use Decimal instead of BigNumber

Author: facuspagnuolo

package.json

@@ -22,8 +22,8 @@
     "body-parser": "^1.19.0",
     "cors": "^2.8.5",
     "chalk": "^4.1.0",
+    "decimal.js": "^10.2.1",
     "dotenv": "^8.2.0",
-    "ethers": "^5.1.0",
     "express": "^4.17.1",
     "knex": "^0.21.1",
     "objection": "^2.1.3",

src/helpers/numbers.ts

@@ -1,5 +1,3 @@
-import { BigNumber } from 'ethers'
+import { Decimal } from 'decimal.js'
 
-export type BigNumberish = string | number | BigNumber
-
-export const bn = (x: BigNumberish): BigNumber => BigNumber.from(x)
+export const decimal = (x: string | number): Decimal => new Decimal(x)

src/lib/MigratedValueCalculator.ts

@@ -1,6 +1,6 @@
-import { BigNumber } from 'ethers'
+import { Decimal } from 'decimal.js'
 
-import { bn } from '../helpers/numbers'
+import { decimal } from '../helpers/numbers'
 import Logger from '../helpers/logger'
 
 import Asset from '../models/Asset'
@@ -25,7 +25,7 @@ class MigratedValueCalculator {
       const balances = await organization.balances()
       const values = await Promise.all(balances.map(balance => this._calcOrganizationBalanceValue(balance, createdAt)))
 
-      const valueUSD = values.reduce((total, value) => total.add(value), bn(0))
+      const valueUSD = values.reduce((total, value) => total.add(value), decimal(0))
       const ant = await this._getAntPrice(createdAt)
       const valueANT = valueUSD.mul(ant)
       const computedAt = new Date().getTime()
@@ -36,21 +36,21 @@ class MigratedValueCalculator {
     }
   }
 
-  private async _calcOrganizationBalanceValue(balance: OrganizationBalance, createdAt: string): Promise<BigNumber> {
+  private async _calcOrganizationBalanceValue(balance: OrganizationBalance, createdAt: string): Promise<Decimal> {
     const asset = await Asset.findById(balance.assetId)
     const price = await this._getAssetPrice(asset!.address, createdAt)
-    const value = bn(balance.amount).mul(price)
+    const value = decimal(balance.amount).mul(price)
     await balance.$query().update({ price: price.toString(), value: value.toString() })
     return value
   }
 
-  async _getAntPrice(createdAt: string): Promise<BigNumber> {
+  async _getAntPrice(createdAt: string): Promise<Decimal> {
     return this._getAssetPrice(ANT_ADDRESS, createdAt)
   }
 
-  async _getAssetPrice(address: string, createdAt: string): Promise<BigNumber> {
+  async _getAssetPrice(address: string, createdAt: string): Promise<Decimal> {
     // TODO: fetch price from coin-gecko
-    return bn(0)
+    return decimal(0)
   }
 }