import { LRUCache } from 'lru-cache';
import { config } from './config.ts';
import { withPage } from './browser/pool.ts';
import { withTimeout } from './browser/queue.ts';
import { ResolveError, type Post } from './types.ts';
import type { PlatformSpec } from './platforms/types.ts';

/**
 * Resolved posts, keyed by canonical URL. Reloading, hitting back, or
 * opening the same link twice must not drive Chromium again.
 */
const cache = new LRUCache<string, Post>({
  max: config.cacheMax,
  ttl: config.cacheTtlMs,
});

export function cacheSize(): number {
  return cache.size;
}

export async function resolvePost(
  spec: PlatformSpec,
  originalUrl: string,
  pathRest: string,
): Promise<Post> {
  const hit = cache.get(originalUrl);
  if (hit) return hit;

  const post = await withTimeout(
    withPage(({ page, detach }) => spec.resolve({ page, detach, spec, originalUrl, pathRest })),
    config.resolveTimeoutMs,
    `${spec.label} resolve`,
  ).catch((error: unknown) => {
    if (error instanceof ResolveError) throw error;
    throw new ResolveError(
      error instanceof Error ? error.message : String(error),
      spec.id,
      originalUrl,
      { cause: error },
    );
  });

  cache.set(originalUrl, post);
  return post;
}