/**
 * computeSubResourceCacheTTL
 *
 * Computes the Redis TTL (in milliseconds) for opportunity sub-resources
 * (notes, contacts, activities, etc.) that share the parent opportunity's
 * activity window.
 *
 * Rules are identical to the main opportunity TTL but use different
 * exported constant names so callers can distinguish them.
 */

export const SUB_TTL_HIGH_ACTIVITY = 60_000;      // 60 seconds
export const SUB_TTL_MODERATE_ACTIVITY = 120_000; // 2 minutes
export const SUB_TTL_LOW_ACTIVITY = 300_000;      // 5 minutes

export interface ComputeSubResourceCacheTTLInput {
  closedFlag: boolean;
  closedDate: Date | null;
  expectedCloseDate: Date | null;
  lastUpdated: Date | null;
  now?: Date;
}

const DAY_MS = 24 * 60 * 60 * 1000;

function ageMs(date: Date, now: Date): number {
  return Math.abs(now.getTime() - date.getTime());
}

export function computeSubResourceCacheTTL(
  input: ComputeSubResourceCacheTTLInput
): number | null {
  const now = input.now ?? new Date();

  // Rule 1a — closed > 30 days → no cache
  if (input.closedFlag) {
    if (!input.closedDate) return null;
    const daysClosed = ageMs(input.closedDate, now) / DAY_MS;
    if (daysClosed > 30) return null;
    return SUB_TTL_LOW_ACTIVITY;
  }

  const dates = [input.lastUpdated, input.expectedCloseDate].filter(
    (d): d is Date => d !== null
  );

  if (dates.length === 0) {
    return SUB_TTL_LOW_ACTIVITY;
  }

  const minDeltaDays =
    Math.min(...dates.map((d) => ageMs(d, now))) / DAY_MS;

  if (minDeltaDays <= 5) return SUB_TTL_HIGH_ACTIVITY;
  if (minDeltaDays <= 14) return SUB_TTL_MODERATE_ACTIVITY;
  return SUB_TTL_LOW_ACTIVITY;
}