document.addEventListener('DOMContentLoaded', () => {
  const app = document.getElementById('chat-app');
  if (!app) return;

  const twilioSelect = document.getElementById('twilio-select');
  const conversationList = document.getElementById('conversation-list');
  const messageList = document.getElementById('message-list');
  const messageForm = document.getElementById('message-form');
  const messageInput = document.getElementById('message-input');
  const conversationTitle = document.getElementById('conversation-title');
  const conversationStatus = document.getElementById('conversation-status');
  const searchInput = document.getElementById('search-input');
  const addContactForm = document.getElementById('add-contact-form');
  const alertBox = document.getElementById('chat-alert');

  let activeConversationId = null;
  let activeTwilioId = twilioSelect ? twilioSelect.value : null;
  let pollTimer = null;

  const showAlert = (text, type = 'info') => {
    if (!alertBox) return;
    alertBox.textContent = text;
    alertBox.className = `alert alert-${type} alert-inline`;
    alertBox.classList.remove('d-none');
    setTimeout(() => alertBox.classList.add('d-none'), 3000);
  };

  const formatTime = (iso) => {
    if (!iso) return '';
    const dt = new Date(iso.replace(' ', 'T'));
    return dt.toLocaleString();
  };

  const renderConversations = (items) => {
    conversationList.innerHTML = '';
    if (!items.length) {
      conversationList.innerHTML = '<div class="p-3 muted">暂无会话。添加号码开始对话。</div>';
      return;
    }
    items.forEach((item) => {
      const div = document.createElement('div');
      div.className = 'conversation-item' + (item.id === activeConversationId ? ' active' : '');
      div.dataset.id = item.id;
      div.innerHTML = `
        <div class="conversation-avatar">${(item.name || item.phone).slice(0, 2).toUpperCase()}</div>
        <div class="conversation-meta">
          <div class="fw-semibold">${item.name || item.phone}</div>
          <small>${item.last_message || '暂无消息'}</small>
        </div>
        <small class="text-muted">${item.last_time ? formatTime(item.last_time) : ''}</small>
      `;
      div.addEventListener('click', () => {
        activeConversationId = item.id;
        conversationTitle.textContent = item.name || item.phone;
        conversationStatus.textContent = item.phone;
        fetchMessages();
        fetchConversations();
      });
      conversationList.appendChild(div);
    });
  };

  const renderMessages = (items) => {
    messageList.innerHTML = '';
    if (!items.length) {
      messageList.innerHTML = '<div class="muted">暂无消息，开始发送第一条短信。</div>';
      return;
    }
    items.forEach((msg) => {
      const div = document.createElement('div');
      div.className = `message ${msg.direction === 'outbound' ? 'outbound' : 'inbound'}`;
      div.innerHTML = `
        <div>${msg.body}</div>
        <span class="timestamp">${formatTime(msg.created_at)}</span>
      `;
      messageList.appendChild(div);
    });
    messageList.scrollTop = messageList.scrollHeight;
  };

  const fetchConversations = async () => {
    if (!activeTwilioId) return;
    const res = await fetch(`api/conversations.php?twilio_number_id=${activeTwilioId}`);
    const data = await res.json();
    renderConversations(data.items || []);
    if (!activeConversationId && data.items && data.items.length) {
      activeConversationId = data.items[0].id;
      conversationTitle.textContent = data.items[0].name || data.items[0].phone;
      conversationStatus.textContent = data.items[0].phone;
      fetchMessages();
    }
  };

  const fetchMessages = async () => {
    if (!activeConversationId) {
      renderMessages([]);
      return;
    }
    const res = await fetch(`api/messages.php?conversation_id=${activeConversationId}`);
    const data = await res.json();
    renderMessages(data.items || []);
  };

  const startPolling = () => {
    if (pollTimer) clearInterval(pollTimer);
    pollTimer = setInterval(() => {
      fetchConversations();
      fetchMessages();
    }, 5000);
  };

  if (twilioSelect) {
    twilioSelect.addEventListener('change', () => {
      activeTwilioId = twilioSelect.value;
      activeConversationId = null;
      conversationTitle.textContent = '请选择会话';
      conversationStatus.textContent = '';
      fetchConversations();
      fetchMessages();
    });
  }

  if (searchInput) {
    searchInput.addEventListener('input', () => {
      const term = searchInput.value.toLowerCase();
      const items = conversationList.querySelectorAll('.conversation-item');
      items.forEach((item) => {
        const text = item.textContent.toLowerCase();
        item.style.display = text.includes(term) ? 'flex' : 'none';
      });
    });
  }

  if (messageForm) {
    messageForm.addEventListener('submit', async (e) => {
      e.preventDefault();
      const body = messageInput.value.trim();
      if (!body) return;
      if (!activeConversationId) {
        showAlert('请先选择一个会话。', 'warning');
        return;
      }
      messageInput.value = '';
      const res = await fetch('api/send_message.php', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ conversation_id: activeConversationId, body })
      });
      const data = await res.json();
      if (!data.success) {
        showAlert(data.error || '发送失败', 'danger');
      }
      fetchMessages();
      fetchConversations();
    });
  }

  if (addContactForm) {
    addContactForm.addEventListener('submit', async (e) => {
      e.preventDefault();
      const formData = new FormData(addContactForm);
      formData.append('twilio_number_id', activeTwilioId || '');
      const res = await fetch('api/add_contact.php', {
        method: 'POST',
        body: formData
      });
      const data = await res.json();
      if (data.success) {
        activeConversationId = data.conversation_id;
        fetchConversations();
        fetchMessages();
        showAlert('已添加号码并创建会话。', 'success');
        const modal = bootstrap.Modal.getInstance(document.getElementById('addContactModal'));
        if (modal) modal.hide();
        addContactForm.reset();
      } else {
        showAlert(data.error || '添加失败', 'danger');
      }
    });
  }

  fetchConversations();
  fetchMessages();
  startPolling();
});