money validator

Author: bumblecoder

code/app/DTO/Request.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\DTO;
+
+use Money\Currency;
+use Money\Money;
+
+final readonly class Request
+{
+    private function __construct(private Money $amount)
+    {
+    }
+
+    public static function create(int $amountInCents, string $currency): self
+    {
+        return new self(new Money($amountInCents, new Currency(strtoupper($currency))));
+    }
+
+    public function getAmount(): Money
+    {
+        return $this->amount;
+    }
+
+    public function getCurrency(): string
+    {
+        return $this->amount->getCurrency()->getCode();
+    }
+}

code/app/DTO/Transaction.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\DTO;
+
+use Money\Currency;
+use Money\Money;
+
+final readonly class Transaction
+{
+    private function __construct(private Money $amount)
+    {
+    }
+
+    public static function create(int $amountInCents, string $currency): self
+    {
+        return new self(new Money($amountInCents, new Currency(strtoupper($currency))));
+    }
+
+    public function getAmount(): Money
+    {
+        return $this->amount;
+    }
+
+    public function getCurrency(): string
+    {
+        return $this->amount->getCurrency()->getCode();
+    }
+}

code/app/Http/Controllers/TransactionController.php

@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Controllers;
+
+use App\DTO\Request;
+use App\DTO\Transaction;
+use App\Services\RequestMoneyValidator;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Routing\Controller;
+use InvalidArgumentException;
+
+final class TransactionController extends Controller
+{
+    public function __construct(private readonly RequestMoneyValidator $validator)
+    {
+    }
+
+    public function validateTransaction(): JsonResponse
+    {
+        try {
+            $userRequest = Request::create(10000, 'USD');
+            $transaction = Transaction::create(9000, 'USD');
+
+            $isValid = $this->validator->validate($userRequest, $transaction);
+
+            return response()->json(['isValid' => $isValid]);
+        } catch (InvalidArgumentException $e) {
+            return response()->json([
+                'error' => 'Validation failed',
+                'message' => $e->getMessage()
+            ], 400);
+        }
+    }
+}

code/app/Providers/AppServiceProvider.php

@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Providers;
+
+use App\Services\RequestMoneyValidator;
+use Illuminate\Support\ServiceProvider;
+
+class AppServiceProvider extends ServiceProvider
+{
+    /**
+     * Register any application services.
+     */
+    public function register(): void
+    {
+        $this->app->singleton(RequestMoneyValidator::class, function ($app) {
+            return new RequestMoneyValidator(
+                deviation: config('app.transaction_deviation')
+            );
+        });
+    }
+
+    /**
+     * Bootstrap any application services.
+     */
+    public function boot(): void
+    {
+        //
+    }
+}

code/app/Services/RequestMoneyValidator.php

@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Services;
+
+use App\DTO\Request;
+use App\DTO\Transaction;
+use InvalidArgumentException;
+
+final readonly class RequestMoneyValidator
+{
+    public function __construct(private int $deviation)
+    {
+        if ($deviation < 0 || $deviation > 100) {
+            throw new InvalidArgumentException('Deviation must be between 0 and 100.');
+        }
+    }
+
+    public function validate(Request $request, Transaction $transaction): bool
+    {
+        if ($request->getCurrency() !== $transaction->getCurrency()) {
+            return false;
+        }
+
+        $deviationPercentage = (string) ($this->deviation / 100);
+        $deviationAmount = $transaction->getAmount()->multiply($deviationPercentage);
+
+        $minAmount = $transaction->getAmount()->subtract($deviationAmount);
+        $maxAmount = $transaction->getAmount()->add($deviationAmount);
+
+        return $request->getAmount()->greaterThanOrEqual($minAmount)
+            && $request->getAmount()->lessThanOrEqual($maxAmount);
+    }
+}

code/routes/web.php

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+<?php
+
+use App\Http\Controllers\TransactionController;
+use Illuminate\Support\Facades\Route;
+
+Route::get('/', function () {
+    return view('welcome');
+});
+
+Route::get('/validate-transaction', [TransactionController::class, 'validateTransaction']);

code/tests/Unit/RequestMoneyValidatorTest.php

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+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Unit;
+
+use App\DTO\Request;
+use App\DTO\Transaction;
+use App\Services\RequestMoneyValidator;
+use InvalidArgumentException;
+use Tests\TestCase;
+
+class RequestMoneyValidatorTest extends TestCase
+{
+    public function test_validate_currency_mismatch(): void
+    {
+        $request = Request::create(10000, 'USD');
+        $transaction = Transaction::create(10000, 'EUR');
+        $validator = new RequestMoneyValidator(10);
+
+        $this->assertFalse($validator->validate($request, $transaction));
+    }
+
+    public function test_validate_within_deviation(): void
+    {
+        $request = Request::create(9500, 'USD');
+        $transaction = Transaction::create(9000, 'USD');
+
+        $validator = new RequestMoneyValidator(10);
+
+        $this->assertTrue($validator->validate($request, $transaction));
+    }
+
+    public function test_validate_outside_deviation(): void
+    {
+        $request = Request::create(10000, 'USD');
+        $transaction = Transaction::create(9000, 'USD');
+
+        $validator = new RequestMoneyValidator(5);
+
+        $this->assertFalse($validator->validate($request, $transaction));
+    }
+
+    public function test_validate_exact_amount(): void
+    {
+        $request = Request::create(10000, 'USD');
+        $transaction = Transaction::create(10000, 'USD');
+
+        $validator = new RequestMoneyValidator(0);
+
+        $this->assertTrue($validator->validate($request, $transaction));
+    }
+
+    public function test_validate_small_deviation(): void
+    {
+        $request = Request::create(9950, 'USD');
+        $transaction = Transaction::create(10000, 'USD');
+
+        $validator = new RequestMoneyValidator(1);
+
+        $this->assertTrue($validator->validate($request, $transaction));
+    }
+
+    public function test_negative_deviation_throws_exception(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Deviation must be between 0 and 100.');
+
+        $validator = new RequestMoneyValidator(-5);
+    }
+}