Fix contacts search and add discount and invoice resources

src/Bexio/Resource/Contact.php

@@ -24,7 +24,7 @@ public function getContacts(array $params = [])
      */
     public function searchContacts(array $params = [])
     {
-        return $this->client->get('contact/search', $params);
+        return $this->client->post('contact/search', $params);
     }
 
     /**

src/Bexio/Resource/Discount.php

@@ -0,0 +1,60 @@
+<?php
+
+namespace Bexio\Resource;
+
+use Bexio\Bexio;
+
+class Discount extends Bexio {
+
+    /**
+     * Gets all discounts
+     * 
+     * @param string $resource
+     * @param int $parentId
+     * @return array
+     */
+    public function getDiscounts($resource, $parentId, array $params = [])
+    {
+        return $this->client->get("$resource/$parentId/kb_position_discount", $params);
+    }
+
+    /**
+     * Search for discounts
+     *
+     * @param string $resource 
+     * @param int $parentId
+     * @param array $params
+     * @return mixed
+     */
+    public function searchDiscounts($resource, $parentId, array $params = [])
+    {
+        return $this->client->get("$resource/$parentId/kb_position_discount", $params);
+    }
+
+    /**
+     * Get specific discount
+     *
+     * @param string $resource
+     * @param $parentId
+     * @param $id
+     * @return mixed
+     */
+    public function getDiscount($resource, $parentId, $id)
+    {
+        return $this->client->get("$resource/$parentId/kb_position_discount/" . $id, []);
+    }
+
+    /**
+     * Add new discount
+     * 
+     * @param string $resource
+     * @param int $parentId
+     * @param array $params
+     * @return mixed
+     */
+    public function createDiscount($resource, $parentId, $params = [])
+    {
+        return $this->client->post("$resource/$parentId/kb_position_discount", $params);
+    }
+
+}

src/Bexio/Resource/Invoice.php

@@ -0,0 +1,52 @@
+<?php
+
+namespace Bexio\Resource;
+
+use Bexio\Bexio;
+
+class Invoice extends Bexio {
+
+    /**
+     * Gets all orders
+     *
+     * @return array
+     */
+    public function getInvoices(array $params = [])
+    {
+        return $this->client->get('kb_invoice', $params);
+    }
+
+    /**
+     * Search for invoices
+     *
+     * @param array $params
+     * @return mixed
+     */
+    public function searchOrders(array $params = [])
+    {
+        return $this->client->get('kb_invoice/search', $params);
+    }
+
+    /**
+     * Get specific invoice
+     *
+     * @param $id
+     * @return mixed
+     */
+    public function getInvoice($id)
+    {
+        return $this->client->get('kb_invoice/' . $id, []);
+    }
+
+    /**
+     * Add new invoice
+     * 
+     * @param array $params
+     * @return mixed
+     */
+    public function createInvoice($params = [])
+    {
+        return $this->client->post('kb_invoice', $params);
+    }
+
+}