Remapped all library classes.

app/lib/FireflyIII/Database/TransactionJournal/TransactionJournalInterface.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace FireflyIII\Database\TransactionJournal;
+
+use Carbon\Carbon;
+use Illuminate\Support\Collection;
+
+/**
+ * Interface TransactionJournalInterface
+ *
+ * @package FireflyIII\Database
+ */
+interface TransactionJournalInterface
+{
+    /**
+     * Get the very first transaction journal.
+     *
+     * @return mixed
+     */
+    public function first();
+
+    /**
+     * @param Carbon $start
+     * @param Carbon $end
+     *
+     * @return Collection
+     */
+    public function getInDateRange(Carbon $start, Carbon $end);
+
+    /**
+     * @param Carbon $date
+     *
+     * @return float
+     */
+    public function getSumOfExpensesByMonth(Carbon $date);
+
+    /**
+     * @param Carbon $date
+     *
+     * @return float
+     */
+    public function getSumOfIncomesByMonth(Carbon $date);
+
+}