const state = {
  site: null,
  snippet: "",
  conversations: [],
  activeId: null,
  active: null,
  events: null
};

const $ = (selector) => document.querySelector(selector);

boot();

async function boot() {
  const me = await api("/api/admin/me").catch(() => null);
  if (me?.user) showApp();
  else showLogin();
}

$("#loginForm").addEventListener("submit", async (event) => {
  event.preventDefault();
  const form = new FormData(event.currentTarget);
  const result = await api("/api/admin/login", {
    method: "POST",
    body: { username: form.get("username"), password: form.get("password") }
  }).catch(() => null);
  if (!result?.ok) {
    $("#loginError").textContent = "Prihlaseni se nepodarilo.";
    return;
  }
  showApp();
});

$("#logoutButton").addEventListener("click", async () => {
  await api("/api/admin/logout", { method: "POST" });
  location.reload();
});

$("#settingsButton").addEventListener("click", () => $("#settingsPanel").classList.remove("hidden"));
$("#closeSettingsButton").addEventListener("click", () => $("#settingsPanel").classList.add("hidden"));

$("#onlineToggle").addEventListener("change", async () => {
  await saveSite({ isOnline: $("#onlineToggle").checked });
});

$("#settingsForm").addEventListener("submit", async (event) => {
  event.preventDefault();
  const form = new FormData(event.currentTarget);
  const settings = structuredClone(state.site.settings);
  settings.title.cs = form.get("titleCs");
  settings.intro.cs = form.get("introCs");
  settings.title.en = form.get("titleEn");
  settings.intro.en = form.get("introEn");
  settings.colors.brand = form.get("brand");
  settings.desktop.side = form.get("desktopSide");
  settings.desktop.bottomPx = Number(form.get("desktopBottom"));
  settings.desktop.sideOffsetPx = Number(form.get("desktopOffset"));
  settings.mobile.side = form.get("mobileSide");
  settings.mobile.bottomPx = Number(form.get("mobileBottom"));
  settings.mobile.sideOffsetPx = Number(form.get("mobileOffset"));
  await saveSite({ settings, isOnline: state.site.isOnline });
});

$("#replyForm").addEventListener("submit", async (event) => {
  event.preventDefault();
  if (!state.activeId) return;
  const form = new FormData(event.currentTarget);
  await api(`/api/admin/conversations/${state.activeId}/messages`, {
    method: "POST",
    body: { message: form.get("message") }
  });
  event.currentTarget.reset();
  await openConversation(state.activeId);
});

$("#replyForm textarea").addEventListener("input", debounce(() => {
  if (!state.activeId) return;
  api(`/api/admin/conversations/${state.activeId}/typing`, { method: "POST" }).catch(() => {});
}, 600));

$("#statusSelect").addEventListener("change", async () => {
  if (!state.activeId) return;
  await api(`/api/admin/conversations/${state.activeId}/status`, {
    method: "PATCH",
    body: { status: $("#statusSelect").value }
  });
  await loadConversations();
});

$("#messages").addEventListener("click", (event) => {
  const preview = event.target.closest("[data-photo-url]");
  if (!preview) return;
  openPhotoPreview(preview.dataset.photoUrl, preview.dataset.photoName);
});

async function showApp() {
  $("#loginView").classList.add("hidden");
  $("#appView").classList.remove("hidden");
  await loadBootstrap();
  await loadConversations();
  connectEvents();
}

function showLogin() {
  $("#loginView").classList.remove("hidden");
  $("#appView").classList.add("hidden");
}

async function loadBootstrap() {
  const data = await api("/api/admin/bootstrap");
  state.site = data.site;
  state.snippet = data.snippet;
  renderSite();
}

async function loadConversations() {
  const data = await api("/api/admin/conversations");
  state.conversations = data.conversations;
  renderConversations();
}

async function openConversation(id) {
  state.activeId = id;
  const data = await api(`/api/admin/conversations/${id}`);
  state.active = data;
  renderConversations();
  renderActive();
}

function connectEvents() {
  if (state.events) state.events.close();
  state.events = new EventSource("/api/admin/events");
  state.events.addEventListener("message", async (event) => {
    const data = JSON.parse(event.data);
    if (data.type === "typing" && data.actor === "visitor" && data.conversationId !== state.activeId) return;
    if (data.type === "typing" && data.actor === "visitor") return flashTyping();
    if (data.type === "site:update") {
      state.site = data.site;
      renderSite();
      return;
    }
    await loadConversations();
    if (state.activeId) await openConversation(state.activeId);
    if (data.type === "conversation:new" || data.type === "message:new") notify();
  });
}

function renderSite() {
  $("#onlineToggle").checked = state.site.isOnline;
  $("#snippet").textContent = state.snippet;
  const s = state.site.settings;
  const form = $("#settingsForm");
  form.titleCs.value = s.title.cs || "";
  form.introCs.value = s.intro.cs || "";
  form.titleEn.value = s.title.en || "";
  form.introEn.value = s.intro.en || "";
  form.brand.value = s.colors.brand || "#0f8f6f";
  form.desktopSide.value = s.desktop.side || "right";
  form.desktopBottom.value = s.desktop.bottomPx || 22;
  form.desktopOffset.value = s.desktop.sideOffsetPx || 22;
  form.mobileSide.value = s.mobile.side || "right";
  form.mobileBottom.value = s.mobile.bottomPx || 14;
  form.mobileOffset.value = s.mobile.sideOffsetPx || 12;
}

function renderConversations() {
  $("#conversationList").innerHTML = state.conversations.map((item) => `
    <button class="conversation-item ${item.id === state.activeId ? "active" : ""} ${item.status === "new" ? "fresh" : ""}" data-id="${item.id}">
      <span class="row"><strong>${escapeHtml(item.visitor.name || item.visitor.email || "Navstevnik")}</strong><span class="status">${item.status}</span></span>
      <span class="preview">${escapeHtml(item.lastBody || "")}</span>
      <span class="meta">${flag(item.countryCode)} ${escapeHtml(item.language || "")} ${escapeHtml(item.currentUrl || "")}</span>
    </button>
  `).join("");
  for (const button of document.querySelectorAll(".conversation-item")) {
    button.addEventListener("click", () => openConversation(button.dataset.id));
  }
}

function renderActive() {
  const { conversation, messages } = state.active;
  const statusSelect = $("#statusSelect");
  $("#conversationHeader").innerHTML = `
    <div>
      <h2>${escapeHtml(conversation.visitor.name || conversation.visitor.email || "Navstevnik")}</h2>
      <p>${flag(conversation.countryCode)} ${escapeHtml(conversation.currentUrl || "")}</p>
      <p>${escapeHtml(conversation.device.userAgent || "")}</p>
    </div>
  `;
  $("#conversationHeader").append(statusSelect);
  statusSelect.classList.remove("hidden");
  statusSelect.value = conversation.status;
  $("#replyForm").classList.remove("hidden");
  $("#messages").innerHTML = messages.map((message) => `
    <article class="message ${message.senderType}">
      <div class="by">${escapeHtml(message.senderName || message.senderType)} · ${escapeHtml(message.createdAt)}</div>
      <p>${escapeHtml(message.body)}</p>
      ${renderAttachments(message.attachments)}
    </article>
  `).join("");
  $("#messages").scrollTop = $("#messages").scrollHeight;
}

function renderAttachments(attachments) {
  if (!attachments.length) return "";
  return `<div class="attachments">${attachments.map((attachment) => {
    if (!attachment.type?.startsWith("image/")) {
      return `<a href="${escapeHtml(attachment.url)}" target="_blank" rel="noreferrer">${escapeHtml(attachment.name)}</a>`;
    }
    return `
      <button class="photo-preview" type="button" data-photo-url="${escapeHtml(attachment.url)}" data-photo-name="${escapeHtml(attachment.name)}">
        <img src="${escapeHtml(attachment.url)}" alt="${escapeHtml(attachment.name)}">
        <span>${escapeHtml(attachment.name)}</span>
      </button>
    `;
  }).join("")}</div>`;
}

function openPhotoPreview(url, name) {
  let modal = $("#photoModal");
  if (!modal) {
    modal = document.createElement("div");
    modal.id = "photoModal";
    modal.className = "photo-modal hidden";
    modal.innerHTML = `
      <button class="photo-backdrop" type="button" aria-label="Zavrit nahled"></button>
      <figure>
        <button class="photo-close" type="button" aria-label="Zavrit nahled">×</button>
        <img alt="">
        <figcaption></figcaption>
      </figure>
    `;
    document.body.append(modal);
    modal.addEventListener("click", (event) => {
      if (event.target.closest(".photo-close") || event.target.classList.contains("photo-backdrop")) {
        modal.classList.add("hidden");
      }
    });
    document.addEventListener("keydown", (event) => {
      if (event.key === "Escape") modal.classList.add("hidden");
    });
  }
  modal.querySelector("img").src = url;
  modal.querySelector("img").alt = name || "Fotka";
  modal.querySelector("figcaption").textContent = name || "";
  modal.classList.remove("hidden");
}

async function saveSite(patch) {
  const data = await api("/api/admin/site", { method: "PATCH", body: patch });
  state.site = data.site;
  state.snippet = data.snippet;
  renderSite();
}

function notify() {
  document.title = "* Nova zprava - MaalFlows";
  const audio = new AudioContext();
  const osc = audio.createOscillator();
  const gain = audio.createGain();
  osc.frequency.value = 880;
  gain.gain.value = 0.04;
  osc.connect(gain);
  gain.connect(audio.destination);
  osc.start();
  setTimeout(() => {
    osc.stop();
    audio.close();
  }, 160);
}

function flashTyping() {
  $("#typingNotice").classList.remove("hidden");
  clearTimeout(flashTyping.timer);
  flashTyping.timer = setTimeout(() => $("#typingNotice").classList.add("hidden"), 1800);
}

async function api(url, options = {}) {
  const response = await fetch(url, {
    method: options.method || "GET",
    headers: { "Content-Type": "application/json" },
    body: options.body ? JSON.stringify(options.body) : undefined
  });
  if (!response.ok) throw new Error(`HTTP ${response.status}`);
  return response.json();
}

function debounce(fn, delay) {
  let timer;
  return (...args) => {
    clearTimeout(timer);
    timer = setTimeout(() => fn(...args), delay);
  };
}

function escapeHtml(value) {
  return String(value ?? "").replace(/[&<>"']/g, (char) => ({
    "&": "&amp;",
    "<": "&lt;",
    ">": "&gt;",
    '"': "&quot;",
    "'": "&#039;"
  })[char]);
}

function flag(countryCode) {
  if (!countryCode || countryCode.length !== 2) return "";
  return countryCode.toUpperCase().replace(/./g, (char) => String.fromCodePoint(127397 + char.charCodeAt()));
}