package internal

// ProtoBuffer decodes a subset of the protobuf wire format for MMKV payloads.

type ProtoBuffer struct {
	buf []byte
	idx int
}

// NewProtoBuffer returns a buffer whose unread portion is buf.
func NewProtoBuffer(buf []byte) *ProtoBuffer {
	return &ProtoBuffer{buf: buf}
}

// DecodeStringBytes consumes a length-prefixed string.
func (b *ProtoBuffer) DecodeStringBytes() (string, error) {
	v, n := ConsumeString(b.buf[b.idx:])
	if n < 0 {
		return "", parseError(n)
	}
	b.idx += n
	return v, nil
}

// DecodeRawBytes consumes a length-prefixed bytes field.
func (b *ProtoBuffer) DecodeRawBytes(alloc bool) ([]byte, error) {
	v, n := ConsumeBytes(b.buf[b.idx:])
	if n < 0 {
		return nil, parseError(n)
	}
	b.idx += n
	if alloc {
		v = append([]byte(nil), v...)
	}
	return v, nil
}

// Unread returns the unread portion of the buffer.
func (b *ProtoBuffer) Unread() []byte {
	return b.buf[b.idx:]
}