// frontend/js/filechat.js — Chat intégré par fichier (#169)
// Panneau latéral : historique + saisie. Les messages entrants arrivent par
// SSE (event `chat_message` relayé depuis sync.js) ; si le panneau est fermé
// ou affiche un autre fichier, un toast notifie l'utilisateur.
import { api, AuthManager } from "./auth.js";
import { t } from "./i18n.js";
import { showToast } from "./ui.js";
import { escapeHtml } from "./utils.js";

const PANEL_ID = "file-chat-panel";
let _vault = null;
let _path = null;
let _sending = false;

function _panel() {
  let el = document.getElementById(PANEL_ID);
  if (!el) {
    el = document.createElement("aside");
    el.id = PANEL_ID;
    el.className = "file-chat-panel hidden";
    el.setAttribute("aria-label", t("chat.title"));
    document.body.appendChild(el);
  }
  return el;
}

function _esc(s) {
  return escapeHtml(String(s == null ? "" : s));
}

function _formatTime(ts) {
  try {
    return new Date(ts * 1000).toLocaleString(undefined, {
      day: "2-digit", month: "2-digit", hour: "2-digit", minute: "2-digit",
    });
  } catch (_) {
    return "";
  }
}

export function renderChatMessages(container, messages, currentUser) {
  container.innerHTML = "";
  if (!messages || messages.length === 0) {
    const empty = document.createElement("div");
    empty.className = "file-chat-empty";
    empty.textContent = t("chat.empty");
    container.appendChild(empty);
    return;
  }
  messages.forEach((m) => container.appendChild(_messageEl(m, currentUser)));
  container.scrollTop = container.scrollHeight;
}

function _messageEl(m, currentUser) {
  const mine = currentUser && m.user === currentUser;
  const wrap = document.createElement("div");
  wrap.className = "file-chat-msg" + (mine ? " mine" : "");
  wrap.dataset.id = m.id || "";
  const meta = document.createElement("div");
  meta.className = "file-chat-meta";
  meta.innerHTML =
    `<span class="file-chat-user">${_esc(m.user)}</span>` +
    `<span class="file-chat-ts">${_esc(_formatTime(m.ts))}</span>`;
  const body = document.createElement("div");
  body.className = "file-chat-body";
  body.textContent = m.text || "";
  wrap.appendChild(meta);
  wrap.appendChild(body);
  return wrap;
}

async function _load() {
  const panel = _panel();
  const list = panel.querySelector(".file-chat-list");
  try {
    const data = await api(
      `/api/file/${encodeURIComponent(_vault)}/chat?path=${encodeURIComponent(_path)}`,
    );
    renderChatMessages(list, data.messages || [], _currentUser());
  } catch (_) {
    list.innerHTML = "";
    const err = document.createElement("div");
    err.className = "file-chat-empty";
    err.textContent = t("chat.load_error");
    list.appendChild(err);
  }
}

function _currentUser() {
  const u = AuthManager.getUser();
  return (u && u.username) || "";
}

function _renderShell(panel) {
  panel.innerHTML = "";
  const header = document.createElement("div");
  header.className = "file-chat-header";
  const title = document.createElement("h3");
  title.textContent = t("chat.title");
  const close = document.createElement("button");
  close.type = "button";
  close.className = "file-chat-close";
  close.title = t("chat.close");
  close.setAttribute("aria-label", t("chat.close"));
  close.textContent = "✕";
  close.addEventListener("click", closeFileChat);
  header.appendChild(title);
  header.appendChild(close);

  const list = document.createElement("div");
  list.className = "file-chat-list";

  const form = document.createElement("form");
  form.className = "file-chat-form";
  const input = document.createElement("input");
  input.type = "text";
  input.className = "file-chat-input";
  input.placeholder = t("chat.placeholder");
  input.maxLength = 4000;
  input.setAttribute("aria-label", t("chat.placeholder"));
  const send = document.createElement("button");
  send.type = "submit";
  send.className = "file-chat-send";
  send.textContent = t("chat.send");
  form.appendChild(input);
  form.appendChild(send);
  form.addEventListener("submit", (e) => {
    e.preventDefault();
    _send(input);
  });

  panel.appendChild(header);
  panel.appendChild(list);
  panel.appendChild(form);
}

export async function openFileChat(vault, path) {
  _vault = vault;
  _path = path;
  const panel = _panel();
  _renderShell(panel);
  panel.classList.remove("hidden");
  await _load();
  const input = panel.querySelector(".file-chat-input");
  if (input) input.focus();
}

export function closeFileChat() {
  const panel = document.getElementById(PANEL_ID);
  if (panel) panel.classList.add("hidden");
}

export function toggleFileChat(vault, path) {
  const panel = document.getElementById(PANEL_ID);
  if (panel && !panel.classList.contains("hidden") && _vault === vault && _path === path) {
    closeFileChat();
    return;
  }
  openFileChat(vault, path);
}

async function _send(input) {
  if (_sending) return;
  const text = (input.value || "").trim();
  if (!text) return;
  _sending = true;
  try {
    const data = await api(`/api/file/${encodeURIComponent(_vault)}/chat`, {
      method: "POST",
      body: JSON.stringify({ path: _path, text }),
    });
    input.value = "";
    const list = _panel().querySelector(".file-chat-list");
    const empty = list.querySelector(".file-chat-empty");
    if (empty) empty.remove();
    list.appendChild(_messageEl(data.message, _currentUser()));
    list.scrollTop = list.scrollHeight;
  } catch (_) {
    showToast(t("chat.send_error"), "error");
  } finally {
    _sending = false;
    input.focus();
  }
}

// --- SSE relay (appelé par sync.js sur l'événement `chat_message`) ---------
export function onChatMessage(data) {
  if (!data || !data.message) return;
  const panel = document.getElementById(PANEL_ID);
  const isOpen =
    panel && !panel.classList.contains("hidden") &&
    _vault === data.vault && _path === data.path;
  if (isOpen) {
    const list = panel.querySelector(".file-chat-list");
    if (list) {
      const empty = list.querySelector(".file-chat-empty");
      if (empty) empty.remove();
      // Évite le doublon si l'envoi local a déjà rendu ce message
      const id = data.message.id;
      if (id && list.querySelector(`[data-id="${CSS.escape(id)}"]`)) return;
      list.appendChild(_messageEl(data.message, _currentUser()));
      list.scrollTop = list.scrollHeight;
    }
    return;
  }
  if (data.message.user === _currentUser()) return; // son propre message
  showToast(t("chat.new_message", { user: data.message.user }), "info");
}