type SalesEditableLine = {
  itemId: number
  uomId: number
  warehouseId: number
  qty: number
  freeQty: number
  unitPrice?: number | null
  discountPct?: number
  taxPct?: number
}

type SalesDocumentValidationInput = {
  customerId: number | null
  warehouseId: number | null
  cashierUserId?: number | null
  requireCashierUser?: boolean
  lines: SalesEditableLine[]
  lineLabel?: string
}

type BundleEditableLine = {
  itemId: number
  uomId: number
  qty: number
  unitPrice: number
}

type BundleValidationInput = {
  customerId: number | null
  warehouseId: number | null
  cashierUserId: number | null
  templateId: number | null
  bundleName: string
  bundlePrice: number
  lines: BundleEditableLine[]
}

function invalidNumber(value: number | null | undefined) {
  return value === null || value === undefined || !Number.isFinite(value)
}

export function validateSalesDocument(input: SalesDocumentValidationInput): string | null {
  const {
    customerId,
    warehouseId,
    cashierUserId,
    requireCashierUser = false,
    lines,
    lineLabel = "line",
  } = input

  if (!customerId) return "Select a customer."
  if (!warehouseId) return "Select a warehouse."
  if (requireCashierUser && !cashierUserId) return "Select a cashier."
  if (lines.length === 0) return `Add at least one ${lineLabel}.`

  for (const [index, line] of lines.entries()) {
    const row = index + 1
    if (!line.itemId) return `Select an item for ${lineLabel} ${row}.`
    if (!line.uomId) return `Select a valid UOM for ${lineLabel} ${row}.`
    if (!line.warehouseId) return `Select a warehouse for ${lineLabel} ${row}.`
    if (warehouseId && line.warehouseId !== warehouseId) {
      return `${lineLabel[0]?.toUpperCase() ?? "L"}${lineLabel.slice(1)} ${row} warehouse must match the selected header warehouse.`
    }
    if (invalidNumber(line.qty) || line.qty <= 0) return `Enter a quantity greater than zero for ${lineLabel} ${row}.`
    if (invalidNumber(line.freeQty) || line.freeQty < 0) return `Enter a valid free quantity for ${lineLabel} ${row}.`
    if (line.unitPrice !== null && line.unitPrice !== undefined && (invalidNumber(line.unitPrice) || line.unitPrice < 0)) {
      return `Enter a valid unit price for ${lineLabel} ${row}.`
    }
    if (line.discountPct !== undefined && (invalidNumber(line.discountPct) || line.discountPct < 0 || line.discountPct > 100)) {
      return `Enter a discount percentage between 0 and 100 for ${lineLabel} ${row}.`
    }
    if (line.taxPct !== undefined && (invalidNumber(line.taxPct) || line.taxPct < 0 || line.taxPct > 100)) {
      return `Enter a tax percentage between 0 and 100 for ${lineLabel} ${row}.`
    }
  }

  return null
}

export function validateBundleSale(input: BundleValidationInput): string | null {
  const { customerId, warehouseId, cashierUserId, templateId, bundleName, bundlePrice, lines } = input

  if (!customerId) return "Select a customer."
  if (!warehouseId) return "Select a warehouse."
  if (!cashierUserId) return "Select a cashier."
  if (!templateId) return "Select a bundle template."
  if (!bundleName.trim()) return "Enter a bundle name."
  if (invalidNumber(bundlePrice) || bundlePrice < 0) return "Enter a valid bundle price."
  if (lines.length === 0) return "Add at least one bundle component line."

  for (const [index, line] of lines.entries()) {
    const row = index + 1
    if (!line.itemId) return `Select an item for component line ${row}.`
    if (!line.uomId) return `Select a valid UOM for component line ${row}.`
    if (invalidNumber(line.qty) || line.qty <= 0) return `Enter a quantity greater than zero for component line ${row}.`
    if (invalidNumber(line.unitPrice) || line.unitPrice < 0) return `Enter a valid unit price for component line ${row}.`
  }

  return null
}