/**
 * 格式化工具函数
 */

/**
 * 格式化日期时间
 * @param {string|Date|number} dateTimeStr
 * @param {string} [fallback] - 无效日期时的回退文本
 * @returns {string}
 */
export function formatDateTime(dateTimeStr, fallback = '-') {
  if (!dateTimeStr) return fallback
  
  const date = new Date(dateTimeStr)
  if (isNaN(date.getTime())) return fallback
  
  const pad = (n) => String(n).padStart(2, '0')
  
  const year = date.getFullYear()
  const month = pad(date.getMonth() + 1)
  const day = pad(date.getDate())
  const hours = pad(date.getHours())
  const minutes = pad(date.getMinutes())
  const seconds = pad(date.getSeconds())
  
  return `${year}-${month}-${day} ${hours}:${minutes}:${seconds}`
}

/**
 * 格式化时间（简化版）
 * @param {string|Date|number} timeStr
 * @param {string} [fallback]
 * @returns {string}
 */
export function formatTime(timeStr, fallback = '-') {
  if (!timeStr) return fallback
  
  const date = new Date(timeStr)
  if (isNaN(date.getTime())) return fallback
  
  return date.toLocaleString('zh-CN')
}

/**
 * 格式化数字（添加千分位）
 * @param {number} num
 * @param {number} [decimals] - 小数位数
 * @returns {string}
 */
export function formatNumber(num, decimals = 0) {
  if (typeof num !== 'number' || isNaN(num)) return '-'
  return num.toLocaleString('zh-CN', {
    minimumFractionDigits: decimals,
    maximumFractionDigits: decimals
  })
}

/**
 * 格式化百分比
 * @param {number} value
 * @param {number} [total]
 * @param {number} [decimals]
 * @returns {string}
 */
export function formatPercent(value, total, decimals = 1) {
  if (total !== undefined) {
    if (!total) return '0%'
    value = (value / total) * 100
  }
  return `${value.toFixed(decimals)}%`
}

/**
 * 格式化文件大小
 * @param {number} bytes
 * @param {number} [decimals]
 * @returns {string}
 */
export function formatFileSize(bytes, decimals = 2) {
  if (bytes === 0) return '0 B'
  
  const k = 1024
  const sizes = ['B', 'KB', 'MB', 'GB', 'TB']
  const i = Math.floor(Math.log(bytes) / Math.log(k))
  
  return `${(bytes / Math.pow(k, i)).toFixed(decimals)} ${sizes[i]}`
}

/**
 * 格式化时长（秒转可读文本）
 * @param {number} seconds
 * @returns {string}
 */
export function formatDuration(seconds) {
  if (!seconds || seconds < 0) return '-'
  
  const hours = Math.floor(seconds / 3600)
  const minutes = Math.floor((seconds % 3600) / 60)
  const secs = Math.floor(seconds % 60)
  
  if (hours > 0) {
    return `${hours}小时${minutes}分${secs}秒`
  } else if (minutes > 0) {
    return `${minutes}分${secs}秒`
  } else {
    return `${secs}秒`
  }
}