"use client";

import Link from "next/link";
import { useEffect, useState } from "react";
import { LAST_PAGE_KEY, isRecordable, restoreCandidates } from "@/lib/last-page";

// Where you were, as a LINK rather than a redirect. The dashboard is a page in
// its own right now, so / no longer replaces itself with your last URL -- it
// offers it. Same storage, same guard, same HEAD-probed walk-up as the old
// restore, so a stale URL degrades to its parent instead of to a 404.
export default function ResumeChip() {
  const [target, setTarget] = useState<string | null>(null);

  useEffect(() => {
    let done = false;
    (async () => {
      let stored: string | null = null;
      try {
        stored = localStorage.getItem(LAST_PAGE_KEY);
      } catch {
        stored = null;
      }
      if (!stored || !isRecordable(stored)) return;
      for (const url of restoreCandidates(stored)) {
        if (done) return;
        let alive = false;
        try {
          const res = await fetch(url, { method: "HEAD", cache: "no-store" });
          alive = res.status !== 404;
        } catch {
          alive = false;
        }
        if (alive) {
          setTarget(url);
          return;
        }
      }
      // Nothing down to the floor answered. A URL that can never resolve must
      // not cost a probe on every open, so it goes.
      try {
        localStorage.removeItem(LAST_PAGE_KEY);
      } catch {
        /* nothing to clean up */
      }
    })();
    return () => {
      done = true;
    };
  }, []);

  if (!target) return null;
  return (
    <Link
      href={target}
      data-resume={target}
      className="rounded border border-[var(--color-line)] px-2 py-0.5 text-[11px] text-[var(--color-dim)] hover:border-[var(--color-sel)] hover:text-[var(--color-sel)]"
    >
      resume {target} →
    </Link>
  );
}