/**
 * 通用工具函数
 */

/**
 * 格式化时间
 * @param {Date|string|number} timestamp 时间戳或日期字符串
 * @param {string} format 格式，默认：yyyy-MM-dd HH:mm:ss
 * @returns {string} 格式化后的时间字符串
 */
export const formatTime = (timestamp, format = 'yyyy-MM-dd HH:mm:ss') => {
  if (!timestamp) return ''
  
  const date = new Date(timestamp)
  if (isNaN(date.getTime())) return ''
  
  const map = {
    'M+': date.getMonth() + 1,
    'd+': date.getDate(),
    'H+': date.getHours(),
    'm+': date.getMinutes(),
    's+': date.getSeconds(),
    'q+': Math.floor((date.getMonth() + 3) / 3),
    'S': date.getMilliseconds()
  }
  
  if (/(y+)/.test(format)) {
    format = format.replace(RegExp.$1, (date.getFullYear() + '').substr(4 - RegExp.$1.length))
  }
  
  for (const k in map) {
    if (new RegExp('(' + k + ')').test(format)) {
      format = format.replace(RegExp.$1, 
        RegExp.$1.length === 1 ? map[k] : ('00' + map[k]).substr(('' + map[k]).length))
    }
  }
  
  return format
}

/**
 * 格式化相对时间（如：3分钟前）
 * @param {Date|string|number} timestamp 时间戳或日期字符串
 * @returns {string} 相对时间字符串
 */
export const formatRelativeTime = (timestamp) => {
  if (!timestamp) return ''
  
  const date = new Date(timestamp)
  if (isNaN(date.getTime())) return ''
  
  const now = new Date()
  const diff = now.getTime() - date.getTime()
  
  const minute = 60 * 1000
  const hour = 60 * minute
  const day = 24 * hour
  const month = 30 * day
  const year = 365 * day
  
  if (diff < minute) {
    return '刚刚'
  } else if (diff < hour) {
    return `${Math.floor(diff / minute)}分钟前`
  } else if (diff < day) {
    return `${Math.floor(diff / hour)}小时前`
  } else if (diff < month) {
    return `${Math.floor(diff / day)}天前`
  } else if (diff < year) {
    return `${Math.floor(diff / month)}个月前`
  } else {
    return `${Math.floor(diff / year)}年前`
  }
}

/**
 * 防抖函数
 * @param {Function} func 要执行的函数
 * @param {number} wait 等待时间（毫秒）
 * @param {boolean} immediate 是否立即执行
 * @returns {Function} 防抖后的函数
 */
export const debounce = (func, wait = 300, immediate = false) => {
  let timeout
  
  return function executedFunction(...args) {
    const context = this
    
    const later = () => {
      timeout = null
      if (!immediate) func.apply(context, args)
    }
    
    const callNow = immediate && !timeout
    
    clearTimeout(timeout)
    timeout = setTimeout(later, wait)
    
    if (callNow) func.apply(context, args)
  }
}

/**
 * 节流函数
 * @param {Function} func 要执行的函数
 * @param {number} limit 限制时间（毫秒）
 * @returns {Function} 节流后的函数
 */
export const throttle = (func, limit = 300) => {
  let inThrottle
  let lastFunc
  let lastRan
  
  return function executedFunction(...args) {
    const context = this
    
    if (!inThrottle) {
      func.apply(context, args)
      lastRan = Date.now()
      inThrottle = true
    } else {
      clearTimeout(lastFunc)
      lastFunc = setTimeout(() => {
        if (Date.now() - lastRan >= limit) {
          func.apply(context, args)
          lastRan = Date.now()
        }
      }, limit - (Date.now() - lastRan))
    }
  }
}

/**
 * 深度克隆对象
 * @param {any} obj 要克隆的对象
 * @returns {any} 克隆后的对象
 */
export const deepClone = (obj) => {
  if (obj === null || typeof obj !== 'object') return obj
  
  if (obj instanceof Date) return new Date(obj.getTime())
  if (obj instanceof RegExp) return new RegExp(obj)
  
  if (Array.isArray(obj)) {
    const arrCopy = []
    for (let i = 0; i < obj.length; i++) {
      arrCopy[i] = deepClone(obj[i])
    }
    return arrCopy
  }
  
  if (typeof obj === 'object') {
    const objCopy = {}
    for (const key in obj) {
      if (obj.hasOwnProperty(key)) {
        objCopy[key] = deepClone(obj[key])
      }
    }
    return objCopy
  }
  
  return obj
}

/**
 * 生成随机ID
 * @param {number} length ID长度
 * @returns {string} 随机ID
 */
export const generateId = (length = 8) => {
  const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'
  let result = ''
  for (let i = 0; i < length; i++) {
    result += chars.charAt(Math.floor(Math.random() * chars.length))
  }
  return result
}

/**
 * 检查是否为空（null、undefined、空字符串、空数组、空对象）
 * @param {any} value 要检查的值
 * @returns {boolean} 是否为空
 */
export const isEmpty = (value) => {
  if (value === null || value === undefined) return true
  if (typeof value === 'string' && value.trim() === '') return true
  if (Array.isArray(value) && value.length === 0) return true
  if (typeof value === 'object' && Object.keys(value).length === 0) return true
  return false
}

/**
 * 安全获取嵌套对象属性
 * @param {Object} obj 对象
 * @param {string} path 属性路径，如：'a.b.c'
 * @param {any} defaultValue 默认值
 * @returns {any} 属性值或默认值
 */
export const getSafe = (obj, path, defaultValue = null) => {
  if (!obj || typeof obj !== 'object') return defaultValue
  
  const keys = path.split('.')
  let result = obj
  
  for (const key of keys) {
    if (result === null || result === undefined || typeof result !== 'object') {
      return defaultValue
    }
    result = result[key]
  }
  
  return result === undefined ? defaultValue : result
}

/**
 * 格式化文件大小
 * @param {number} bytes 字节数
 * @returns {string} 格式化后的文件大小
 */
export const formatFileSize = (bytes) => {
  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 parseFloat((bytes / Math.pow(k, i)).toFixed(2)) + ' ' + sizes[i]
}

/**
 * 复制文本到剪贴板
 * @param {string} text 要复制的文本
 * @returns {Promise} 复制结果
 */
export const copyToClipboard = (text) => {
  return new Promise((resolve, reject) => {
    if (uni.setClipboardData) {
      uni.setClipboardData({
        data: text,
        success: () => resolve(true),
        fail: (err) => reject(err)
      })
    } else {
      // 兼容H5环境
      const textarea = document.createElement('textarea')
      textarea.value = text
      textarea.style.position = 'fixed'
      textarea.style.opacity = '0'
      document.body.appendChild(textarea)
      textarea.select()
      
      try {
        const successful = document.execCommand('copy')
        document.body.removeChild(textarea)
        successful ? resolve(true) : reject(new Error('复制失败'))
      } catch (err) {
        document.body.removeChild(textarea)
        reject(err)
      }
    }
  })
}