# All files / lib/messages DlcOffer.ts

94.25% Statements 213/226
74.4% Branches 93/125
86.96% Functions 20/23
94.04% Lines 205/218

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     import { Script } from '@node-dlc/bitcoin';
    import { BufferReader, BufferWriter } from '@node-dlc/bufio';
    import { hash160 } from '@node-dlc/crypto';
    import { BitcoinNetwork } from 'bitcoin-networks';
    import { address } from 'bitcoinjs-lib';
    import secp256k1 from 'secp256k1';

    import { MessageType, PROTOCOL_VERSION } from '../MessageType';
    import { deserializeTlv } from '../serialize/deserializeTlv';
    import { getTlv } from '../serialize/getTlv';
    import { bigIntToNumber, toBigInt } from '../util';
    import { BatchFundingGroup, IBatchFundingGroupJSON } from './BatchFundingGroup';
    import {
      ContractInfo,
      IDisjointContractInfoJSON,
      ISingleContractInfoJSON,
    } from './ContractInfo';
    import { IDlcMessage } from './DlcMessage';
    import { FundingInput, IFundingInputJSON } from './FundingInput';
    import {
      IOrderIrcInfoJSON,
      OrderIrcInfo,
      OrderIrcInfoV0,
    } from './OrderIrcInfo';
    import {
      IOrderMetadataJSON,
      OrderMetadata,
      OrderMetadataV0,
    } from './OrderMetadata';
    import { IOrderPositionInfoJSON, OrderPositionInfo } from './OrderPositionInfo';

    export const LOCKTIME_THRESHOLD = 500000000;

    /**
     * DlcOffer message contains information about a node and indicates its
     * desire to enter into a new contract. This is the first step toward
     * creating the funding transaction and CETs.
     * Updated to support dlcspecs PR #163 format.
     */
    export class DlcOffer implements IDlcMessage {
      public static type = MessageType.DlcOffer;

      /**
       * Creates a DlcOffer from JSON data (e.g., from test vectors)
       * Handles both our internal format and external test vector formats
       * @param json JSON object representing a DLC offer
       */
      // eslint-disable-next-line @typescript-eslint/explicit-module-boundary-types, @typescript-eslint/no-explicit-any
      public static fromJSON(json: any): DlcOffer {
        const instance = new DlcOffer();

        // Basic fields with field name variations
        instance.protocolVersion =
          json.protocolVersion || json.protocol_version || PROTOCOL_VERSION;
        instance.contractFlags = Buffer.from(
          json.contractFlags || json.contract_flags || '00',
          'hex',
        );
        instance.chainHash = Buffer.from(json.chainHash || json.chain_hash, 'hex');
        instance.temporaryContractId = Buffer.from(
          json.temporaryContractId || json.temporary_contract_id,
          'hex',
        );

        instance.fundingPubkey = Buffer.from(
          json.fundingPubkey || json.fundingPubKey || json.funding_pubkey,
          'hex',
        );
        instance.payoutSpk = Buffer.from(
          json.payoutSpk || json.payoutSPK || json.payout_spk,
          'hex',
        );

        // Use toBigInt helper to handle BigInt values from json-bigint
        instance.payoutSerialId = toBigInt(
          json.payoutSerialId || json.payout_serial_id,
        );

        instance.offerCollateral = toBigInt(
          json.offerCollateral ||
            json.offerCollateralSatoshis ||
            json.offer_collateral,
        );

        instance.changeSpk = Buffer.from(
          json.changeSpk || json.changeSPK || json.change_spk,
          'hex',
        );
        instance.changeSerialId = toBigInt(
          json.changeSerialId || json.change_serial_id,
        );
        instance.fundOutputSerialId = toBigInt(
          json.fundOutputSerialId || json.fund_output_serial_id,
        );
        instance.feeRatePerVb = toBigInt(json.feeRatePerVb || json.fee_rate_per_vb);
        instance.cetLocktime = json.cetLocktime || json.cet_locktime || 0;
        instance.refundLocktime = json.refundLocktime || json.refund_locktime || 0;

        // Use ContractInfo.fromJSON() - proper delegation
        instance.contractInfo = ContractInfo.fromJSON(
          json.contractInfo || json.contract_info,
        );

        // Use FundingInput.fromJSON() for each funding input - proper delegation
        instance.fundingInputs = (json.fundingInputs || json.funding_inputs || [])
          // eslint-disable-next-line @typescript-eslint/no-explicit-any
          .map((inputJson: any) => FundingInput.fromJSON(inputJson));

        return instance;
      }

      /**
       * Deserializes an offer_dlc message with backward compatibility
       * Detects old format (without protocol_version) vs new format (with protocol_version)
       * @param buf
       */
      public static deserialize(buf: Buffer): DlcOffer {
        const instance = new DlcOffer();
        const reader = new BufferReader(buf);

        const type = reader.readUInt16BE(); // read type

        // Validate type matches expected DlcOffer type
        if (type !== MessageType.DlcOffer) {
          throw new Error(
            `Invalid message type. Expected ${MessageType.DlcOffer}, got ${type}`,
          );
        }

        // BACKWARD COMPATIBILITY: Detect old vs new format
        // New format: [type][protocol_version: 4 bytes][contract_flags: 1 byte][chain_hash: 32 bytes]
        // Old format: [type][contract_flags: 1 byte][chain_hash: 32 bytes]

        const nextBytes = reader.buffer.subarray(
          reader.position,
          reader.position + 5,
        );
        const possibleProtocolVersion = nextBytes.readUInt32BE(0);
        const possibleContractFlags = nextBytes.readUInt8(4);

        // Heuristic: protocol_version should be 1, contract_flags should be 0
        // If first 4 bytes are reasonable protocol version (1-10) and next byte is 0, assume new format
        const isNewFormat =
          possibleProtocolVersion >= 1 &&
          possibleProtocolVersion <= 10 &&
          possibleContractFlags === 0;

        Eif (isNewFormat) {
          // New format with protocol_version
          instance.protocolVersion = reader.readUInt32BE();
          instance.contractFlags = reader.readBytes(1);
        } else {
          // Old format without protocol_version
          instance.protocolVersion = 1; // Default to version 1
          instance.contractFlags = reader.readBytes(1);
        }

        instance.chainHash = reader.readBytes(32);
        instance.temporaryContractId = reader.readBytes(32);

        // ContractInfo is serialized as sibling type in dlcspecs PR #163 format
        instance.contractInfo = ContractInfo.deserialize(
          reader.buffer.subarray(reader.position),
        );
        // Skip past the ContractInfo we just read
        const contractInfoLength = instance.contractInfo.serialize().length;
        reader.position += contractInfoLength;
        instance.fundingPubkey = reader.readBytes(33);
        const payoutSpkLen = reader.readUInt16BE();
        instance.payoutSpk = reader.readBytes(payoutSpkLen);
        instance.payoutSerialId = reader.readUInt64BE();
        instance.offerCollateral = reader.readUInt64BE();

        // Changed from u16 to bigsize as per dlcspecs PR #163
        const fundingInputsLen = Number(reader.readBigSize());

        for (let i = 0; i < fundingInputsLen; i++) {
          // FundingInput body is serialized directly without TLV wrapper in rust-dlc format
          const fundingInput = FundingInput.deserializeBody(
            reader.buffer.subarray(reader.position),
          );
          instance.fundingInputs.push(fundingInput);

          // Skip past the FundingInput we just read
          const fundingInputLength = fundingInput.serializeBody().length;
          reader.position += fundingInputLength;
        }

        const changeSpkLen = reader.readUInt16BE();
        instance.changeSpk = reader.readBytes(changeSpkLen);
        instance.changeSerialId = reader.readUInt64BE();
        instance.fundOutputSerialId = reader.readUInt64BE();
        instance.feeRatePerVb = reader.readUInt64BE();
        instance.cetLocktime = reader.readUInt32BE();
        instance.refundLocktime = reader.readUInt32BE();

        // Parse TLV stream as per dlcspecs PR #163
        while (!reader.eof) {
          const buf = getTlv(reader);
          const tlvReader = new BufferReader(buf);
          const { type } = deserializeTlv(tlvReader);

          switch (Number(type)) {
            case MessageType.OrderMetadataV0:
              instance.metadata = OrderMetadataV0.deserialize(buf);
              break;
            case MessageType.OrderIrcInfoV0:
              instance.ircInfo = OrderIrcInfoV0.deserialize(buf);
              break;
            case MessageType.OrderPositionInfo:
              instance.positionInfo = OrderPositionInfo.deserialize(buf);
              break;
            case MessageType.BatchFundingGroup:
              Eif (!instance.batchFundingGroups) {
                instance.batchFundingGroups = [];
              }
              instance.batchFundingGroups.push(BatchFundingGroup.deserialize(buf));
              break;
            default:
              // Store unknown TLVs for future compatibility
              if (!instance.unknownTlvs) {
                instance.unknownTlvs = [];
              }
              instance.unknownTlvs.push({ type: Number(type), data: buf });
              break;
          }
        }

        // Auto-detect single funded DLCs
        if (
          instance.contractInfo.getTotalCollateral() === instance.offerCollateral
        ) {
          instance.singleFunded = true;
        }

        return instance;
      }

      /**
       * The type for offer_dlc message. offer_dlc = 42778
       */
      public type = DlcOffer.type;

      // New fields as per dlcspecs PR #163
      public protocolVersion: number = PROTOCOL_VERSION; // Default to current protocol version

      public temporaryContractId: Buffer; // New field for contract identification

      // Existing fields
      public contractFlags: Buffer;

      public chainHash: Buffer;

      public contractInfo: ContractInfo;

      public fundingPubkey: Buffer;

      public payoutSpk: Buffer;

      public payoutSerialId: bigint;

      public offerCollateral: bigint;

      public fundingInputs: FundingInput[] = [];

      public changeSpk: Buffer;

      public changeSerialId: bigint;

      public fundOutputSerialId: bigint;

      public feeRatePerVb: bigint;

      public cetLocktime: number;

      public refundLocktime: number;

      public metadata?: OrderMetadata;

      public ircInfo?: OrderIrcInfo;

      public positionInfo?: OrderPositionInfo;

      public batchFundingGroups?: BatchFundingGroup[];

      // Store unknown TLVs for forward compatibility
      public unknownTlvs?: Array<{ type: number; data: Buffer }>;

      /**
       * Flag to indicate if this is a single funded DLC
       * In single funded DLCs, totalCollateral equals offerCollateral
       */
      public singleFunded = false;

      /**
       * Marks this DLC offer as single funded and validates that collateral amounts are correct
       * @throws Will throw an error if totalCollateral doesn't equal offerCollateral
       */
      public markAsSingleFunded(): void {
        const totalCollateral = this.contractInfo.getTotalCollateral();
        if (totalCollateral !== this.offerCollateral) {
          throw new Error(
            `Cannot mark as single funded: totalCollateral (${totalCollateral}) must equal offerCollateral (${this.offerCollateral})`,
          );
        }
        this.singleFunded = true;
      }

      /**
       * Checks if this DLC offer is single funded (totalCollateral == offerCollateral)
       * @returns True if this is a single funded DLC
       */
      public isSingleFunded(): boolean {
        return (
          this.singleFunded ||
          this.contractInfo.getTotalCollateral() === this.offerCollateral
        );
      }

      /**
       * Get funding, change and payout address from DlcOffer
       * @param network Bitcoin Network
       * @returns {IDlcOfferAddresses}
       */
      public getAddresses(network: BitcoinNetwork): IDlcOfferAddresses {
        const fundingSPK = Script.p2wpkhLock(hash160(this.fundingPubkey))
          .serialize()
          .slice(1);
        const fundingAddress = address.fromOutputScript(fundingSPK, network);
        const changeAddress = address.fromOutputScript(this.changeSpk, network);
        const payoutAddress = address.fromOutputScript(this.payoutSpk, network);

        return {
          fundingAddress,
          changeAddress,
          payoutAddress,
        };
      }

      /**
       * Validates correctness of all fields in DlcOffer
       * Updated validation rules as per dlcspecs PR #163
       * @throws Will throw an error if validation fails
       */
      public validate(): void {
        // 1. Type is set automatically in class
        // 2. protocol_version validation
        if (this.protocolVersion !== PROTOCOL_VERSION) {
          throw new Error(
            `Unsupported protocol version: ${this.protocolVersion}, expected: ${PROTOCOL_VERSION}`,
          );
        }

        // 3. temporary_contract_id validation
        if (!this.temporaryContractId || this.temporaryContractId.length !== 32) {
          throw new Error('temporaryContractId must be 32 bytes');
        }

        // 4. contract_flags field is ignored
        // 5. chain_hash must be validated as input by end user
        // 6. payout_spk and change_spk must be standard script pubkeys

        try {
          address.fromOutputScript(this.payoutSpk);
        } catch (e) {
          throw new Error('DlcOffer payoutSpk is invalid');
        }

        try {
          address.fromOutputScript(this.changeSpk);
        } catch (e) {
          throw new Error('DlcOffer changeSpk is invalid');
        }

        // 7. funding_pubkey must be a valid secp256k1 pubkey in compressed format
        // https://github.com/bitcoin/bips/blob/master/bip-0137.mediawiki#background-on-ecdsa-signatures

        if (secp256k1.publicKeyVerify(Buffer.from(this.fundingPubkey))) {
          if (this.fundingPubkey[0] != 0x02 && this.fundingPubkey[0] != 0x03) {
            throw new Error('fundingPubkey must be in compressed format');
          }
        } else {
          throw new Error('fundingPubkey is not a valid secp256k1 key');
        }

        // 8. offer_collateral must be greater than or equal to 1000
        if (this.offerCollateral < 1000) {
          throw new Error('offer_collateral must be greater than or equal to 1000');
        }

        if (this.cetLocktime < 0) {
          throw new Error('cet_locktime must be greater than or equal to 0');
        }

        if (this.refundLocktime < 0) {
          throw new Error('refund_locktime must be greater than or equal to 0');
        }

        // 9. cet_locktime and refund_locktime must either both be unix timestamps, or both be block heights.
        // https://en.bitcoin.it/wiki/NLockTime
        // https://github.com/bitcoin/bips/blob/master/bip-0065.mediawiki#detailed-specification
        // https://github.com/bitcoin/bitcoin/blob/master/src/script/script.h#L39
        if (
          !(
            (this.cetLocktime < LOCKTIME_THRESHOLD &&
              this.refundLocktime < LOCKTIME_THRESHOLD) ||
            (this.cetLocktime >= LOCKTIME_THRESHOLD &&
              this.refundLocktime >= LOCKTIME_THRESHOLD)
          )
        ) {
          throw new Error('cetLocktime and refundLocktime must be in same units');
        }

        // 10. cetLocktime must be less than refundLocktime
        if (this.cetLocktime >= this.refundLocktime) {
          throw new Error('cetLocktime must be less than refundLocktime');
        }

        // 11. inputSerialId must be unique for each input

        const inputSerialIds = this.fundingInputs.map(
          (input: FundingInput) => input.inputSerialId,
        );

        if (new Set(inputSerialIds).size !== inputSerialIds.length) {
          throw new Error('inputSerialIds must be unique');
        }

        // 12. changeSerialId and fundOutputSerialID must be different

        if (this.changeSerialId === this.fundOutputSerialId) {
          throw new Error(
            'changeSerialId and fundOutputSerialId must be different',
          );
        }

        // validate contractInfo
        this.contractInfo.validate();

        // totalCollateral should be > offerCollateral (logical validation)
        // Exception: for single funded DLCs, totalCollateral == offerCollateral is allowed
        if (this.isSingleFunded()) {
          Iif (this.contractInfo.getTotalCollateral() !== this.offerCollateral) {
            throw new Error(
              'For single funded DLCs, totalCollateral must equal offerCollateral',
            );
          }
        } else {
          if (this.contractInfo.getTotalCollateral() <= this.offerCollateral) {
            throw new Error(
              'totalCollateral should be greater than offerCollateral',
            );
          }
        }

        // validate funding amount
        const fundingAmount = this.fundingInputs.reduce((acc, fundingInput) => {
          const input = fundingInput as FundingInput;
          return acc + input.prevTx.outputs[input.prevTxVout].value.sats;
        }, BigInt(0));

        if (this.isSingleFunded()) {
          // For single funded DLCs, funding amount must cover the full total collateral plus fees
          if (fundingAmount < this.contractInfo.getTotalCollateral()) {
            throw new Error(
              'For single funded DLCs, fundingAmount must be at least totalCollateral',
            );
          }
        } else {
          // For regular DLCs, funding amount must be greater than offer collateral
          Iif (this.offerCollateral >= fundingAmount) {
            throw new Error('fundingAmount must be greater than offerCollateral');
          }
        }
      }

      /**
       * Converts dlc_offer to JSON (canonical rust-dlc format)
       */
      public toJSON(): IDlcOfferJSON {
        const tlvs = [];

        if (this.metadata) tlvs.push(this.metadata.toJSON());
        if (this.ircInfo) tlvs.push(this.ircInfo.toJSON());
        if (this.positionInfo) tlvs.push(this.positionInfo.toJSON());
        if (this.batchFundingGroups)
          this.batchFundingGroups.forEach((fundingInfo) =>
            tlvs.push(fundingInfo.toJSON()),
          );

        // Include unknown TLVs for debugging
        Iif (this.unknownTlvs) {
          this.unknownTlvs.forEach((tlv) =>
            tlvs.push({ type: tlv.type, data: tlv.data.toString('hex') }),
          );
        }

        // Return canonical rust-dlc format only
        return {
          protocolVersion: this.protocolVersion,
          temporaryContractId: this.temporaryContractId.toString('hex'),
          contractFlags: Number(this.contractFlags[0]),
          chainHash: this.chainHash.toString('hex'),
          contractInfo: this.contractInfo.toJSON(),
          fundingPubkey: this.fundingPubkey.toString('hex'), // lowercase 'k'
          payoutSpk: this.payoutSpk.toString('hex'), // lowercase
          payoutSerialId: bigIntToNumber(this.payoutSerialId),
          offerCollateral: bigIntToNumber(this.offerCollateral), // no "Satoshis"
          fundingInputs: this.fundingInputs.map((input) => input.toJSON()),
          changeSpk: this.changeSpk.toString('hex'), // lowercase
          changeSerialId: bigIntToNumber(this.changeSerialId),
          fundOutputSerialId: bigIntToNumber(this.fundOutputSerialId),
          feeRatePerVb: bigIntToNumber(this.feeRatePerVb),
          cetLocktime: this.cetLocktime,
          refundLocktime: this.refundLocktime,
        }; // Allow different field names from interface
      }

      /**
       * Serializes the offer_dlc message into a Buffer
       * Updated serialization format as per dlcspecs PR #163
       */
      public serialize(): Buffer {
        const writer = new BufferWriter();
        writer.writeUInt16BE(this.type);

        // New fields as per dlcspecs PR #163
        writer.writeUInt32BE(this.protocolVersion);
        writer.writeBytes(this.contractFlags);
        writer.writeBytes(this.chainHash);
        writer.writeBytes(this.temporaryContractId); // New field

        writer.writeBytes(this.contractInfo.serialize());
        writer.writeBytes(this.fundingPubkey);
        writer.writeUInt16BE(this.payoutSpk.length);
        writer.writeBytes(this.payoutSpk);
        writer.writeUInt64BE(this.payoutSerialId);
        writer.writeUInt64BE(this.offerCollateral);

        // Changed from u16 to bigsize as per dlcspecs PR #163
        writer.writeBigSize(this.fundingInputs.length);

        for (const fundingInput of this.fundingInputs) {
          // Use serializeBody() to match rust-dlc behavior - funding inputs in vec are serialized without TLV wrapper
          writer.writeBytes(fundingInput.serializeBody());
        }

        writer.writeUInt16BE(this.changeSpk.length);
        writer.writeBytes(this.changeSpk);
        writer.writeUInt64BE(this.changeSerialId);
        writer.writeUInt64BE(this.fundOutputSerialId);
        writer.writeUInt64BE(this.feeRatePerVb);
        writer.writeUInt32BE(this.cetLocktime);
        writer.writeUInt32BE(this.refundLocktime);

        // TLV stream as per dlcspecs PR #163
        if (this.metadata) writer.writeBytes(this.metadata.serialize());
        if (this.ircInfo) writer.writeBytes(this.ircInfo.serialize());
        if (this.positionInfo) writer.writeBytes(this.positionInfo.serialize());
        if (this.batchFundingGroups)
          this.batchFundingGroups.forEach((fundingInfo) =>
            writer.writeBytes(fundingInfo.serialize()),
          );

        // Write unknown TLVs for forward compatibility
        Iif (this.unknownTlvs) {
          this.unknownTlvs.forEach((tlv) => {
            writer.writeBytes(tlv.data);
          });
        }

        return writer.toBuffer();
      }
    }

    export interface IDlcOfferJSON {
      type?: number; // Made optional for rust-dlc compatibility
      protocolVersion: number;
      temporaryContractId: string;
      contractFlags: number;
      chainHash: string;
      contractInfo: ISingleContractInfoJSON | IDisjointContractInfoJSON;
      fundingPubkey: string;
      payoutSpk: string;
      payoutSerialId: number;
      offerCollateral: number;
      fundingInputs: IFundingInputJSON[];
      changeSpk: string;
      changeSerialId: number;
      fundOutputSerialId: number;
      feeRatePerVb: number;
      cetLocktime: number;
      refundLocktime: number;
      serialized?: string; // Made optional - hex serialization for compatibility testing
      tlvs?: (
        | IOrderMetadataJSON
        | IOrderIrcInfoJSON
        | IOrderPositionInfoJSON
        | IBatchFundingGroupJSON
        | unknown
      )[]; // Made optional - for unknown TLVs
    }

    export interface IDlcOfferAddresses {
      fundingAddress: string;
      changeAddress: string;
      payoutAddress: string;
    }

    export class DlcOfferContainer {
      private offers: DlcOffer[] = [];

      /**
       * Adds a DlcOffer to the container.
       * @param offer The DlcOffer to add.
       */
      public addOffer(offer: DlcOffer): void {
        this.offers.push(offer);
      }

      /**
       * Returns all DlcOffers in the container.
       * @returns An array of DlcOffer instances.
       */
      public getOffers(): DlcOffer[] {
        return this.offers;
      }

      /**
       * Serializes all DlcOffers in the container to a Buffer.
       * @returns A Buffer containing the serialized DlcOffers.
       */
      public serialize(): Buffer {
        const writer = new BufferWriter();
        // Write the number of offers in the container first.
        writer.writeBigSize(this.offers.length);
        // Serialize each offer and write it.
        this.offers.forEach((offer) => {
          const serializedOffer = offer.serialize();
          // Optionally, write the length of the serialized offer for easier deserialization.
          writer.writeBigSize(serializedOffer.length);
          writer.writeBytes(serializedOffer);
        });
        return writer.toBuffer();
      }

      /**
       * Deserializes a Buffer into a DlcOfferContainer with DlcOffers.
       * @param buf The Buffer to deserialize.
       * @returns A DlcOfferContainer instance.
       */
      public static deserialize(buf: Buffer): DlcOfferContainer {
        const reader = new BufferReader(buf);
        const container = new DlcOfferContainer();
        const offersCount = reader.readBigSize();
        for (let i = 0; i < offersCount; i++) {
          // Optionally, read the length of the serialized offer if it was written during serialization.
          const offerLength = reader.readBigSize();
          const offerBuf = reader.readBytes(Number(offerLength));
          const offer = DlcOffer.deserialize(offerBuf);
          container.addOffer(offer);
        }
        return container;
      }
    }