Implementation of the currency conversion API

src/ExchangeService.php

@@ -0,0 +1,59 @@
+<?php
+/**
+ * Service responsible for performing currency conversion.
+ *
+ * PHP version 7.4+
+ *
+ * @category Service
+ * @package  App
+ * @author   Andre Ruegger <rueggertec@gmail.com>
+ * @license  http://opensource.org/licenses/MIT MIT
+ * @link     https://github.com/apiki/back-end-challenge
+ */
+
+namespace App;
+
+/**
+ * ExchangeService class
+ *
+ * Handles the calculation of converted values and returns currency symbols.
+ *
+ * @category Service
+ * @package  App
+ * @author   Andre Ruegger <rueggertec@gmail.com>
+ * @license  http://opensource.org/licenses/MIT MIT
+ * @link     https://github.com/apiki/back-end-challenge
+ */
+class ExchangeService
+{
+    /**
+     * Converts a value from one currency to another using a given rate.
+     *
+     * @param float  $amount Value to be converted
+     * @param string $from   Source currency
+     * @param string $to     Target currency
+     * @param float  $rate   Conversion rate
+     *
+     * @return float Converted value
+     */
+    public function convert(float $amount, string $from, string $to, float $rate): float
+    {
+        return $amount * $rate;
+    }
+
+    /**
+     * Returns the symbol of the given currency.
+     *
+     * @param string $currency Currency code (BRL, USD, EUR)
+     *
+     * @return string Currency symbol
+     */
+    public function getSymbol(string $currency): string
+    {
+        return [
+            'BRL' => 'R$',
+            'USD' => '$',
+            'EUR' => '€',
+        ][$currency];
+    }
+}

src/index.php

@@ -8,11 +8,82 @@
  *
  * @category Challenge
  * @package  Back-end
- * @author   Seu Nome <seu-email@seu-provedor.com>
+ * @author   Andre Ruegger <rueggertec@gmail.com>
  * @license  http://opensource.org/licenses/MIT MIT
  * @link     https://github.com/apiki/back-end-challenge
  */
 declare(strict_types=1);
 
 require __DIR__ . '/../vendor/autoload.php';
 
+use App\ExchangeService;
+
+// Routing to the built-in PHP server
+if (php_sapi_name() === 'cli-server') {
+    $path = __DIR__ . parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH);
+    if (is_file($path)) {
+        return false;
+    }
+}
+
+// Reads the URL
+$uri = strtok($_SERVER['REQUEST_URI'], '?');
+
+// Divide into parts
+$parts = array_values(array_filter(explode('/', $uri)));
+
+// If the route starts with "exchange", remove
+if (isset($parts[0]) && $parts[0] === 'exchange') {
+    array_shift($parts);
+}
+
+// To ensure that we have 4 parameters
+if (count($parts) !== 4) {
+    http_response_code(400);
+    header('Content-Type: application/json');
+    echo json_encode(['error' => 'Invalid parameters']);
+    exit;
+}
+
+[$amount, $from, $to, $rate] = $parts;
+
+// Valida amount
+if (!is_numeric($amount) || (float)$amount <= 0) {
+    http_response_code(400);
+    header('Content-Type: application/json');
+    echo json_encode(['error' => 'Invalid amount']);
+    exit;
+}
+
+// Validates currencies
+$validCurrencies = ['BRL', 'USD', 'EUR'];
+
+if (!in_array($from, $validCurrencies, true) || !in_array($to, $validCurrencies, true)) {
+    http_response_code(400);
+    header('Content-Type: application/json');
+    echo json_encode(['error' => 'Invalid currency']);
+    exit;
+}
+
+// Validates rate
+if (!is_numeric($rate) || (float)$rate <= 0) {
+    http_response_code(400);
+    header('Content-Type: application/json');
+    echo json_encode(['error' => 'Invalid rate']);
+    exit;
+}
+
+// Process conversion
+$service = new ExchangeService();
+$converted = $service->convert((float)$amount, $from, $to, (float)$rate);
+$symbol = $service->getSymbol($to);
+
+// Returns JSON
+http_response_code(200);
+header('Content-Type: application/json');
+echo json_encode(
+    [
+    'valorConvertido' => $converted,
+    'simboloMoeda' => $symbol,
+    ]
+);