import { BufferReader, BufferWriter } from "@node-lightning/bufio";
import { MessageType } from "../MessageType";
import { ChannelId } from "@node-lightning/core";
import { IWireMessage } from "./IWireMessage";

/**
 * ShutdownMessage represents the `shutdown` message defined in BOLT #2 of the Lightning
 * Specification. This message can be sent by either node. The scriptPubKey must be a valid P2WPKH,
 * P2WSH, P2SH-P2WPKH, P2SH-P2WSH, or any valid witness script if option_shutdown_anysegwit is
 * negotiated and it should be same as `shutdown_scriptpubkey` value if it was sent during
 * `'open/accept' channel message`. Therefore, if both conditions hold true resulting transaction
 * will propagate to miners. If shutdown is sent by either node, corresponding node should send
 * commitment_signed to commit any outstanding changes before replying shutdown. Once shutdown is
 * sent by both nodes no new HTLCs should be added or accepted by the channel. After successful
 * handshake of shutdown message, fee negotiation and signature sending can begin with
 * `closing_signed` message.
 */
export class ShutdownMessage implements IWireMessage {
    public static type = MessageType.Shutdown;

    /**
     * Deserializes a shutdown message
     * @param buf
     */
    public static deserialize(buf: Buffer): ShutdownMessage {
        const instance = new ShutdownMessage();
        const reader = new BufferReader(buf);

        reader.readUInt16BE(); // read type
        instance.channelId = new ChannelId(reader.readBytes(32));
        const len = reader.readUInt16BE();
        instance.scriptPubKey = reader.readBytes(len);

        return instance;
    }

    /**
     * The type for message. Shutdown = 38
     */
    public readonly type: MessageType = ShutdownMessage.type;

    /**
     * ChannelId generated from the funding transactions outpoint.
     */
    public channelId: ChannelId;

    /**
     * scriptPubKey is used by the sender to get paid, it must be a valid P2WPKH, P2WSH, P2SH-P2WPKH,
     *  P2SH-P2WSH, or any valid witness script if option_shutdown_anysegwit is negotiated and it
     * should be same as `shutdown_scriptpubkey` value if it was sent during `'open/accept' channel
     * message`.
     */
    public scriptPubKey: Buffer;

    /**
     * Serializes the message into a Buffer
     */
    public serialize(): Buffer {
        const writer = new BufferWriter();
        writer.writeUInt16BE(this.type);
        writer.writeBytes(this.channelId.toBuffer());
        writer.writeUInt16BE(this.scriptPubKey.length);
        writer.writeBytes(this.scriptPubKey);
        return writer.toBuffer();
    }
}