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();
}