export function safeTruncate(num, decimals = 2) {
  if (Number.isNaN(num) || !Number.isFinite(num))
    return '0.00'

  const factor = 10 ** decimals
  const scaled = Math.trunc(num * factor)
  return (scaled / factor).toFixed(decimals)
}

function toTruncatedCents(num) {
  if (Number.isNaN(num) || !Number.isFinite(num))
    return 0
  return Math.trunc((num + Number.EPSILON) * 100)
}

function centsToFixed(cents) {
  return (cents / 100).toFixed(2)
}

function calculatePlatformOverpricingCost(price, config) {
  if (price <= config.p_pricing_standard)
    return 0
  return (price - config.p_pricing_standard) * config.p_overpricing_ratio
}

function calculateSuperiorOverpricingCost(price, config) {
  if (config.a_overpricing_ratio <= 0)
    return 0
  if (price <= config.a_pricing_standard)
    return 0
  if (config.a_pricing_end <= config.a_pricing_standard)
    return 0

  const superiorRangeAmount = Math.min(price, config.a_pricing_end) - config.a_pricing_standard
  return Math.max(0, superiorRangeAmount) * config.a_overpricing_ratio
}

export function calculatePromotionPricing(priceInput, config) {
  if (!config)
    return { costPrice: '0.00', promotionRevenue: '0.00' }

  const price = Number(priceInput)
  if (!Number.isFinite(price))
    return { costPrice: '0.00', promotionRevenue: '0.00' }

  const baseCost = Number(config.cost_price) || 0
  const platformOverpricingCost = calculatePlatformOverpricingCost(price, config)
  const superiorOverpricingCost = calculateSuperiorOverpricingCost(price, config)
  const totalCost = baseCost + platformOverpricingCost + superiorOverpricingCost
  const priceCents = toTruncatedCents(price)
  const costCents = toTruncatedCents(totalCost)
  const revenueCents = priceCents - costCents

  return {
    costPrice: centsToFixed(costCents),
    promotionRevenue: centsToFixed(revenueCents),
  }
}