add handle percent (#446)

src/lib/util/handlePercent.test.ts

@@ -0,0 +1,58 @@
+import { fromMAS } from '@massalabs/web3-utils';
+import { massaToken } from '../massa-react/const';
+import { handlePercent } from './handlePercent';
+
+describe('handlePercent', () => {
+  it('should return correctly formatted amount when no conditions are met', () => {
+    const result = handlePercent(
+      1000000000000000000n,
+      25n,
+      0n,
+      2000000000000000000n,
+      18,
+      'ETH',
+    );
+    expect(result).toBe('0.250000000000000000');
+  });
+
+  it('should return correctly formatted amount when symbol is massaToken and newAmount is within balance', () => {
+    const result = handlePercent(
+      1000000000n,
+      50n,
+      fromMAS(0.1),
+      1000000000000n,
+      9,
+      massaToken,
+    );
+    expect(result).toBe('0.500000000');
+  });
+
+  it('should return 0 when balance minus fees is less than 0', () => {
+    const result = handlePercent(
+      1000000000n,
+      100n,
+      fromMAS(30000),
+      2000n,
+      9,
+      massaToken,
+    );
+    expect(result).toBe('0.000000000');
+  });
+
+  it('should return balance minus fees when newAmount exceeds balance', () => {
+    const result = handlePercent(
+      1000000000n,
+      100n,
+      fromMAS(0.1),
+      1000000000n,
+      9,
+      massaToken,
+    );
+    expect(result).toBe('0.900000000');
+  });
+
+  it('should handle zero amount correctly', () => {
+    const result = handlePercent(0n, 10n, 0n, 1000n, 9, massaToken);
+    expect(result).toBe('0.000000000');
+  });
+});

src/lib/util/handlePercent.ts

@@ -0,0 +1,25 @@
+import { massaToken } from '../massa-react/const';
+import { formatAmount } from './parseAmount';
+
+export function handlePercent(
+  amount = 0n,
+  percent: bigint,
+  fees: bigint,
+  balance: bigint,
+  decimals: number,
+  symbol: string,
+): string {
+  let newAmount = (amount * percent) / 100n;
+
+  if (symbol === massaToken) {
+    if (newAmount > balance - fees) {
+      if (balance - fees < 0) {
+        newAmount = 0n;
+      } else {
+        newAmount = balance - fees;
+      }
+    }
+  }
+
+  return formatAmount(newAmount.toString(), decimals).amountFormattedFull;
+}