import { clsx, type ClassValue } from "clsx"
import { twMerge } from "tailwind-merge"
import { format as formatDateFns } from "date-fns"

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

export function formatCurrency(amount: number, currency: string = 'SEK'): string {
  return new Intl.NumberFormat('sv-SE', {
    style: 'currency',
    currency,
    minimumFractionDigits: 0,
    maximumFractionDigits: 2,
  }).format(amount)
}

export function formatDate(date: Date | string): string {
  const d = typeof date === 'string' ? new Date(date) : date
  return formatDateFns(d, 'yyyy-MM-dd')
}

export function formatOrgNumber(orgNumber: string): string {
  // Format Swedish org number: XXXXXX-XXXX
  const cleaned = orgNumber.replace(/\D/g, '')
  if (cleaned.length === 10) {
    return `${cleaned.slice(0, 6)}-${cleaned.slice(6)}`
  }
  return orgNumber
}

export function generateInvoiceNumber(): string {
  const year = new Date().getFullYear()
  const random = Math.floor(Math.random() * 10000).toString().padStart(4, '0')
  return `${year}-${random}`
}