adapter.ts

import { Value } from '@sinclair/typebox/value';
import {
  OpaqueTransportMessage,
  OpaqueTransportMessageSchema,
} from '../transport';
import { Codec } from './types';
import { DeserializeResult, SerializeResult } from '../transport/results';
import { coerceErrorString } from '../transport/stringifyError';

/**
 * Adapts a {@link Codec} to the {@link OpaqueTransportMessage} format,
 * accounting for fallibility of toBuffer and fromBuffer and wrapping
 * it with a Result type.
 */
export class CodecMessageAdapter {
  constructor(private readonly codec: Codec) {}

  toBuffer(msg: OpaqueTransportMessage): SerializeResult {
    try {
      return {
        ok: true,
        value: this.codec.toBuffer(msg),
      };
    } catch (e) {
      return {
        ok: false,
        reason: coerceErrorString(e),
      };
    }
  }

  fromBuffer(buf: Uint8Array): DeserializeResult {
    try {
      const parsedMsg = this.codec.fromBuffer(buf);
      if (!Value.Check(OpaqueTransportMessageSchema, parsedMsg)) {
        return {
          ok: false,
          reason: 'transport message schema mismatch',
        };
      }

      return {
        ok: true,
        value: parsedMsg,
      };
    } catch (e) {
      return {
        ok: false,
        reason: coerceErrorString(e),
      };
    }
  }
}