/**
 * ADIF (Amateur Data Interchange Format) Parser
 * Handles standard ADIF format from LoTW, DCL, and other sources
 *
 * ADIF format: <FIELD_NAME:length>value
 * Example: <CALL:5>DK0MU<BAND:3>80m<QSO_DATE:8>20250621
 */

/**
 * Parse ADIF data into array of QSO records
 * @param {string} adifData - Raw ADIF data string
 * @returns {Array<Object>} Array of parsed QSO records
 */
export function parseADIF(adifData) {
  const qsos = [];

  // Split by <EOR> (case-insensitive to handle <EOR>, <eor>, <Eor>, etc.)
  const regex = new RegExp('<eor>', 'gi');
  const records = adifData.split(regex);

  for (const record of records) {
    if (!record.trim()) continue;

    // Skip header records
    const trimmed = record.trim();
    if (trimmed.startsWith('<') && !trimmed.includes('<CALL:') && !trimmed.includes('<call:')) {
      continue;
    }

    const qso = {};

    // Use matchAll for cleaner parsing (creates new iterator for each record)
    const matches = record.matchAll(/<([A-Z0-9_]+):(\d+)(?::[A-Z]+)?>/gi);

    for (const match of matches) {
      const [fullMatch, fieldName, lengthStr] = match;
      const length = parseInt(lengthStr, 10);
      const valueStart = match.index + fullMatch.length;

      // Extract exactly 'length' characters from the string
      const value = record.substring(valueStart, valueStart + length);

      qso[fieldName.toLowerCase()] = value.trim();
    }

    // Only add if we have at least a callsign
    if (Object.keys(qso).length > 0 && (qso.call || qso.callsign)) {
      qsos.push(qso);
    }
  }

  return qsos;
}

/**
 * Parse DCL API response
 * DCL returns JSON with an "adif" field containing ADIF data
 * @param {Object} response - DCL API response
 * @returns {Array<Object>} Array of parsed QSO records
 */
export function parseDCLResponse(response) {
  if (!response || !response.adif) {
    return [];
  }

  const adifData = response.adif;
  const qsos = parseADIF(adifData);

  // Map DCL-specific fields to standard names
  return qsos.map(qso => ({
    ...qso,
    dcl_qsl_rcvd: qso.dcl_qsl_rcvd,
    dcl_qslrdate: qso.dcl_qslrdate,
    darc_dok: qso.darc_dok,
    my_darc_dok: qso.my_darc_dok,
  }));
}

/**
 * Normalize band name to standard format
 * @param {string} band - Band name
 * @returns {string|null} Normalized band name
 */
export function normalizeBand(band) {
  if (!band) return null;

  const bandMap = {
    '160m': '160m', '1800': '160m',
    '80m': '80m', '3500': '80m', '3.5mhz': '80m',
    '60m': '60m', '5mhz': '60m',
    '40m': '40m', '7000': '40m', '7mhz': '40m',
    '30m': '30m', '10100': '30m', '10mhz': '30m',
    '20m': '20m', '14000': '20m', '14mhz': '20m',
    '17m': '17m', '18100': '17m', '18mhz': '17m',
    '15m': '15m', '21000': '15m', '21mhz': '15m',
    '12m': '12m', '24890': '12m', '24mhz': '12m',
    '10m': '10m', '28000': '10m', '28mhz': '10m',
    '6m': '6m', '50000': '6m', '50mhz': '6m',
    '4m': '4m', '70000': '4m', '70mhz': '4m',
    '2m': '2m', '144000': '2m', '144mhz': '2m',
    '1.25m': '1.25m', '222000': '1.25m', '222mhz': '1.25m',
    '70cm': '70cm', '432000': '70cm', '432mhz': '70cm',
    '33cm': '33cm', '902000': '33cm', '902mhz': '33cm',
    '23cm': '23cm', '1296000': '23cm', '1296mhz': '23cm',
  };

  const normalized = bandMap[band.toLowerCase()];
  return normalized || band;
}

/**
 * Normalize mode name to standard format
 * @param {string} mode - Mode name
 * @returns {string} Normalized mode name
 */
export function normalizeMode(mode) {
  if (!mode) return '';

  const modeMap = {
    'cw': 'CW',
    'ssb': 'SSB', 'lsb': 'SSB', 'usb': 'SSB',
    'am': 'AM',
    'fm': 'FM',
    'rtty': 'RTTY',
    'psk31': 'PSK31',
    'psk63': 'PSK63',
    'ft8': 'FT8',
    'ft4': 'FT4',
    'jt65': 'JT65',
    'jt9': 'JT9',
    'js8': 'JS8',
    'mfsk': 'MFSK',
    'olivia': 'OLIVIA',
    'sstv': 'SSTV',
    'packet': 'PACKET',
    'pactor': 'PACTOR',
    'winlink': 'WINLINK',
    'fax': 'FAX',
    'hell': 'HELL',
    'tor': 'TOR',
  };

  const normalized = modeMap[mode.toLowerCase()];
  return normalized || mode.toUpperCase();
}