# All files / lib/messages OracleEvent.ts

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59.46% Branches 22/37
71.43% Functions 10/14
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     import { BufferReader, BufferWriter } from '@node-dlc/bufio';

    import { MessageType } from '../MessageType';
    import { getTlv } from '../serialize/getTlv';
    import { IDlcMessage } from './DlcMessage';
    import {
      DigitDecompositionEventDescriptor,
      EnumEventDescriptor,
      EventDescriptor,
      IDigitDecompositionEventDescriptorJSON,
      IEnumEventDescriptorJSON,
    } from './EventDescriptor';

    /**
     * Oracle event containing information about an event and the way that the
     * oracle will attest to it. Updated to be rust-dlc compliant.
     *
     * For users to be able to create DLCs based on a given event, they also
     * need to obtain information about the oracle and the time at which it
     * plans on releasing a signature over the event outcome. OracleEvent
     * messages contain such information, which includes:
     *   - the nonce(s) that will be used to sign the event outcome(s)
     *   - the earliest time (UTC) at which it plans on releasing a signature
     *     over the event outcome, in epoch seconds
     *   - the event descriptor
     *   - the event ID which can be a name or categorization associated with
     *     the event by the oracle
     */
    export class OracleEvent implements IDlcMessage {
      public static type = MessageType.OracleEvent;

      /**
       * Creates an OracleEvent from JSON data
       * @param json JSON object representing oracle event
       */
      // eslint-disable-next-line @typescript-eslint/explicit-module-boundary-types, @typescript-eslint/no-explicit-any
      public static fromJSON(json: any): OracleEvent {
        const instance = new OracleEvent();

        // Parse oracle nonces array
        const nonces = json.oracleNonces || json.oracle_nonces || [];
        instance.oracleNonces = nonces.map((nonce: string) =>
          Buffer.from(nonce, 'hex'),
        );

        instance.eventMaturityEpoch =
          json.eventMaturityEpoch || json.event_maturity_epoch || 0;

        // Parse event descriptor
        instance.eventDescriptor = EventDescriptor.fromJSON(
          json.eventDescriptor || json.event_descriptor,
        );

        instance.eventId = json.eventId || json.event_id || '';

        return instance;
      }

      /**
       * Deserializes an oracle_event message
       * @param buf
       */
      public static deserialize(buf: Buffer): OracleEvent {
        const instance = new OracleEvent();
        const reader = new BufferReader(buf);

        reader.readBigSize(); // read type
        instance.length = reader.readBigSize();
        const nonceCount = reader.readUInt16BE();

        for (let i = 0; i < nonceCount; i++) {
          instance.oracleNonces.push(reader.readBytes(32));
        }

        instance.eventMaturityEpoch = reader.readUInt32BE();
        instance.eventDescriptor = EventDescriptor.deserialize(getTlv(reader));
        const eventIdLength = reader.readBigSize();
        const eventIdBuf = reader.readBytes(Number(eventIdLength));
        instance.eventId = eventIdBuf.toString();

        return instance;
      }

      /**
       * The type for oracle_event message. oracle_event = 55330
       */
      public type = OracleEvent.type;

      public length: bigint;

      /** The nonces that the oracle will use to attest to the event outcome. */
      public oracleNonces: Buffer[] = [];

      /** The expected maturity of the contract (Unix timestamp). */
      public eventMaturityEpoch: number;

      /** The description of the event. */
      public eventDescriptor: EventDescriptor;

      /** The ID of the event. */
      public eventId: string;

      /**
       * Validates correctness of all fields in the message according to rust-dlc specification.
       * This includes validating that the number of nonces matches the expected count for the event type.
       * https://github.com/discreetlogcontracts/dlcspecs/blob/master/Oracle.md
       * @throws Will throw an error if validation fails
       */
      public validate(): void {
        // Validate event maturity epoch
        if (this.eventMaturityEpoch < 0) {
          throw new Error('eventMaturityEpoch must be greater than or equal to 0');
        }

        // Validate event ID
        Iif (!this.eventId || this.eventId.length === 0) {
          throw new Error('eventId cannot be empty');
        }

        // Validate oracle nonces (must be 32 bytes each)
        if (this.oracleNonces.length === 0) {
          throw new Error('Must have at least one oracle nonce');
        }

        this.oracleNonces.forEach((nonce, index) => {
          Iif (!nonce || nonce.length !== 32) {
            throw new Error(`Oracle nonce at index ${index} must be 32 bytes`);
          }
        });

        // Validate expected number of nonces based on event descriptor type
        const expectedNbNonces = this.getExpectedNonceCount();

        if (expectedNbNonces !== this.oracleNonces.length) {
          throw new Error(
            `OracleEvent nonce count mismatch: expected ${expectedNbNonces}, got ${this.oracleNonces.length}`,
          );
        }

        // Validate the event descriptor itself
        if (this.eventDescriptor instanceof DigitDecompositionEventDescriptor) {
          this.eventDescriptor.validate();
        }
        // EnumEventDescriptorV0 doesn't have validation requirements beyond basic structure
      }

      /**
       * Returns the expected number of nonces based on the event descriptor type.
       * This matches the rust-dlc validation logic.
       */
      private getExpectedNonceCount(): number {
        if (this.eventDescriptor instanceof EnumEventDescriptor) {
          // Enum events require exactly 1 nonce
          return 1;
        } else Eif (
          this.eventDescriptor instanceof DigitDecompositionEventDescriptor
        ) {
          // Digit decomposition events require nbDigits nonces, plus 1 if signed
          const descriptor = this.eventDescriptor;
          return descriptor.isSigned
            ? descriptor.nbDigits + 1
            : descriptor.nbDigits;
        } else {
          throw new Error('Unknown event descriptor type');
        }
      }

      /**
       * Returns whether this event is for enumerated outcomes.
       */
      public isEnumEvent(): boolean {
        return this.eventDescriptor instanceof EnumEventDescriptor;
      }

      /**
       * Returns whether this event is for numerical outcomes.
       */
      public isDigitDecompositionEvent(): boolean {
        return this.eventDescriptor instanceof DigitDecompositionEventDescriptor;
      }

      /**
       * Returns the event descriptor as EnumEventDescriptor if it's an enum event.
       * @throws Error if not an enum event
       */
      public getEnumEventDescriptor(): EnumEventDescriptor {
        if (!this.isEnumEvent()) {
          throw new Error('Event is not an enum event');
        }
        return this.eventDescriptor as EnumEventDescriptor;
      }

      /**
       * Returns the event descriptor as DigitDecompositionEventDescriptor if it's a numerical event.
       * @throws Error if not a numerical event
       */
      public getDigitDecompositionEventDescriptor(): DigitDecompositionEventDescriptor {
        if (!this.isDigitDecompositionEvent()) {
          throw new Error('Event is not a digit decomposition event');
        }
        return this.eventDescriptor as DigitDecompositionEventDescriptor;
      }

      /**
       * Converts oracle_event to JSON
       */
      public toJSON(): IOracleEventJSON {
        return {
          oracleNonces: this.oracleNonces.map((oracle) => oracle.toString('hex')),
          eventMaturityEpoch: this.eventMaturityEpoch,
          eventDescriptor: this.eventDescriptor.toJSON(),
          eventId: this.eventId,
        };
      }

      /**
       * Serializes the oracle_event message into a Buffer
       */
      public serialize(): Buffer {
        const writer = new BufferWriter();
        writer.writeBigSize(this.type);

        const dataWriter = new BufferWriter();
        dataWriter.writeUInt16BE(this.oracleNonces.length);

        for (const nonce of this.oracleNonces) {
          dataWriter.writeBytes(nonce);
        }

        dataWriter.writeUInt32BE(this.eventMaturityEpoch);
        dataWriter.writeBytes(this.eventDescriptor.serialize());
        dataWriter.writeBigSize(this.eventId.length);
        dataWriter.writeBytes(Buffer.from(this.eventId));

        writer.writeBigSize(dataWriter.size);
        writer.writeBytes(dataWriter.toBuffer());

        return writer.toBuffer();
      }
    }

    export interface IOracleEventJSON {
      type?: number; // Made optional for rust-dlc compatibility
      oracleNonces: string[];
      eventMaturityEpoch: number;
      eventDescriptor:
        | IEnumEventDescriptorJSON
        | IDigitDecompositionEventDescriptorJSON;
      eventId: string;
    }