// 工具函数库

/**
 * 格式化时间
 */
const formatTime = date => {
  const year = date.getFullYear()
  const month = date.getMonth() + 1
  const day = date.getDate()
  const hour = date.getHours()
  const minute = date.getMinutes()
  const second = date.getSeconds()

  return `${[year, month, day].map(formatNumber).join('/')} ${[hour, minute, second].map(formatNumber).join(':')}`
}

const formatNumber = n => {
  n = n.toString()
  return n[1] ? n : `0${n}`
}

/**
 * 显示成功提示
 */
const showSuccess = (title = '操作成功') => {
  wx.showToast({
    title: title,
    icon: 'success',
    duration: 2000
  })
}

/**
 * 显示失败提示
 */
const showError = (title = '操作失败') => {
  wx.showToast({
    title: title,
    icon: 'none',
    duration: 2000
  })
}

/**
 * 显示加载中
 */
const showLoading = (title = '加载中...') => {
  wx.showLoading({
    title: title,
    mask: true
  })
}

/**
 * 隐藏加载
 */
const hideLoading = () => {
  wx.hideLoading()
}

/**
 * 计算GPA
 * @param {Array} courses 课程列表 [{score: 90, credit: 4}, ...]
 */
const calculateGPA = (courses) => {
  if (!courses || courses.length === 0) return 0;
  
  let totalPoints = 0;
  let totalCredits = 0;
  
  courses.forEach(course => {
    const gradePoint = scoreToGradePoint(course.score);
    totalPoints += gradePoint * course.credit;
    totalCredits += course.credit;
  });
  
  return totalCredits > 0 ? (totalPoints / totalCredits).toFixed(2) : 0;
}

/**
 * 分数转绩点
 * 公式：60分及以上 = 成绩/10-5，60分以下 = 0
 */
const scoreToGradePoint = (score) => {
  if (score >= 60) {
    return parseFloat((score / 10 - 5).toFixed(2));
  }
  return 0;
}

/**
 * 计算倒计时
 */
const getCountdown = (targetDate) => {
  const now = new Date().getTime();
  const target = new Date(targetDate).getTime();
  const diff = target - now;
  
  if (diff <= 0) {
    return { days: 0, hours: 0, minutes: 0, seconds: 0, isExpired: true };
  }
  
  const days = Math.floor(diff / (1000 * 60 * 60 * 24));
  const hours = Math.floor((diff % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
  const minutes = Math.floor((diff % (1000 * 60 * 60)) / (1000 * 60));
  const seconds = Math.floor((diff % (1000 * 60)) / 1000);
  
  return { days, hours, minutes, seconds, isExpired: false };
}

/**
 * 日期格式化
 */
const formatDate = (date, format = 'YYYY-MM-DD') => {
  const d = new Date(date)
  const year = d.getFullYear()
  const month = String(d.getMonth() + 1).padStart(2, '0')
  const day = String(d.getDate()).padStart(2, '0')
  const hour = String(d.getHours()).padStart(2, '0')
  const minute = String(d.getMinutes()).padStart(2, '0')
  const second = String(d.getSeconds()).padStart(2, '0')

  return format
    .replace('YYYY', year)
    .replace('MM', month)
    .replace('DD', day)
    .replace('HH', hour)
    .replace('mm', minute)
    .replace('ss', second)
}

/**
 * 相对时间
 */
const formatRelativeTime = (timestamp) => {
  const now = Date.now()
  const diff = now - new Date(timestamp).getTime()
  
  const minute = 60 * 1000
  const hour = 60 * minute
  const day = 24 * hour
  const week = 7 * day
  const month = 30 * day
  
  if (diff < minute) return '刚刚'
  if (diff < hour) return `${Math.floor(diff / minute)}分钟前`
  if (diff < day) return `${Math.floor(diff / hour)}小时前`
  if (diff < week) return `${Math.floor(diff / day)}天前`
  if (diff < month) return `${Math.floor(diff / week)}周前`
  
  return formatDate(timestamp, 'YYYY-MM-DD')
}

/**
 * 文件大小格式化
 */
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 (bytes / Math.pow(k, i)).toFixed(2) + ' ' + sizes[i]
}

/**
 * 验证手机号
 */
const validatePhone = (phone) => {
  return /^1[3-9]\d{9}$/.test(phone)
}

/**
 * 验证邮箱
 */
const validateEmail = (email) => {
  return /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(email)
}

/**
 * 验证学号（示例：8位数字）
 */
const validateStudentId = (id) => {
  return /^\d{8,10}$/.test(id)
}

/**
 * 深拷贝
 */
const deepClone = (obj) => {
  if (obj === null || typeof obj !== 'object') return obj
  if (obj instanceof Date) return new Date(obj)
  if (obj instanceof Array) return obj.map(item => deepClone(item))
  
  const clonedObj = {}
  for (const key in obj) {
    if (obj.hasOwnProperty(key)) {
      clonedObj[key] = deepClone(obj[key])
    }
  }
  return clonedObj
}

/**
 * 数组去重
 */
const unique = (arr, key) => {
  if (!key) return [...new Set(arr)]
  
  const seen = new Set()
  return arr.filter(item => {
    const val = item[key]
    if (seen.has(val)) return false
    seen.add(val)
    return true
  })
}

/**
 * 数组分组
 */
const groupBy = (arr, key) => {
  return arr.reduce((result, item) => {
    const group = typeof key === 'function' ? key(item) : item[key]
    if (!result[group]) result[group] = []
    result[group].push(item)
    return result
  }, {})
}

/**
 * 生成UUID
 */
const generateUUID = () => {
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
    const r = Math.random() * 16 | 0
    const v = c === 'x' ? r : (r & 0x3 | 0x8)
    return v.toString(16)
  })
}

/**
 * 节流
 */
const throttle = (fn, delay = 300) => {
  let timer = null
  return function(...args) {
    if (timer) return
    timer = setTimeout(() => {
      fn.apply(this, args)
      timer = null
    }, delay)
  }
}

/**
 * 防抖
 */
const debounce = (fn, delay = 300) => {
  let timer = null
  return function(...args) {
    clearTimeout(timer)
    timer = setTimeout(() => {
      fn.apply(this, args)
    }, delay)
  }
}

/**
 * 分享配置
 */
const getShareConfig = (title, imageUrl = '') => {
  return {
    title: title || '知芽小筑 - 学习辅助小程序',
    path: '/pages/index/index',
    imageUrl: imageUrl || '/images/share.png'
  }
}

module.exports = {
  formatTime,
  formatDate,
  formatRelativeTime,
  formatFileSize,
  formatNumber,
  showSuccess,
  showError,
  showLoading,
  hideLoading,
  calculateGPA,
  scoreToGradePoint,
  getCountdown,
  validatePhone,
  validateEmail,
  validateStudentId,
  deepClone,
  unique,
  groupBy,
  generateUUID,
  throttle,
  debounce,
  getShareConfig
}