/** 分期缴费：期数对齐、应缴日/金额计算（与 ProtocolFormDialog 逻辑一致） */

export function addMonthsYmd(dateStr: string, months: number): string {
  const compact = String(dateStr || '').replace(/-/g, '')
  if (compact.length !== 8) return ''
  const y = parseInt(compact.slice(0, 4), 10)
  const m = parseInt(compact.slice(4, 6), 10) - 1
  const d = parseInt(compact.slice(6, 8), 10)
  const date = new Date(y, m + months, d)
  const yy = date.getFullYear()
  const mm = String(date.getMonth() + 1).padStart(2, '0')
  const dd = String(date.getDate()).padStart(2, '0')
  return `${yy}${mm}${dd}`
}

export function calcInstallmentDueAmounts(
  contractAmount: number | null | undefined,
  count: number
): number[] {
  if (contractAmount == null || !count || count < 1) return []
  const totalCents = Math.round(Number(contractAmount) * 100)
  const baseCents = Math.floor(totalCents / count)
  const amounts: number[] = []
  let sumCents = 0
  for (let i = 0; i < count; i++) {
    if (i === count - 1) {
      amounts.push((totalCents - sumCents) / 100)
    } else {
      amounts.push(baseCents / 100)
      sumCents += baseCents
    }
  }
  return amounts
}

type PaymentLike = Record<string, unknown> | null | undefined
type DetailLike = Record<string, any>

/**
 * 分期模式下按 installmentCount 补齐缺失期次（保留已有明细数据），仅用于编辑表单。
 */
export function alignFqPaymentDetailsForDisplay(
  payment: PaymentLike,
  details: DetailLike[]
): DetailLike[] {
  if (!payment || payment.payMode !== 'fq') return details
  const count = Number(payment.installmentCount)
  if (!count || count < 1) return details

  const rows = [...details]
  const byNo = new Map<number, DetailLike>()
  const unnumbered: DetailLike[] = []
  for (const row of rows) {
    const no = row.installmentNo
    if (no != null && no !== '') {
      byNo.set(Number(no), row)
    } else {
      unnumbered.push(row)
    }
  }

  const needed = new Set(Array.from({ length: count }, (_, i) => i + 1))
  const have = new Set(byNo.keys())
  let missing = false
  for (const n of needed) {
    if (!have.has(n)) {
      missing = true
      break
    }
  }
  if (!missing && rows.length >= count) {
    return sortFqPaymentDetails(rows).slice(0, count)
  }

  const contract = payment.contractAmount != null ? Number(payment.contractAmount) : null
  const amounts = calcInstallmentDueAmounts(contract, count)
  const startDate = String(payment.installmentStartDate || '')
  const interval = Number(payment.installmentIntervalMonths || 0)

  const result: DetailLike[] = []
  for (let i = 0; i < count; i++) {
    const no = i + 1
    if (byNo.has(no)) {
      result.push(byNo.get(no)!)
      continue
    }
    if (i < unnumbered.length) {
      const raw = { ...unnumbered[i], installmentNo: no }
      if (!raw.installmentDueDate && startDate && interval) {
        raw.installmentDueDate = addMonthsYmd(startDate, i * interval)
      }
      result.push(raw)
      continue
    }
    result.push({
      installmentNo: no,
      installmentDueDate:
        startDate && interval ? addMonthsYmd(startDate, i * interval) : '',
      dueAmount: amounts[i] ?? null,
      payStatus: 'dfj',
      transferType: '',
      transferAmount: null,
      attachments: []
    })
  }
  return result
}

export function sortFqPaymentDetails(details: DetailLike[]): DetailLike[] {
  return [...details].sort((a, b) => {
    const na = a.installmentNo != null && a.installmentNo !== '' ? Number(a.installmentNo) : 9999
    const nb = b.installmentNo != null && b.installmentNo !== '' ? Number(b.installmentNo) : 9999
    if (na !== nb) return na - nb
    return Number(a.orderNum || 0) - Number(b.orderNum || 0)
  })
}

/** 编辑表单：将缴费明细行数与分期期数对齐（不覆盖已有行） */
export function syncFqPaymentDetailRowCount(
  payment: {
    payMode: string
    installmentCount: number | null
    contractAmount: number | null
    installmentStartDate: string
    installmentIntervalMonths: number | null
  },
  paymentDetails: DetailLike[]
): void {
  if (payment.payMode !== 'fq') return
  const count = Number(payment.installmentCount)
  if (!count || count < 1) return

  const aligned = alignFqPaymentDetailsForDisplay(payment, paymentDetails)
  paymentDetails.splice(0, paymentDetails.length, ...aligned)
}