Add ExternalTaskManager class

app/Core/ExternalTask/ExternalTaskManager.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace Kanboard\Core\ExternalTask;
+
+/**
+ * Class ExternalTaskManager
+ *
+ * @package Kanboard\Core\ExternalTask
+ * @author  Frederic Guillot
+ */
+class ExternalTaskManager
+{
+    protected $providers = array();
+
+    /**
+     * Register a new task provider
+     *
+     * @param ExternalTaskProviderInterface $externalTaskProvider
+     * @return $this
+     */
+    public function register(ExternalTaskProviderInterface $externalTaskProvider)
+    {
+        $this->providers[$externalTaskProvider->getName()] = $externalTaskProvider;
+        return $this;
+    }
+
+    /**
+     * Get task provider
+     *
+     * @param  string $name
+     * @return ExternalTaskProviderInterface|null
+     * @throws ProviderNotFoundException
+     */
+    public function getProvider($name)
+    {
+        if (isset($this->providers[$name])) {
+            return $this->providers[$name];
+        }
+
+        throw new ProviderNotFoundException('Unable to load this provider: '.$name);
+    }
+
+    /**
+     * Get list of task providers
+     *
+     * @return array
+     */
+    public function getProvidersList()
+    {
+        $providers = array_keys($this->providers);
+        return array_combine($providers, $providers);
+    }
+}