package wire

import (
	"fmt"
	"io"
)

const (
	// MaxFilterAddDataSize is the maximum byte size of a data element to add to the Bloom filter. It is equal to the
	// maximum element size of a script.
	MaxFilterAddDataSize = 520
)

// MsgFilterAdd implements the Message interface and represents a bitcoin filteradd message. It is used to add a data
// element to an existing Bloom filter. This message was not added until protocol version BIP0037Version.
type MsgFilterAdd struct {
	Data []byte
}

// BtcDecode decodes r using the bitcoin protocol encoding into the receiver. This is part of the Message interface implementation.
func (msg *MsgFilterAdd) BtcDecode(r io.Reader, pver uint32, enc MessageEncoding) (e error) {
	if pver < BIP0037Version {
		str := fmt.Sprintf(
			"filteradd message invalid for protocol version %d", pver,
		)
		return messageError("MsgFilterAdd.BtcDecode", str)
	}
	msg.Data, e = ReadVarBytes(r, pver, MaxFilterAddDataSize, "filteradd data")
	return e
}

// BtcEncode encodes the receiver to w using the bitcoin protocol encoding. This is part of the Message interface
// implementation.
func (msg *MsgFilterAdd) BtcEncode(w io.Writer, pver uint32, enc MessageEncoding) (e error) {
	if pver < BIP0037Version {
		str := fmt.Sprintf(
			"filteradd message invalid for protocol version %d", pver,
		)
		return messageError("MsgFilterAdd.BtcEncode", str)
	}
	size := len(msg.Data)
	if size > MaxFilterAddDataSize {
		str := fmt.Sprintf(
			"filteradd size too large for message [size %v, max %v]", size, MaxFilterAddDataSize,
		)
		return messageError("MsgFilterAdd.BtcEncode", str)
	}
	return WriteVarBytes(w, pver, msg.Data)
}

// Command returns the protocol command string for the message.  This is part of the Message interface implementation.
func (msg *MsgFilterAdd) Command() string {
	return CmdFilterAdd
}

// MaxPayloadLength returns the maximum length the payload can be for the receiver. This is part of the Message
// interface implementation.
func (msg *MsgFilterAdd) MaxPayloadLength(pver uint32) uint32 {
	return uint32(VarIntSerializeSize(MaxFilterAddDataSize)) +
		MaxFilterAddDataSize
}

// NewMsgFilterAdd returns a new bitcoin filteradd message that conforms to the Message interface. See MsgFilterAdd for
// details.
func NewMsgFilterAdd(data []byte) *MsgFilterAdd {
	return &MsgFilterAdd{
		Data: data,
	}
}