// chat-sessions.js — 채팅 세션 저장/로드/전환/삭제 (sidebar 세션 목록).
// extracted from app.js (v4.3.19-3 split).

function saveChatSessions() {
  localStorage.setItem(chatSessionsKey(), JSON.stringify(chatSessions));
}

function makeSessionTitle(history) {
  const firstUser = (history || []).find(m => m.role === 'user');
  if (!firstUser) return 'New chat';
  // Strip markdown image/link syntax for clean session title
  let text = firstUser.content
    .replace(/!\[[^\]]*\]\([^)]+\)/g, '[image]')
    .replace(/\[[^\]]+\]\([^)]+\)/g, (m) => m.replace(/\[([^\]]*)\].*/, '$1'))
    .replace(/```[\s\S]*?```/g, '')
    .replace(/\n/g, ' ')
    .trim();
  return text.slice(0, 42) || 'New chat';
}

function loadChatSessions() {
  const key = chatSessionsKey();
  try {
    const raw = localStorage.getItem(key);
    if (raw) {
      chatSessions = JSON.parse(raw);
    } else {
      // Migrate from old non-namespaced key once, then delete it so other users can't see it.
      const oldRaw = localStorage.getItem(CHAT_SESSIONS_KEY_BASE);
      if (oldRaw) {
        chatSessions = JSON.parse(oldRaw);
        localStorage.setItem(key, oldRaw);
        localStorage.removeItem(CHAT_SESSIONS_KEY_BASE);
      } else {
        chatSessions = [];
      }
    }
  } catch {
    chatSessions = [];
  }
  if (!Array.isArray(chatSessions)) chatSessions = [];
  let isFreshDevice = false;
  if (chatSessions.length === 0) {
    isFreshDevice = true;
    const id = crypto?.randomUUID?.() || ('chat_' + Math.random().toString(36).slice(2));
    chatSessions.push({ id, title: 'New chat', history: [], processLog: [], createdAt: Date.now(), updatedAt: Date.now() });
    activeChatSessionId = id;
    setAgentSessionId(id);
    saveChatSessions();
  } else if (!activeChatSessionId || !chatSessions.some(s => s.id === activeChatSessionId)) {
    activeChatSessionId = chatSessions[0].id;
    setAgentSessionId(activeChatSessionId);
  }
  if (!agentSessionId || agentSessionId !== activeChatSessionId) setAgentSessionId(activeChatSessionId);
  syncActiveChat();
  // 서버 세션 목록과 비교해 누락된 세션을 사이드바에 추가
  syncServerSessions();
  // 새 기기에서 처음 열었다면, 다른 기기에서 이어가던 대화로 자동 복귀
  if (isFreshDevice) resumeMainSessionPointer();
}

// 메인챗의 "마지막 활성 세션"을 서버에 기록 — 다른 기기에서 새로 열었을 때 이어보기용
function updateMainSessionPointer(id) {
  if (!id) return;
  api('/api/user/app-sessions', { method: 'PUT', body: JSON.stringify({ appKey: 'main', sessionId: id }) }).catch(() => {});
}

async function resumeMainSessionPointer() {
  try {
    const d = await api('/api/user/app-sessions');
    const ptr = d && d.main;
    if (!ptr) { updateMainSessionPointer(activeChatSessionId); return; } // 최초 로그인: 이 세션을 기준점으로 등록
    if (ptr === activeChatSessionId) return;
    const cur = chatSessions.find(s => s.id === activeChatSessionId);
    if (cur && cur.history && cur.history.length > 0) return; // 이미 이 기기에서 대화가 시작됐으면 건드리지 않음
    const hd = await api('/api/chat/sessions/' + encodeURIComponent(ptr));
    if (!hd || !hd.success || !Array.isArray(hd.history) || hd.history.length === 0) return;
    // 비어있던 자리표시자 세션은 제거하고 포인터가 가리키는 세션으로 전환
    chatSessions = chatSessions.filter(s => s.id !== activeChatSessionId);
    let existing = chatSessions.find(s => s.id === ptr);
    if (!existing) {
      existing = { id: ptr, title: makeSessionTitle(hd.history), history: hd.history, processLog: [], createdAt: hd.createdAt || Date.now(), updatedAt: hd.lastActiveAt || Date.now() };
      chatSessions.unshift(existing);
    } else {
      existing.history = hd.history;
      delete existing.serverOnly;
    }
    activeChatSessionId = ptr;
    setAgentSessionId(ptr);
    saveChatSessions();
    syncActiveChat();
  } catch { /* 서버 미응답 시 무시 */ }
}

async function syncServerSessions() {
  try {
    const res = await fetch('/api/chat/sessions');
    if (!res.ok) return;
    const data = await res.json();
    if (!data.success || !Array.isArray(data.sessions)) return;
    let changed = false;
    for (const srv of data.sessions) {
      const existing = chatSessions.find(s => s.id === srv.id);
      if (!existing) {
        // 서버에만 있는 세션 → 스텁으로 추가 (history는 열 때 로드)
        chatSessions.push({
          id: srv.id,
          title: srv.title || 'New chat',
          history: [],
          processLog: [],
          createdAt: srv.createdAt,
          updatedAt: srv.lastActiveAt,
          serverOnly: true,  // 열 때 서버에서 history 로드
        });
        changed = true;
      } else if (existing.serverOnly) {
        // 이미 스텁으로 있으면 메타만 업데이트
        existing.title = srv.title || existing.title;
        existing.updatedAt = srv.lastActiveAt;
        changed = true;
      }
    }
    if (changed) {
      saveChatSessions();
      renderSessionsList();
    }
  } catch { /* 서버 미응답 시 무시 */ }
}

function syncActiveChat() {
  const sess = chatSessions.find(s => s.id === activeChatSessionId);
  chatHistory = sess ? (sess.history || []) : [];
  processLogEntries = sess ? (sess.processLog || []) : [];
  liveTaskSteps = [];  // clear live steps so a different session never inherits in-progress tool display
  // Mark session as read when opening it
  if (sess) sess.unread = false;
  renderChatMessages();
  renderProcessLog();
  renderLiveStepsPanel();
  renderSessionsList();
  updateStats([]);
  loadAgentSessionContext();
}

function persistActiveChat() {
  const idx = chatSessions.findIndex(s => s.id === activeChatSessionId);
  if (idx === -1) return;
  chatSessions[idx].history = chatHistory;
  chatSessions[idx].processLog = processLogEntries;
  chatSessions[idx].title = makeSessionTitle(chatHistory);
  chatSessions[idx].updatedAt = Date.now();
  saveChatSessions();
  renderSessionsList();
  updateStats([]);
}

function newChatSession() {
  const id = crypto?.randomUUID?.() || ('chat_' + Math.random().toString(36).slice(2));
  chatSessions.unshift({ id, title: 'New chat', history: [], processLog: [], createdAt: Date.now(), updatedAt: Date.now() });
  activeChatSessionId = id;
  setAgentSessionId(id);
  syncActiveChat();
  updateMainSessionPointer(id);
}

function toggleSessionsEditMode() {
  sessionsEditMode = !sessionsEditMode;
  const btn = document.getElementById('sessions-edit-btn');
  if (btn) btn.textContent = sessionsEditMode ? '완료' : '편집';
  renderSessionsList();
}

function deleteChatSession(id, ev) {
  if (ev) ev.stopPropagation();
  const idx = chatSessions.findIndex(s => s.id === id);
  if (idx === -1) return;

  chatSessions.splice(idx, 1);
  if (chatSessions.length === 0) {
    const newId = crypto?.randomUUID?.() || ('chat_' + Math.random().toString(36).slice(2));
    chatSessions.push({ id: newId, title: 'New chat', history: [], processLog: [], createdAt: Date.now(), updatedAt: Date.now() });
    activeChatSessionId = newId;
    setAgentSessionId(newId);
  } else if (activeChatSessionId === id) {
    activeChatSessionId = chatSessions[0].id;
    setAgentSessionId(activeChatSessionId);
  }

  saveChatSessions();
  syncActiveChat();
  updateMainSessionPointer(activeChatSessionId);
  // 서버 세션 파일도 삭제 (재로드 시 재등장 방지)
  api(`/api/chat/sessions/${id}`, { method: 'DELETE' }).catch(() => {});
}

function openSession(id) {
  activeChatSessionId = id;
  setAgentSessionId(id);
  updateMainSessionPointer(id);
  const sess = chatSessions.find(s => s.id === id);
  if (sess && sess.serverOnly && sess.history.length === 0) {
    // 서버에서 history 로드 후 렌더
    fetch(`/api/chat/sessions/${id}`)
      .then(r => r.json())
      .then(data => {
        if (data.success && Array.isArray(data.history)) {
          sess.history = data.history;
          sess.title = makeSessionTitle(data.history) || sess.title;
          delete sess.serverOnly;
          saveChatSessions();
          syncActiveChat();
          renderSessionsList();
        }
      })
      .catch(() => syncActiveChat());
    renderSessionsList(); // 즉시 세션 활성화 표시
    return;
  }
  syncActiveChat();
}

function markSessionUnread(sessionId) {
  const sess = chatSessions.find(s => s.id === sessionId);
  if (sess && sessionId !== activeChatSessionId) {
    sess.unread = true;
    renderSessionsList();
  }
}

// ---- Mode switching ----
function setMode(mode) {
  if (!['chat','bgtasks'].includes(mode)) mode = 'chat';
  currentMode = mode;
  document.getElementById('chat-view').style.display = mode === 'chat' ? 'flex' : 'none';
  const bgtView = document.getElementById('bgtasks-view');
  if (bgtView) bgtView.style.display = mode === 'bgtasks' ? 'flex' : 'none';
  const aside = document.querySelector('aside');
  const rightPanel = document.getElementById('right-panel');
  if (aside) aside.style.display = '';
  if (rightPanel) rightPanel.style.display = mode === 'chat' ? '' : 'none';
  // sidebar tab 하이라이트 동기화
  document.getElementById('tab-bgtasks')?.classList.toggle('active', mode === 'bgtasks');
  if (mode === 'bgtasks') refreshBgTasks();
}