import { WearPart, MaintenanceHistory } from '@prisma/client'

export function calculateServiceStatus(
  part: WearPart & { maintenanceHistory: MaintenanceHistory[] }
): {
  status: 'OK' | 'WARNING' | 'CRITICAL'
  remainingKm: number
  percentageUsed: number
} {
  const latestMaintenance = part.maintenanceHistory[0]
  const currentMileage = latestMaintenance?.mileage ?? part.installMileage
  const kmSinceInstall = currentMileage - part.installMileage
  const remainingKm = part.serviceInterval - kmSinceInstall
  const percentageUsed = (kmSinceInstall / part.serviceInterval) * 100

  let status: 'OK' | 'WARNING' | 'CRITICAL' = 'OK'
  if (percentageUsed >= 90) {
    status = 'CRITICAL'
  } else if (percentageUsed >= 75) {
    status = 'WARNING'
  }

  return {
    status,
    remainingKm: Math.max(0, remainingKm),
    percentageUsed: Math.min(100, percentageUsed),
  }
}

export function calculateTotalCosts(
  parts: (WearPart & { maintenanceHistory: MaintenanceHistory[] })[]
): number {
  return parts.reduce((total, part) => {
    const partCost = part.cost ?? 0
    const maintenanceCost = part.maintenanceHistory.reduce(
      (sum, m) => sum + (m.cost ?? 0),
      0
    )
    return total + partCost + maintenanceCost
  }, 0)
}

export function calculateAverageLifespan(
  parts: (WearPart & { maintenanceHistory: MaintenanceHistory[] })[]
): number | null {
  const replacedParts = parts.filter(
    (p) => p.status === 'REPLACED' && p.maintenanceHistory.length > 0
  )

  if (replacedParts.length === 0) return null

  const totalKm = replacedParts.reduce((sum, part) => {
    const installHistory = part.maintenanceHistory.find(
      (h) => h.action === 'INSTALL'
    )
    const replaceHistory = part.maintenanceHistory.find(
      (h) => h.action === 'REPLACE'
    )

    if (installHistory && replaceHistory) {
      return sum + (replaceHistory.mileage - installHistory.mileage)
    }
    return sum
  }, 0)

  return totalKm / replacedParts.length
}

export function formatDate(date: Date | string): string {
  const d = typeof date === 'string' ? new Date(date) : date
  return d.toLocaleDateString('de-DE', {
    year: 'numeric',
    month: '2-digit',
    day: '2-digit',
  })
}

export function formatCurrency(amount: number | null | undefined): string {
  if (amount === null || amount === undefined) return '0,00 €'
  return new Intl.NumberFormat('de-DE', {
    style: 'currency',
    currency: 'EUR',
  }).format(amount)
}