function parseCsv(content) {
  const rows = [];
  let row = [];
  let field = "";
  let inQuotes = false;

  // Character-level parser to correctly handle commas/newlines inside quotes.
  for (let i = 0; i < content.length; i += 1) {
    const char = content[i];
    const next = content[i + 1];

    if (char === "\"") {
      if (inQuotes && next === "\"") {
        field += "\"";
        i += 1;
      } else {
        inQuotes = !inQuotes;
      }
      continue;
    }

    if (char === "," && !inQuotes) {
      row.push(field);
      field = "";
      continue;
    }

    if ((char === "\n" || char === "\r") && !inQuotes) {
      if (char === "\r" && next === "\n") {
        i += 1;
      }
      row.push(field);
      field = "";
      if (row.length > 1 || (row.length === 1 && row[0] !== "")) {
        rows.push(row);
      }
      row = [];
      continue;
    }

    field += char;
  }

  if (field.length || row.length) {
    row.push(field);
    rows.push(row);
  }

  if (!rows.length) {
    return { headers: [], records: [] };
  }

  const headers = rows[0].map((h) => h.trim());
  const records = rows.slice(1).map((r) => {
    const obj = {};
    headers.forEach((h, idx) => {
      obj[h] = (r[idx] || "").trim();
    });
    return obj;
  });

  return { headers, records };
}

function escapeCsvValue(value) {
  const s = String(value ?? "");
  if (/[",\n\r]/.test(s)) {
    return `"${s.replace(/"/g, "\"\"")}"`;
  }
  return s;
}

function toCsv(headers, records) {
  const lines = [headers.map(escapeCsvValue).join(",")];
  records.forEach((record) => {
    const row = headers.map((h) => escapeCsvValue(record[h] ?? ""));
    lines.push(row.join(","));
  });
  return `${lines.join("\n")}\n`;
}

module.exports = {
  parseCsv,
  toCsv
};