const formatTime = (seconds) => {
  const m = Math.floor(seconds / 60)
  const s = seconds % 60
  return `${String(m).padStart(2, '0')}:${String(s).padStart(2, '0')}`
}

const formatDuration = (seconds) => {
  if (seconds < 60) return `${seconds}秒`
  const m = Math.floor(seconds / 60)
  const s = seconds % 60
  return s > 0 ? `${m}分${s}秒` : `${m}分钟`
}

const getDaysInMonth = (year, month) => new Date(year, month, 0).getDate()

const getMonthCalendar = (year, month) => {
  const firstDay = new Date(year, month - 1, 1)
  const daysInMonth = new Date(year, month, 0).getDate()
  const startDayOfWeek = firstDay.getDay()

  const weeks = []
  let week = [null, null, null, null, null, null, null]

  for (let d = 1; d <= daysInMonth; d++) {
    const dow = (startDayOfWeek + d - 1) % 7
    week[dow] = d
    if (dow === 6 || d === daysInMonth) {
      weeks.push(week.slice())
      week = [null, null, null, null, null, null, null]
    }
  }

  return weeks
}

/**
 * Format a Date as `YYYY-MM-DD HH:MM:SS` in local time.
 *
 * Used as the canonical `record.date` string so each record has a
 * precise timestamp (e.g. "2026-06-11 14:30:45"). Use `_dateOnly()`
 * to strip back to YYYY-MM-DD for date-level comparisons (streak,
 * leaderboard day filter, etc.).
 */
const formatDate = (date) => {
  const y = date.getFullYear()
  const mo = String(date.getMonth() + 1).padStart(2, '0')
  const d = String(date.getDate()).padStart(2, '0')
  const h = String(date.getHours()).padStart(2, '0')
  const mi = String(date.getMinutes()).padStart(2, '0')
  const s = String(date.getSeconds()).padStart(2, '0')
  return `${y}-${mo}-${d} ${h}:${mi}:${s}`
}

/** Strip the time portion of a formatDate string → "YYYY-MM-DD". */
const _dateOnly = (s) => (typeof s === 'string' && s.length >= 10) ? s.substring(0, 10) : ''

const _normalizeDuration = (value) => Math.max(0, Math.floor(Number(value) || 0))

const _formatTrendDuration = (seconds) => {
  const duration = _normalizeDuration(seconds)
  if (duration >= 3600) return `${Math.floor(duration / 60)}m`
  return formatTime(duration)
}

/** Build daily or monthly duration totals from one training-record snapshot. */
const getTrendData = (recordGroups, mode, now = new Date()) => {
  const dateTotals = {}
  const groups = recordGroups && typeof recordGroups === 'object' ? recordGroups : {}

  Object.values(groups).forEach((records) => {
    if (!Array.isArray(records)) return
    records.forEach((record) => {
      const date = _dateOnly(record && record.date)
      if (!date) return
      dateTotals[date] = (dateTotals[date] || 0) + _normalizeDuration(record.duration)
    })
  })

  const today = new Date(now)
  const weekdays = ['日', '一', '二', '三', '四', '五', '六']
  const pad = (n) => String(n).padStart(2, '0')

  if (mode === 'month') {
    const monthTotals = {}
    Object.keys(dateTotals).forEach((date) => {
      const month = date.substring(0, 7)
      monthTotals[month] = (monthTotals[month] || 0) + dateTotals[date]
    })
    return Array.from({ length: 6 }, (_, index) => {
      const offset = 5 - index
      const date = new Date(today.getFullYear(), today.getMonth() - offset, 1)
      const monthKey = `${date.getFullYear()}-${pad(date.getMonth() + 1)}`
      const value = monthTotals[monthKey] || 0
      return {
        label: `${date.getMonth() + 1}月`,
        value,
        valueText: value > 0 ? _formatTrendDuration(value) : '',
        highlight: offset === 0
      }
    })
  }

  return Array.from({ length: 7 }, (_, index) => {
    const offset = 6 - index
    const date = new Date(today)
    date.setDate(date.getDate() - offset)
    const dateKey = `${date.getFullYear()}-${pad(date.getMonth() + 1)}-${pad(date.getDate())}`
    const value = dateTotals[dateKey] || 0
    return {
      label: offset === 0 ? '今天' : weekdays[date.getDay()],
      value,
      valueText: value > 0 ? _formatTrendDuration(value) : '',
      highlight: offset === 0
    }
  })
}

const getBestTrendData = (recordGroups, mode, now = new Date()) => {
  const peaks = {}
  const groups = recordGroups && typeof recordGroups === 'object' ? recordGroups : {}
  Object.values(groups).forEach((records) => {
    if (!Array.isArray(records)) return
    records.forEach((record) => {
      const date = _dateOnly(record && record.date)
      if (!date) return
      const key = mode === 'month' ? date.substring(0, 7) : date
      peaks[key] = Math.max(peaks[key] || 0, _normalizeDuration(record.duration))
    })
  })

  const today = new Date(now)
  const weekdays = ['日', '一', '二', '三', '四', '五', '六']
  const pad = (n) => String(n).padStart(2, '0')
  const count = mode === 'month' ? 6 : 7
  return Array.from({ length: count }, (_, index) => {
    const offset = count - 1 - index
    const date = mode === 'month'
      ? new Date(today.getFullYear(), today.getMonth() - offset, 1)
      : new Date(today.getFullYear(), today.getMonth(), today.getDate() - offset)
    const key = mode === 'month'
      ? `${date.getFullYear()}-${pad(date.getMonth() + 1)}`
      : `${date.getFullYear()}-${pad(date.getMonth() + 1)}-${pad(date.getDate())}`
    const value = peaks[key] || 0
    return {
      label: mode === 'month' ? `${date.getMonth() + 1}月` : offset === 0 ? '今天' : weekdays[date.getDay()],
      value,
      valueText: value > 0 ? _formatTrendDuration(value) : '',
      highlight: offset === 0
    }
  })
}

const getBarPercent = (value, max) => {
  const amount = _normalizeDuration(value)
  const maximum = _normalizeDuration(max)
  return maximum > 0 ? amount / maximum * 100 : 0
}

const getTrendSummary = (trendData, mode) => {
  const items = Array.isArray(trendData) ? trendData : []
  const total = items.reduce((sum, item) => sum + _normalizeDuration(item && item.value), 0)
  const activeItems = items.filter(item => _normalizeDuration(item && item.value) > 0)
  const peak = activeItems.reduce((current, item) => {
    return !current || _normalizeDuration(item.value) > _normalizeDuration(current.value) ? item : current
  }, null)
  const isMonth = mode === 'month'

  return {
    totalText: _formatTrendDuration(total),
    activeCount: activeItems.length,
    activeLabel: isMonth ? '活跃月份' : '训练天数',
    peakTitle: isMonth ? '最高训练月' : '最高训练日',
    peakText: peak ? `${peak.label} · ${_formatTrendDuration(peak.value)}` : '暂无训练数据'
  }
}

/**
 * Convert a local file path (typically `wxfile://...` from chooseAvatar) to a
 * base64 data URI. Used to make temporary file URLs survive the WeChat
 * expiration window (a few days) by embedding the bytes inline.
 *
 * Rejects if the file exceeds `maxBytes` (default 512KB) so a stray huge
 * image doesn't blow the 10MB total wx.storage budget. Caller should
 * fall back to the raw URL on rejection.
 */
const fileToDataURI = (filePath, maxBytes = 512 * 1024) => {
  return new Promise((resolve, reject) => {
    if (!filePath || typeof wx.getFileSystemManager !== 'function') {
      reject(new Error('FileSystemManager unavailable'))
      return
    }
    const fs = wx.getFileSystemManager()
    fs.getFileInfo({
      filePath,
      success: (info) => {
        if (info.size > maxBytes) {
          reject(new Error(`File too large: ${info.size} > ${maxBytes}`))
          return
        }
        fs.readFile({
          filePath,
          encoding: 'base64',
          success: (res) => {
            // chooseAvatar returns PNG; allow JPG/GIF/WEBP fallbacks.
            const m = ((filePath.match(/\.(\w+)(?:\?|$)/) || [])[1] || 'png').toLowerCase()
            const mime = { png: 'image/png', jpg: 'image/jpeg', jpeg: 'image/jpeg', gif: 'image/gif', webp: 'image/webp' }[m] || 'image/png'
            resolve(`data:${mime};base64,${res.data}`)
          },
          fail: reject
        })
      },
      fail: reject
    })
  })
}

module.exports = {
  formatTime,
  formatDuration,
  getDaysInMonth,
  getMonthCalendar,
  formatDate,
  dateOnly: _dateOnly,
  getTrendData,
  getBestTrendData,
  getTrendSummary,
  getBarPercent,
  fileToDataURI
}