Validate amount

app/routes.php

@@ -25,6 +25,7 @@
 use WMDE\Fundraising\Frontend\UseCases\CancelDonation\CancelDonationRequest;
 use WMDE\Fundraising\Frontend\UseCases\ListComments\CommentListingRequest;
 use WMDE\Fundraising\Frontend\UseCases\AddSubscription\SubscriptionRequest;
+use WMDE\Fundraising\Frontend\Validation\ConstraintViolation;
 
 $app->get(
 	'validate-email',
@@ -37,6 +38,26 @@ function( Request $request ) use ( $app, $ffFactory ) {
 	}
 );
 
+$app->post(
+	'validate-amount',
+	function( Request $request ) use ( $app, $ffFactory ) {
+
+		$amount = (float) $ffFactory->newDecimalNumberFormatter()->parse( $request->get( 'amount', 0 ) );
+		$amountValidator = $ffFactory->newAmountValidator();
+		$validationResult = $amountValidator->validate( $amount, (string) $request->get( 'paymentType', '' ) );
+
+		if ( $validationResult->isSuccessful() ) {
+			return $app->json( [ 'status' => 'OK' ] );
+		}
+		else {
+			$errors = array_map( function ( ConstraintViolation $constraintViolation ) {
+				return $constraintViolation->getMessage();
+			}, $validationResult->getViolations() );
+			return $app->json( [ 'status' => 'ERR', 'message' => implode( "\n", $errors ) ] );
+		}
+	}
+);
+
 $app->get(
 	'list-comments.json',
 	function( Request $request ) use ( $app, $ffFactory ) {

src/FunFunFactory.php

@@ -19,6 +19,7 @@
 use Monolog\Handler\BufferHandler;
 use Monolog\Handler\StreamHandler;
 use Monolog\Logger;
+use NumberFormatter;
 use Psr\Log\LoggerInterface;
 use Swift_MailTransport;
 use Symfony\Component\Translation\TranslatorInterface;
@@ -610,7 +611,7 @@ public function getDonationRepository(): DonationRepository {
 		return $this->pimple['donation_repository'];
 	}
 
-	private function newAmountValidator(): AmountValidator {
+	public function newAmountValidator(): AmountValidator {
 		return new AmountValidator(
 			0.01,
 			[
@@ -620,6 +621,10 @@ private function newAmountValidator(): AmountValidator {
 		);
 	}
 
+	public function newDecimalNumberFormatter(): NumberFormatter {
+		return new NumberFormatter( $this->config['locale'], NumberFormatter::DECIMAL );
+	}
+
 	public function newAddCommentUseCase(): AddCommentUseCase {
 		return new AddCommentUseCase(
 			$this->getCommentRepository()

tests/System/Routes/ValidateAmountRouteTest.php

@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace WMDE\Fundraising\Frontend\Tests\System\Routes;
+
+use WMDE\Fundraising\Frontend\Tests\System\WebRouteTestCase;
+use WMDE\Fundraising\Frontend\Domain\Model\PaymentType;
+
+/**
+ * @licence GNU GPL v2+
+ * @author Gabriel Birke < gabriel.birke@wikimedia.de >
+ */
+class ValidateAmountRouteTest extends WebRouteTestCase {
+
+	public function testGivenValidAmount_successResponseIsReturned() {
+		$client = $this->createClient();
+
+		$client->request(
+			'POST',
+			'/validate-amount',
+			[ 'amount' => '23', 'paymentType' => PaymentType::BANK_TRANSFER ]
+		);
+
+		$this->assertJsonSuccessResponse(
+			[ 'status' => 'OK' ],
+			$client->getResponse()
+		);
+	}
+
+	public function testGivenInvalidAmount_failureResponseIsReturned() {
+		$client = $this->createClient();
+
+		$client->request(
+			'POST',
+			'/validate-amount',
+			[ 'amount' => '-1', 'paymentType' => PaymentType::BANK_TRANSFER ]
+		);
+
+		$this->assertErrorJsonResponse( $client->getResponse() );
+	}
+
+}