import { type ClassValue, clsx } from 'clsx'
import { twMerge } from 'tailwind-merge'

export function cn(...inputs: ClassValue[]) {
  return twMerge(clsx(inputs))
}

export function formatDate(date: Date | string): string {
  return new Intl.DateTimeFormat('en-US', {
    dateStyle: 'medium',
    timeStyle: 'short',
  }).format(new Date(date))
}

export function formatDateOnly(date: Date | string): string {
  return new Intl.DateTimeFormat('en-US', {
    dateStyle: 'long',
  }).format(new Date(date))
}

export function truncate(str: string, length: number): string {
  if (str.length <= length) return str
  return str.slice(0, length) + '...'
}

export function getInitials(name: string): string {
  return name
    .split(' ')
    .map((n) => n[0])
    .join('')
    .toUpperCase()
    .slice(0, 2)
}

export function slugify(str: string): string {
  return str
    .toLowerCase()
    .replace(/[^\w\s-]/g, '')
    .replace(/[\s_-]+/g, '-')
    .replace(/^-+|-+$/g, '')
}

export function formatFileSize(bytes: number): string {
  if (bytes === 0) return '0 Bytes'
  const k = 1024
  const sizes = ['Bytes', 'KB', 'MB', 'GB']
  const i = Math.floor(Math.log(bytes) / Math.log(k))
  return parseFloat((bytes / Math.pow(k, i)).toFixed(2)) + ' ' + sizes[i]
}

export function formatEnumLabel(value: string): string {
  return value
    .replace(/_/g, ' ')
    .replace(/\b\w/g, (c) => c.toUpperCase())
}

export function daysUntil(date: Date | string): number {
  const target = new Date(date)
  const now = new Date()
  return Math.ceil((target.getTime() - now.getTime()) / (1000 * 60 * 60 * 24))
}

export function formatRelativeTime(date: Date | string): string {
  const now = new Date()
  const target = new Date(date)
  const diffMs = now.getTime() - target.getTime()
  const diffSec = Math.floor(diffMs / 1000)
  const diffMin = Math.floor(diffSec / 60)
  const diffHour = Math.floor(diffMin / 60)
  const diffDay = Math.floor(diffHour / 24)
  const diffWeek = Math.floor(diffDay / 7)

  if (diffSec < 60) return 'just now'
  if (diffMin < 60) return `${diffMin}m ago`
  if (diffHour < 24) return `${diffHour}h ago`
  if (diffDay < 7) return `${diffDay}d ago`
  if (diffWeek < 4) return `${diffWeek}w ago`

  return new Intl.DateTimeFormat('en-US', {
    month: 'short',
    day: 'numeric',
  }).format(target)
}