import { directMessages } from '../mock-data.js';
import {
  getChatMessages,
  isSessionInvalidError,
  setContacts,
  state,
  terminateCurrentSession,
} from '../state.js';
import { loadCurrentRelations } from '../services/user-connections.js';
import { renderUserAvatar } from '../components/avatar-image.js';
import { loadProfileSnapshot } from '../services/user-profile-params.js';

export const pageMeta = { id: 'messages-list', title: 'Личные сообщения' };
const dmAvatarSnapshotCache = new Map();
const dmAvatarPendingByLogin = new Map();

async function loadDmAvatarSnapshot(login) {
  const cleanLogin = String(login || '').trim();
  if (!cleanLogin) return null;
  const key = cleanLogin.toLowerCase();
  if (dmAvatarSnapshotCache.has(key)) return dmAvatarSnapshotCache.get(key);
  if (dmAvatarPendingByLogin.has(key)) return dmAvatarPendingByLogin.get(key);
  const pending = loadProfileSnapshot(cleanLogin)
    .then((snapshot) => {
      dmAvatarSnapshotCache.set(key, snapshot || null);
      dmAvatarPendingByLogin.delete(key);
      return snapshot || null;
    })
    .catch(() => {
      dmAvatarSnapshotCache.set(key, null);
      dmAvatarPendingByLogin.delete(key);
      return null;
    });
  dmAvatarPendingByLogin.set(key, pending);
  return pending;
}

function createDmAvatar(login) {
  const cleanLogin = String(login || '').trim();
  const title = cleanLogin ? `Профиль ${cleanLogin}` : '';
  const avatarEl = renderUserAvatar({
    login: cleanLogin || 'unknown',
    size: 'small',
    title,
  });
  if (!cleanLogin) return avatarEl;
  void loadDmAvatarSnapshot(cleanLogin).then((snapshot) => {
    if (!avatarEl.isConnected) return;
    const upgraded = renderUserAvatar({
      login: cleanLogin,
      avatar: snapshot?.avatar?.txId
        ? {
          ar: String(snapshot.avatar.txId || '').trim(),
          sha256Hex: String(snapshot?.avatar?.sha256Hex || '').trim().toLowerCase(),
        }
        : null,
      size: 'small',
      title,
    });
    upgraded.classList.add('avatar');
    avatarEl.replaceWith(upgraded);
  });
  return avatarEl;
}

function formatChatRowTime(ts) {
  const value = Number(ts || 0);
  if (!Number.isFinite(value) || value <= 0) return '';
  return new Intl.DateTimeFormat('ru-RU', {
    day: '2-digit',
    month: '2-digit',
    hour: '2-digit',
    minute: '2-digit',
  }).format(new Date(value));
}

const SVG_CHEVRON = '<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><path d="M9 6l6 6-6 6"/></svg>';

export function render({ navigate }) {
  const screen = document.createElement('section');
  screen.className = 'stack dm-screen dm-list-screen';
  const login = String(state.session.login || '').trim();

  const head = document.createElement('header');
  head.className = 'dm-head';
  head.innerHTML = `
    <div class="dm-head-brand">
      <div class="dm-head-hex">${(login[0] || 'A').toUpperCase()}</div>
      <div class="dm-head-id">
        <span class="dm-head-name">${login}</span>
      </div>
    </div>
    <h1 class="dm-head-title">Контакты</h1>
    <button type="button" class="dm-head-plus" aria-label="Новый диалог">+</button>
  `;
  head.querySelector('.dm-head-plus')?.addEventListener('click', () => navigate('contact-search-view'));

  const divider = document.createElement('div');
  divider.className = 'dm-divider';

  const list = document.createElement('div');
  list.className = 'stack dm-list';

  function renderRow(item) {
    const row = document.createElement('article');
    row.className = 'list-item dm-dialog-card';
    const avatarEl = createDmAvatar(item.id);
    avatarEl.classList.add('avatar');
    const avatarWrap = document.createElement('div');
    avatarWrap.className = 'dm-av dm-av--default';
    avatarWrap.append(avatarEl);
    row.innerHTML = `
      <div class="dm-row-main">
        <div class="dm-row-titleline dm-row-titlewrap">
          <strong class="dm-row-title">${item.name}</strong>
          ${item.notInContacts ? '<span class="dm-contact-note">не в контактах</span>' : ''}
        </div>
        <p class="dm-row-last-message">${item.lastMessage}</p>
      </div>
      <div class="dm-row-meta-col">
        ${item.unread ? `<span class="dm-unread-badge">${item.unread > 99 ? '99+' : item.unread}</span>` : '<span class="dm-row-meta-spacer" aria-hidden="true"></span>'}
        <div class="dm-row-meta-line">
          ${item.time ? `<span class="dm-row-time">${item.time}</span>` : '<span class="dm-row-time dm-row-time--empty"></span>'}
          <span class="dm-chevron">${SVG_CHEVRON}</span>
        </div>
      </div>
    `;
    row.prepend(avatarWrap);
    row.addEventListener('click', () => navigate(`chat-view/${encodeURIComponent(item.id)}`));
    return row;
  }

  async function loadList() {
    try {
      const relations = await loadCurrentRelations();
      const contacts = relations.outContacts || [];
      setContacts(contacts);
      list.innerHTML = '';

      const contactRows = contacts.map((login) => {
        const preview = directMessages.find((item) => item.id.toLowerCase() === login.toLowerCase());
        const chat = getChatMessages(login);
        const lastChat = chat[chat.length - 1];
        const unread = chat.filter((m) => m?.from === 'in' && m?.unread).length;
        const lastTimeMs = Number(lastChat?.createdAtMs || 0);
        return {
          id: login,
          name: preview?.name || login,
          lastMessage: lastChat?.text || preview?.lastMessage || 'Диалог пока пуст.',
          time: formatChatRowTime(lastTimeMs),
          unread,
          notInContacts: false,
        };
      });

      const allChatIds = Object.keys(state.chats || {})
        .filter((id) => id && id.toLowerCase() !== String(state.session.login || '').toLowerCase())
        .filter((id) => (getChatMessages(id) || []).length > 0);

      const contactKeys = new Set(contacts.map((x) => String(x || '').toLowerCase()));
      const extraRows = allChatIds
        .filter((login) => !contactKeys.has(String(login || '').toLowerCase()))
        .map((login) => {
          const chat = getChatMessages(login);
          const lastChat = chat[chat.length - 1];
          const unread = chat.filter((m) => m?.from === 'in' && m?.unread).length;
          const lastTimeMs = Number(lastChat?.createdAtMs || 0);
          return {
            id: login,
            name: login,
            lastMessage: lastChat?.text || 'Диалог пока пуст.',
            time: formatChatRowTime(lastTimeMs),
            unread,
            notInContacts: true,
          };
        });

      const rows = [...contactRows, ...extraRows];
      if (!rows.length) {
        const empty = document.createElement('div');
        empty.className = 'card meta-muted';
        empty.textContent = 'Пока нет ни контактов, ни сообщений';
        list.append(empty);
        return;
      }

      rows.forEach((item) => list.append(renderRow(item)));
    } catch (error) {
      if (isSessionInvalidError(error)) {
        list.innerHTML = '';

        const card = document.createElement('div');
        card.className = 'card stack';

        const title = document.createElement('strong');
        title.textContent = 'Сессия устарела';

        const details = document.createElement('p');
        details.className = 'meta-muted';
        details.textContent = 'Ваша сессия больше не действует. Авторизуйтесь заново.';

        const okBtn = document.createElement('button');
        okBtn.type = 'button';
        okBtn.className = 'primary-btn';
        okBtn.textContent = 'ОК';
        okBtn.addEventListener('click', async () => {
          await terminateCurrentSession({
            infoMessage: 'Ваша сессия устарела. Выполните вход заново.',
          });
          navigate('start-view');
        });

        card.append(title, details, okBtn);
        list.append(card);
        return;
      }

      list.innerHTML = '';
      const fail = document.createElement('div');
      fail.className = 'card meta-muted';
      fail.textContent = `Не удалось загрузить сообщения: ${error.message || 'unknown'}`;
      list.append(fail);
    }
  }

  screen.append(head, divider, list);
  loadList();
  return screen;
}