onchain oracle support

package-lock.json

@@ -42,6 +42,12 @@
       "integrity": "sha512-ZvO2tAcjmMi8V/5Z3JsyofMe3hasRcaw88cto5etSVMwVQfeivGAlEYmaQgceUSVYFofVjT+ioHsATjdWcFt1w==",
       "dev": true
     },
+    "@types/mockery": {
+      "version": "1.4.29",
+      "resolved": "https://registry.npmjs.org/@types/mockery/-/mockery-1.4.29.tgz",
+      "integrity": "sha1-m6It838H43gP/4Ux0aOOYz+UV6U=",
+      "dev": true
+    },
     "@types/node": {
       "version": "14.0.5",
       "resolved": "https://registry.npmjs.org/@types/node/-/node-14.0.5.tgz",
@@ -118,6 +124,11 @@
       "integrity": "sha1-ibTRmasr7kneFk6gK4nORi1xt2c=",
       "dev": true
     },
+    "bignumber.js": {
+      "version": "9.0.0",
+      "resolved": "https://registry.npmjs.org/bignumber.js/-/bignumber.js-9.0.0.tgz",
+      "integrity": "sha512-t/OYhhJ2SD+YGBQcjY8GzzDHEk9f3nerxjtfa6tlMXfe7frs/WozhvCNoGvpM0P3bNf3Gq5ZRMlGr5f3r4/N8A=="
+    },
     "binary-extensions": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/binary-extensions/-/binary-extensions-2.0.0.tgz",
@@ -180,6 +191,15 @@
         "type-detect": "^4.0.5"
       }
     },
+    "chai-as-promised": {
+      "version": "7.1.1",
+      "resolved": "https://registry.npmjs.org/chai-as-promised/-/chai-as-promised-7.1.1.tgz",
+      "integrity": "sha512-azL6xMoi+uxu6z4rhWQ1jbdUhOMhis2PvscD/xjLqNMkv3BPPp2JyyuTHOrf9BOosGpNQ11v6BKv/g57RXbiaA==",
+      "dev": true,
+      "requires": {
+        "check-error": "^1.0.2"
+      }
+    },
     "chalk": {
       "version": "2.4.2",
       "resolved": "https://registry.npmjs.org/chalk/-/chalk-2.4.2.tgz",
@@ -774,6 +794,12 @@
         }
       }
     },
+    "mockery": {
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/mockery/-/mockery-2.1.0.tgz",
+      "integrity": "sha512-9VkOmxKlWXoDO/h1jDZaS4lH33aWfRiJiNT/tKj+8OGzrcFDLo8d0syGdbsc3Bc4GvRXPb+NMMvojotmuGJTvA==",
+      "dev": true
+    },
     "ms": {
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/ms/-/ms-2.1.1.tgz",

package.json

@@ -7,7 +7,7 @@
   "prepare": "npm run build",
   "prepublishOnly": "npm run lint",
   "scripts": {
-    "test": "mocha -r ts-node/register tests/*.test.ts",
+    "test": "mocha --timeout 30000 -r ts-node/register tests/*.test.ts",
     "build": "tsc",
     "lint": "tslint -p tsconfig.json"
   },
@@ -16,14 +16,18 @@
   "devDependencies": {
     "@types/chai": "^4.2.11",
     "@types/mocha": "^7.0.2",
+    "@types/mockery": "^1.4.29",
     "chai": "^4.2.0",
+    "chai-as-promised": "^7.1.1",
     "mocha": "^7.2.0",
+    "mockery": "^2.1.0",
     "tslint": "^6.1.2",
     "tslint-config-standard": "^9.0.0"
   },
   "dependencies": {
     "@types/node": "^14.0.5",
     "@types/node-fetch": "^2.5.7",
+    "bignumber.js": "^9.0.0",
     "node-fetch": "^2.6.0",
     "ts-node": "^8.10.1",
     "typescript": "^3.9.3"

src/config.ts

@@ -1,7 +1,7 @@
 
-import { Oracle } from './types';
+import { OffChainOracle, OnChainOracle } from './types';
 
-const ethgasstation: Oracle = {
+const ethgasstation: OffChainOracle = {
   name: 'ethgasstation',
   url: 'https://ethgasstation.info/json/ethgasAPI.json',
   instantPropertyName: 'fastest',
@@ -11,7 +11,7 @@ const ethgasstation: Oracle = {
   denominator: 10
 };
 
-const zoltu: Oracle = {
+const zoltu: OffChainOracle = {
   name: 'zoltu',
   url: 'https://gas-oracle.zoltu.io/',
   instantPropertyName: 'percentile_99',
@@ -21,8 +21,18 @@ const zoltu: Oracle = {
   denominator: 1
 };
 
+const chainLink: OnChainOracle = {
+  name: 'chainLink',
+  callData: '0x50d25bcd',
+  contract: '0xA417221ef64b1549575C977764E651c9FAB50141',
+  denominator: '1000000000'
+};
+
 export default {
-  oracles: [
+  offChainOracles: [
     ethgasstation, zoltu
+  ],
+  onChainOracles: [
+    chainLink
   ]
 };

src/index.ts

@@ -1,6 +1,7 @@
 import fetch from 'node-fetch';
 import config from './config';
-import { GasPrice, Oracle } from './types';
+import { GasPrice, OffChainOracle, OnChainOracle } from './types';
+import BigNumber from 'bignumber.js';
 
 export class GasPriceOracle {
   lastGasPrice: GasPrice = {
@@ -9,9 +10,16 @@ export class GasPriceOracle {
     standard: 10,
     low: 1
   };
+  defaultRpc = 'https://api.mycryptoapi.com/eth';
 
-  async fetchGasPrices(): Promise<GasPrice> {
-    for (let oracle of config.oracles) {
+  constructor(defaultRpc?: string) {
+    if (defaultRpc) {
+      this.defaultRpc = defaultRpc;
+    }
+  }
+
+  async fetchGasPricesOffChain(throwIfFailsToFetch = true): Promise<GasPrice> {
+    for (let oracle of config.offChainOracles) {
       const { name, url, instantPropertyName, fastPropertyName, standardPropertyName, lowPropertyName, denominator } = oracle;
       try {
         const response = await fetch(url);
@@ -27,6 +35,7 @@ export class GasPriceOracle {
             low: parseFloat(gas[lowPropertyName]) / denominator
           };
           this.lastGasPrice = gasPrices;
+          return this.lastGasPrice;
         } else {
           throw new Error(`Fetch gasPrice from ${name} oracle failed. Trying another one...`);
         }
@@ -34,11 +43,63 @@ export class GasPriceOracle {
         console.error(e.message);
       }
     }
-    // TODO: additional arg `throwIfFailsToFetch` that throws if it fails to fetch from all oracles
+    if (throwIfFailsToFetch) {
+      throw new Error('All oracles are down. Probaly network error.');
+    }
     return this.lastGasPrice;
   }
 
-  addOracle(oracle: Oracle) {
-    config.oracles.push(oracle);
+  async fetchGasPricesOnChain(throwIfFailsToFetch = true): Promise<GasPrice> {
+    for (let oracle of config.onChainOracles) {
+      const { name, callData, contract, denominator } = oracle;
+      let { rpc } = oracle;
+      rpc = rpc ? rpc : this.defaultRpc;
+      const body = { jsonrpc: '2.0',
+        id: 1337,
+        method: 'eth_call',
+        params: [{ 'data': callData, 'to': contract }, 'latest']
+      };
+      try {
+        const response = await fetch(rpc, {
+          headers: {
+            'content-type': 'application/json'
+          },
+          body: JSON.stringify(body),
+          method: 'POST'
+        });
+        if (response.status === 200) {
+          const { result } = await response.json();
+          let fastGasPrice = new BigNumber(result);
+          if (fastGasPrice.isZero()) {
+            throw new Error(`${name} oracle provides corrupted values`);
+          }
+          fastGasPrice = fastGasPrice.div(denominator);
+          const gasPrices: GasPrice = {
+            instant: fastGasPrice.multipliedBy(1.3).toNumber(),
+            fast: fastGasPrice.toNumber(),
+            standard: fastGasPrice.multipliedBy(0.85).toNumber(),
+            low: fastGasPrice.multipliedBy(0.5).toNumber()
+          };
+          this.lastGasPrice = gasPrices;
+          return this.lastGasPrice;
+        } else {
+          throw new Error(`Fetch gasPrice from ${name} oracle failed. Trying another one...`);
+        }
+      } catch (e) {
+        console.error(e.message);
+      }
+    }
+    if (throwIfFailsToFetch) {
+      throw new Error('All oracles are down. Probaly network error.');
+    }
+    return this.lastGasPrice;
+  }
+
+  addOffChainOracle(oracle: OffChainOracle) {
+    config.offChainOracles.push(oracle);
+  }
+
+  addOnChainOracle(oracle: OnChainOracle) {
+    config.onChainOracles.push(oracle);
   }
 }

src/types.ts

@@ -1,11 +1,19 @@
-export type Oracle = {
-  name: string
-  url: string
-  instantPropertyName: string,
-  fastPropertyName: string,
-  standardPropertyName: string,
-  lowPropertyName: string,
-  denominator: number
+export type OffChainOracle = {
+  name: string;
+  url: string;
+  instantPropertyName: string;
+  fastPropertyName: string;
+  standardPropertyName: string;
+  lowPropertyName: string;
+  denominator: number;
+};
+
+export type OnChainOracle = {
+  name: string;
+  rpc?: string;
+  contract: string;
+  callData: string;
+  denominator: string;
 };
 
 export type GasPrice = {

tests/index.test.ts

@@ -1,10 +1,91 @@
 import { GasPriceOracle } from '../src/index';
 import { GasPrice } from '../src/types';
+import mockery from 'mockery';
+import chai from 'chai';
 
-describe('Get gas price', function () {
+chai.use(require('chai-as-promised'));
+chai.should();
+
+describe('fetchGasPricesOffChain', function () {
   it('should work', async function () {
     const oracle = new GasPriceOracle();
-    const gas: GasPrice = await oracle.fetchGasPrices();
-    console.log(gas);
+    const gas: GasPrice = await oracle.fetchGasPricesOffChain();
+
+    gas.instant.should.be.a('number');
+    gas.fast.should.be.a('number');
+    gas.standard.should.be.a('number');
+    gas.low.should.be.a('number');
+
+    gas.instant.should.be.above(gas.fast);
+    gas.fast.should.be.above(gas.standard);
+    gas.standard.should.be.above(gas.low);
+    gas.low.should.not.be.equal(0);
+  });
+});
+
+describe('throw checks', function () {
+  before('before', function () {
+    // Mocking the mod1 module
+    let fetchMock = () => {
+      throw new Error('Mocked for tests');
+    };
+
+    // replace the module with mock for any `require`
+    mockery.registerMock('node-fetch', fetchMock);
+
+    // set additional parameters
+    mockery.enable({
+      useCleanCache:      true,
+      // warnOnReplace:      false,
+      warnOnUnregistered: false
+    });
+  });
+
+  it('should throw if all offchain oracles are down', async function () {
+    const { GasPriceOracle } = require('../src/index');
+    const oracle = new GasPriceOracle();
+    await oracle.fetchGasPricesOffChain().should.be.rejectedWith('All oracles are down. Probaly network error.');
+  });
+
+  it('should throw if all onchain oracles are down', async function () {
+    const { GasPriceOracle } = require('../src/index');
+    const oracle = new GasPriceOracle();
+    await oracle.fetchGasPricesOnChain().should.be.rejectedWith('All oracles are down. Probaly network error.');
+  });
+
+  it('should not throw if throwIfFailsToFetch is false', async function () {
+    const { GasPriceOracle } = require('../src/index');
+    const oracle = new GasPriceOracle();
+    await oracle.fetchGasPricesOnChain(false);
+  });
+
+  it('should not throw if throwIfFailsToFetch is false', async function () {
+    const { GasPriceOracle } = require('../src/index');
+    const oracle = new GasPriceOracle();
+    await oracle.fetchGasPricesOffChain(false);
+  });
+
+  after('after', function () {
+    after(function () {
+      mockery.disable();
+      mockery.deregisterMock('node-fetch');
+    });
+  });
+});
+
+describe('fetchGasPricesOnChain', function () {
+  it('should work', async function () {
+    const oracle = new GasPriceOracle();
+    const gas: GasPrice = await oracle.fetchGasPricesOnChain();
+
+    gas.instant.should.be.a('number');
+    gas.fast.should.be.a('number');
+    gas.standard.should.be.a('number');
+    gas.low.should.be.a('number');
+
+    gas.instant.should.be.above(gas.fast);
+    gas.fast.should.be.above(gas.standard);
+    gas.standard.should.be.above(gas.low);
+    gas.low.should.not.be.equal(0);
   });
 });

tslint.json

@@ -3,7 +3,8 @@
   "defaultSeverity": "error",
   "rules": {
     "semicolon": [true, "always"],
-    "space-before-function-paren": [true, {"anonymous": "always", "named": "never", "asyncArrow": "always"}]
+    "space-before-function-paren": [true, {"anonymous": "always", "named": "never", "asyncArrow": "always"}],
+    "type-literal-delimiter": true
   }
 }