import type { OFXAccount, OFXTransaction } from "./types"

export function parseOFX(content: string): OFXAccount | null {
  try {
    // Remove SGML header and clean up
    const xmlStart = content.indexOf("<OFX>")
    if (xmlStart === -1) return null

    let xml = content.substring(xmlStart)

    // Convert SGML to XML-like format
    xml = xml.replace(/<(\w+)>([^<]+)(?=<)/g, "<$1>$2</$1>")

    // Extract account info
    const bankId = extractValue(xml, "BANKID") || extractValue(xml, "ORG") || "UNKNOWN"
    const accountId = extractValue(xml, "ACCTID") || "UNKNOWN"
    const accountType = extractValue(xml, "ACCTTYPE") || "CHECKING"
    const balanceStr = extractValue(xml, "BALAMT") || "0"
    const balance = Number.parseFloat(balanceStr)
    const balanceDate = extractValue(xml, "DTASOF") || new Date().toISOString()
    const currency = extractValue(xml, "CURDEF") || "EUR"

    // Extract transactions
    const transactions: OFXTransaction[] = []
    const stmtTrnRegex = /<STMTTRN>([\s\S]*?)<\/STMTTRN>/gi
    let match

    while ((match = stmtTrnRegex.exec(xml)) !== null) {
      const trnXml = match[1]

      const fitId = extractValue(trnXml, "FITID") || `${Date.now()}-${Math.random()}`
      const dateStr = extractValue(trnXml, "DTPOSTED") || ""
      const amountStr = extractValue(trnXml, "TRNAMT") || "0"
      const name = extractValue(trnXml, "NAME") || extractValue(trnXml, "MEMO") || "Unknown"
      const memo = extractValue(trnXml, "MEMO")
      const checkNum = extractValue(trnXml, "CHECKNUM")
      const type = extractValue(trnXml, "TRNTYPE") || "OTHER"

      transactions.push({
        fitId,
        date: parseOFXDate(dateStr),
        amount: Number.parseFloat(amountStr),
        name: cleanString(name),
        memo: memo ? cleanString(memo) : undefined,
        checkNum: checkNum ?? undefined,
        type,
      })
    }

    return {
      bankId,
      accountId,
      accountType: mapAccountType(accountType),
      balance,
      balanceDate: parseOFXDate(balanceDate),
      currency,
      transactions,
    }
  } catch (error) {
    console.error("Error parsing OFX:", error)
    return null
  }
}

function extractValue(xml: string, tag: string): string | null {
  const regex = new RegExp(`<${tag}>([^<]+)`, "i")
  const match = xml.match(regex)
  return match ? match[1].trim() : null
}

function parseOFXDate(dateStr: string): string {
  if (!dateStr || dateStr.length < 8) return new Date().toISOString()

  const year = dateStr.substring(0, 4)
  const month = dateStr.substring(4, 6)
  const day = dateStr.substring(6, 8)

  return `${year}-${month}-${day}`
}

function mapAccountType(type: string): "CHECKING" | "SAVINGS" | "CREDIT_CARD" | "OTHER" {
  const upper = type.toUpperCase()
  if (upper.includes("CHECK") || upper.includes("CURRENT")) return "CHECKING"
  if (upper.includes("SAV")) return "SAVINGS"
  if (upper.includes("CREDIT")) return "CREDIT_CARD"
  return "OTHER"
}

function cleanString(str: string): string {
  return str.replace(/\s+/g, " ").trim()
}