package wire

import (
	"fmt"
	"io"
)

// MsgFeeFilter implements the Message interface and represents a bitcoin feefilter message. It is used to request the
// receiving peer does not announce any transactions below the specified minimum fee rate. This message was not added
// until protocol versions starting with FeeFilterVersion.
type MsgFeeFilter struct {
	MinFee int64
}

// BtcDecode decodes r using the bitcoin protocol encoding into the receiver. This is part of the Message interface
// implementation.
func (msg *MsgFeeFilter) BtcDecode(r io.Reader, pver uint32, enc MessageEncoding) (e error) {
	if pver < FeeFilterVersion {
		str := fmt.Sprintf("feefilter message invalid for protocol "+
			"version %d", pver,
		)
		return messageError("MsgFeeFilter.BtcDecode", str)
	}
	return readElement(r, &msg.MinFee)
}

// BtcEncode encodes the receiver to w using the bitcoin protocol encoding. This is part of the Message interface
// implementation.
func (msg *MsgFeeFilter) BtcEncode(w io.Writer, pver uint32, enc MessageEncoding) (e error) {
	if pver < FeeFilterVersion {
		str := fmt.Sprintf("feefilter message invalid for protocol "+
			"version %d", pver,
		)
		return messageError("MsgFeeFilter.BtcEncode", str)
	}
	return writeElement(w, msg.MinFee)
}

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

// MaxPayloadLength returns the maximum length the payload can be for the receiver. This is part of the Message
// interface implementation.
func (msg *MsgFeeFilter) MaxPayloadLength(pver uint32) uint32 {
	return 8
}

// NewMsgFeeFilter returns a new bitcoin feefilter message that conforms to the Message interface. See MsgFeeFilter for
// details.
func NewMsgFeeFilter(minfee int64) *MsgFeeFilter {
	return &MsgFeeFilter{
		MinFee: minfee,
	}
}