/**
 * Plan limits for client-side pacing (same account limits the dashboard shows).
 */

import { OPENFERENCE_ORIGIN, OPENFERENCE_USER_AGENT } from "./constants.ts";

export interface AccountLimits {
  maxRpm: number;
}

const DEFAULT_MAX_RPM = 60;

/**
 * Fetch effective plan RPM via GET /api/user/me (authMiddleware accepts OAuth JWTs).
 */
export async function fetchAccountLimits(
  accessToken: string,
  fetchImpl: typeof fetch = fetch,
  signal?: AbortSignal,
): Promise<AccountLimits> {
  const res = await fetchImpl(`${OPENFERENCE_ORIGIN}/api/user/me`, {
    headers: {
      Authorization: `Bearer ${accessToken}`,
      "User-Agent": OPENFERENCE_USER_AGENT,
    },
    signal,
  });
  if (!res.ok) {
    throw new Error(`GET /api/user/me -> HTTP ${res.status}`);
  }
  const json = (await res.json()) as {
    limits?: { maxRpm?: number };
    plan?: { maxRpm?: number };
  };
  const maxRpm = Number(json.limits?.maxRpm ?? json.plan?.maxRpm ?? DEFAULT_MAX_RPM);
  return {
    maxRpm: Number.isFinite(maxRpm) && maxRpm > 0 ? maxRpm : DEFAULT_MAX_RPM,
  };
}

/** Minimum spacing between request starts for a given RPM (ms). */
export function minIntervalMsForRpm(maxRpm: number): number {
  const rpm = Math.max(1, maxRpm);
  return Math.ceil(60_000 / rpm);
}