package magna

import (
	"encoding/binary"
	"fmt"
)

// Decode decodes a question from buf at the offset
func (q *Question) Decode(buf []byte, offset int) (int, error) {
	var err error
	q.QName, offset, err = decodeDomain(buf, offset)
	if err != nil {
		return offset, fmt.Errorf("question decode: failed to decode QName: %w", err)
	}

	qtype, offset, err := getU16(buf, offset)
	if err != nil {
		return offset, fmt.Errorf("question decode: failed to decode QType for %s: %w", q.QName, err)
	}

	qclass, offset, err := getU16(buf, offset)
	if err != nil {
		return offset, fmt.Errorf("question decode: failed to decode QClass for %s: %w", q.QName, err)
	}

	q.QType = DNSType(qtype)
	q.QClass = DNSClass(qclass)
	return offset, nil
}

// Encode serializes a Question into bytes, using a map to handle domain name compression offsets.
func (q *Question) Encode(bytes []byte, offsets *map[string]uint16) ([]byte, error) {
	var err error
	bytes, err = encodeDomain(bytes, q.QName, offsets)
	if err != nil {
		return nil, fmt.Errorf("question encode: failed to encode QName %s: %w", q.QName, err)
	}

	bytes = binary.BigEndian.AppendUint16(bytes, uint16(q.QType))
	bytes = binary.BigEndian.AppendUint16(bytes, uint16(q.QClass))
	return bytes, nil
}