import { BufferReader , BufferWriter } from "@node-lightning/bufio" ; import { ChannelId , Value } from "@node-lightning/core" ; import { MessageType } from "../MessageType" ; import { IWireMessage } from "./IWireMessage" ; /**
 * The `closing_signed` message is sent by the channel funder after
 * the `shutdown_message`. The funder chooses a fee it thinks
 * is fair, and signs the closing transaction with the scriptpubkey fields from
 * the shutdown messages (along with its chosen fee) and sends the signature.
 * The other node then replies similarly, using a fee it thinks is fair.
 * One of the benefits of mutual close is that the fee rate can be negotiated
 * down from the existing fee rate(which is generally expensive) to a more reasonable one.
 * In order for fee rate to converge, it has to be strictly between the last proposed
 * and the counterparty's last proposed value. This exchange continues using the
 * channelID until both agree on the same fee or when one side fails the channel.
 */ export class ClosingSignedMessage implements IWireMessage { public static type : MessageType = MessageType . ClosingSigned ; param buf returns public static deserialize ( buf ) { const instance = new ClosingSignedMessage ( ) ; const reader = new BufferReader ( buf ) ; reader . readUInt16BE ( ) ; instance . channelId = new ChannelId ( reader . readBytes ( 32 ) ) ; instance . feeSatoshis = Value . fromSats ( reader . readUInt64BE ( ) ) ; instance . signature = reader . readBytes ( 64 ) ; return instance ; } /**
     * The type for message. Closing_Signed = 39
     */ public readonly type : MessageType = ClosingSignedMessage . type ; /**
     * ChannelId generated from the funding transactions outpoint.
     */ public channelId : ChannelId ; /**
     * Expected value for fee_satoshis could vary how fee rate negotiations happens between the
     * two nodes.Assuming initially both nodes have different fee estimates, in every iteration
     * they should ensure fee rate is strictly between their last proposed and the counterparty's
     * last proposed value. Hence changes are made accordingly on both ends and communicated
     * between the channel until both of them comes to an agreement or when one side fails the
     * channel.
     */ public feeSatoshis : Value ; /**
     * Sender signs the closing transaction with the scriptpubkey fields from the
     * shutdown messages (along with its chosen fee) and sends the signature;
     */ public signature : Buffer ; /**
     * Serializes the message into a Buffer
     */ public serialize ( ) { const writer = new BufferWriter ( ) ; writer . writeUInt16BE ( this . type ) ; writer . writeBytes ( this . channelId . toBuffer ( ) ) ; writer . writeUInt64BE ( this . feeSatoshis . sats ) ; writer . writeBytes ( this . signature ) ; return writer . toBuffer ( ) ; } }