[WIP] Add rates GQL query to return details from payment rates config

packages/util/package.json

@@ -5,16 +5,19 @@
   "license": "AGPL-3.0",
   "dependencies": {
     "@apollo/utils.keyvaluecache": "^1.0.1",
-    "@cerc-io/nitro-client": "^0.1.5",
+    "@cerc-io/nitro-client": "^0.1.6",
     "@cerc-io/solidity-mapper": "^0.2.50",
     "@cerc-io/ts-channel": "1.0.3-ts-nitro-0.1.1",
     "@ethersproject/providers": "^5.4.4",
+    "@graphql-tools/graphql-file-loader": "^8.0.0",
+    "@graphql-tools/load": "^8.0.0",
     "@graphql-tools/schema": "^9.0.10",
     "@graphql-tools/utils": "^9.1.1",
     "@ipld/dag-cbor": "^6.0.12",
     "apollo-server-core": "^3.11.1",
     "apollo-server-express": "^3.11.1",
     "apollo-server-plugin-response-cache": "^3.8.1",
+    "apollo-type-bigint": "^0.1.3",
     "debug": "^4.3.1",
     "decimal.js": "^10.3.1",
     "ethers": "^5.4.4",

packages/util/src/payments-schema.gql

@@ -0,0 +1,16 @@
+scalar BigInt
+
+enum RateType {
+  QUERY
+  MUTATION
+}
+
+type RateInfo {
+  type: RateType!
+  name: String!
+  amount: BigInt!
+}
+
+type Query {
+  _rates_: [RateInfo!]!
+}

packages/util/src/payments.ts

@@ -3,18 +3,22 @@ import { LRUCache } from 'lru-cache';
 import { FieldNode } from 'graphql';
 import { ApolloServerPlugin, GraphQLResponse, GraphQLRequestContext } from 'apollo-server-plugin-base';
 import { Response as HTTPResponse } from 'apollo-server-env';
+import ApolloBigInt from 'apollo-type-bigint';
 
 import Channel from '@cerc-io/ts-channel';
 import type { ReadWriteChannel } from '@cerc-io/ts-channel';
 import type { Client, Voucher } from '@cerc-io/nitro-client';
 import { utils as nitroUtils, ChannelStatus } from '@cerc-io/nitro-client';
+import { IResolvers } from '@graphql-tools/utils';
 
 import { BaseRatesConfig, PaymentsConfig } from './config';
+import { gqlQueryCount, gqlTotalQueryCount } from './gql-metrics';
 
 const log = debug('laconic:payments');
 
-const IntrospectionQuery = 'IntrospectionQuery';
-const IntrospectionQuerySelection = '__schema';
+const INTROSPECTION_QUERY = 'IntrospectionQuery';
+const INTROSPECTION_QUERY_SELECTION = '__schema';
+const RATES_QUERY_SELECTION = '_rates_';
 
 const PAYMENT_HEADER_KEY = 'x-payment';
 const PAYMENT_HEADER_REGEX = /vhash:(.*),vsig:(.*)/;
@@ -49,6 +53,17 @@ interface Payment {
   amount: bigint;
 }
 
+enum RateType {
+  Query = 'QUERY',
+  Mutation = 'MUTATION'
+}
+
+interface RateInfo {
+  type: RateType;
+  name: string;
+  amount: bigint;
+}
+
 export class PaymentsManager {
   clientAddress?: string;
 
@@ -83,7 +98,7 @@ export class PaymentsManager {
   }
 
   get freeQueriesList (): string[] {
-    return this.ratesConfig.freeQueriesList ?? DEFAULT_FREE_QUERIES_LIST;
+    return [RATES_QUERY_SELECTION, ...(this.ratesConfig.freeQueriesList ?? DEFAULT_FREE_QUERIES_LIST)];
   }
 
   get queryRates (): { [key: string]: string } {
@@ -94,6 +109,35 @@ export class PaymentsManager {
     return this.ratesConfig.mutations ?? {};
   }
 
+  getResolvers (): IResolvers {
+    return {
+      BigInt: new ApolloBigInt('bigInt'),
+      Query: {
+        _rates_: async (): Promise<RateInfo[]> => {
+          log('_rates_');
+          gqlTotalQueryCount.inc(1);
+          gqlQueryCount.labels('_rates_').inc(1);
+
+          const queryRates = this.queryRates;
+          const rateInfos = Object.entries(queryRates).map(([name, amount]) => ({
+            type: RateType.Query,
+            name,
+            amount: BigInt(amount)
+          }));
+
+          const mutationRates = this.mutationRates;
+          Object.entries(mutationRates).forEach(([name, amount]) => rateInfos.push({
+            type: RateType.Mutation,
+            name,
+            amount: BigInt(amount)
+          }));
+
+          return rateInfos;
+        }
+      }
+    };
+  }
+
   async subscribeToVouchers (client: Client): Promise<void> {
     this.clientAddress = client.address;
 
@@ -291,15 +335,16 @@ export const paymentsPlugin = (paymentsManager?: PaymentsManager): ApolloServerP
           // Continue if it's an introspection query for schema
           // (made by ApolloServer playground / default landing page)
           if (
-            requestContext.operationName === IntrospectionQuery &&
+            requestContext.operationName === INTROSPECTION_QUERY &&
             querySelections && querySelections.length === 1 &&
-            querySelections[0] === IntrospectionQuerySelection
+            querySelections[0] === INTROSPECTION_QUERY_SELECTION
           ) {
             return null;
           }
 
           const paymentHeader = requestContext.request.http?.headers.get(PAYMENT_HEADER_KEY);
           if (paymentHeader == null) {
+            // TODO: Make payment header optional and check only for rate configured queries in loop below
             return {
               errors: [{ message: ERR_HEADER_MISSING }],
               http: new HTTPResponse(undefined, {

packages/util/src/server.ts

@@ -1,3 +1,4 @@
+import path from 'path';
 import { Application } from 'express';
 import { ApolloServer } from 'apollo-server-express';
 import { createServer } from 'http';
@@ -6,11 +7,13 @@ import { useServer } from 'graphql-ws/lib/use/ws';
 import { ApolloServerPluginDrainHttpServer, ApolloServerPluginLandingPageLocalDefault } from 'apollo-server-core';
 import debug from 'debug';
 import responseCachePlugin from 'apollo-server-plugin-response-cache';
-import { InMemoryLRUCache } from '@apollo/utils.keyvaluecache';
 import queue from 'express-queue';
 
+import { InMemoryLRUCache } from '@apollo/utils.keyvaluecache';
 import { TypeSource } from '@graphql-tools/utils';
-import { makeExecutableSchema } from '@graphql-tools/schema';
+import { makeExecutableSchema, addResolversToSchema, mergeSchemas } from '@graphql-tools/schema';
+import { GraphQLFileLoader } from '@graphql-tools/graphql-file-loader';
+import { loadSchema } from '@graphql-tools/load';
 
 import { DEFAULT_MAX_GQL_CACHE_SIZE } from './constants';
 import { ServerConfig } from './config';
@@ -33,7 +36,19 @@ export const createAndStartServer = async (
   const httpServer = createServer(app);
 
   // Create the schema
-  const schema = makeExecutableSchema({ typeDefs, resolvers });
+  let schema = makeExecutableSchema({ typeDefs, resolvers });
+
+  if (paymentsManager) {
+    let paymentsSchema = await loadSchema(path.join(__dirname, 'payments-schema.gql'), {
+      loaders: [new GraphQLFileLoader()]
+    });
+
+    const resolvers = paymentsManager.getResolvers();
+    paymentsSchema = addResolversToSchema({ schema: paymentsSchema, resolvers });
+    schema = mergeSchemas({
+      schemas: [schema, paymentsSchema]
+    });
+  }
 
   // Create our WebSocket server using the HTTP server we just set up.
   const wsServer = new WebSocketServer({