/**
 * Markdown工具模块
 * 提供Markdown相关的辅助函数
 */

/**
 * 提取Markdown中的标题用于目录
 */
export function extractHeadings(content: string): Array<{
  level: number;
  text: string;
  id: string;
}> {
  const headingRegex = /^(#{1,6})\s+(.+)$/gm;
  const headings: Array<{ level: number; text: string; id: string }> = [];
  let match;

  while ((match = headingRegex.exec(content)) !== null) {
    const level = match[1].length;
    const text = match[2].trim();
    const id = text.toLowerCase().replace(/[^\w\u4e00-\u9fa5]+/g, '-');

    headings.push({ level, text, id });
  }

  return headings;
}

/**
 * 计算阅读时间
 */
export function calculateReadingTime(content: string): number {
  const chineseChars = content.match(/[\u4e00-\u9fa5]/g) || [];
  const englishWords = content.match(/\b\w+\b/g) || [];

  const chineseTime = chineseChars.length / 500;
  const englishTime = englishWords.length / 200;

  return Math.max(1, Math.ceil(chineseTime + englishTime));
}

/**
 * 计算字数统计
 */
export function calculateWordCount(content: string): {
  characters: number;
  words: number;
  lines: number;
} {
  const chineseChars = content.match(/[\u4e00-\u9fa5]/g) || [];
  const englishWords = content.match(/\b\w+\b/g) || [];
  const lines = content.split('\n').length;

  return {
    characters: chineseChars.length,
    words: englishWords.length,
    lines,
  };
}

/**
 * 自动保存到本地存储
 */
export function saveToLocalStorage(key: string, content: string): void {
  try {
    localStorage.setItem(`markdown-editor-${key}`, content);
  } catch (error) {
    console.warn('Failed to save to localStorage:', error);
  }
}

/**
 * 从本地存储加载内容
 */
export function loadFromLocalStorage(key: string): string | null {
  try {
    return localStorage.getItem(`markdown-editor-${key}`);
  } catch (error) {
    console.warn('Failed to load from localStorage:', error);
    return null;
  }
}

/**
 * 格式化文件大小
 */
export function formatFileSize(bytes: number): string {
  if (bytes === 0) return '0 B';

  const k = 1024;
  const sizes = ['B', 'KB', 'MB', 'GB'];
  const i = Math.floor(Math.log(bytes) / Math.log(k));

  return `${parseFloat((bytes / Math.pow(k, i)).toFixed(2))} ${sizes[i]}`;
}

/**
 * 格式化时间戳
 */
export function formatDate(timestamp: number): string {
  const date = new Date(timestamp);
  const now = new Date();
  const diff = now.getTime() - date.getTime();

  if (diff < 60000) return '刚刚';
  if (diff < 3600000) return `${Math.floor(diff / 60000)}分钟前`;
  if (diff < 86400000) return `${Math.floor(diff / 3600000)}小时前`;
  if (diff < 604800000) return `${Math.floor(diff / 86400000)}天前`;

  return date.toLocaleDateString('zh-CN');
}