fix: withdraw/deposit converts from BZZ (10^16 base units) (#66)

* refactor: added toBZZbaseUnit function

* feat: added utility for attesting value is BZZ convertible to base units

* fix: conversion from 15 to 16 decimal places, added unsafe versions

* refactor: withdraw modal uses the safe conversion from BZZ

* refactor: added BigNumber and Token class to handle BZZ digits correctly

* refactor: extract deposit and withdraw functionality into single modal

* test: added tests for Token

* chore: removed unused component

* chore: addressed PR review, token decimal is now integer 0-18

* chore: added comment to clarify the value restriction on token amount

src/utils/common.tsx

@@ -1,3 +0,0 @@
-export const ConvertBalanceToBZZ = (amount: number): number => {
-  return amount / 10 ** 16
-}

src/utils/index.test.ts

@@ -0,0 +1,71 @@
+import BigNumber from 'bignumber.js'
+import { fromBZZbaseUnit, isInteger, makeBigNumber } from './index'
+
+describe('utils', () => {
+  describe('fromBZZbaseUnit', () => {
+    const values = [
+      { bzz: 0, baseUnits: 0 },
+      { bzz: 0.1, baseUnits: 1e15 },
+      { bzz: 0.9, baseUnits: 9e15 },
+    ]
+
+    values.forEach(({ bzz, baseUnits }) => {
+      test(`converting ${bzz} => ${baseUnits}`, () => {
+        expect(fromBZZbaseUnit(baseUnits)).toBe(bzz)
+      })
+    })
+  })
+
+  describe('isInteger', () => {
+    const correctValues = [
+      BigInt(0),
+      BigInt(1),
+      BigInt(-1),
+      new BigNumber('1'),
+      new BigNumber('0'),
+      new BigNumber('-1'),
+    ]
+    const wrongValues = ['1', new BigNumber('-0.1'), new BigNumber(NaN), new BigNumber(Infinity)]
+
+    correctValues.forEach(v => {
+      test(`testing ${v}`, () => {
+        expect(isInteger(v)).toBe(true)
+      })
+    })
+
+    wrongValues.forEach(v => {
+      test(`testing ${v}`, () => {
+        expect(isInteger(v)).toBe(false)
+      })
+    })
+  })
+
+  describe('makeBigNumber', () => {
+    const correctValues = [
+      BigInt(0),
+      BigInt(1),
+      BigInt(-1),
+      '1',
+      '0',
+      '-1',
+      '0.1',
+      new BigNumber('1'),
+      new BigNumber('0'),
+      new BigNumber('-1'),
+    ]
+    const wrongValues = [new Function(), 0, 1]
+
+    correctValues.forEach(v => {
+      test(`testing ${v}`, () => {
+        expect(BigNumber.isBigNumber(makeBigNumber(v))).toBe(true)
+      })
+    })
+
+    wrongValues.forEach(v => {
+      test(`testing ${v}`, () => {
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        expect(() => makeBigNumber((v as unknown) as any)).toThrow()
+      })
+    })
+  })
+})

src/utils/index.ts

@@ -0,0 +1,48 @@
+import { BigNumber } from 'bignumber.js'
+
+/**
+ * @deprecated Should be removed in favour of Token class
+ */
+const BZZ_BASE_UNIT = 1e16
+
+/**
+ * Convert from base units of BZZ token to BZZ
+ * @deprecated This should only be used for displaying values, it's unsafe and should be replaced with Token class
+ *
+ * @param amount Amount in base units of BZZ token
+ *
+ * @returns amount in BZZ
+ */
+export const fromBZZbaseUnit = (amount: number): number => {
+  return amount / BZZ_BASE_UNIT
+}
+
+/**
+ * Test if value is an integer
+ *
+ * @param value Value to be tested if it is an integer
+ *
+ * @returns True if the passed in value is integer
+ */
+export function isInteger(value: unknown): value is BigNumber | bigint {
+  return (BigNumber.isBigNumber(value) && value.isInteger()) || typeof value === 'bigint'
+}
+
+/**
+ *Convert value into a BigNumber if not already
+ *
+ * @param value Value to be converted
+ *
+ * @throws {TypeError} if the value is not convertible to a BigNumber
+ *
+ * @returns BigNumber - but it may still be NaN or Infinite
+ */
+export function makeBigNumber(value: BigNumber | bigint | string): BigNumber | never {
+  if (BigNumber.isBigNumber(value)) return value
+
+  if (typeof value === 'string') return new BigNumber(value)
+
+  if (typeof value === 'bigint') return new BigNumber(value.toString())
+
+  throw new TypeError('Not a BigNumber or BigNumber convertible value')
+}