Complete VAT Calculator

config/routes.yaml

@@ -5,3 +5,23 @@ controllers:
 kernel:
     resource: ../src/Kernel.php
     type: annotation
+
+index:
+    path: /
+    controller: App\Controller\IndexController::new
+    methods: [GET]
+
+new_calculation:
+    path: /new-calculation
+    controller: App\Controller\NewCalculationController::new
+    methods: [GET, POST]
+
+delete_calculations:
+    path: /delete-calculations
+    controller: App\Controller\DeleteCalculationsController::new
+    methods: [GET]
+
+download_calculations:
+    path: /download-calculations
+    controller: App\Controller\DownloadCalculationsController::new
+    methods: [GET]

migrations/Version20230527111225.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DoctrineMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+/**
+ * Auto-generated Migration: Please modify to your needs!
+ */
+final class Version20230527111225 extends AbstractMigration
+{
+    public function getDescription(): string
+    {
+        return '';
+    }
+
+    public function up(Schema $schema): void
+    {
+        // this up() migration is auto-generated, please modify it to your needs
+        $this->addSql('CREATE TABLE vat_calculation (id INT AUTO_INCREMENT NOT NULL, v DOUBLE PRECISION NOT NULL, r DOUBLE PRECISION NOT NULL, is_vat_included TINYINT(1) NOT NULL, PRIMARY KEY(id)) DEFAULT CHARACTER SET utf8mb4 COLLATE `utf8mb4_unicode_ci` ENGINE = InnoDB');
+        $this->addSql('CREATE TABLE messenger_messages (id BIGINT AUTO_INCREMENT NOT NULL, body LONGTEXT NOT NULL, headers LONGTEXT NOT NULL, queue_name VARCHAR(190) NOT NULL, created_at DATETIME NOT NULL, available_at DATETIME NOT NULL, delivered_at DATETIME DEFAULT NULL, INDEX IDX_75EA56E0FB7336F0 (queue_name), INDEX IDX_75EA56E0E3BD61CE (available_at), INDEX IDX_75EA56E016BA31DB (delivered_at), PRIMARY KEY(id)) DEFAULT CHARACTER SET utf8mb4 COLLATE `utf8mb4_unicode_ci` ENGINE = InnoDB');
+    }
+
+    public function down(Schema $schema): void
+    {
+        // this down() migration is auto-generated, please modify it to your needs
+        $this->addSql('DROP TABLE vat_calculation');
+        $this->addSql('DROP TABLE messenger_messages');
+    }
+}

public/.gitignore

@@ -0,0 +1 @@
+vat-calculations.csv

src/Controller/DeleteCalculationsController.php

@@ -0,0 +1,30 @@
+<?php
+/* 
+    What this does
+        This controller handles the `/delete-calculations` route.
+        It fetches all calculations from the database using the findAll() method.
+        We then loop over each calculation and delete it.
+        We then redirect to the homepage to show that there are no more calculations.
+*/
+
+namespace App\Controller;
+
+use App\Entity\VatCalculation;
+use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
+use Symfony\Component\HttpFoundation\Response;
+use Doctrine\ORM\EntityManagerInterface;
+
+class DeleteCalculationsController extends AbstractController
+{
+    public function new(EntityManagerInterface $entityManager): Response
+    {
+        $calculations = $entityManager->getRepository(VatCalculation::class)->findAll();
+
+        foreach ($calculations as $calculation) {
+            $entityManager->remove($calculation);
+        }
+        $entityManager->flush();
+
+        return $this->redirectToRoute('index');
+    }
+}

src/Controller/DownloadCalculationsController.php

@@ -0,0 +1,64 @@
+<?php
+/* 
+    What this does
+        This controller handles the `/download-calculations` route.
+        It fetches all calculations from the database using the findAll() method.
+        We then loop over each calculation and add it to a CSV.
+        We then download that CSV.
+*/
+
+namespace App\Controller;
+
+use App\Entity\VatCalculation;
+use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
+use Symfony\Component\HttpFoundation\Response;
+use Doctrine\ORM\EntityManagerInterface;
+
+class DownloadCalculationsController extends AbstractController
+{
+    public function new(EntityManagerInterface $entityManager): Response
+    {
+        $calculations = $entityManager->getRepository(VatCalculation::class)->findAll();
+
+        $csvData = [];
+        // Set up the column titles
+        $csvData[] = [
+            'ID',
+            'Input: Monetary Value',
+            'Input: VAT Rate',
+            'Input: Is VAT included?',
+            'Output: Monetary value excluding VAT',
+            'Output: Amount of VAT',
+            'Output: Monetary value including VAT'
+        ];
+
+        foreach ($calculations as $calculation) {
+            // Add the $calculation to the CSV
+            $csvData[] = [
+                $calculation->getId(),
+                $calculation->getV(),
+                $calculation->getR(),
+                $calculation->getIsVatIncluded(),
+                $calculation->getResultWithoutVat(),
+                $calculation->getAmountOfVat(),
+                $calculation->getResultWithVat()
+            ];
+        }
+        $entityManager->flush();
+
+        // Download the CSV
+        $csvFileName = 'vat-calculations.csv';
+        $csvFile = fopen($csvFileName, 'w');
+        foreach ($csvData as $csvRow) {
+            fputcsv($csvFile, $csvRow);
+        }
+        fclose($csvFile);
+
+        $response = new Response();
+        $response->headers->set('Content-Type', 'text/csv');
+        $response->headers->set('Content-Disposition', 'attachment; filename="' . $csvFileName . '"');
+        $response->setContent(file_get_contents($csvFileName));
+
+        return $response;
+    }
+}

src/Controller/IndexController.php

@@ -0,0 +1,41 @@
+<?php
+/* 
+    What this does
+        This controller handles the `/` route.
+        It fetches all calculations from the database using the findAll() method.
+        We pass this array through to the twig template.
+*/
+
+namespace App\Controller;
+
+use App\Entity\VatCalculation;
+use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\HttpFoundation\Request;
+use Doctrine\ORM\EntityManagerInterface;
+
+class IndexController extends AbstractController
+{
+    public function new(EntityManagerInterface $entityManager, Request $request): Response
+    {
+        $calculations = $entityManager->getRepository(VatCalculation::class)->findAll();
+        /*
+            We can pass a highlighted VatCalculation through from the form
+            to show a user what they have just submitted.
+            If we do get a highlightId in the query string, we try to find this calculation from the database.
+            This ensures that only ids that are associated with a calculation get passed through.
+            We then pass it through to the twig template to let it be highlighted
+        */
+        $highlightId = $request->query->get('highlightId');
+
+        $highlightedCalculation = null;
+        if ($highlightId !== null) {
+            $highlightedCalculation = $entityManager->getRepository(VatCalculation::class)->find($highlightId);
+        }
+
+        return $this->render('index.html.twig', [
+            'calculations' => $calculations,
+            'highlightedCalculation' => $highlightedCalculation,
+        ]);
+    }
+}

src/Controller/NewCalculationController.php

@@ -0,0 +1,42 @@
+<?php
+/*
+    What this does
+        This controller handles the /new-calculation route.
+        We create the form from the CalculateVatForm class and either return the rendered form or process the form.
+        We call handleRequest on the form object which validates the inputs.
+        If the inputs are invalid, it returns the form with the appropriate error messages.
+        If the inputs are valid, it gets the submitted data from the form, which is a new instance of the VatCalculation class.
+        Then it passes it through to the EntityManagerInterface to persist the data in the database.
+    SQL Injection
+        We handle the isValid() method on the form which only allows data to be persisted if it passes validation.
+*/
+
+namespace App\Controller;
+
+use App\Form\CalculateVatForm;
+use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+use Doctrine\ORM\EntityManagerInterface;
+
+class NewCalculationController extends AbstractController
+{
+    public function new(Request $request, EntityManagerInterface $entityManager): Response
+    {
+        $form = $this->createForm(CalculateVatForm::class);
+
+        $form->handleRequest($request);
+
+        if ($form->isSubmitted() && $form->isValid()) {
+            $vatCalculation = $form->getData();
+            $entityManager->persist($vatCalculation);
+            $entityManager->flush();
+            // Pass this calculation to IndexController so that we can highlight it
+            return $this->redirectToRoute('index', ['highlightId' => $vatCalculation->getId()]);
+        }
+
+        return $this->render('calculateVat.html.twig', [
+            'form' => $form->createView(),
+        ]);
+    }
+}

src/Entity/VatCalculation.php

@@ -0,0 +1,131 @@
+<?php
+/*
+    What this does
+        This is a class of VAT Calculation.
+        We use a special commented markup for Doctrine which handles database mapping for us.
+        Because this is in the entity folder, we can run `php bin/console make:migration` to make a migration.
+        We can then run `php bin/console doctrine:migrations:migrate` to perform the migrations.
+        A migration makes sure our database has the correct columns to handle this data.
+    SQL Injection
+        Doctrine handles SQL parameterization, making SQL injection attacks less likely
+*/
+
+namespace App\Entity;
+
+use Doctrine\ORM\Mapping as ORM;
+
+/**
+ * @ORM\Entity()
+ */
+class VatCalculation
+{
+    /**
+     * @ORM\Id()
+     * @ORM\GeneratedValue()
+     * @ORM\Column(type="integer")
+     */
+    private $id;
+
+    /**
+     * @ORM\Column(type="float")
+     */
+    private $v;
+
+    /**
+     * @ORM\Column(type="float")
+     */
+    private $r;
+
+    /**
+     * @ORM\Column(type="boolean")
+     */
+    private $isVatIncluded;
+
+    // Getters and setters
+
+    public function getId(): ?int
+    {
+        return $this->id;
+    }
+
+    public function getV(): ?float
+    {
+        return $this->v;
+    }
+
+    public function setV(float $v): self
+    {
+        $this->v = $v;
+
+        return $this;
+    }
+
+    public function getR(): ?float
+    {
+        return $this->r;
+    }
+
+    public function setR(float $r): self
+    {
+        $this->r = $r;
+
+        return $this;
+    }
+
+    public function getIsVatIncluded(): ?bool
+    {
+        return $this->isVatIncluded;
+    }
+
+    public function setIsVatIncluded(bool $isVatIncluded): self
+    {
+        $this->isVatIncluded = $isVatIncluded;
+
+        return $this;
+    }
+
+    /*
+        We perform the calculations on the fly rather than storing them in the database.
+        This allows us to add or change calculations in the future without having to update all items in the database.
+    */
+
+    public function getResultWithVat(): ?float
+    {
+        /*
+            If VAT is included in the original value, we just return the original value rounded to 2 decimal places.
+            We use a return early style to make the code more readable.
+        */
+        if ($this->isVatIncluded) {
+            return round($this->getV(), 2);
+        }
+        /*
+            If VAT is not included, we work out the amount to add, which is v * r * .01.
+            We're asking for the percentage so have to times it by .01 to get a decimal.
+            We round this to 2 decimal places too.
+        */
+        return round($this->getV() + $this->getV() * $this->getR() * .01, 2);
+    }
+
+    public function getResultWithoutVat(): ?float
+    {
+        /*
+            If VAT is included, we divide the original value by 1 + percentage of VAT.
+            We round the result.
+        */
+        if ($this->isVatIncluded) {
+            return round($this->getV() / (1 + $this->getR() * .01), 2);
+        }
+        /*
+            If VAT is not included, we can just return the original value.
+        */
+        return round($this->getV(), 2);
+    }
+
+    public function getAmountOfVat(): ?float
+    {
+        /*
+            The amount of VAT is just the result with VAT minus the result without.
+        */
+        return round($this->getResultWithVat() - $this->getResultWithoutVat(), 2);
+    }
+}