/* ****************************************************************************************************************** *\
  Helper Functions
\* ****************************************************************************************************************** */

/* -------------------------------------------------------------------------- *\
  Basic Builders
\* -------------------------------------------------------------------------- */

/**
 * Create CNAME records from "comment@subdomain" strings
 * @param {string} domain - Domain to extend
 * @param {string} target - Server target
 * @param {string[]} records - Array of "comment@subdomain" strings
 */
function cnames(domain, target, records) {
  records.forEach(function(rec) {
    var part = rec.split("@");
    D_EXTEND(domain, CNAME(part[1], target, CF_COMMENT(part[0])));
  });
}

/**
 * Create a Minecraft server subdomain with CNAME and SRV records
 * @param {string} comment - Human-readable server name
 * @param {string} subdomain - Subdomain for the server
 * @param {string} domain - Domain to extend
 * @param {number} port - Port the server listens on
 */
function minecraft(comment, subdomain, domain, port) {
  var fqdn = subdomain + "." + domain + ".";
  D_EXTEND(domain,
    CNAME(subdomain, rexbox, CF_COMMENT("Minecraft > " + comment)),
    SRV("_minecraft._tcp." + subdomain, 0, 0, port, fqdn, CF_COMMENT("Minecraft > " + comment)),
  );
}

/* -------------------------------------------------------------------------- *\
  Email Builders
\* -------------------------------------------------------------------------- */

/**
 * Generate ProtonMail DNS records (MX, SPF, DMARC, verification, DKIM)
 * @param {string} verification - ProtonMail verification token
 * @param {string} dkimKey - ProtonMail DKIM domain key
 * @returns {DomainModifier[]} Array of DNS records
 */
function protonmail(verification, dkimKey) {
  return [
    // Stage 1: Verify
    TXT("@", "protonmail-verification=" + verification, CF_COMMENT("ProtonMail Verify")),
    // Stage 2: MX
    MX("@", 10, "mail.protonmail.ch.", CF_COMMENT("ProtonMail MX")),
    MX("@", 20, "mailsec.protonmail.ch.", CF_COMMENT("ProtonMail MX")),
    // Stage 3: SPF
    TXT("@", "v=spf1 include:_spf.protonmail.ch mx ~all", CF_COMMENT("ProtonMail SPF")),
    // Stage 3: DKIM
    CNAME("protonmail._domainkey", "protonmail.domainkey." + dkimKey + ".domains.proton.ch.", CF_COMMENT("ProtonMail DKIM")),
    CNAME("protonmail2._domainkey", "protonmail2.domainkey." + dkimKey + ".domains.proton.ch.", CF_COMMENT("ProtonMail DKIM")),
    CNAME("protonmail3._domainkey", "protonmail3.domainkey." + dkimKey + ".domains.proton.ch.", CF_COMMENT("ProtonMail DKIM")),
    // Stage 4: DMARC
    dmarcRecord,
  ];
}

/**
 * Generate SimpleLogin DNS records (MX, SPF, DMARC, verification, DKIM)
 * @param {string} verification - SimpleLogin verification token
 * @returns {DomainModifier[]} Array of DNS records
 */
function simplelogin(verification) {
  return [
    // Stage 1: Verify
    TXT("@", "sl-verification=" + verification, CF_COMMENT("SimpleLogin Verify")),
    // Stage 2: MX
    MX("@", 10, "mx1.simplelogin.co.", CF_COMMENT("SimpleLogin MX")),
    MX("@", 20, "mx2.simplelogin.co.", CF_COMMENT("SimpleLogin MX")),
    // Stage 3: SPF
    TXT("@", "v=spf1 include:simplelogin.co ~all", CF_COMMENT("SimpleLogin SPF")),
    // Stage 4: DKIM
    CNAME("dkim._domainkey", "dkim._domainkey.simplelogin.co.", CF_COMMENT("SimpleLogin DKIM")),
    CNAME("dkim02._domainkey", "dkim02._domainkey.simplelogin.co.", CF_COMMENT("SimpleLogin DKIM")),
    CNAME("dkim03._domainkey", "dkim03._domainkey.simplelogin.co.", CF_COMMENT("SimpleLogin DKIM")),
    // Stage 5: DMARC
    dmarcRecord,
  ];
}

/* -------------------------------------------------------------------------- *\
  OpenAlias Builder
\* -------------------------------------------------------------------------- */

/**
 * Generate OpenAlias TXT record
 * @param {string} prefix - Application prefix (e.g., "xmr", "btc")
 * @param {string} address - Recipient address
 * @param {object} [opts] - Optional key-value pairs
 * @param {string} [opts.name] - Recipient name
 * @param {string} [opts.description] - Transaction description
 * @param {string} [opts.amount] - Transaction amount
 * @param {string} [opts.paymentId] - Payment ID (e.g., for Monero)
 * @param {string} [opts.signature] - Address signature
 * @param {boolean} [opts.checksum] - Optional CRC-32 checksum
 * @returns {DomainModifier} TXT record
 */
function openalias(prefix, address, opts) {
  // Prefix and address are minimum requirement.
  // Everything else is optional.

  opts = opts || {};
  var record = "oa1:" + prefix + " recipient_address=" + address + ";";

  if (typeof opts.name === "string") record += " recipient_name=" + opts.name + ";";
  if (typeof opts.description === "string") record += " tx_description=" + opts.description + ";";
  if (typeof opts.amount === "string") record += " tx_amount=" + opts.amount + ";";
  if (typeof opts.paymentId === "string") record += " tx_payment_id=" + opts.paymentId + ";";
  if (typeof opts.signature === "string") record += " address_signature=" + opts.signature + ";";
  if (opts.checksum === true) record += " checksum=" + crc32(record.trim()).toString(16).toUpperCase() + ";";
  // Checksum must be last: CRC-32 of the record trimmed of surrounding spaces.

  return TXT("@", record, CF_COMMENT("OpenAlias > " + prefix.toUpperCase() + (opts.name ? " > " + opts.name : "")));
}

/**
 * Calculate CRC-32 checksum of a string
 * Handles UTF-8 strings correctly for use with DNSControl.
 * @param {string} str - Input string
 * @returns {number} CRC-32 value
 * @see https://github.com/nabijaczleweli/openalias.rs/blob/master/src/crypto_addr.rs
 */
function crc32(str) {
  // 1. Generate the CRC Table
  var table = [];
  for (var i = 0; i < 256; i++) {
    var c = i;
    for (var j = 0; j < 8; j++) {
      c = (c & 1) ? (0xEDB88320 ^ (c >>> 1)) : (c >>> 1);
    }
    table[i] = c;
  }

  // 2. Convert string to UTF-8 "binary" string
  // This ensures characters like '€' are treated as 3 bytes, not 1.
  var utf8Str = unescape(encodeURIComponent(str));

  // 3. Calculate CRC
  var crc = 0xFFFFFFFF;
  for (var k = 0; k < utf8Str.length; k++) {
    crc = table[(crc ^ utf8Str.charCodeAt(k)) & 0xFF] ^ (crc >>> 8);
  }

  return (crc ^ 0xFFFFFFFF) >>> 0;
}