"use server"

import { and, eq, isNull, like } from "drizzle-orm"
import { revalidatePath } from "next/cache"
import { auth } from "@/lib/auth"
import { db } from "@/lib/db"
import {
  channels,
  transactions,
  transactionsDirty,
  type NewTransactionDirty,
} from "@/lib/db/schema"

export interface CcbaParsedRow {
  transDate: string
  postDate: string
  description: string
  refNo: string
  amt: string
  ccy: string
  account: string
  fxAmt: string | null
  fxCcy: string | null
  fxRate: string | null
}

export interface CcbaImportResult {
  success: boolean
  imported?: number
  skipped?: number
  unmatchedAccounts?: string[]
  error?: string
}

/** 存入 rawData 的原始行结构（含去重签名） */
interface CcbaRawData {
  transDate: string
  postDate: string
  description: string
  refNo: string
  amt: string
  ccy: string
  account: string
  fxAmt: string | null
  fxCcy: string | null
  fxRate: string | null
  dedupHash: string
}

interface ChannelMatchContext {
  userChannelIds: Set<string>
  fullDigitsMap: Map<string, string>
  suffixMap: Map<string, string>
}

async function requireUser() {
  const session = await auth()
  if (!session?.user?.id) {
    throw new Error("请先登录")
  }
  return session.user.id
}

/** 去掉金额字符串的前导正负号，保留原始精度（不经过浮点往返） */
function stripSign(value: string): string {
  return value.trim().replace(/^[-+]/, "")
}

/** 解析 CCBA "YYYY-MM-DD" 日期，非法时返回 null */
function parseImportDate(value: string): Date | null {
  const date = new Date(`${value}T00:00:00`)
  return Number.isNaN(date.getTime()) ? null : date
}

/** 从账户描述中提取不少于 12 位的连续数字卡号 */
function extractCardDigits(
  account: string
): { fullDigits: string; last4: string } | null {
  const match = /\d{12,}/.exec(account)
  if (!match) return null
  return { fullDigits: match[0], last4: match[0].slice(-4) }
}

/** 去掉描述末尾的大写两位国家码，返回商户名与地理位置 */
function splitMerchantAndGeo(description: string): {
  merchantName: string
  geo: string | null
} {
  const trimmed = description.trim()
  const match = /\s+([A-Z]{2})$/.exec(trimmed)
  if (!match) {
    return { merchantName: trimmed.slice(0, 255), geo: null }
  }
  return {
    merchantName: trimmed.slice(0, match.index).trim().slice(0, 255),
    geo: match[1],
  }
}

/** 构建渠道匹配索引：完整卡号 -> id、卡号后缀 -> id */
function buildChannelMatchContext(
  userChannels: {
    id: string
    cardNumberFull: string | null
    cardNumberSuffix: string | null
  }[]
): ChannelMatchContext {
  const userChannelIds = new Set<string>()
  const fullDigitsMap = new Map<string, string>()
  const suffixMap = new Map<string, string>()

  for (const channel of userChannels) {
    userChannelIds.add(channel.id)

    const fullDigits = channel.cardNumberFull?.replace(/\D/g, "") ?? ""
    if (fullDigits && !fullDigitsMap.has(fullDigits)) {
      fullDigitsMap.set(fullDigits, channel.id)
    }

    const suffix = channel.cardNumberSuffix?.replace(/\D/g, "") ?? ""
    if (suffix.length >= 4 && !suffixMap.has(suffix)) {
      suffixMap.set(suffix, channel.id)
    }
  }

  return { userChannelIds, fullDigitsMap, suffixMap }
}

/**
 * 解析账户字符串对应的渠道 id：
 * 手动映射优先（且必须属于当前用户），否则按完整卡号、再按后四位自动匹配。
 */
function resolveChannelId(
  account: string,
  accountChannelMap: Record<string, string> | undefined,
  ctx: ChannelMatchContext
): string | null {
  const manualId = accountChannelMap?.[account]
  if (manualId && ctx.userChannelIds.has(manualId)) {
    return manualId
  }

  const digits = extractCardDigits(account)
  if (!digits) return null

  const byFull = ctx.fullDigitsMap.get(digits.fullDigits)
  if (byFull) return byFull

  return ctx.suffixMap.get(digits.last4) ?? null
}

/** 导入去重签名：优先银行流水号，缺失时退化为行内容哈希 */
function buildSignature(row: CcbaParsedRow): string {
  const refNo = row.refNo.trim()
  return refNo !== ""
    ? `ccba:ref:${refNo}`
    : `ccba:hash:${row.transDate}|${row.account}|${row.amt}|${row.description}`
}

export async function importCcbaRowsAction(
  rows: CcbaParsedRow[],
  accountChannelMap?: Record<string, string>
): Promise<CcbaImportResult> {
  try {
    const userId = await requireUser()

    if (rows.length === 0) {
      return { success: false, error: "没有可导入的账单记录" }
    }

    const userChannels = await db
      .select({
        id: channels.id,
        cardNumberFull: channels.cardNumberFull,
        cardNumberSuffix: channels.cardNumberSuffix,
      })
      .from(channels)
      .where(and(eq(channels.userId, userId), isNull(channels.deletedAt)))

    const ctx = buildChannelMatchContext(userChannels)

    // 已存在的导入签名（待清洗表 + 正式账本）
    const [dirtyExts, txnExts] = await Promise.all([
      db
        .select({ ext: transactionsDirty.ext })
        .from(transactionsDirty)
        .where(
          and(
            eq(transactionsDirty.userId, userId),
            isNull(transactionsDirty.deletedAt),
            like(transactionsDirty.ext, "ccba:%")
          )
        ),
      db
        .select({ ext: transactions.ext })
        .from(transactions)
        .where(
          and(
            eq(transactions.userId, userId),
            isNull(transactions.deletedAt),
            like(transactions.ext, "ccba:%")
          )
        ),
    ])

    const existingSignatures = new Set<string>()
    for (const existing of dirtyExts) {
      if (existing.ext) existingSignatures.add(existing.ext)
    }
    for (const existing of txnExts) {
      if (existing.ext) existingSignatures.add(existing.ext)
    }

    const insertedValues: NewTransactionDirty[] = []
    const batchSignatures = new Set<string>()
    const unmatchedAccounts = new Set<string>()
    let skipped = 0

    for (const row of rows) {
      const txnDate = parseImportDate(row.transDate)
      const postingDate = parseImportDate(row.postDate)
      if (!txnDate || !postingDate) {
        skipped++
        continue
      }

      const amtNum = parseFloat(row.amt)
      if (Number.isNaN(amtNum)) {
        skipped++
        continue
      }

      const channelId = resolveChannelId(row.account, accountChannelMap, ctx)
      if (!channelId) {
        unmatchedAccounts.add(row.account)
        continue
      }

      const signature = buildSignature(row)
      if (existingSignatures.has(signature) || batchSignatures.has(signature)) {
        skipped++
        continue
      }
      batchSignatures.add(signature)

      const ccy = row.ccy.toUpperCase()
      const isForeign = Boolean(
        row.fxAmt && row.fxCcy && row.fxCcy.toUpperCase() !== ccy
      )
      const { merchantName, geo } = splitMerchantAndGeo(row.description)

      const dcFlag = amtNum < 0 ? "CREDIT" : "DEBIT"
      let txnScene = "PAYMENT"
      if (row.description.includes("INHOUSE FUND TRANSFER")) {
        txnScene = "TRANSFER"
      } else if (amtNum < 0 && /rebate/i.test(row.description)) {
        txnScene = "MISC_IN"
      }

      let txnAmt: string
      let txnCcy: string
      let postingAmt: string | null
      let postingCcy: string | null
      let fxRates: { fromCcy: string; toCcy: string; rate: string }[] | null

      if (isForeign && row.fxAmt && row.fxCcy) {
        const fxCcy = row.fxCcy.toUpperCase()
        txnAmt = stripSign(row.fxAmt)
        txnCcy = fxCcy
        postingAmt = stripSign(row.amt)
        postingCcy = ccy
        fxRates = row.fxRate
          ? [{ fromCcy: fxCcy, toCcy: ccy, rate: row.fxRate }]
          : null
      } else {
        txnAmt = stripSign(row.amt)
        txnCcy = ccy
        postingAmt = null
        postingCcy = null
        fxRates = null
      }

      const rawData: CcbaRawData = {
        transDate: row.transDate,
        postDate: row.postDate,
        description: row.description,
        refNo: row.refNo,
        amt: row.amt,
        ccy: row.ccy,
        account: row.account,
        fxAmt: row.fxAmt,
        fxCcy: row.fxCcy,
        fxRate: row.fxRate,
        dedupHash: signature,
      }

      insertedValues.push({
        userId,
        txnDate,
        postingDate,
        txnAmt,
        txnCcy,
        postingAmt,
        postingCcy,
        fxRates,
        dcFlag,
        refChannels: [channelId],
        txnScene,
        merchantName,
        description: row.description,
        rawDescription: row.description,
        rawData,
        // ext 存导入去重签名；银行 ref_no 仅保留在上方 rawData 内
        ext: signature,
        geo,
      })
    }

    if (insertedValues.length > 0) {
      await db.insert(transactionsDirty).values(insertedValues)
    }

    revalidatePath("/bookkeeping")
    revalidatePath("/import")

    const result: CcbaImportResult = {
      success: true,
      imported: insertedValues.length,
      skipped,
    }
    if (unmatchedAccounts.size > 0) {
      result.unmatchedAccounts = Array.from(unmatchedAccounts)
    }
    return result
  } catch (err) {
    console.error("importCcbaRowsAction error:", err)
    return {
      success: false,
      error: err instanceof Error ? err.message : "导入账单失败",
    }
  }
}