Added a way to see report/statements. Added more gems to the Gemfile.

src/database.rb

@@ -85,4 +85,25 @@ class Database
             @conn.exec_params(sql_update, [user_id, amount])
         end
     end
+
+    def fetch_report(user_id, interval_string)
+        sql = <<~SQL
+        SELECT
+            SUM(CASE WHEN amount > 0 THEN amount ELSE 0 END) as income,
+            SUM(CASE WHEN amount < 0 THEN amount ELSE 0 END) as expenses,
+            SUM(amount) AS net_change
+        FROM transactions
+        WHERE user_id = $1
+        AND created_at >= NOW() - $2::INTERVAL
+        SQL
+
+        result = @conn.exec_params(sql, [user_id, interval_string])
+        row = result[0]
+
+        {
+            income: row['income'].to_i,
+            expenses: row['expenses'].to_i,
+            net: row['net_change'].to_i
+        }
+    end
 end