relay-plugin-eth/src/client/rpc/rpc.ts

import NodeCache from "node-cache";
import { PluginAPI } from "@lumeweb/interface-relay";
import stringify from "json-stringify-deterministic";

export type RPCRequest = {
  method: string;
  params: any[];
};

export type RPCRequestRaw = RPCRequest & {
  jsonrpc: string;
  id: string;
};

export type RPCResponse = {
  success: boolean;
  result: any;
};

export type ProviderConfig = {
  URL: string;
  unsupportedMethods?: string[];
  supportBatchRequests?: boolean;
  batchSize?: number;
};

export class RPC {
  get cache(): NodeCache {
    return this._cache;
  }
  private provider: ProviderConfig;
  private _cache = new NodeCache({ stdTTL: 60 * 60 * 12 });

  constructor(provider: ProviderConfig) {
    this.provider = provider;
  }

  private _pluginApi?: PluginAPI;

  set pluginApi(value: PluginAPI) {
    this._pluginApi = value;
  }

  async request(request: RPCRequest) {
    if (this.provider.unsupportedMethods?.includes(request.method)) {
      throw new Error("method not supported by the provider");
    }
    return await this._retryRequest(request);
  }

  async requestBatch(requests: RPCRequest[]) {
    if (
      this.provider?.unsupportedMethods &&
      requests.some((r) => this.provider.unsupportedMethods!.includes(r.method))
    ) {
      throw new Error("method not supported by the provider");
    }

    const res = [];
    for (const request of requests) {
      const r = await this._retryRequest(request);
      res.push(r);
    }
    return res;
  }

  protected async _request(request: RPCRequestRaw): Promise<RPCResponse> {
    try {
      const response = await (
        await fetch(this.provider.URL, {
          method: "POST",
          body: JSON.stringify(request),
        })
      ).json();

      if (response.result) {
        const tempRequest = {
          method: request.method,
          params: request.params,
        };
        const hash = this._pluginApi.util.crypto
          .createHash(stringify(tempRequest))
          .toString("hex");
        //  this._cache.set(hash, response);
      }
      return {
        success: !response.error,
        result: response.error || response.result,
      };
    } catch (e) {
      return {
        success: false,
        result: { message: `request failed: ${e}` },
      };
    }
  }

  private async _retryRequest(
    _request: RPCRequest,
    retry = 5
  ): Promise<RPCResponse> {
    const request = {
      ..._request,
      jsonrpc: "2.0",
      id: this.generateId(),
    };

    for (let i = retry; i > 0; i--) {
      const res = await this._request(request);
      if (res.success) {
        return res;
      } else if (i == 1) {
        console.error(
          `RPC batch request failed after maximum retries: ${JSON.stringify(
            request,
            null,
            2
          )} ${JSON.stringify(res, null, 2)}`
        );
      }
    }
    throw new Error("RPC request failed");
  }

  private generateId(): string {
    return Math.floor(Math.random() * 2 ** 64).toFixed();
  }

  public getCachedRequest(request: RPCRequest): RPCResponse | null {
    const hash = this.hashRequest(request);

    if (this.cache.has(hash)) {
      this.cache.ttl(hash);
      return this.cache.get(hash);
    }

    return null;
  }

  public deleteCachedRequest(request: RPCRequest): void {
    const hash = this.hashRequest(request);

    this.cache.del(hash);
  }

  private hashRequest(request: RPCRequest): string {
    const tempRequest = {
      method: request.method,
      params: request.params,
    };

    return this._pluginApi.util.crypto
      .createHash(stringify(tempRequest))
      .toString("hex");
  }
}