import crypto from "crypto";
import { cacheGet, cacheSet } from "./cache";
import type { SearchResult } from "./types";

const DEDUPE_NS = "dedupe";

export function normalizeThreadsUrl(url: string): string {
  try {
    const u = new URL(url);
    u.hostname = u.hostname.replace(/^www\./, "");
    u.search = "";
    u.hash = "";
    const pathname = u.pathname.replace(/\/+$/, "") || "/";
    u.pathname = pathname;
    return u.toString();
  } catch {
    return url.trim();
  }
}

export function extractThreadId(url: string): string | undefined {
  const m = url.match(/threads\.com\/@[^/]+\/post\/([^/?#]+)/i);
  return m?.[1];
}

export function dedupeKeyForResult(result: SearchResult): string {
  const threadId = result.threadId ?? extractThreadId(result.url);
  if (threadId) return `thread:${threadId}`;
  const normalized = normalizeThreadsUrl(result.url);
  const hash = crypto.createHash("sha256").update(normalized).digest("hex").slice(0, 16);
  return `url_hash:${hash}`;
}

export function dedupeResults(results: SearchResult[]): SearchResult[] {
  const seen = new Set<string>();
  const out: SearchResult[] = [];
  for (const r of results) {
    const key = dedupeKeyForResult(r);
    if (seen.has(key)) continue;
    seen.add(key);
    out.push(r);
  }
  return out;
}

export function isNotifyDuplicate(key: string): boolean {
  return cacheGet<boolean>(DEDUPE_NS, `notify:${key}`) === true;
}

export function markNotified(key: string, ttlMs: number): void {
  cacheSet(DEDUPE_NS, `notify:${key}`, true, ttlMs);
}

export function filterNotifyDuplicates(results: SearchResult[]): SearchResult[] {
  return results.filter((r) => {
    const key = dedupeKeyForResult(r);
    if (isNotifyDuplicate(key)) return false;
    return true;
  });
}