Implement currency routes.

app/Api/V1/Controllers/Models/TransactionCurrency/DestroyController.php

@@ -0,0 +1,75 @@
+<?php
+
+
+namespace FireflyIII\Api\V1\Controllers\Models\TransactionCurrency;
+
+
+use FireflyIII\Api\V1\Controllers\Controller;
+use FireflyIII\Exceptions\FireflyException;
+use FireflyIII\Models\TransactionCurrency;
+use FireflyIII\Repositories\Currency\CurrencyRepositoryInterface;
+use FireflyIII\Repositories\User\UserRepositoryInterface;
+use FireflyIII\User;
+use Illuminate\Http\JsonResponse;
+
+/**
+ * Class DestroyController
+ */
+class DestroyController extends Controller
+{
+    private CurrencyRepositoryInterface $repository;
+    private UserRepositoryInterface     $userRepository;
+
+    /**
+     * CurrencyRepository constructor.
+     *
+     * @codeCoverageIgnore
+     */
+    public function __construct()
+    {
+        parent::__construct();
+        $this->middleware(
+            function ($request, $next) {
+                /** @var User $admin */
+                $admin = auth()->user();
+
+                /** @var CurrencyRepositoryInterface repository */
+                $this->repository     = app(CurrencyRepositoryInterface::class);
+                $this->userRepository = app(UserRepositoryInterface::class);
+                $this->repository->setUser($admin);
+
+                return $next($request);
+            }
+        );
+    }
+
+    /**
+     * Remove the specified resource from storage.
+     *
+     * @param TransactionCurrency $currency
+     *
+     * @return JsonResponse
+     * @throws FireflyException
+     * @codeCoverageIgnore
+     */
+    public function destroy(TransactionCurrency $currency): JsonResponse
+    {
+        /** @var User $admin */
+        $admin = auth()->user();
+
+        if (!$this->userRepository->hasRole($admin, 'owner')) {
+            // access denied:
+            throw new FireflyException('200005: You need the "owner" role to do this.'); // @codeCoverageIgnore
+        }
+        if ($this->repository->currencyInUse($currency)) {
+            throw new FireflyException('200006: Currency in use.'); // @codeCoverageIgnore
+        }
+        if ($this->repository->isFallbackCurrency($currency)) {
+            throw new FireflyException('200026: Currency is fallback.'); // @codeCoverageIgnore
+        }
+
+        $this->repository->destroy($currency);
+
+        return response()->json([], 204);
+    }
+}