@lodestar/api/src/utils/codecs.ts

A Typescript REST client for the Ethereum Consensus API

import {Type} from "@chainsafe/ssz";
import {ForkName} from "@lodestar/params";
import {objectToExpectedCase} from "@lodestar/utils";
import {
  Endpoint,
  RequestWithBodyCodec,
  RequestWithoutBodyCodec,
  ResponseCodec,
  ResponseDataCodec,
  ResponseMetadataCodec,
  SszRequestMethods,
} from "./types.js";
import {WireFormat} from "./wireFormat.js";

// Utility types / codecs

export type EmptyArgs = void;
export type EmptyRequest = Record<never, never>;
export type EmptyResponseData = void;
export type EmptyMeta = void;

// biome-ignore lint/suspicious/noExplicitAny: We can not use `unknown` type here
export type AnyEndpoint = Endpoint<any, any, any, any, any>;
// biome-ignore lint/suspicious/noExplicitAny: We can not use `unknown` type here
export type EmptyRequestEndpoint = Endpoint<any, EmptyArgs, EmptyRequest, any, any>;
// biome-ignore lint/suspicious/noExplicitAny: We can not use `unknown` type here
export type EmptyResponseEndpoint = Endpoint<any, any, any, EmptyResponseData, EmptyMeta>;

/** Shortcut for routes that have no params, query */
export const EmptyRequestCodec: RequestWithoutBodyCodec<EmptyRequestEndpoint> = {
  writeReq: () => ({}),
  parseReq: () => {},
  schema: {},
};

export function JsonOnlyReq<E extends Endpoint>(
  req: Omit<RequestWithBodyCodec<E>, keyof SszRequestMethods<E>>
): RequestWithBodyCodec<E> {
  return {
    ...req,
    writeReqSsz: () => {
      throw Error("Not implemented");
    },
    parseReqSsz: () => {
      throw Error("Not implemented");
    },
    onlySupport: WireFormat.json,
  };
}

export const EmptyResponseDataCodec: ResponseDataCodec<EmptyResponseData, EmptyMeta> = {
  toJson: () => {},
  fromJson: () => {},
  serialize: () => new Uint8Array(),
  deserialize: () => {},
};

export const EmptyMetaCodec: ResponseMetadataCodec<EmptyMeta> = {
  toJson: () => {},
  fromJson: () => {},
  toHeadersObject: () => ({}),
  fromHeaders: () => {},
};

export const EmptyResponseCodec: ResponseCodec<EmptyResponseEndpoint> = {
  data: EmptyResponseDataCodec,
  meta: EmptyMetaCodec,
  isEmpty: true,
};

export function WithMeta<T, M extends {version: ForkName}>(getType: (m: M) => Type<T>): ResponseDataCodec<T, M> {
  return {
    toJson: (data, meta: M) => getType(meta).toJson(data),
    fromJson: (data, meta: M) => getType(meta).fromJson(data),
    serialize: (data, meta: M) => getType(meta).serialize(data),
    deserialize: (data, meta: M) => getType(meta).deserialize(data),
  };
}

export function WithVersion<T, M extends {version: ForkName}>(
  getType: (v: ForkName) => Type<T>
): ResponseDataCodec<T, M> {
  return {
    toJson: (data, meta: M) => getType(meta.version).toJson(data),
    fromJson: (data, meta: M) => getType(meta.version).fromJson(data),
    serialize: (data, meta: M) => getType(meta.version).serialize(data),
    deserialize: (data, meta: M) => getType(meta.version).deserialize(data),
  };
}

export function JsonOnlyResp<E extends Endpoint>(
  resp: Omit<ResponseCodec<E>, "data"> & {
    data: Omit<ResponseCodec<E>["data"], "serialize" | "deserialize">;
  }
): ResponseCodec<E> {
  return {
    ...resp,
    data: {
      ...resp.data,
      serialize: () => {
        throw Error("Not implemented");
      },
      deserialize: () => {
        throw Error("Not implemented");
      },
    },
    onlySupport: WireFormat.json,
  };
}

export const JsonOnlyResponseCodec: ResponseCodec<AnyEndpoint> = {
  data: {
    toJson: (data: Record<string, unknown>) => {
      // JSON fields use snake case across all existing routes
      return objectToExpectedCase(data, "snake");
    },
    fromJson: (data) => {
      if (typeof data !== "object" || data === null) {
        throw Error("JSON must be of type object");
      }
      // All JSON inside the JS code must be camel case
      return objectToExpectedCase(data as Record<string, unknown>, "camel");
    },
    serialize: () => {
      throw Error("Not implemented");
    },
    deserialize: () => {
      throw Error("Not implemented");
    },
  },
  meta: EmptyMetaCodec,
  onlySupport: WireFormat.json,
};