First set of data mappers.

app/Import/Mapper/OpposingAccounts.php

@@ -0,0 +1,57 @@
+<?php
+/**
+ * OpposingAccounts.php
+ * Copyright (C) 2016 thegrumpydictator@gmail.com
+ *
+ * This software may be modified and distributed under the terms
+ * of the MIT license.  See the LICENSE file for details.
+ */
+
+declare(strict_types = 1);
+
+namespace FireflyIII\Import\Mapper;
+
+use FireflyIII\Crud\Account\AccountCrudInterface;
+use FireflyIII\Models\Account;
+use FireflyIII\Models\AccountType;
+
+/**
+ * Class OpposingAccounts
+ *
+ * @package FireflyIII\Import\Mapper
+ */
+class OpposingAccounts implements MapperInterface
+{
+
+    /**
+     * @return array
+     */
+    public function getMap(): array
+    {
+        /** @var AccountCrudInterface $crud */
+        $crud = app(AccountCrudInterface::class);
+        $set  = $crud->getAccountsByType(
+            [
+                AccountType::DEFAULT, AccountType::ASSET,
+                AccountType::EXPENSE, AccountType::BENEFICIARY,
+                AccountType::REVENUE
+            ]);
+        $list = [];
+
+        /** @var Account $account */
+        foreach ($set as $account) {
+            $name = $account->name;
+            $iban = $account->iban ?? '';
+            if (strlen($iban) > 0) {
+                $name .= ' (' . $account->iban . ')';
+            }
+            $list[$account->id] = $name;
+        }
+
+        asort($list);
+
+        $list = [0 => trans('csv.do_not_map')] + $list;
+
+        return $list;
+    }
+}