Implement currency exchange rate API.

app/Api/V1/Controllers/CurrencyExchangeRateController.php

@@ -0,0 +1,115 @@
+<?php
+/**
+ * CurrencyExchangeRateController.php
+ * Copyright (c) 2018 thegrumpydictator@gmail.com
+ *
+ * This file is part of Firefly III.
+ *
+ * Firefly III is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Firefly III is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Firefly III. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace FireflyIII\Api\V1\Controllers;
+
+use Carbon\Carbon;
+use FireflyIII\Exceptions\FireflyException;
+use FireflyIII\Repositories\Currency\CurrencyRepositoryInterface;
+use FireflyIII\Services\Currency\ExchangeRateInterface;
+use FireflyIII\Transformers\CurrencyExchangeRateTransformer;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+use InvalidArgumentException;
+use League\Fractal\Manager;
+use League\Fractal\Resource\Item;
+use Log;
+
+/**
+ *
+ * Class CurrencyExchangeRateController
+ */
+class CurrencyExchangeRateController extends Controller
+{
+    /** @var CurrencyRepositoryInterface */
+    private $repository;
+
+    /**
+     * CurrencyExchangeRateController constructor.
+     */
+    public function __construct()
+    {
+        parent::__construct();
+        $this->middleware(
+            function ($request, $next) {
+                $this->repository = app(CurrencyRepositoryInterface::class);
+                $this->repository->setUser(auth()->user());
+
+                return $next($request);
+            }
+        );
+
+    }
+
+    /**
+     * @param Request $request
+     *
+     * @return JsonResponse
+     * @throws FireflyException
+     */
+    public function index(Request $request): JsonResponse
+    {
+        // create some objects:
+        $manager = new Manager;
+        $baseUrl = $request->getSchemeAndHttpHost() . '/api/v1';
+
+        // currencies
+        $fromCurrency = $this->repository->findByCodeNull($request->get('from') ?? 'EUR');
+        $toCurrency   = $this->repository->findByCodeNull($request->get('to') ?? 'USD');
+
+        if (null === $fromCurrency) {
+            throw new FireflyException('Unknown source currency.');
+        }
+        if (null === $toCurrency) {
+            throw new FireflyException('Unknown destination currency.');
+        }
+
+        $dateObj = new Carbon;
+        try {
+            $dateObj = Carbon::createFromFormat('Y-m-d', $request->get('date') ?? date('Y-m-d'));
+        } catch (InvalidArgumentException $e) {
+            Log::debug($e->getMessage());
+        }
+
+
+        $this->parameters->set('from', $fromCurrency->code);
+        $this->parameters->set('to', $toCurrency->code);
+        $this->parameters->set('date', $dateObj->format('Y-m-d'));
+
+        // get the exchange rate.
+        $rate = $this->repository->getExchangeRate($fromCurrency, $toCurrency, $dateObj);
+        if (null === $rate) {
+            // create service:
+            /** @var ExchangeRateInterface $service */
+            $service = app(ExchangeRateInterface::class);
+            $service->setUser(auth()->user());
+
+            // get rate:
+            $rate = $service->getRate($fromCurrency, $toCurrency, $dateObj);
+        }
+
+        $resource = new Item($rate, new CurrencyExchangeRateTransformer($this->parameters), 'currency_exchange_rates');
+
+        return response()->json($manager->createData($resource)->toArray())->header('Content-Type', 'application/vnd.api+json');
+    }
+}