"use strict";
const choices = {
  tue: "Tuesday, November 10",
  wed: "Wednesday, November 11",
  thu: "Thursday, November 12",
};
const keys = Object.keys(choices),
  nights = [...document.querySelectorAll(".night")];
const $ = (id) => document.getElementById(id);
let current = 0,
  selected = null,
  busy = false,
  recorded = false,
  pending = null,
  pendingKey = "",
  checked = false,
  terminal = false;
// Only a choice key is shared, never the bearer. Web Locks make claiming it
// atomic across same-origin tabs. Unresolved attempts must not be replaced.
function showFailure(error) {
  if (!error.terminal) { showUnknown(); return; }
  terminal = true;
  if (error.expired) {
    try { localStorage.removeItem(pendingKey); } catch {}
    pending = null;
  }
  $("reply").hidden = false;
  $("reply-title").textContent = "This pick cannot be sent.";
  $("send-status").textContent = error.message;
  $("send").hidden = true;
  $("change").hidden = true;
  $("confirmation-note").textContent = "No new pick was confirmed by this response. If you sent one earlier, check with Niq in your usual conversation.";
  choiceLock();
}
function storageFailure() {
  return Object.assign(new Error("This browser cannot safely remember an unfinished pick. Use a browser with site storage and Web Locks enabled, or tell Niq directly."), {terminal:true});
}
function readPending() {
  let value;
  try { value = localStorage.getItem(pendingKey); } catch { throw storageFailure(); }
  if (value !== null && !Object.hasOwn(choices, value)) throw storageFailure();
  return value;
}
function showUnknown() {
  if (pending) confirm(pending, false);
  $("reply").hidden = false;
  $("change").hidden = true;
  $("send").textContent = pending ? "Try this pick again" : "Check saved pick";
  $("send-status").textContent = pending
    ? "We couldn’t confirm whether your pick was recorded. Try again with this pick, or check with Niq."
    : "We couldn’t check for a saved pick. Check again before choosing a night.";
  $("confirmation-note").textContent = "A previous request may still finish. A different pick cannot be sent until this is resolved.";
}
async function reconcile() {
  const result = await request();
  checked = true;
  if (result.recorded) showRecorded(result);
  else if (pending) showUnknown();
  else {
    $("reply").hidden = true;
    $("browse").hidden = false;
    $("change").hidden = false;
    $("send").textContent = "Send my pick";
    $("confirmation-note").textContent = "This saves one pick. You can change it before sending.";
  }
}
function choiceLock() {
  document.querySelectorAll("[data-choice]").forEach(b => {
    b.disabled = terminal || busy || recorded || !!pending || (token && !checked);
  });
}
let token = location.hash.slice(1);
if (!/^[a-f0-9]{64}$/.test(token)) token = "";
try {
  if (token) {
    sessionStorage.setItem("invitation-token", token);
    history.replaceState(null, "", location.pathname);
  } else token = sessionStorage.getItem("invitation-token") || "";
} catch {
  /* The fragment remains available if storage is disabled. */
}
function showNight(index, announce = true) {
  current = (index + keys.length) % keys.length;
  nights.forEach((n, i) => {
    n.classList.toggle("active", i === current);
    n.hidden = i !== current;
  });
  document
    .querySelectorAll("[data-open]")
    .forEach((b, i) => b.setAttribute("aria-pressed", String(i === current)));
  $("counter").textContent = current + 1 + " / 3";
  if (announce)
    $("browse-status").textContent =
      choices[keys[current]] +
      ". " +
      nights[current].querySelector("h2").textContent;
}
function confirm(key, focus = true) {
  selected = key;
  $("stamp").textContent = choices[key].split(",")[0];
  $("choice-description").textContent = choices[key] + ".";
  $("browse").hidden = true;
  $("reply").hidden = false;
  if (focus) $("reply-title").focus();
}
function showRecorded(result) {
  const attempted = selected;
  recorded = true;
  try { localStorage.removeItem(pendingKey); } catch {}
  pending = null;
  confirm(result.choice);
  $("browse").hidden = false;
  showNight(keys.indexOf(result.choice), false);
  choiceLock();
  $("reply-title").textContent = "Your pick is recorded.";
  $("send-status").textContent =
    (attempted && attempted !== result.choice
      ? choices[attempted] + " was not saved. " + choices[result.choice] + " was already recorded. "
      : "") + "Niq’s automatic notification isn’t connected yet. Your choice is saved here.";
  $("send").hidden = true;
  $("change").hidden = true;
  $("confirmation-note").textContent =
    "If you need to change it, let Niq know in your usual conversation.";
}
function lock(value) {
  busy = value;
  $("send").disabled = value;
  $("change").disabled = value;
  choiceLock();
}
async function request(method = "GET") {
  const controller = new AbortController(),
    timer = setTimeout(() => controller.abort(), 8000);
  try {
    const response = await fetch("/api/pick", {
      method,
      headers: {
        Authorization: "Bearer " + token,
        ...(method === "POST" ? { "Content-Type": "application/json" } : {}),
      },
      ...(method === "POST"
        ? { body: JSON.stringify({ choice: selected }) }
        : {}),
      cache: "no-store",
      signal: controller.signal,
    });
    let data;
    try { data = await response.json(); } catch {
      if (response.status >= 400 && response.status < 500)
        throw Object.assign(new Error("This invitation request was rejected. Check the link with Niq."), {terminal:true});
      throw new Error("unconfirmed");
    }
    const failures = {
      expired: "This invitation is closed. No new pick can be saved.",
      invalid_invitation: "This invitation link is invalid. Ask Niq for the full link.",
      not_configured: "This invitation is not configured to accept picks. Let Niq know.",
    };
    if (failures[data.error] || (response.status >= 400 && response.status < 500 && response.status !== 409))
      throw Object.assign(new Error(failures[data.error] || "This invitation request was rejected. Check the link with Niq."), {terminal:true, expired:data.error === "expired"});
    if (
      (response.status === 200 || response.status === 409) &&
      data.recorded === true &&
      Object.hasOwn(choices, data.choice) &&
      data.notification === "not_connected"
    )
      return data;
    if (response.status === 200 && data.recorded === false) return data;
    throw new Error("unconfirmed");
  } finally {
    clearTimeout(timer);
  }
}
document
  .querySelectorAll("[data-open]")
  .forEach((b) =>
    b.addEventListener("click", () => showNight(keys.indexOf(b.dataset.open))),
  );
$("prev").addEventListener("click", () => showNight(current - 1));
$("next").addEventListener("click", () => showNight(current + 1));
document.querySelectorAll("[data-choice]").forEach((b) =>
  b.addEventListener("click", () => {
    if (terminal || busy || recorded || pending || (token && !checked)) return;
    confirm(b.dataset.choice);
    $("send-status").textContent = "";
    if (!token) {
      $("send").disabled = true;
      $("send-status").textContent =
        "Open the full invitation link to send a pick. You can also tell Niq in your usual conversation.";
    }
  }),
);
$("change").addEventListener("click", () => {
  if (terminal || busy || recorded || pending || (token && !checked)) return;
  $("reply").hidden = true;
  $("browse").hidden = false;
  showNight(keys.indexOf(selected), false);
  nights[current].querySelector(".choose").focus();
});
$("send").addEventListener("click", async () => {
  if (terminal || busy || recorded || !token) return;
  lock(true);
  try {
    if (!selected && !pending) { await reconcile(); return; }
    // Claim atomically across tabs before issuing any POST.
    if (!navigator.locks) throw storageFailure();
    await navigator.locks.request(pendingKey, () => {
      const shared = readPending();
      if (shared && shared !== selected) {
        pending = shared;
        showUnknown();
        throw new Error("other_pending");
      }
      try { localStorage.setItem(pendingKey, selected); } catch { throw storageFailure(); }
      pending = selected;
    });
    $("change").hidden = true;
    $("confirmation-note").textContent = "Only this pick can be retried while its result is uncertain.";
    $("send-status").textContent = "Saving your pick…";
    const result = await request("POST");
    if (result.recorded) showRecorded(result);
    else throw new Error("unconfirmed");
  } catch (error) {
    if (error.terminal) showFailure(error);
    else { try { await reconcile(); } catch (error) { showFailure(error); } }
  } finally {
    lock(false);
  }
});
showNight(0, false);
document.documentElement.classList.add("js");
if (token) {
  lock(true);
  $("browse-status").textContent = "Checking for a saved pick…";
  (async () => {
    pendingKey = "invitation-pending-" + Array.from(new Uint8Array(
      await crypto.subtle.digest("SHA-256", new TextEncoder().encode(token))
    ), b => b.toString(16).padStart(2, "0")).join("");
    pending = readPending();
    if (pending) showUnknown();
    await reconcile();
  })().catch(showFailure).finally(() => {
    lock(false);
    $("browse-status").textContent = "";
  });
}
window.addEventListener("storage", async (event) => {
  if (event.key !== pendingKey || busy || recorded || terminal) return;
  try {
    pending = readPending();
    if (pending) showUnknown();
    else await reconcile();
  } catch (error) { showFailure(error); }
  choiceLock();
});