# All files / lib/messages DlcAccept.ts

87.62% Statements 177/202
57.14% Branches 52/91
82.76% Functions 24/29
87.44% Lines 174/199

Press n or j to go to the next uncovered block, b, p or k for the previous block.

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74
    75
    76
    77
    78
    79
    80
    81
    82
    83
    84
    85
    86
    87
    88
    89
    90
    91
    92
    93
    94
    95
    96
    97
    98
    99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127
    128
    129
    130
    131
    132
    133
    134
    135
    136
    137
    138
    139
    140
    141
    142
    143
    144
    145
    146
    147
    148
    149
    150
    151
    152
    153
    154
    155
    156
    157
    158
    159
    160
    161
    162
    163
    164
    165
    166
    167
    168
    169
    170
    171
    172
    173
    174
    175
    176
    177
    178
    179
    180
    181
    182
    183
    184
    185
    186
    187
    188
    189
    190
    191
    192
    193
    194
    195
    196
    197
    198
    199
    200
    201
    202
    203
    204
    205
    206
    207
    208
    209
    210
    211
    212
    213
    214
    215
    216
    217
    218
    219
    220
    221
    222
    223
    224
    225
    226
    227
    228
    229
    230
    231
    232
    233
    234
    235
    236
    237
    238
    239
    240
    241
    242
    243
    244
    245
    246
    247
    248
    249
    250
    251
    252
    253
    254
    255
    256
    257
    258
    259
    260
    261
    262
    263
    264
    265
    266
    267
    268
    269
    270
    271
    272
    273
    274
    275
    276
    277
    278
    279
    280
    281
    282
    283
    284
    285
    286
    287
    288
    289
    290
    291
    292
    293
    294
    295
    296
    297
    298
    299
    300
    301
    302
    303
    304
    305
    306
    307
    308
    309
    310
    311
    312
    313
    314
    315
    316
    317
    318
    319
    320
    321
    322
    323
    324
    325
    326
    327
    328
    329
    330
    331
    332
    333
    334
    335
    336
    337
    338
    339
    340
    341
    342
    343
    344
    345
    346
    347
    348
    349
    350
    351
    352
    353
    354
    355
    356
    357
    358
    359
    360
    361
    362
    363
    364
    365
    366
    367
    368
    369
    370
    371
    372
    373
    374
    375
    376
    377
    378
    379
    380
    381
    382
    383
    384
    385
    386
    387
    388
    389
    390
    391
    392
    393
    394
    395
    396
    397
    398
    399
    400
    401
    402
    403
    404
    405
    406
    407
    408
    409
    410
    411
    412
    413
    414
    415
    416
    417
    418
    419
    420
    421
    422
    423
    424
    425
    426
    427
    428
    429
    430
    431
    432
    433
    434
    435
    436
    437
    438
    439
    440
    441
    442
    443
    444
    445
    446
    447
    448
    449
    450
    451
    452
    453
    454
    455
    456
    457
    458
    459
    460
    461
    462
    463
    464
    465
    466
    467
    468
    469
    470
    471
    472
    473
    474
    475
    476
    477
    478
    479
    480
    481
    482
    483
    484
    485
    486
    487
    488
    489
    490
    491
    492
    493
    494
    495
    496
    497
    498
    499
    500
    501
    502
    503
    504
    505
    506
    507
    508
    509
    510
    511
    512
    513
    514
    515
    516
    517
    518
    519
    520
    521
    522
    523
    524
    525
    526
    527
    528
    529
    530
    531
    532
    533
    534
    535
    536
    537
    538
    539
    540
    541
    542
    543
    544
    545
    546
    547
    548
    549
    550
    551
    552
    553
    554
    555
    556
    557
    558
    559
    560
    561
    562
    563
    564
    565
    566
    567
    568
    569
    570
    571
    572
    573
    574
    575
    576
    577
    578
    579
    580
    581
    582
    583
    584
    585
    586
    587
    588
    589
    590
    591
    592
    593
    594
    595
    596
    597
    598
    599
    600
    601
    602
    603
    604
    605
    606
    607
    608
    609
    610
    611
    612
    613
    614
    615
    616
    617
    618
    619
    620
    621
    622
    623
    624
    625
    626
    627
    628
    629
    630
    631
    632
    633
    634
    635
    636
    637
    638
    639
    6401x
    1x
    1x

    1x
    1x

    1x
    1x
    1x
    1x
    1x
    1x

    1x
    1x

    1x
    1x

    30x

    30x
    30x

    30x

    30x
    30x
    30x

    30x

    30x

    30x

    30x

    30x

    30x

    30x

    30x

    30x

    30x

    30x
    30x

    30x

    30x

    30x

    30x

    30x

    30x

    30x

    30x

    5110x
    5110x

    30x

    54x
    54x

    54x

    54x
    54x
    54x
    54x
    54x
    54x
    54x

    54x
    54x

    54x

    54x

    54x
    54x

    54x
    54x
    54x

    54x

    52x

    52x
    52x

    2x

    54x

    54x

    54x

    54x
    54x
    54x
    54x

    54x
    213x
    213x
    213x

    213x

    213x
    3x

    213x
    213x

    54x
    1x

    54x

    107x

    107x

    107x

    107x

    4x

    7x

    8x

    8x

    8x
    8x

    1x

    7x
    7x

    1x

    6x
    5x
    1x

    1x

    4x
    3x

    4x
    1x

    3x

    2x

    2x

    2x
    1x

    17x

    17x

    17x

    60x
    60x

    60x
    60x
    60x
    60x
    60x
    60x
    60x

    60x

    60x

    60x

    60x
    60x
    60x
    60x
    60x

    60x

    60x

    60x

    60x
    1x
    71x

    60x

    1x

    1x

    1x
    1x
    1x
    1x
    1x
    1x
    1x
    1x
    1x
    1x
    1x

    1x
    2x

    4x

    3x

    3x

    3x
    6x

    6x
    6x

    3x

    1x
    1x
    1x
    1x
    2x
    2x
    2x
    2x

    1x

     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 } from './BatchFundingGroup';
    import {
      CetAdaptorSignatures,
      ICetAdaptorSignaturesJSON,
    } from './CetAdaptorSignatures';
    import { IDlcMessage } from './DlcMessage';
    import { FundingInput, IFundingInputJSON } from './FundingInput';
    import {
      INegotiationFieldsV0JSON,
      INegotiationFieldsV1JSON,
      INegotiationFieldsV2JSON,
      NegotiationFields,
    } from './NegotiationFields';

    /**
     * DlcAccept contains information about a node and indicates its
     * acceptance of the new DLC, as well as its CET and refund
     * transaction signatures. This is the second step toward creating
     * the funding transaction and closing transactions.
     * Updated to support dlcspecs PR #163 format.
     */
    export class DlcAccept implements IDlcMessage {
      public static type = MessageType.DlcAccept;

      /**
       * Creates a DlcAccept 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 accept
       */
      // eslint-disable-next-line @typescript-eslint/explicit-module-boundary-types, @typescript-eslint/no-explicit-any
      public static fromJSON(json: any): DlcAccept {
        const instance = new DlcAccept();

        // Helper function to parse DER-encoded signature and extract raw r,s values (64 bytes total)
        const parseDerSignature = (hexSig: string): Buffer => {
          const sigBuffer = Buffer.from(hexSig, 'hex');

          // If it's already 64 bytes, assume it's raw
          Iif (sigBuffer.length === 64) {
            return sigBuffer;
          }

          // Use secp256k1.signatureImport to parse DER signature
          try {
            const rawSig = secp256k1.signatureImport(sigBuffer);
            return Buffer.from(rawSig);
          } catch (ex) {
            throw new Error(`Invalid DER signature: ${ex.message}`);
          }
        };

        // Handle both internal and external field naming conventions
        instance.protocolVersion =
          json.protocolVersion || json.protocol_version || PROTOCOL_VERSION;
        instance.temporaryContractId = Buffer.from(
          json.temporaryContractId ||
            json.tempContractId ||
            json.temporary_contract_id,
          'hex',
        );

        instance.acceptCollateral = toBigInt(
          json.acceptCollateral ||
            json.acceptCollateralSatoshis ||
            json.accept_collateral,
        );

        // Handle field name variations between formats
        instance.fundingPubkey = Buffer.from(
          json.fundingPubkey || json.fundingPubKey || json.funding_pubkey,
          'hex',
        );
        instance.payoutSpk = Buffer.from(
          json.payoutSpk || json.payoutSPK || json.payout_spk,
          'hex',
        );
        instance.payoutSerialId = toBigInt(
          json.payoutSerialId || json.payout_serial_id,
        );

        instance.changeSpk = Buffer.from(
          json.changeSpk || json.changeSPK || json.change_spk,
          'hex',
        );
        instance.changeSerialId = toBigInt(
          json.changeSerialId || json.change_serial_id,
        );

        // Parse FundingInputs
        instance.fundingInputs = DlcAccept.parseFundingInputsFromJSON(
          json.fundingInputs || json.funding_inputs || [],
        );

        // Parse CET adaptor signatures
        instance.cetAdaptorSignatures = DlcAccept.parseCetAdaptorSignaturesFromJSON(
          json.cetAdaptorSignatures || json.cet_adaptor_signatures,
        );

        // Parse refund signature - handle DER encoding
        const refundSigHex = json.refundSignature || json.refund_signature;
        instance.refundSignature = parseDerSignature(refundSigHex);

        // Parse optional negotiation fields
        Iif (json.negotiationFields || json.negotiation_fields) {
          instance.negotiationFields = DlcAccept.parseNegotiationFieldsFromJSON(
            json.negotiationFields || json.negotiation_fields,
          );
        }

        return instance;
      }

      /**
       * Parses FundingInputs from JSON
       * @param fundingInputsJson Array of JSON objects representing funding inputs
       */
      private static parseFundingInputsFromJSON(
        // eslint-disable-next-line @typescript-eslint/no-explicit-any
        fundingInputsJson: any[],
      ): FundingInput[] {
        return fundingInputsJson.map((inputJson) => {
          // Use the existing FundingInput.fromJSON method which handles all the field mapping correctly
          return FundingInput.fromJSON(inputJson) as FundingInput;
        });
      }

      /**
       * Parses CetAdaptorSignatures from JSON
       * @param cetSigsJson JSON object representing CET adaptor signatures
       */
      private static parseCetAdaptorSignaturesFromJSON(
        // eslint-disable-next-line @typescript-eslint/no-explicit-any
        cetSigsJson: any,
      ): CetAdaptorSignatures {
        const instance = new CetAdaptorSignatures();

        Eif (
          cetSigsJson.ecdsaAdaptorSignatures ||
          cetSigsJson.ecdsa_adaptor_signatures
        ) {
          const ecdsaSigs =
            cetSigsJson.ecdsaAdaptorSignatures ||
            cetSigsJson.ecdsa_adaptor_signatures;
          // eslint-disable-next-line @typescript-eslint/no-explicit-any
          instance.sigs = ecdsaSigs.map((sig: any) => {
            // The test vectors use 'signature' field, but our internal format uses encryptedSig/dleqProof
            // Adaptor signatures have different format than regular ECDSA (65 bytes + 97 bytes)
            const sigBuffer = Buffer.from(sig.signature, 'hex');
            return {
              encryptedSig: sigBuffer.slice(0, 65), // First 65 bytes
              dleqProof:
                sigBuffer.length > 65 ? sigBuffer.slice(65, 162) : Buffer.alloc(97), // Next 97 bytes or empty
            };
          });
        }

        return instance;
      }

      /**
       * Parses NegotiationFields from JSON
       * @param negotiationJson JSON object representing negotiation fields
       */
      private static parseNegotiationFieldsFromJSON(
        // eslint-disable-next-line @typescript-eslint/no-explicit-any
        negotiationJson: any,
      ): NegotiationFields {
        return NegotiationFields.fromJSON(negotiationJson);
      }

      /**
       * Deserializes an accept_dlc message
       * @param buf
       */
      public static deserialize(buf: Buffer, parseCets = true): DlcAccept {
        const instance = new DlcAccept();
        const reader = new BufferReader(buf);

        reader.readUInt16BE(); // read type

        // New fields as per dlcspecs PR #163
        instance.protocolVersion = reader.readUInt32BE();
        instance.temporaryContractId = reader.readBytes(32);
        instance.acceptCollateral = reader.readUInt64BE();
        instance.fundingPubkey = reader.readBytes(33);
        const payoutSpkLen = reader.readUInt16BE();
        instance.payoutSpk = reader.readBytes(payoutSpkLen);
        instance.payoutSerialId = 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();

        if (parseCets) {
          // Read CET adaptor signatures directly to match serialize format (no TLV wrapping)
          instance.cetAdaptorSignatures = CetAdaptorSignatures.deserialize(
            reader.buffer.subarray(reader.position),
          );

          // Skip past the CET adaptor signatures we just read
          const cetLength = instance.cetAdaptorSignatures.serialize().length;
          reader.position += cetLength;
        } else {
          instance.cetAdaptorSignatures = new CetAdaptorSignatures();
        }

        instance.refundSignature = reader.readBytes(64);

        // negotiation_fields is now optional as per dlcspecs PR #163
        // Check if there's enough data left for the new format fields (backward compatibility)
        // The old format ends exactly after refundSignature. If there's more data, it should be new format.
        const remainingBytes = reader.buffer.length - reader.position;

        Eif (remainingBytes > 0) {
          // Only try to parse new fields if we have a reasonable amount of extra data
          // A single stray byte is likely not valid new format data
          Eif (remainingBytes >= 1) {
            try {
              const hasNegotiationFields = reader.readUInt8();
              Iif (hasNegotiationFields === 0x01) {
                instance.negotiationFields = NegotiationFields.deserialize(
                  getTlv(reader),
                );
              }

              // Parse TLV stream as per dlcspecs PR #163
              // Only continue if there's still data left after the hasNegotiationFields flag
              while (reader.position < reader.buffer.length) {
                const buf = getTlv(reader);
                const tlvReader = new BufferReader(buf);
                const { type } = deserializeTlv(tlvReader);

                switch (Number(type)) {
                  case MessageType.BatchFundingGroup:
                    if (!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;
                }
              }
            } catch (error) {
              // If parsing new format fails, assume it's old format and ignore the extra bytes
              // This provides backward compatibility for malformed or old format data
              // Silently ignore parsing errors for backward compatibility
            }
          }
        }

        // Auto-detect single funded DLCs based on minimal acceptCollateral
        // In single funded DLCs, acceptCollateral is typically 0 or very small
        if (instance.acceptCollateral === BigInt(0)) {
          instance.singleFunded = true;
        }

        return instance;
      }

      /**
       * The type for accept_dlc message. accept_dlc = 42780
       */
      public type = DlcAccept.type;

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

      // Existing fields
      public temporaryContractId: Buffer;

      public acceptCollateral: bigint;

      public fundingPubkey: Buffer;

      public payoutSpk: Buffer;

      public payoutSerialId: bigint;

      public fundingInputs: FundingInput[] = [];

      public changeSpk: Buffer;

      public changeSerialId: bigint;

      public cetAdaptorSignatures: CetAdaptorSignatures;

      public refundSignature: Buffer;

      // negotiation_fields is now optional
      public negotiationFields?: NegotiationFields;

      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, the acceptor provides minimal or no collateral
       */
      public singleFunded = false;

      /**
       * Marks this DLC accept as single funded
       * For single funded DLCs, acceptCollateral is typically 0 or minimal
       */
      public markAsSingleFunded(): void {
        this.singleFunded = true;
      }

      /**
       * Checks if this DLC accept is for a single funded DLC
       * @returns True if this is a single funded DLC
       */
      public isSingleFunded(): boolean {
        return this.singleFunded;
      }

      /**
       * Get funding, change and payout address from DlcAccept
       * @param network Bitcoin Network
       * @returns {IDlcAcceptAddresses}
       */
      public getAddresses(network: BitcoinNetwork): IDlcAcceptAddresses {
        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
       * Updated validation rules as per dlcspecs PR #163
       * https://github.com/discreetlogcontracts/dlcspecs/blob/master/Protocol.md#the-accept_dlc-message
       * @throws Will throw an error if validation fails
       */
      public validate(): void {
        // 1. Type is set automatically in class
        // 2. protocol_version validation
        Iif (this.protocolVersion !== PROTOCOL_VERSION) {
          throw new Error(
            `Unsupported protocol version: ${this.protocolVersion}, expected: ${PROTOCOL_VERSION}`,
          );
        }

        // 3. temporary_contract_id must match the one from offer_dlc
        Iif (!this.temporaryContractId || this.temporaryContractId.length !== 32) {
          throw new Error('temporaryContractId must be 32 bytes');
        }

        // 4. payout_spk and change_spk must be standard script pubkeys
        try {
          address.fromOutputScript(this.payoutSpk);
        } catch (e) {
          throw new Error('payoutSpk is invalid');
        }

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

        // 5. 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');
        }

        // 6. 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');
        }

        // 7. Ensure funding inputs are segwit
        this.fundingInputs.forEach((input: FundingInput) => input.validate());

        // 8. 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));

        Eif (this.isSingleFunded()) {
          // For single funded DLCs, acceptor may provide minimal or no collateral
          // fundingAmount should be >= acceptCollateral (allowing for 0 collateral case)
          if (this.acceptCollateral > 0 && fundingAmount < this.acceptCollateral) {
            throw new Error(
              'For single funded DLCs, fundingAmount must be at least acceptCollateral',
            );
          }
        } else {
          // For regular DLCs, funding amount must be greater than accept collateral
          if (this.acceptCollateral >= fundingAmount) {
            throw new Error('fundingAmount must be greater than acceptCollateral');
          }
        }
      }

      /**
       * Converts accept_dlc to JSON (canonical rust-dlc format)
       */
      public toJSON(): IDlcAcceptJSON {
        // Convert raw signature back to DER format for canonical rust-dlc JSON
        const derRefundSignature = secp256k1.signatureExport(this.refundSignature);

        return {
          protocolVersion: this.protocolVersion,
          temporaryContractId: this.temporaryContractId.toString('hex'),
          acceptCollateral: bigIntToNumber(this.acceptCollateral),
          fundingPubkey: this.fundingPubkey.toString('hex'), // lowercase 'k'
          payoutSpk: this.payoutSpk.toString('hex'), // lowercase
          payoutSerialId: bigIntToNumber(this.payoutSerialId),
          fundingInputs: this.fundingInputs.map((input) => input.toJSON()),
          changeSpk: this.changeSpk.toString('hex'), // lowercase
          changeSerialId: bigIntToNumber(this.changeSerialId),
          cetAdaptorSignatures: this.cetAdaptorSignatures.toJSON(),
          refundSignature: Buffer.from(derRefundSignature).toString('hex'),
          negotiationFields: this.negotiationFields?.toJSON(),
        };
      }

      /**
       * Serializes the accept_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.temporaryContractId);
        writer.writeUInt64BE(this.acceptCollateral);
        writer.writeBytes(this.fundingPubkey);
        writer.writeUInt16BE(this.payoutSpk.length);
        writer.writeBytes(this.payoutSpk);
        writer.writeUInt64BE(this.payoutSerialId);

        // 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.writeBytes(this.cetAdaptorSignatures.serialize());
        writer.writeBytes(this.refundSignature);

        // negotiation_fields is now optional as per dlcspecs PR #163
        Iif (this.negotiationFields) {
          writer.writeUInt8(0x01); // present
          writer.writeBytes(this.negotiationFields.serialize());
        } else {
          writer.writeUInt8(0x00); // absent
        }

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

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

        return writer.toBuffer();
      }

      public withoutSigs(): DlcAcceptWithoutSigs {
        return new DlcAcceptWithoutSigs(
          this.protocolVersion,
          this.temporaryContractId,
          this.acceptCollateral,
          this.fundingPubkey,
          this.payoutSpk,
          this.payoutSerialId,
          this.fundingInputs,
          this.changeSpk,
          this.changeSerialId,
          this.negotiationFields,
          this.batchFundingGroups,
        );
      }
    }

    export class DlcAcceptWithoutSigs {
      constructor(
        readonly protocolVersion: number,
        readonly temporaryContractId: Buffer,
        readonly acceptCollateral: bigint,
        readonly fundingPubkey: Buffer,
        readonly payoutSpk: Buffer,
        readonly payoutSerialId: bigint,
        readonly fundingInputs: FundingInput[],
        readonly changeSpk: Buffer,
        readonly changeSerialId: bigint,
        readonly negotiationFields?: NegotiationFields,
        readonly batchFundingGroups?: BatchFundingGroup[],
      ) {}
    }

    export interface IDlcAcceptJSON {
      protocolVersion: number;
      temporaryContractId: string;
      acceptCollateral: number;
      fundingPubkey: string;
      payoutSpk: string;
      payoutSerialId: number;
      fundingInputs: IFundingInputJSON[];
      changeSpk: string;
      changeSerialId: number;
      cetAdaptorSignatures: ICetAdaptorSignaturesJSON;
      refundSignature: string;
      negotiationFields?: // Now optional
      | INegotiationFieldsV0JSON
        | INegotiationFieldsV1JSON
        | INegotiationFieldsV2JSON;
    }

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

    export class DlcAcceptContainer {
      private accepts: DlcAccept[] = [];

      /**
       * Adds a DlcAccept to the container.
       * @param accept The DlcAccept to add.
       */
      public addAccept(accept: DlcAccept): void {
        this.accepts.push(accept);
      }

      /**
       * Returns all DlcAccepts in the container.
       * @returns An array of DlcAccept instances.
       */
      public getAccepts(): DlcAccept[] {
        return this.accepts;
      }

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

      /**
       * Deserializes a Buffer into a DlcAcceptContainer with DlcAccepts.
       * @param buf The Buffer to deserialize.
       * @returns A DlcAcceptContainer instance.
       */
      public static deserialize(buf: Buffer, parseCets = true): DlcAcceptContainer {
        const reader = new BufferReader(buf);
        const container = new DlcAcceptContainer();
        const acceptsCount = reader.readBigSize();
        for (let i = 0; i < acceptsCount; i++) {
          const acceptLength = reader.readBigSize();
          const acceptBuf = reader.readBytes(Number(acceptLength));
          const accept = DlcAccept.deserialize(acceptBuf, parseCets);
          container.addAccept(accept);
        }
        return container;
      }
    }