feat: add token approve builder

src/Enums/AbiFunction.php

@@ -23,6 +23,7 @@ enum AbiFunction: string
     case USERNAME_RESIGNATION         = 'resignUsername';
     case MULTIPAYMENT                 = 'pay';
     case TRANSFER                     = 'transfer';
+    case APPROVE                      = 'approve';
 
     public function transactionClass(): string
     {
@@ -35,6 +36,7 @@ public function transactionClass(): string
             self::USERNAME_RESIGNATION       => UsernameResignation::class,
             self::MULTIPAYMENT               => Multipayment::class,
             self::TRANSFER                   => EvmCall::class,
+            self::APPROVE                    => EvmCall::class,
         };
     }
 }

src/Transactions/Builder/TokenApproveBuilder.php

@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ArkEcosystem\Crypto\Transactions\Builder;
+
+use ArkEcosystem\Crypto\Enums\AbiFunction;
+use ArkEcosystem\Crypto\Enums\ContractAbiType;
+use ArkEcosystem\Crypto\Helpers;
+use ArkEcosystem\Crypto\Transactions\Types\AbstractTransaction;
+use ArkEcosystem\Crypto\Transactions\Types\EvmCall;
+use ArkEcosystem\Crypto\Utils\AbiEncoder;
+use Brick\Math\BigDecimal;
+
+class TokenApproveBuilder extends AbstractTransactionBuilder
+{
+    public function contractAddress(string $address): self
+    {
+        return $this->to($address);
+    }
+
+    public function spender(string $address, BigDecimal $amount): self
+    {
+        $payload = (new AbiEncoder(ContractAbiType::TOKEN))->encodeFunctionCall(
+            AbiFunction::APPROVE->value,
+            [$address, $amount]
+        );
+
+        $this->transaction->data['data'] = Helpers::removeLeadingHexZero($payload);
+
+        return $this;
+    }
+
+    protected function getTransactionInstance(array $data): AbstractTransaction
+    {
+        return new EvmCall($data);
+    }
+}

tests/Unit/Transactions/Builder/TokenApproveBuilderTest.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+use ArkEcosystem\Crypto\Transactions\Builder\TokenApproveBuilder;
+use ArkEcosystem\Crypto\Utils\UnitConverter;
+use Brick\Math\BigDecimal;
+
+it('should build a token approve payload', function () {
+    $contractAddress = '0x6F0182a0cc707b055322CcF6d4CB6a5Aff1aEb22';
+    $spender         = '0xA5cc0BfEB09742C5e4C610f2EBaaB82Eb142Ca10';
+    $amount          = BigDecimal::of('1000000000000');
+    $expectedPayload = '095ea7b3000000000000000000000000a5cc0bfeb09742c5e4c610f2ebaab82eb142ca10000000000000000000000000000000000000000000000000000000e8d4a51000';
+
+    $builder = TokenApproveBuilder::new()
+        ->contractAddress($contractAddress)
+        ->spender($spender, $amount);
+
+    expect($builder->transaction->data['to'])->toBe($contractAddress);
+    expect($builder->transaction->data['value']->isZero())->toBeTrue();
+    expect($builder->transaction->data['data'])->toBe($expectedPayload);
+});
+
+it('should sign and verify a token approve', function () {
+    $builder = TokenApproveBuilder::new()
+        ->contractAddress('0x6F0182a0cc707b055322CcF6d4CB6a5Aff1aEb22')
+        ->spender('0xA5cc0BfEB09742C5e4C610f2EBaaB82Eb142Ca10', BigDecimal::of('1000000000000'))
+        ->gasPrice(UnitConverter::parseUnits('5000000000', 'wei'))
+        ->gasLimit(UnitConverter::parseUnits('21000', 'wei'))
+        ->nonce('1')
+        ->sign($this->passphrase);
+
+    expect($builder->verify())->toBeTrue();
+    expect($builder->transaction->data['data'])->toStartWith('095ea7b3');
+    expect($builder->transaction->data['to'])->toBe('0x6F0182a0cc707b055322CcF6d4CB6a5Aff1aEb22');
+    expect($builder->transaction->data['value']->isZero())->toBeTrue();
+});