidates].sort((left, right) => left.rank - right.rank);
  const top = ranked[0]!;
  const minutes = ranked
    .map((candidate) => timeToMinutes(candidate.time))
    .filter((value): value is number => value !== null);
  const span = minutes.length === 0
    ? 0
    : Math.max(...minutes) - Math.min(...minutes) + 1;
  return Math.max(top.tiedMinuteCount, span, 1);
}

export function confirmationAllowedForWidth(
  storedConfirmationAllowed: boolean,
  widthMinutes: number,
): boolean {
  return storedConfirmationAllowed
    && widthMinutes <= RECTIFICATION_POLICY.maxConfirmationWidthMinutes;
}