script.js

const header = document.querySelector(".site-header");
const revealItems = document.querySelectorAll(".reveal");

function updateHeader() {
  if (!header) return;
  header.classList.toggle("scrolled", window.scrollY > 24);
}

if (revealItems.length) {
  const observer = new IntersectionObserver(
    (entries) => {
      entries.forEach((entry) => {
        if (entry.isIntersecting) {
          entry.target.classList.add("visible");
          observer.unobserve(entry.target);
        }
      });
    },
    { threshold: 0.12, rootMargin: "0px 0px -40px" }
  );

  revealItems.forEach((item, index) => {
    item.style.transitionDelay = `${Math.min(index % 4, 3) * 70}ms`;
    observer.observe(item);
  });
}

window.addEventListener("scroll", updateHeader, { passive: true });
updateHeader();

document.querySelectorAll('a[href^="#"]').forEach((link) => {
  link.addEventListener("click", (event) => {
    const target = document.querySelector(link.getAttribute("href"));
    if (!target) return;
    event.preventDefault();
    target.scrollIntoView({ behavior: "smooth", block: "start" });
  });
});

const modal = document.getElementById("cv-modal");
const form = document.getElementById("cv-form");
const input = document.getElementById("cv-code");
const error = document.getElementById("cv-error");

function openCvModal() {
  if (!modal) return;
  modal.hidden = false;
  document.body.classList.add("modal-open");
  error.hidden = true;
  input.value = "";
  input.focus();
}

function closeCvModal() {
  if (!modal) return;
  modal.hidden = true;
  document.body.classList.remove("modal-open");
}

async function deriveKey(password, salt) {
  const material = await crypto.subtle.importKey(
    "raw",
    new TextEncoder().encode(password),
    "PBKDF2",
    false,
    ["deriveKey"]
  );

  return crypto.subtle.deriveKey(
    { name: "PBKDF2", salt, iterations: 210000, hash: "SHA-256" },
    material,
    { name: "AES-GCM", length: 256 },
    false,
    ["decrypt"]
  );
}

async function downloadResume(password) {
  const response = await fetch("./files/cv.enc", { cache: "no-store" });
  if (!response.ok) throw new Error("missing");

  const bytes = new Uint8Array(await response.arrayBuffer());
  const magic = new TextDecoder().decode(bytes.slice(0, 4));
  if (magic !== "TSJ1") throw new Error("format");

  const salt = bytes.slice(4, 20);
  const iv = bytes.slice(20, 32);
  const tag = bytes.slice(32, 48);
  const encrypted = bytes.slice(48);
  const payload = new Uint8Array(encrypted.length + tag.length);
  payload.set(encrypted, 0);
  payload.set(tag, encrypted.length);

  const key = await deriveKey(password, salt);
  const plain = await crypto.subtle.decrypt({ name: "AES-GCM", iv }, key, payload);
  const blob = new Blob([plain], { type: "application/pdf" });
  const url = URL.createObjectURL(blob);
  const link = document.createElement("a");
  link.href = url;
  link.download = "童绍俊-港科AIE硕士-产品经理实习-2028届.pdf";
  document.body.appendChild(link);
  link.click();
  link.remove();
  URL.revokeObjectURL(url);
}

document.querySelectorAll("[data-cv-open]").forEach((button) => {
  button.addEventListener("click", openCvModal);
});

document.querySelectorAll("[data-cv-close]").forEach((button) => {
  button.addEventListener("click", closeCvModal);
});

modal?.addEventListener("click", (event) => {
  if (event.target === modal) closeCvModal();
});

document.addEventListener("keydown", (event) => {
  if (event.key === "Escape" && modal && !modal.hidden) closeCvModal();
});

form?.addEventListener("submit", async (event) => {
  event.preventDefault();
  error.hidden = true;
  const submit = form.querySelector("[type='submit']");
  submit.disabled = true;
  submit.textContent = "解密中…";

  try {
    await downloadResume(input.value.trim());
    closeCvModal();
  } catch {
    error.hidden = false;
  } finally {
    submit.disabled = false;
    submit.textContent = "下载 PDF";
  }
});