/**
 * DOM 构建模块 - 悬浮按钮 + 聊天弹窗容器
 */
import { ResolvedConfig } from './types';
import { debounce } from './utils';

// ==================== 悬浮按钮 ====================

/** 创建悬浮按钮 */
export function createLauncher(config: ResolvedConfig, onClick: () => void): HTMLElement {
  const launcher = document.createElement('div');
  launcher.id = 'csk-launcher';
  launcher.className = `csk-launcher csk-launcher--${config.position === 'left-bottom' ? 'left' : 'right'}`;
  launcher.setAttribute('title', config.title);
  launcher.setAttribute('aria-label', config.title);
  launcher.setAttribute('role', 'button');
  launcher.setAttribute('tabindex', '0');

  // 图标内容
  launcher.innerHTML = config.launcherIcon;

  // 点击事件（300ms 防抖）
  const debouncedClick = debounce(onClick, 300);
  launcher.addEventListener('click', debouncedClick);

  // 键盘支持
  launcher.addEventListener('keydown', (e) => {
    if (e.key === 'Enter' || e.key === ' ') {
      e.preventDefault();
      debouncedClick();
    }
  });

  return launcher;
}

// ==================== 聊天弹窗 ====================

/** 创建聊天弹窗完整结构，返回各区域引用 */
export function createChatWindow(config: ResolvedConfig): {
  window: HTMLElement;
  messagesContainer: HTMLElement;
  inputEl: HTMLTextAreaElement;
  sendBtn: HTMLElement;
  clearBtn: HTMLElement | null;
  showLoading: () => HTMLElement;
  hideLoading: () => void;
} {
  // 最外层容器
  const windowEl = document.createElement('div');
  windowEl.id = 'csk-window';
  windowEl.className = `csk-root csk-window csk-window--${config.position === 'left-bottom' ? 'left' : 'right'} csk-window--hidden`;

  // === 头部 ===
  const header = document.createElement('div');
  header.className = 'csk-header';

  const titleEl = document.createElement('span');
  titleEl.className = 'csk-header__title';
  titleEl.textContent = config.title;

  const actions = document.createElement('div');
  actions.className = 'csk-header__actions';

  // 最小化按钮
  const minimizeBtn = document.createElement('button');
  minimizeBtn.className = 'csk-header__btn csk-header__btn--minimize';
  minimizeBtn.setAttribute('title', '最小化');
  minimizeBtn.innerHTML = `<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><line x1="5" y1="12" x2="19" y2="12"/></svg>`;
  minimizeBtn.addEventListener('click', () => {
    windowEl.classList.add('csk-window--hidden');
  });

  // 关闭按钮
  const closeBtn = document.createElement('button');
  closeBtn.className = 'csk-header__btn csk-header__btn--close';
  closeBtn.setAttribute('title', '关闭');
  closeBtn.innerHTML = `<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><line x1="18" y1="6" x2="6" y2="18"/><line x1="6" y1="6" x2="18" y2="18"/></svg>`;
  closeBtn.addEventListener('click', () => {
    windowEl.classList.add('csk-window--hidden');
  });

  actions.appendChild(minimizeBtn);
  actions.appendChild(closeBtn);
  header.appendChild(titleEl);
  header.appendChild(actions);

  // === 消息区 ===
  const messagesContainer = document.createElement('div');
  messagesContainer.id = 'csk-messages';
  messagesContainer.className = 'csk-messages';

  // === 输入区 ===
  const inputArea = document.createElement('div');
  inputArea.className = 'csk-input-area';

  const inputEl = document.createElement('textarea');
  inputEl.id = 'csk-input';
  inputEl.className = 'csk-input';
  inputEl.setAttribute('placeholder', '输入您的问题...');
  inputEl.setAttribute('rows', '1');
  inputEl.setAttribute('autofocus', '');

  const sendBtn = document.createElement('button');
  sendBtn.id = 'csk-send-btn';
  sendBtn.className = 'csk-send-btn';
  sendBtn.setAttribute('title', '发送');
  sendBtn.setAttribute('disabled', 'true');
  sendBtn.innerHTML = `<svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><line x1="22" y1="2" x2="11" y2="13"/><polygon points="22 2 15 22 11 13 2 9 22 2"/></svg>`;

  inputArea.appendChild(inputEl);
  inputArea.appendChild(sendBtn);

  // === 组装 ===
  windowEl.appendChild(header);
  windowEl.appendChild(messagesContainer);
  windowEl.appendChild(inputArea);

  // 清空按钮（可选）
  let clearBtn: HTMLElement | null = null;
  if (config.showClear) {
    clearBtn = document.createElement('button');
    clearBtn.className = 'csk-clear-btn';
    clearBtn.textContent = '清空对话';
    clearBtn.style.display = 'none'; // 初始隐藏，有消息后才显示
    // 插入到 messages 之后、inputArea 之前
    windowEl.insertBefore(clearBtn, inputArea);
  }

  // === Loading 动画 ===
  let loadingEl: HTMLElement | null = null;

  function showLoading(): HTMLElement {
    if (loadingEl) {
      loadingEl.style.display = 'flex';
      return loadingEl;
    }
    const el = document.createElement('div');
    el.className = 'csk-loading';
    el.innerHTML = `
      <div class="csk-loading__dot"></div>
      <div class="csk-loading__dot"></div>
      <div class="csk-loading__dot"></div>
    `;
    messagesContainer.appendChild(el);
    loadingEl = el;
    return el;
  }

  function hideLoading(): void {
    if (loadingEl && loadingEl.parentNode) {
      loadingEl.parentNode.removeChild(loadingEl);
      loadingEl = null;
    }
  }

  return {
    window: windowEl,
    messagesContainer,
    inputEl,
    sendBtn,
    clearBtn,
    showLoading,
    hideLoading,
  };
}

// ==================== 拖拽支持 ====================

/** 启用弹窗拖拽 */
export function enableDrag(headerEl: HTMLElement, windowEl: HTMLElement): () => void {
  let dragging = false;
  let startX = 0;
  let startY = 0;
  let offsetX = 0;
  let offsetY = 0;

  const onMouseDown = (e: MouseEvent) => {
    dragging = true;
    startX = e.clientX;
    startY = e.clientY;
    const rect = windowEl.getBoundingClientRect();
    offsetX = startX - rect.left;
    offsetY = startY - rect.top;
    document.addEventListener('mousemove', onMouseMove);
    document.addEventListener('mouseup', onMouseUp);
  };

  const onMouseMove = (e: MouseEvent) => {
    if (!dragging) return;
    const x = e.clientX - offsetX;
    const y = e.clientY - offsetY;
    // 边界限制，防止拖出视口
    const maxX = window.innerWidth - windowEl.offsetWidth;
    const maxY = window.innerHeight - windowEl.offsetHeight;
    windowEl.style.right = 'auto';
    windowEl.style.bottom = 'auto';
    windowEl.style.left = `${Math.max(0, Math.min(x, maxX))}px`;
    windowEl.style.top = `${Math.max(0, Math.min(y, maxY))}px`;
  };

  const onMouseUp = () => {
    dragging = false;
    document.removeEventListener('mousemove', onMouseMove);
    document.removeEventListener('mouseup', onMouseUp);
  };

  headerEl.addEventListener('mousedown', onMouseDown);

  // 清理函数
  return () => {
    headerEl.removeEventListener('mousedown', onMouseDown);
    document.removeEventListener('mousemove', onMouseMove);
    document.removeEventListener('mouseup', onMouseUp);
  };
}

// ==================== 消息渲染 ====================

/** 渲染用户消息气泡 */
export function renderUserBubble(container: HTMLElement, text: string, timestamp: number): HTMLElement {
  const wrapper = document.createElement('div');
  wrapper.className = 'csk-msg csk-msg--user';

  const bubble = document.createElement('div');
  bubble.className = 'csk-msg__bubble';
  bubble.textContent = text;

  const time = document.createElement('div');
  time.className = 'csk-msg__time';
  time.textContent = formatTime(timestamp);

  wrapper.appendChild(bubble);
  wrapper.appendChild(time);
  container.appendChild(wrapper);

  return wrapper;
}

/** 渲染 AI 消息气泡 */
export function renderAIBubble(container: HTMLElement, text: string, timestamp: number): HTMLElement {
  const wrapper = document.createElement('div');
  wrapper.className = 'csk-msg csk-msg--ai';

  const bubble = document.createElement('div');
  bubble.className = 'csk-msg__bubble';
  bubble.textContent = text;

  const time = document.createElement('div');
  time.className = 'csk-msg__time';
  time.textContent = formatTime(timestamp);

  wrapper.appendChild(bubble);
  wrapper.appendChild(time);
  container.appendChild(wrapper);

  return wrapper;
}

/** 创建空的 AI 气泡（流式追加用） */
export function createEmptyAIBubble(container: HTMLElement, timestamp: number): { wrapper: HTMLElement; bubble: HTMLElement } {
  const wrapper = document.createElement('div');
  wrapper.className = 'csk-msg csk-msg--ai';

  const bubble = document.createElement('div');
  bubble.className = 'csk-msg__bubble';
  bubble.innerHTML = '';

  const time = document.createElement('div');
  time.className = 'csk-msg__time';
  time.textContent = formatTime(timestamp);

  wrapper.appendChild(bubble);
  wrapper.appendChild(time);
  container.appendChild(wrapper);

  return { wrapper, bubble };
}

/** 滚动消息区到底部 */
export function scrollToBottom(container: HTMLElement): void {
  container.scrollTop = container.scrollHeight;
}

/** 格式化时间戳 */
function formatTime(timestamp: number): string {
  const d = new Date(timestamp);
  const hh = String(d.getHours()).padStart(2, '0');
  const mm = String(d.getMinutes()).padStart(2, '0');
  return `${hh}:${mm}`;
}