Feature: added support for Ticket linking

.gitignore

@@ -5,3 +5,4 @@
 /examples/test.php
 /test*.php
 *~
+.phpunit.result.cache

README.md

@@ -47,7 +47,7 @@ $client = new Client([
 ]);
 ```
 Besides using a combination of `username` and `password`, you can alternatively give an `http_token` or an `oauth2_token`.
-**Important:** You have to activate API access in Zammad.
+**Important:** You have to activate API access in Zammad. Should be active by default.
 
 ### Fetching a single Resource object
 To fetch a `Resource` object by ID, e. g. a ticket with ID 34, use the `Client` object:
@@ -83,6 +83,7 @@ Additionally you can have a look at the REST interface documentation of Zammad:
    * [Ticket priorities](https://docs.zammad.org/en/latest/api/ticket-priority.html)
    * [Ticket states](https://docs.zammad.org/en/latest/api/ticket-state.html)
 * [Tags](https://docs.zammad.org/en/latest/api/tags.html)
+* [Linking Tickets](https://docs.zammad.org/en/latest/api/ticket/links.html)
 
 #### Fetching a ticket's articles
 If you already have a ticket object, you can easily fetch its articles:
@@ -244,6 +245,21 @@ use ZammadAPIClient\ResourceType;
 
 $tags = $client->resource( ResourceType::TAG )->search('my tag');
 ```
+### Linking Tickets
+
+#### Linking two Tickets
+
+Zammad can link two or more Ticket objects. Allowed Link Types are `normal`, `parent` or `child`.
+
+```php
+use ZammadAPIClient\ResourceType;
+
+// First parameter $sourceTicket is the Ticket that should be linked
+// Second parameter $targetTicket is the Ticket that $sourceTicket should be linked to
+// Third parameter is the LinkType the $sourceTicket will be linked to $targetTicket with.
+$client->resource( ResourceType::LINK )->add( $sourceTicket, $targetTicket, 'normal' );
+```
+
 ### Object import
 
 Besides the usual methods available for objects, there is also a method available to import these via CSV. Example for text module CSV import:
@@ -308,6 +324,7 @@ $client->resource( ResourceType::TICKET );
 | GROUP|✔|✔|–|✔|✔|–|–|–|
 | USER|✔|✔|✔|✔|✔|–|–|✔|
 | TAG|✔|–|✔|–|–|✔|✔|–|
+| LINK|✔|–|–|–|–|✔|✔|–|
 
 ## Publishing
 

src/Client.php

@@ -165,12 +165,18 @@ public function put( $url, array $data = [], array $url_parameters = [] )
      *
      * @return Response object
      */
-    public function delete( $url, array $url_parameters = [] )
+    public function delete( $url, array $url_parameters = [], array $data = [] )
     {
+        $options = [];
+        if ( !empty($data) ) {
+            $options['json'] = $data;
+        }
+
         $response = $this->request(
             'DELETE',
             $url,
-            $url_parameters
+            $url_parameters,
+            $options
         );
 
         return $response;

src/Resource/Link.php

@@ -0,0 +1,145 @@
+<?php
+
+/**
+ * @package Zammad API Client
+ * @author  Fran Rey <franreycastedo@gmail.com>
+ */
+
+namespace ZammadAPIClient\Resource;
+
+class Link extends AbstractResource
+{
+    const URLS = [
+        'get'    => 'links',
+        'add'    => 'links/add',
+        'remove' => 'links/remove'
+    ];
+
+    const LINKTYPES = [
+        'normal',
+        'parent',
+        'child'
+    ];
+
+    /**
+     * Fetches links of an object.
+     *
+     * @param int    $object_id     ID of the object to fetch links for.
+     * @param string $object_type   Type of object to fetch links for (e. g. 'Ticket').
+     *
+     * @return object               This object.
+     */
+    public function get($object_id, $object_type = 'Ticket')
+    {
+        $this->clearError();
+
+        $object_id = intval($object_id);
+        if ( empty($object_id) ) {
+            throw new \RuntimeException('Missing object ID');
+        }
+
+        $response = $this->getClient()->get(
+            $this->getURL('get'),
+            [
+                'link_object' => $object_type,
+                'link_object_value'   => $object_id,
+            ]
+        );
+
+        if ( $response->hasError() ) {
+            $this->setError( $response->getError() );
+        }
+        else {
+            $this->clearError();
+            $this->setRemoteData( $response->getData() );
+        }
+
+        return $this;
+    }
+
+    /**
+     * Adds a link between two tickets.
+     *
+     * @param Ticket $source        Source ticket object.
+     * @param Ticket $target        Target ticket object.
+     * @param string $type          Link type (default: 'normal').
+     *
+     * @return object               This object.
+     */
+    public function add(Ticket $source, Ticket $target, $type = 'normal')
+    {
+        $this->clearError();
+
+        if ( empty($source->getID()) || empty($target->getID()) ) {
+            $this->setError('Tickets not valid.');
+            return $this;
+        }
+        if ( !in_array($type, self::LINKTYPES, true) ) {
+            $this->setError('Linktype is not supported.');
+            return $this;
+        }
+
+        $response = $this->getClient()->post(
+            $this->getURL('add'),
+            [
+                'link_type'                 => $type,
+                'link_object_target'        => 'Ticket',
+                'link_object_target_value'  => $target->getID(),
+                'link_object_source'        => 'Ticket',
+                'link_object_source_number' => $source->getValue('number')
+            ]
+        );
+
+        if ( $response->hasError() ) {
+            $this->setError( $response->getError() );
+        }
+
+        return $this;
+    }
+
+    /**
+     * Removes a link between two tickets.
+     *
+     * @param Ticket $source        Source ticket object.
+     * @param Ticket $target        Target ticket object.
+     * @param string $type          Link type (default: 'normal').
+     *
+     * @return object               This object.
+     */
+    public function remove(Ticket $source, Ticket $target, $type = 'normal')
+    {
+        $this->clearError();
+
+        if ( empty($source->getID()) || empty($target->getID()) ) {
+            $this->setError('Tickets not valid.');
+            return $this;
+        }
+        if ( !in_array($type, self::LINKTYPES, true) ) {
+            $this->setError('Linktype is not supported.');
+            return $this;
+        }
+
+        $response = $this->getClient()->delete(
+            $this->getURL('remove'),
+            [],
+            [
+                'link_type'                => $type,
+                'link_object_source'       => 'Ticket',
+                'link_object_source_value' => $source->getID(),
+                'link_object_target'       => 'Ticket',
+                'link_object_target_value' => $target->getID()
+            ]
+        );
+
+        if ( $response->hasError() ) {
+            $this->setError( $response->getError() );
+            return $this;
+        }
+
+        $this->clearError();
+        $this->clearRemoteData();
+        $this->clearUnsavedValues();
+
+        return $this;
+    }
+}

src/ResourceType.php

@@ -18,4 +18,5 @@ class ResourceType
     const TICKET          = '\\ZammadAPIClient\\Resource\\Ticket';
     const TICKET_ARTICLE  = '\\ZammadAPIClient\\Resource\\TicketArticle';
     const TAG             = '\\ZammadAPIClient\\Resource\\Tag';
+    const LINK            = '\\ZammadAPIClient\\Resource\\Link';
 }