export function formatDistance(meters: number): string {
  if (meters < 1000) return `${Math.round(meters)}m`
  return `${(meters / 1000).toFixed(1)}km`
}

export function formatTime(isoString: string): string {
  const date = new Date(isoString)
  const now = new Date()
  const diffMs = now.getTime() - date.getTime()
  const diffMin = Math.floor(diffMs / 60000)
  const diffHour = Math.floor(diffMin / 60)
  const diffDay = Math.floor(diffHour / 24)

  if (diffMin < 1) return '刚刚'
  if (diffMin < 60) return `${diffMin}分钟前`
  if (diffHour < 24) return `${diffHour}小时前`
  if (diffDay < 7) return `${diffDay}天前`

  const month = date.getMonth() + 1
  const day = date.getDate()
  return `${month}月${day}日`
}

export function formatLastSeen(isoString: string): string {
  const diffMin = Math.floor((Date.now() - new Date(isoString).getTime()) / 60000)
  if (diffMin < 2) return '刚刚在线'
  if (diffMin < 60) return `${diffMin}分钟前`
  const diffHour = Math.floor(diffMin / 60)
  if (diffHour < 24) return `${diffHour}小时前`
  return '昨天在线'
}

export function formatCount(n: number): string {
  if (n < 1000) return String(n)
  if (n < 10000) return `${(n / 1000).toFixed(1)}k`
  return `${Math.floor(n / 10000)}w`
}

export function getAvatarGradient(seed: string): string {
  // 紫/冷灰单色家族,深浅交错保证相邻头像可区分
  const gradients = [
    'linear-gradient(135deg, #d9d2fb, #efedfd)',
    'linear-gradient(135deg, #e3e5ec, #f4f5f8)',
    'linear-gradient(135deg, #cfc6fa, #e9e6fc)',
    'linear-gradient(135deg, #d8dbe4, #eef0f5)',
    'linear-gradient(135deg, #e6e1fd, #f3f1fe)',
  ]
  let hash = 0
  for (let i = 0; i < seed.length; i++) hash = (hash * 31 + seed.charCodeAt(i)) & 0xffffffff
  return gradients[Math.abs(hash) % gradients.length]
}

export function getPetEmoji(species: string, breed?: string): string {
  if (species === 'cat') return '🐱'
  if (species === 'other') return '🐾'
  const dogBreedEmoji: Record<string, string> = {
    '比熊': '🐩',
    '柴犬': '🐕',
    '金毛': '🦮',
    '哈士奇': '🐺',
    '萨摩耶': '🐕‍🦺',
  }
  return (breed && dogBreedEmoji[breed]) || '🐶'
}