From 94a48543660f72252c3dde5a06cc91552fc662d0 Mon Sep 17 00:00:00 2001
From: kraikov <raykov@weichain.tech>
Date: Tue, 18 Aug 2020 18:12:03 +0300
Subject: [PATCH] Add transferFee estimation.

---
 packages/aeternity/src/fee.ts | 19 +++++++++++++++++++
 packages/bitcoin/src/fee.ts   | 16 ++++++++++++++++
 packages/erc20/src/fee.ts     | 23 +++++++++++++++++++++++
 packages/ethereum/src/fee.ts  | 16 ++++++++++++++++
 4 files changed, 74 insertions(+)
 create mode 100644 packages/aeternity/src/fee.ts
 create mode 100644 packages/bitcoin/src/fee.ts
 create mode 100644 packages/erc20/src/fee.ts
 create mode 100644 packages/ethereum/src/fee.ts

diff --git a/packages/aeternity/src/fee.ts b/packages/aeternity/src/fee.ts
new file mode 100644
index 0000000..1d01645
--- /dev/null
+++ b/packages/aeternity/src/fee.ts
@@ -0,0 +1,19 @@
+import BigNumber from 'bignumber.js';
+import { TxBuilder } from '@aeternity/aepp-sdk/es';
+
+const MAX_UINT = '0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff';
+const TO = 'ak_2cjPjJJfKSosxSs3HY9mU7CW5DfAC1ywxzzps8EzaR3rpUVeTH';
+
+export const tranferFee = async (provider: any, balance: any) => {
+    const MAGNITUDE = 18;
+
+    const MIN_FEE = TxBuilder.calculateMinFee('spendTx', { senderId: TO, amount: MAX_UINT });
+
+    const txFee = new BigNumber(MIN_FEE).shiftedBy(-MAGNITUDE).toString();
+
+    const amount = new BigNumber(balance).minus(txFee).toString();
+
+    const maxAmount = balance;
+
+    return { txFee, amount, maxAmount, feeAsset: 'AE', gasPrice: 1000000000, gasLimit: 15000 };
+};
diff --git a/packages/bitcoin/src/fee.ts b/packages/bitcoin/src/fee.ts
new file mode 100644
index 0000000..2cb7177
--- /dev/null
+++ b/packages/bitcoin/src/fee.ts
@@ -0,0 +1,16 @@
+import BigNumber from 'bignumber.js';
+
+export const tranferFee = async (provider: any, balance: any) => {
+    const feePerByte = await provider.getFeePerByte();
+
+    const vBytes = 160; // approx
+
+    const txFee = new BigNumber(feePerByte).multipliedBy(vBytes).div(100000000).toString();
+
+    const amount = balance;
+
+    const maxAmount = new BigNumber(balance).minus(txFee).toString();
+
+    // to keep consistency use gasPrice and gasLimit as terms
+    return { txFee, amount, maxAmount, feeAsset: 'BTC', gasPrice: feePerByte, gasLimit: vBytes };
+};
diff --git a/packages/erc20/src/fee.ts b/packages/erc20/src/fee.ts
new file mode 100644
index 0000000..ee70a93
--- /dev/null
+++ b/packages/erc20/src/fee.ts
@@ -0,0 +1,23 @@
+import { utils, Contract } from 'ethers';
+import BigNumber from 'bignumber.js';
+
+import ERC20ABI from './config/abi/erc20';
+
+const EXTRA_GAS = 20000;
+const TO = '0xFFfFfFffFFfffFFfFFfFFFFFffFFFffffFfFFFfF';
+
+export const tranferFee = async (provider: any, balance: any, tokenAddress: string) => {
+    const contract = new Contract(tokenAddress, ERC20ABI, provider);
+
+    const gasPrice = await provider.getGasPrice();
+
+    const gasLimit = (await contract.estimate.transfer(TO, Number(balance))).add(EXTRA_GAS);
+
+    const txFee = utils.formatEther(gasPrice.mul(gasLimit));
+
+    const amount = new BigNumber(balance).minus(txFee);
+
+    const maxAmount = balance;
+
+    return { txFee, amount, maxAmount, feeAsset: 'ETH', gasPrice, gasLimit };
+};
diff --git a/packages/ethereum/src/fee.ts b/packages/ethereum/src/fee.ts
new file mode 100644
index 0000000..0d5fb8a
--- /dev/null
+++ b/packages/ethereum/src/fee.ts
@@ -0,0 +1,16 @@
+import { utils } from 'ethers';
+import BigNumber from 'bignumber.js';
+
+export const tranferFee = async (provider: any, balance: any) => {
+    const gasPrice = await provider.getGasPrice();
+
+    const gasLimit = 21000;
+
+    const txFee = utils.formatEther(gasPrice.mul(gasLimit));
+
+    const amount = new BigNumber(balance).minus(txFee).toString();
+
+    const maxAmount = amount;
+
+    return { txFee, amount, maxAmount, feeAsset: 'ETH', gasPrice, gasLimit };
+};