Fix fee estimate for Stake mediator (#4)

my-plugin/package.json

@@ -10,6 +10,7 @@
     "start-local": "tsc -w"
   },
   "dependencies": {
+    "@burner-wallet/exchange": "^1.1.4",
     "@poanet/tokenbridge-bw-exchange": "^0.0.3"
   },
   "devDependencies": {

my-plugin/src/abis/HomeStakeMediatorAbi.ts

@@ -0,0 +1,35 @@
+export default [
+  {
+    constant: true,
+    inputs: [],
+    name: 'getFee',
+    outputs: [
+      {
+        name: '',
+        type: 'uint256'
+      }
+    ],
+    payable: false,
+    stateMutability: 'view',
+    type: 'function'
+  },
+  {
+    constant: true,
+    inputs: [
+      {
+        name: '_value',
+        type: 'uint256'
+      }
+    ],
+    name: 'calculateFee',
+    outputs: [
+      {
+        name: '',
+        type: 'uint256'
+      }
+    ],
+    payable: false,
+    stateMutability: 'view',
+    type: 'function'
+  }
+]

my-plugin/src/pairs/StakeBridge.ts

@@ -1,13 +1,63 @@
 import { Mediator } from '@poanet/tokenbridge-bw-exchange'
 import { Stake, xStake } from '../index'
+import BN from 'bn.js'
+import { EstimateReturn, ValueTypes } from '@burner-wallet/exchange'
+import HomeStakeMediatorAbi from '../abis/HomeStakeMediatorAbi'
+import { fromWei, toBN } from 'web3-utils'
+
+// TODO set stake mediator addresses
+const homeMediatorAddress = '0x'
+const foreignMediatorAddress = '0x'
 
 export default class StakeBridge extends Mediator {
-  constructor() {
+  constructor({
+    assetA = xStake.id,
+    assetABridge = homeMediatorAddress,
+    assetB = Stake.id,
+    assetBBridge = foreignMediatorAddress
+  }) {
     super({
-      assetA: xStake.id,
+      assetA,
-      assetABridge: '0x', // TODO set address
+      assetABridge,
-      assetB: Stake.id,
+      assetB,
-      assetBBridge: '0x' // TODO set address
+      assetBBridge
     })
   }
+
+  async estimateAtoB(value: ValueTypes): Promise<EstimateReturn> {
+    const web3 = this.getExchange()
+      .getAsset(this.assetA)
+      .getWeb3()
+
+    const userAmount = this._getValue(value)
+
+    const contract = new web3.eth.Contract(HomeStakeMediatorAbi, this.assetABridge)
+    const { feeAmount, feePercentage } = await this.getFee(web3, contract, userAmount)
+    const finalAmount = toBN(userAmount).sub(feeAmount)
+    const estimateInfo = feeAmount.isZero()
+      ? null
+      : `Estimation takes fee charges into consideration. Fee: ${feePercentage}%`
+
+    return {
+      estimate: finalAmount.toString(),
+      estimateInfo
+    }
+  }
+
+  async estimateBtoA(value: ValueTypes): Promise<EstimateReturn> {
+    return {
+      estimate: this._getValue(value),
+      estimateInfo: null
+    }
+  }
+
+  async getFee(web3: any, contract: any, value: any): Promise<{ feeAmount: BN; feePercentage: number }> {
+    const fee = toBN(await contract.methods.getFee().call())
+    const feePercentage = Number(fromWei(fee, 'ether')) * 100
+    const feeAmount = toBN(await contract.methods.calculateFee(value).call())
+    return {
+      feeAmount,
+      feePercentage
+    }
+  }
 }

test-wallet/package.json

@@ -5,7 +5,7 @@
   "dependencies": {
     "@burner-wallet/assets": "^1.1.10",
     "@burner-wallet/core": "^1.1.9",
-    "@burner-wallet/exchange": "^1.1.3",
+    "@burner-wallet/exchange": "^1.1.4",
     "@burner-wallet/metamask-plugin": "^1.0.1",
     "@burner-wallet/modern-ui": "^1.0.7",
     "@poanet/tokenbridge-bw-exchange": "^0.0.3",

test-wallet/src/index.tsx

@@ -6,7 +6,8 @@ import { InfuraGateway, InjectedGateway } from '@burner-wallet/core/gateways'
 import ModernUI from '@burner-wallet/modern-ui'
 import Exchange from '@burner-wallet/exchange'
 import MetamaskPlugin from '@burner-wallet/metamask-plugin'
-import { ERC677Asset, Mediator, TokenBridgeGateway } from '@poanet/tokenbridge-bw-exchange'
+import { ERC677Asset, TokenBridgeGateway } from '@poanet/tokenbridge-bw-exchange'
+import { StakeBridge } from 'my-plugin'
 
 const sStake = new ERC677Asset({
   id: 'assetAtHome',
@@ -28,7 +29,7 @@ const kStake = new ERC677Asset({
   address: process.env.REACT_APP_FOREIGN_TOKEN_ADDRESS
 })
 
-const StakeBridgePair = new Mediator({
+const StakeBridgePair = new StakeBridge({
   assetA: sStake.id,
   // @ts-ignore
   assetABridge: process.env.REACT_APP_HOME_MEDIATOR_ADDRESS,
@@ -43,9 +44,7 @@ const core = new BurnerCore({
   assets: [sStake, kStake]
 })
 
-const exchange = new Exchange({
+const exchange = new Exchange([StakeBridgePair])
-  pairs: [StakeBridgePair]
-})
 
 const BurnerWallet = () => <ModernUI title="Burner Wallet" core={core} plugins={[exchange, new MetamaskPlugin()]} />
 

wallet/package.json

@@ -5,7 +5,7 @@
   "dependencies": {
     "@burner-wallet/assets": "^1.1.10",
     "@burner-wallet/core": "^1.1.9",
-    "@burner-wallet/exchange": "^1.1.3",
+    "@burner-wallet/exchange": "^1.1.4",
     "@burner-wallet/metamask-plugin": "^1.0.1",
     "@burner-wallet/modern-ui": "^1.0.7",
     "@poanet/tokenbridge-bw-exchange": "^0.0.3",

yarn.lock

@@ -1215,16 +1215,6 @@
     web3 "^1.2.2"
     web3-provider-engine "15.0.3"
 
-"@burner-wallet/exchange@^1.1.3":
-  version "1.1.3"
-  resolved "https://registry.yarnpkg.com/@burner-wallet/exchange/-/exchange-1.1.3.tgz#18a3d6ad74e6b755318a390aa7936416aa614f05"
-  integrity sha512-8eWVhT5/Om0JmilsaaIRo4jDbsiTxMH+wwLOjJfZ868i0qIQmdwyvdKqk7PBNz+vwjt+tkpE5XTqRafGcZtyAg==
-  dependencies:
-    "@burner-wallet/types" "^1.0.0"
-    "@types/react" "*"
-    "@types/styled-components" "4.1.8"
-    styled-components "^5.0.1"
-
 "@burner-wallet/exchange@^1.1.4":
   version "1.1.4"
   resolved "https://registry.yarnpkg.com/@burner-wallet/exchange/-/exchange-1.1.4.tgz#8763d9444aaf0cbf715dcbe377819b08fa751d67"