/**
 * 采集协议单 · 缴费模式切换（dj / fq / djfq）
 * 规则见 docs/superpowers/specs/2026-06-04-protocol-pay-mode-switch-design.md
 */

import {
  calcFqInstallmentDueDate,
  DEFAULT_INSTALLMENT_ADVANCE_DAYS,
  defaultInstallmentAmounts
} from '@/utils/protocol-payment-installment'
import { type PayMode, isInstallmentPayMode } from '@/utils/protocol-payment-presets'

export type { PayMode }
export type DetailLike = Record<string, any>

const LOCKED_STATUSES = new Set(['jfqrz', 'yjf', 'tfqrz', 'ytf'])
const BLOCKING_STATUSES = new Set(['jfqrz', 'tfqrz', 'ytf'])

export interface PayModeSwitchContext {
  contractAmount: number | null
  lumpSumDeadline: string
  installmentCount: number | null
  installmentIntervalMonths: number | null
  installmentStartDate: string
  installmentAdvanceDays: number | null
  installmentRatios: number[]
}

export type EvaluateResult =
  | { action: 'noop' }
  | { action: 'blocked'; reason: string }
  | { action: 'confirm'; summary: string }

export function isPayDetailLocked(detail: DetailLike): boolean {
  if (detail._payModeLocked) return true
  return LOCKED_STATUSES.has(String(detail.payStatus || ''))
}

export function markPayDetailLocks(details: DetailLike[]): void {
  for (const d of details) {
    d._payModeLocked = isPayDetailLocked(d)
  }
}

export function sumPaidAmount(details: DetailLike[]): number {
  return details
    .filter((d) => String(d.payStatus) === 'yjf')
    .reduce((sum, d) => sum + (Number(d.dueAmount) || 0), 0)
}

export function calcRemainingAmount(contractAmount: number | null, details: DetailLike[]): number {
  if (contractAmount == null) return 0
  const remaining = Number(contractAmount) - sumPaidAmount(details)
  return Math.round(remaining * 100) / 100
}

/** 趸交：应缴合计与合同金额不一致时返回提醒文案（不阻断保存） */
export function djDueAmountMismatchHint(
  contractAmount: number | null | undefined,
  details: DetailLike[]
): string | null {
  if (contractAmount == null || Number(contractAmount) === 0) return null
  const totalDue = details.reduce((sum, d) => sum + (Number(d.dueAmount) || 0), 0)
  const contract = Number(contractAmount)
  if (Math.abs(totalDue - contract) > 0.015) {
    return `趸交各明细应缴金额之和应为 ${contract.toFixed(2)}，当前为 ${totalDue.toFixed(2)}，请核对`
  }
  return null
}

function formatMoneySummary(v: number): string {
  return `¥${v.toFixed(2).replace(/\B(?=(\d{3})+(?!\d))/g, ',')}`
}

function activeDetails(details: DetailLike[]): DetailLike[] {
  return details.filter((d) => !d._voided)
}

function hasBlockingStatus(details: DetailLike[]): boolean {
  return details.some((d) => BLOCKING_STATUSES.has(String(d.payStatus || '')))
}

function countByStatus(details: DetailLike[], status: string): number {
  return details.filter((d) => String(d.payStatus || 'dfj') === status).length
}

function buildInstallmentDetails(
  ctx: PayModeSwitchContext,
  rows: DetailLike[]
): DetailLike[] {
  const count = Number(ctx.installmentCount) || 6
  const interval = Number(ctx.installmentIntervalMonths) || 6
  const startDate = ctx.installmentStartDate || ''
  const advanceDays = Number(ctx.installmentAdvanceDays ?? DEFAULT_INSTALLMENT_ADVANCE_DAYS)
  const amounts =
    ctx.installmentRatios?.length && sumPaidAmount(rows) === 0
      ? ctx.installmentRatios.map((v) => Number(v || 0))
      : defaultInstallmentAmounts(ctx.contractAmount, count)
  const result: DetailLike[] = []
  for (let i = 0; i < count; i++) {
    result.push(
      createPaymentDetailRow({
        dueAmount: amounts[i] ?? null,
        installmentNo: i + 1,
        installmentDueDate:
          startDate && interval
            ? calcFqInstallmentDueDate(startDate, i, interval, advanceDays)
            : '',
        expanded: i === 0
      })
    )
  }
  return result
}

export function createPaymentDetailRow(options: {
  dueAmount: number | null
  installmentDueDate?: string
  installmentNo?: number | null
  payStatus?: string
  expanded?: boolean
}): DetailLike {
  const now = new Date()
  const pad = (n: number) => String(n).padStart(2, '0')
  const defaultTime = `${now.getFullYear()}-${pad(now.getMonth() + 1)}-${pad(now.getDate())} ${pad(now.getHours())}:${pad(now.getMinutes())}:${pad(now.getSeconds())}`
  return {
    transferType: '',
    dueAmount: options.dueAmount,
    transferAmount: null,
    transferTime: defaultTime,
    payStatus: options.payStatus ?? 'dfj',
    installmentNo: options.installmentNo ?? null,
    installmentDueDate: options.installmentDueDate ?? '',
    _expanded: options.expanded ?? false,
    _payModeLocked: false,
    attachments: []
  }
}

export function evaluatePayModeSwitch(
  fromMode: PayMode,
  toMode: PayMode,
  details: DetailLike[],
  ctx: PayModeSwitchContext
): EvaluateResult {
  if (fromMode === toMode) return { action: 'noop' }

  const rows = activeDetails(details)

  if (hasBlockingStatus(rows)) {
    return {
      action: 'blocked',
      reason: '存在缴费确认中或退费处理中的明细，请先完成相关流程后再切换缴费模式。'
    }
  }

  if (fromMode === 'dj' && isInstallmentPayMode(toMode)) {
    if (rows.some((d) => isPayDetailLocked(d))) {
      return {
        action: 'blocked',
        reason: '趸交已有缴费记录，无法改为分期。'
      }
    }
    const count = ctx.installmentCount || 6
    const label = toMode === 'djfq' ? '趸交+分期' : '分期'
    return {
      action: 'confirm',
      summary: `将清除当前趸交计划，按 ${count} 期${label}重新生成缴费明细。是否继续？`
    }
  }

  if (isInstallmentPayMode(fromMode) && toMode === 'dj') {
    const dfjCount = countByStatus(rows, 'dfj')
    const yjfCount = countByStatus(rows, 'yjf')

    if (yjfCount > 0 && dfjCount === 0) {
      return {
        action: 'blocked',
        reason: '分期已全部缴清，无需改为趸交。'
      }
    }

    const remaining = calcRemainingAmount(ctx.contractAmount, rows)
    if (yjfCount > 0 && remaining <= 0) {
      return {
        action: 'blocked',
        reason: '已缴清，无需改为趸交。'
      }
    }

    if (yjfCount > 0) {
      return {
        action: 'confirm',
        summary: `将作废 ${dfjCount} 期未缴计划，保留 ${yjfCount} 期已缴记录，并新增 1 条趸交明细（剩余 ${formatMoneySummary(remaining)}）。是否继续？`
      }
    }

    return {
      action: 'confirm',
      summary: `将作废 ${dfjCount || rows.length} 期分期计划，并合并为 1 条趸交明细。是否继续？`
    }
  }

  if (isInstallmentPayMode(fromMode) && isInstallmentPayMode(toMode) && fromMode !== toMode) {
    if (rows.some((d) => isPayDetailLocked(d))) {
      return {
        action: 'blocked',
        reason: '分期已有缴费记录，无法切换分期类型。'
      }
    }
    const count = ctx.installmentCount || 6
    const label = toMode === 'djfq' ? '趸交+分期' : '分期'
    return {
      action: 'confirm',
      summary: `将按 ${count} 期${label}重新生成缴费明细。是否继续？`
    }
  }

  return { action: 'noop' }
}

export function applyPayModeSwitch(
  fromMode: PayMode,
  toMode: PayMode,
  details: DetailLike[],
  ctx: PayModeSwitchContext
): DetailLike[] {
  const rows = activeDetails(details)

  if (fromMode === 'dj' && isInstallmentPayMode(toMode)) {
    return buildInstallmentDetails(ctx, rows)
  }

  if (isInstallmentPayMode(fromMode) && toMode === 'dj') {
    const yjfRows = rows
      .filter((d) => String(d.payStatus) === 'yjf')
      .map((d) => ({ ...d, _payModeLocked: true }))
    const remaining = calcRemainingAmount(ctx.contractAmount, yjfRows)
    const deadline = ctx.lumpSumDeadline || ''
    const dueAmount = yjfRows.length ? remaining : ctx.contractAmount
    const newDjRow = createPaymentDetailRow({
      dueAmount,
      installmentNo: null,
      installmentDueDate: deadline,
      expanded: yjfRows.length === 0
    })
    return [...yjfRows, newDjRow]
  }

  if (isInstallmentPayMode(fromMode) && isInstallmentPayMode(toMode) && fromMode !== toMode) {
    return buildInstallmentDetails(ctx, rows)
  }

  return rows
}

/** 趸交与分期均允许多条缴费明细（合计须等于合同金额） */
export function canAddPaymentDetail(_payMode: string, _details: DetailLike[]): boolean {
  return true
}