const state = {
  site: null,
  snippet: "",
  conversations: [],
  visitors: [],
  visitorsLoaded: false,
  activeId: null,
  active: null,
  events: null,
  statusFilter: "active",
  hideBots: localStorage.getItem("mf_admin_hide_bots") !== "0",
  replyFiles: [],
  attentionTimer: null,
  attentionOn: false,
  originalTitle: document.title,
  originalFavicon: document.querySelector("link[rel='icon']")?.href || "/favicon.svg"
};

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"));
$("#settingsForm").brand.addEventListener("input", (event) => {
  $("#settingsForm").brandHex.value = normalizeHexColor(event.target.value) || event.target.value;
});
$("#settingsForm").brandHex.addEventListener("input", (event) => {
  const color = normalizeHexColor(event.target.value);
  if (color) $("#settingsForm").brand.value = color;
});

window.addEventListener("focus", stopAttention);
document.addEventListener("visibilitychange", () => {
  if (!document.hidden) stopAttention();
});

$("#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 = normalizeHexColor(form.get("brandHex")) || 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"));
  settings.launcherEffects = {
    breathe: form.get("launcherBreathe") === "on",
    ring: form.get("launcherRing") === "on",
    hoverLabel: form.get("launcherHoverLabel") === "on",
    avatar: form.get("launcherAvatar") === "on"
  };
  settings.notifications = settings.notifications || {};
  settings.notifications.pulseOnAdminReply = form.get("messagePulse") === "on";
  settings.notifications.badgeOnAdminReply = form.get("messageBadge") === "on";
  settings.notifications.labelOnAdminReply = form.get("messageLabel") === "on";
  settings.notifications.wiggleOnAdminReply = form.get("messageWiggle") === "on";
  await saveSite({ settings, isOnline: state.site.isOnline });
  $("#settingsPanel").classList.add("hidden");
});

$("#replyForm").addEventListener("submit", async (event) => {
  event.preventDefault();
  if (!state.activeId) return;
  const replyForm = event.currentTarget;
  const textarea = replyForm.querySelector("textarea[name='message']");
  const originalMessage = textarea.value;
  const form = new FormData(replyForm);
  const payload = {
    message: form.get("message") || "",
    attachments: await Promise.all(state.replyFiles.slice(0, 3).map(fileToPayload))
  };
  if (!payload.message.trim() && !payload.attachments.length) return;
  clearReplyComposer(replyForm);
  try {
    await api(`/api/admin/conversations/${state.activeId}/messages`, {
      method: "POST",
      body: payload
    });
    clearReplyComposer(replyForm);
    setTimeout(() => clearReplyComposer(replyForm), 0);
    setTimeout(() => clearReplyComposer(replyForm), 120);
    state.replyFiles = [];
    renderReplyAttachments();
    await openConversation(state.activeId);
    clearReplyComposer(replyForm);
  } catch (error) {
    textarea.value = originalMessage;
    textarea.defaultValue = originalMessage;
    throw error;
  }
});

$("#replyForm textarea").addEventListener("keydown", (event) => {
  if (event.key !== "Enter" || event.shiftKey) return;
  event.preventDefault();
  $("#replyForm").requestSubmit();
});

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

$("#replyForm input[name='attachments']").addEventListener("change", (event) => {
  addReplyFiles([...event.target.files]);
  event.target.value = "";
});

for (const eventName of ["dragenter", "dragover"]) {
  $(".conversation").addEventListener(eventName, (event) => {
    event.preventDefault();
    if (!state.activeId) return;
    $("#replyForm").classList.add("dragging");
  });
}

for (const eventName of ["dragleave", "drop"]) {
  $(".conversation").addEventListener(eventName, (event) => {
    event.preventDefault();
    $("#replyForm").classList.remove("dragging");
  });
}

$(".conversation").addEventListener("drop", (event) => {
  if (!state.activeId) return;
  addReplyFiles([...event.dataTransfer.files]);
});

$(".conversation").addEventListener("paste", (event) => {
  if (!state.activeId) return;
  const files = [...event.clipboardData?.items || []]
    .filter((item) => item.kind === "file")
    .map((item) => item.getAsFile())
    .filter(Boolean);
  if (!files.length) return;
  event.preventDefault();
  addReplyFiles(files);
});

$("#replyAttachments").addEventListener("click", (event) => {
  const removeButton = event.target.closest("[data-remove-reply]");
  if (!removeButton) return;
  state.replyFiles.splice(Number(removeButton.dataset.removeReply), 1);
  renderReplyAttachments();
});

$("#conversationFilter").addEventListener("change", () => {
  state.statusFilter = $("#conversationFilter").value;
  renderConversations();
});

$("#hideBotsToggle").addEventListener("click", () => {
  state.hideBots = !state.hideBots;
  localStorage.setItem("mf_admin_hide_bots", state.hideBots ? "1" : "0");
  renderVisitors();
});

$("#conversationList").addEventListener("click", async (event) => {
  const photoButton = event.target.closest("[data-photo-url]");
  const openButton = event.target.closest("[data-open]");
  const deleteButton = event.target.closest("[data-delete]");
  if (photoButton) {
    openPhotoPreview(photoButton.dataset.photoUrl, photoButton.dataset.photoName);
    return;
  }
  if (deleteButton) {
    await deleteConversation(deleteButton.dataset.delete);
    return;
  }
  if (openButton) await openConversation(openButton.dataset.open);
});

$("#conversationList").addEventListener("click", async (event) => {
  const statusButton = event.target.closest("[data-status-button]");
  if (!statusButton) return;
  await updateConversationStatus(statusButton.dataset.statusButton, statusButton.dataset.status);
});

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

$("#visitorList").addEventListener("click", async (event) => {
  if (event.target.closest("a")) return;
  const card = event.target.closest("[data-visitor-conversation]");
  const conversationId = card?.dataset.visitorConversation;
  if (!conversationId) return;
  await openConversation(conversationId);
});

$("#conversationHeader").addEventListener("click", async (event) => {
  const button = event.target.closest("[data-rename-visitor]");
  if (!button) return;
  event.preventDefault();
  await renameVisitor(button.dataset.renameVisitor);
});

async function showApp() {
  $("#loginView").classList.add("hidden");
  $("#appView").classList.remove("hidden");
  await loadBootstrap();
  await Promise.all([loadConversations(), loadVisitors()]);
  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;
  syncConversationVisitors();
  renderConversations();
}

async function loadVisitors() {
  const data = await api("/api/admin/visitors");
  state.visitors = data.visitors;
  state.visitorsLoaded = true;
  syncConversationVisitors();
  renderConversations();
  renderVisitors();
}

async function openConversation(id) {
  stopAttention();
  state.activeId = id;
  const data = await api(`/api/admin/conversations/${id}`);
  state.active = data;
  const index = state.conversations.findIndex((item) => item.id === id);
  if (index >= 0) state.conversations[index] = { ...state.conversations[index], ...data.conversation };
  syncConversationVisitors();
  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;
    }
    if (data.type === "visitors:update") {
      state.visitors = data.visitors;
      state.visitorsLoaded = true;
      syncConversationVisitors();
      renderConversations();
      renderVisitors();
      return;
    }
    await loadConversations();
    if (data.type === "conversation:delete" && data.conversationId === state.activeId) {
      clearActiveConversation();
      return;
    }
    if (state.activeId) await openConversation(state.activeId).catch(() => clearActiveConversation());
    if (data.type === "conversation:new" || isVisitorMessageEvent(data)) 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 = normalizeHexColor(s.colors.brand) || "#0f8f6f";
  form.brandHex.value = form.brand.value;
  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;
  form.launcherBreathe.checked = s.launcherEffects?.breathe !== false;
  form.launcherRing.checked = s.launcherEffects?.ring !== false;
  form.launcherHoverLabel.checked = s.launcherEffects?.hoverLabel !== false;
  form.launcherAvatar.checked = s.launcherEffects?.avatar !== false;
  form.messagePulse.checked = s.notifications?.pulseOnAdminReply !== false;
  form.messageBadge.checked = s.notifications?.badgeOnAdminReply !== false;
  form.messageLabel.checked = s.notifications?.labelOnAdminReply !== false;
  form.messageWiggle.checked = s.notifications?.wiggleOnAdminReply !== false;
}

function renderConversations() {
  const conversations = filteredConversations();
  $("#conversationList").innerHTML = conversations.length ? conversations.map((item) => `
    <article class="conversation-item ${item.id === state.activeId ? "active" : ""} ${item.hasUnread ? "unread fresh" : ""}">
      <button class="conversation-open" type="button" data-open="${item.id}">
        <span class="row visitor-row">
          <span class="visitor-name-wrap">
            <span class="unread-dot" aria-label="${item.hasUnread ? "Neprecteno" : "Precteno"}"></span>
            <strong>${escapeHtml(conversationVisitorName(item))}</strong>
            ${presenceDot(item.visitorPresence)}
          </span>
          ${item.imageCount ? `<span class="photo-count">foto ${item.imageCount}</span>` : ""}
        </span>
        <span class="visitor-facts">
          <span title="Zeme">${visitorCountry(item)}</span>
          <span title="Doba na webu">${formatDuration(item.sessionSeconds)}</span>
          <span title="Navstivene stranky">${Number(item.pageCount || 0)} str.</span>
          <span title="Pocet chatu">${Number(item.visitorConversationCount || 1)}x chat</span>
        </span>
      </button>
      <div class="conversation-actions">
        ${statusButtons(item)}
        <button class="delete-chat" type="button" data-delete="${item.id}" aria-label="Smazat chat" title="Smazat chat">
          <svg viewBox="0 0 24 24" aria-hidden="true"><path d="M9 3h6l1 2h4v2H4V5h4l1-2Zm-2 6h10l-.7 11H7.7L7 9Zm3 2 .2 7h1.6l-.2-7H10Zm4 0-.2 7h1.6l.2-7H14Z"></path></svg>
        </button>
      </div>
    </article>
  `).join("") : `<p class="empty-list">Zadny chat pro vybrany filtr.</p>`;
}

function syncConversationVisitors() {
  if (!state.visitorsLoaded) return;
  const visitorsById = new Map(state.visitors.map((visitor) => [visitor.id, visitor]));
  state.conversations = state.conversations.map((item) => ({
    ...item,
    visitorOnline: visitorsById.has(item.visitorToken),
    visitorPresence: visitorsById.get(item.visitorToken)?.presence || "offline"
  }));
}

function conversationVisitorName(item) {
  return item.visitorAlias || item.visitor?.name || item.visitor?.email || item.visitorLabel || "Navstevnik";
}

function renderVisitors() {
  const visitors = state.hideBots ? state.visitors.filter((visitor) => !visitor.isBot) : state.visitors;
  const botCount = state.visitors.filter((visitor) => visitor.isBot).length;
  $("#hideBotsToggle").classList.toggle("active", state.hideBots);
  $("#hideBotsToggle").textContent = state.hideBots ? "Skryt boty" : "Boty videt";
  $("#visitorCount").textContent = `${visitors.length} na webu${state.hideBots && botCount ? ` · ${botCount} bot` : ""}`;
  $("#visitorList").innerHTML = visitors.length ? visitors.map((visitor) => `
    <article class="visitor-card ${visitor.lastConversationId ? "clickable" : ""} ${visitor.lastConversationId === state.activeId ? "active" : ""} ${visitor.isBot ? "bot" : ""}" data-visitor-conversation="${escapeHtml(visitor.lastConversationId || "")}">
      <div class="visitor-card-head">
        <span class="visitor-avatar">${escapeHtml(visitor.initials || "??")}</span>
        <div>
          <strong>${escapeHtml(visitor.label || "Navstevnik")}</strong>
          <small>${escapeHtml(visitor.isBot ? `bot: ${visitor.botReason || "crawler"}` : browserLabel(visitor.device))}</small>
        </div>
        ${presenceDot(visitor.presence)}
      </div>
      <div class="visitor-compact-meta">
        <span>${visitorCountry(visitor)}</span>
        <span>${formatDuration(visitor.sessionSeconds)}</span>
        <span>${Number(visitor.visitCount || visitor.pageCount || 1)} navst.</span>
        <span>${Number(visitor.conversationCount || 0)} chaty</span>
      </div>
      <a class="visitor-page" href="${escapeHtml(visitor.currentUrl || "#")}" target="_blank" rel="noreferrer">${escapeHtml(pageTitle(visitor))}</a>
      <div class="visitor-referrer">${visitor.referrer ? escapeHtml(referrerLabel(visitor.referrer)) : "primy vstup"}${visitor.lastConversationId ? "" : " · bez chatu"}</div>
    </article>
  `).join("") : `<p class="empty-list">Zatim nikdo online.</p>`;
}

function presenceDot(presence) {
  const value = ["active", "idle", "offline"].includes(presence) ? presence : "offline";
  const label = value === "active" ? "Aktivni" : value === "idle" ? "Neaktivni" : "Offline";
  return `<span class="presence-dot ${value}" aria-label="${label}" title="${label}"></span>`;
}

function pageTitle(visitor) {
  const history = Array.isArray(visitor.browsingHistory) ? visitor.browsingHistory : [];
  const current = history.find((item) => item.url === visitor.currentUrl) || history[history.length - 1];
  return current?.title || shortUrl(visitor.currentUrl) || "neznamá stranka";
}

function referrerLabel(value) {
  try {
    return new URL(value).hostname.replace(/^www\./, "");
  } catch {
    return shortUrl(value) || value;
  }
}

function browserLabel(device = {}) {
  const ua = String(device.userAgent || "");
  const browser = ua.includes("Edg/") ? "Edge"
    : ua.includes("Chrome/") ? "Chrome"
    : ua.includes("Firefox/") ? "Firefox"
    : ua.includes("Safari/") ? "Safari"
    : "Browser";
  return [device.platform || "zarizeni", browser].filter(Boolean).join(" - ");
}

function renderActive() {
  const { conversation, messages } = state.active;
  $("#conversationHeader").innerHTML = `
    <div class="visitor-head">
      <div class="visitor-summary-row">
        <button class="visitor-name-edit" type="button" data-rename-visitor="${escapeHtml(conversation.visitorToken)}" title="Prejmenovat navstevnika">
          <span>${escapeHtml(conversationVisitorName(conversation))}</span>
          <svg viewBox="0 0 24 24" aria-hidden="true"><path d="M4 17.5V20h2.5L17.8 8.7l-2.5-2.5L4 17.5Zm15.7-11.1a1 1 0 0 0 0-1.4L18.3 3.6a1 1 0 0 0-1.4 0l-1 1 2.5 2.5 1.3-.7Z"></path></svg>
        </button>
        ${presenceDot(conversation.visitorPresence)}
        <span class="country-pill" title="Zeme">${visitorCountry(conversation)}</span>
        <span title="Doba na webu">${formatDuration(conversation.sessionSeconds)}</span>
        <span title="Navstivene stranky">${Number(conversation.pageCount || 0)} str.</span>
        <span title="Pocet chatu">${Number(conversation.visitorConversationCount || 1)}x chat</span>
        ${visitorDetails(conversation)}
      </div>
    </div>
  `;
  $("#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>
      ${message.body ? `<p>${escapeHtml(message.body)}</p>` : ""}
      ${renderAttachments(message.attachments)}
    </article>
  `).join("") + adminReadReceipt(conversation, messages);
  $("#messages").scrollTop = $("#messages").scrollHeight;
}

async function renameVisitor(visitorToken) {
  if (!state.active?.conversation || !visitorToken) return;
  const currentName = conversationVisitorName(state.active.conversation);
  const nextName = window.prompt("Prejmenovat navstevnika", state.active.conversation.visitorAlias || currentName);
  if (nextName === null) return;
  const result = await api(`/api/admin/visitors/${encodeURIComponent(visitorToken)}`, {
    method: "PATCH",
    body: { displayName: nextName }
  });
  applyVisitorRename(visitorToken, result.label, result.displayName);
}

function applyVisitorRename(visitorToken, label, alias) {
  const update = (item) => item.visitorToken === visitorToken
    ? { ...item, visitorLabel: label, visitorAlias: alias || "" }
    : item;
  state.conversations = state.conversations.map(update);
  state.visitors = state.visitors.map((visitor) => visitor.id === visitorToken
    ? { ...visitor, label, visitorAlias: alias || "" }
    : visitor);
  if (state.active?.conversation?.visitorToken === visitorToken) {
    state.active.conversation = update(state.active.conversation);
  }
  renderConversations();
  renderVisitors();
  if (state.active) renderActive();
}

function adminReadReceipt(conversation, messages) {
  const lastAdminMessage = [...messages].reverse().find((message) => message.senderType === "admin");
  if (!lastAdminMessage) return "";
  const seenAt = conversation.visitorSeenAt;
  const isSeen = Boolean(seenAt && String(seenAt) >= String(lastAdminMessage.createdAt));
  const text = isSeen ? `Precteno zakaznikem ${formatTime(seenAt)}` : "Zatim neprecteno";
  return `<div class="read-receipt ${isSeen ? "seen" : "unseen"}">${escapeHtml(text)}</div>`;
}

function filteredConversations() {
  if (state.statusFilter === "all") return state.conversations;
  if (state.statusFilter === "active") return state.conversations.filter((item) => item.status === "new" || item.status === "open");
  return state.conversations.filter((item) => item.status === state.statusFilter);
}

function statusButtons(item) {
  return [
    ["new", "nove"],
    ["open", "otevrene"],
    ["resolved", "vyresene"]
  ].map(([value, label]) => `
    <button class="status-button ${value} ${item.status === value ? "active" : ""}" type="button" data-status-button="${item.id}" data-status="${value}">
      ${label}
    </button>
  `).join("");
}

function visitorCountry(item) {
  const countryCode = item.countryCode || countryFromLanguage(item.language) || countryFromTimezone(item.timezone);
  const code = String(countryCode || "").toUpperCase();
  if (!/^[A-Z]{2}$/.test(code)) return `<span class="country-badge unknown"><span class="flag-image">?</span><strong>?</strong></span>`;
  return `
    <span class="country-badge">
      <span class="flag-image" style="background-image:url('https://flagcdn.com/24x18/${code.toLowerCase()}.png')" aria-hidden="true"></span>
      <strong>${escapeHtml(code)}</strong>
    </span>
  `;
}

function visitorDetails(conversation) {
  const history = Array.isArray(conversation.browsingHistory) ? conversation.browsingHistory : [];
  const historyItems = history.length ? history.slice().reverse().map((item) => `
    <li>
      <a href="${escapeHtml(item.url || "#")}" target="_blank" rel="noreferrer">${escapeHtml(pageLabel(item))}</a>
      <small>${escapeHtml(formatVisitedAt(item.at))}</small>
    </li>
  `).join("") : `<li><span>Zatim bez historie.</span></li>`;
  return `
    <details class="visitor-details">
      <summary title="Detail navstevnika">
        <span aria-hidden="true">i</span>
      </summary>
      <div class="visitor-detail-popover">
        <div class="visitor-detail-grid">
          <span>Aktualne</span>
          <a href="${escapeHtml(conversation.currentUrl || "#")}" target="_blank" rel="noreferrer">${escapeHtml(shortUrl(conversation.currentUrl) || "-")}</a>
          <span>Prisiel z</span>
          ${conversation.referrer ? `<a href="${escapeHtml(conversation.referrer)}" target="_blank" rel="noreferrer">${escapeHtml(shortUrl(conversation.referrer))}</a>` : `<em>primy vstup / nezname</em>`}
          <span>Zarizeni</span>
          <em>${escapeHtml(deviceLabel(conversation.device, conversation.language, conversation.timezone))}</em>
        </div>
        <ol class="history-list">${historyItems}</ol>
      </div>
    </details>
  `;
}

function formatDuration(seconds) {
  const value = Number(seconds || 0);
  if (value < 60) return `${Math.max(0, value)}s`;
  const minutes = Math.floor(value / 60);
  if (minutes < 60) return `${minutes}m`;
  return `${Math.floor(minutes / 60)}h ${minutes % 60}m`;
}

async function updateConversationStatus(id, status) {
  await api(`/api/admin/conversations/${id}/status`, {
    method: "PATCH",
    body: { status }
  });
  const item = state.conversations.find((conversation) => conversation.id === id);
  if (item) item.status = status;
  if (state.active?.conversation?.id === id) state.active.conversation.status = status;
  renderConversations();
}

async function deleteConversation(id) {
  const item = state.conversations.find((conversation) => conversation.id === id);
  const label = item?.visitor?.name || item?.lastBody || "tento chat";
  if (!confirm(`Smazat ${label}? Tahle akce nejde vratit.`)) return;
  await api(`/api/admin/conversations/${id}`, { method: "DELETE" });
  state.conversations = state.conversations.filter((conversation) => conversation.id !== id);
  if (state.activeId === id) clearActiveConversation();
  renderConversations();
}

function clearActiveConversation() {
  state.activeId = null;
  state.active = null;
  $("#conversationHeader").innerHTML = `
    <div>
      <h2>Vyber konverzaci</h2>
    </div>
  `;
  $("#messages").innerHTML = "";
  $("#replyForm").classList.add("hidden");
}

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">${escapeHtml(attachment.name)}</a>`;
    }
    return `
      <figure class="photo-preview">
        <button class="photo-open" type="button" data-photo-url="${escapeHtml(attachment.url)}" data-photo-name="${escapeHtml(attachment.name)}">
          <img src="${escapeHtml(attachment.url)}" alt="${escapeHtml(attachment.name)}">
        </button>
        <figcaption>
          <span>${escapeHtml(attachment.name)}</span>
          <button class="photo-delete" type="button" data-delete-attachment="${attachment.id}" aria-label="Smazat fotku" title="Smazat fotku">
            <svg viewBox="0 0 24 24" aria-hidden="true"><path d="M9 3h6l1 2h4v2H4V5h4l1-2Zm-2 6h10l-.7 11H7.7L7 9Zm3 2 .2 7h1.6l-.2-7H10Zm4 0-.2 7h1.6l.2-7H14Z"></path></svg>
          </button>
        </figcaption>
      </figure>
    `;
  }).join("")}</div>`;
}

async function deleteAttachment(id) {
  if (!confirm("Smazat tuhle fotku?")) return;
  await api(`/api/admin/attachments/${id}`, { method: "DELETE" });
  if (state.activeId) await openConversation(state.activeId);
  await loadConversations();
}

function renderReplyAttachments() {
  $("#replyAttachments").innerHTML = state.replyFiles.map((file, index) => `
    <span class="reply-chip">
      <span>${escapeHtml(file.name)}</span>
      <button type="button" data-remove-reply="${index}" aria-label="Odebrat fotku">×</button>
    </span>
  `).join("");
}

function addReplyFiles(files) {
  state.replyFiles = mergeImageFiles(state.replyFiles, files);
  renderReplyAttachments();
}

function clearReplyComposer(form = $("#replyForm")) {
  const textarea = form?.querySelector("textarea[name='message']");
  if (!textarea) return;
  textarea.value = "";
  textarea.defaultValue = "";
  textarea.textContent = "";
  textarea.dispatchEvent(new Event("input", { bubbles: true }));
}

function mergeImageFiles(currentFiles, incomingFiles) {
  const allowedTypes = new Set(["image/jpeg", "image/png", "image/webp", "image/gif", "image/avif"]);
  const nextFiles = [...currentFiles];
  for (const file of incomingFiles) {
    if (!allowedTypes.has(file.type) || file.size <= 0 || file.size > 3_000_000) continue;
    const exists = nextFiles.some((item) => item.name === file.name && item.size === file.size && item.lastModified === file.lastModified);
    if (!exists) nextFiles.push(file);
    if (nextFiles.length === 3) break;
  }
  return nextFiles;
}

function fileToPayload(file) {
  return new Promise((resolve) => {
    const reader = new FileReader();
    reader.onload = () => resolve({ name: file.name, type: file.type, size: file.size, dataBase64: reader.result });
    reader.readAsDataURL(file);
  });
}

function countryFromLanguage(language) {
  const match = String(language || "").match(/-([A-Za-z]{2})\b/);
  return match ? match[1].toUpperCase() : null;
}

function countryFromTimezone(timezone) {
  const zones = {
    "Europe/Prague": "CZ",
    "Europe/Bratislava": "SK",
    "Europe/Warsaw": "PL",
    "Europe/Berlin": "DE",
    "Europe/Vienna": "AT",
    "Europe/Budapest": "HU"
  };
  return zones[String(timezone || "")] || null;
}

function shortUrl(value) {
  if (!value) return "";
  try {
    const url = new URL(value);
    const path = `${url.pathname}${url.search}`.replace(/\/$/, "");
    return `${url.hostname}${path || "/"}`;
  } catch {
    return String(value);
  }
}

function pageLabel(item) {
  return item.title || shortUrl(item.url) || item.url || "stranka";
}

function formatVisitedAt(value) {
  if (!value) return "";
  const date = new Date(value);
  if (Number.isNaN(date.getTime())) return "";
  return date.toLocaleTimeString("cs-CZ", { hour: "2-digit", minute: "2-digit" });
}

function formatTime(value) {
  const text = String(value || "");
  const normalized = /^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/.test(text) ? `${text.replace(" ", "T")}Z` : text;
  const date = new Date(normalized);
  if (Number.isNaN(date.getTime())) return "";
  return date.toLocaleTimeString("cs-CZ", { hour: "2-digit", minute: "2-digit" });
}

function deviceLabel(device = {}, language, timezone) {
  return [device.platform, device.viewport, language, timezone].filter(Boolean).join(" | ");
}

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() {
  startAttention();
  playNotifySound();
}

function playNotifySound() {
  const AudioCtor = window.AudioContext || window.webkitAudioContext;
  if (!AudioCtor) return;
  const audio = new AudioCtor();
  const gain = audio.createGain();
  gain.gain.value = 0.055;
  gain.connect(audio.destination);
  [0, 0.14].forEach((offset, index) => {
    const osc = audio.createOscillator();
    osc.type = "sine";
    osc.frequency.value = index ? 1040 : 820;
    osc.connect(gain);
    osc.start(audio.currentTime + offset);
    osc.stop(audio.currentTime + offset + 0.11);
  });
  setTimeout(() => audio.close().catch(() => {}), 520);
}

function startAttention() {
  if (state.attentionTimer) return;
  const favicon = document.querySelector("link[rel='icon']");
  const alertIcon = `data:image/svg+xml,${encodeURIComponent('<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64"><rect width="64" height="64" rx="14" fill="#0f8f6f"/><circle cx="46" cy="18" r="11" fill="#ff3b30"/><path fill="#fff" d="M18 24h22v6H18zm0 11h16v6H18z"/></svg>')}`;
  state.attentionTimer = setInterval(() => {
    state.attentionOn = !state.attentionOn;
    document.title = state.attentionOn ? "* Nova zprava - MaalFlows" : state.originalTitle;
    if (favicon) favicon.href = state.attentionOn ? alertIcon : state.originalFavicon;
  }, 760);
}

function stopAttention() {
  if (state.attentionTimer) clearInterval(state.attentionTimer);
  state.attentionTimer = null;
  state.attentionOn = false;
  document.title = state.originalTitle;
  const favicon = document.querySelector("link[rel='icon']");
  if (favicon) favicon.href = state.originalFavicon;
}

function isVisitorMessageEvent(data) {
  if (data.type !== "message:new") return false;
  const messages = data.payload?.messages || [];
  return messages[messages.length - 1]?.senderType === "visitor";
}

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 normalizeHexColor(value) {
  const match = String(value || "").trim().match(/^#?([0-9a-fA-F]{6})$/);
  return match ? `#${match[1].toLowerCase()}` : "";
}

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