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/// import
import { Buffer } from "node:buffer";
/// util
import { FLUSH_MASK, NOT_FLUSH_MASK } from "./utility/constants.ts";import { Name } from "./name.ts";import { OPT } from "./records/opt.ts";import { Record } from "./record.ts";import * as classes from "./utility/classes.ts";import * as types from "./utility/types.ts";


/// export
export class Answer {  decodeBytes = 0;  encodeBytes = 0;
  decode(buf, offset?) {    if (!offset)      offset = 0;
    const a: { [key: string]: unknown; } = {};    const name = new Name();    const oldOffset = offset;    const opt = new OPT();
    a.name = name.decode(buf, offset);    offset += name.decodeBytes;    a.type = types.toString(buf.readUInt16BE(offset));
    if (a.type === "OPT") {      a.udpPayloadSize = buf.readUInt16BE(offset + 2);      a.extendedRcode = buf.readUInt8(offset + 4);      a.ednsVersion = buf.readUInt8(offset + 5);      a.flags = buf.readUInt16BE(offset + 6);      a.flag_do = ((Number(a.flags) >> 15) & 0x1) === 1;      a.options = opt.decode(buf, offset + 8);      offset += 8 + opt.decodeBytes;    } else {      const klass = buf.readUInt16BE(offset + 2);
      a.ttl = buf.readUInt32BE(offset + 4);      a.class = classes.toString(klass & NOT_FLUSH_MASK);      a.flush = !!(klass & FLUSH_MASK);
      const enc = Record(a.type);
      a.data = enc.decode(buf, offset + 8);      offset += 8 + enc.decodeBytes;    }
    this.decodeBytes = offset - oldOffset;    return a;  }
  encode(a, buf?, offset?) {    if (!buf)      buf = Buffer.alloc(this.encodingLength(a));
    if (!offset)      offset = 0;
    const name = new Name();    const oldOffset = offset;    const opt = new OPT();
    name.encode(a.name, buf, offset);    offset += name.encodeBytes;
    buf.writeUInt16BE(types.toType(a.type), offset);
    if (a.type.toUpperCase() === "OPT") {      if (a.name !== ".")        throw new Error("OPT name must be root.");
      buf.writeUInt16BE(a.udpPayloadSize || 4096, offset + 2);      buf.writeUInt8(a.extendedRcode || 0, offset + 4);      buf.writeUInt8(a.ednsVersion || 0, offset + 5);      buf.writeUInt16BE(a.flags || 0, offset + 6);
      offset += 8;      opt.encode(a.options || [], buf, offset);      offset += opt.encodeBytes;    } else {      let klass = classes.toClass(a.class === undefined ? "IN" : a.class);
      if (a.flush)        klass |= FLUSH_MASK; // the 1st bit of the class is the flush bit
      buf.writeUInt16BE(klass, offset + 2);      buf.writeUInt32BE(a.ttl || 0, offset + 4);      offset += 8;
      const enc = Record(a.type);      enc.encode(a.data, buf, offset);      offset += enc.encodeBytes;    }
    this.encodeBytes = offset - oldOffset;    return buf;  }
  encodingLength(a) {    const data = (a.data !== null && a.data !== undefined) ?      a.data :      a.options;    const name = new Name();
    return name.encodingLength(a.name) + 8 + Record(a.type).encodingLength(data);  }}