Work on #1270. (#164)

* Work on #1270.

* Remove cruft.

* Remove more cruft.

* Removed extra comma.

* Changed 'context' to 'context_definitions'.

* Added additional Context Condition, MediaIsIslandoraMedia.

* Removed the node_is_islandora_object and media_is_islandora_media Conditions from the core block placement UI.

islandora.module

@@ -352,6 +352,8 @@ function islandora_form_block_form_alter(&$form, FormStateInterface $form_state,
   unset($form['visibility']['node_has_parent']);
   unset($form['visibility']['media_uses_filesystem']);
   unset($form['visibility']['media_has_mimetype']);
+  unset($form['visibility']['node_is_islandora_object']);
+  unset($form['visibility']['media_is_islandora_media']);
 }
 
 /**

src/Plugin/Condition/MediaIsIslandoraMedia.php

@@ -0,0 +1,59 @@
+<?php
+
+namespace Drupal\islandora\Plugin\Condition;
+
+use Drupal\Core\Condition\ConditionPluginBase;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Checks if media entity has fields that qualify it as an "Islandora" media.
+ *
+ * @Condition(
+ *   id = "media_is_islandora_media",
+ *   label = @Translation("Media is an Islandora media"),
+ *   context_definitions = {
+ *     "media" = @ContextDefinition("entity:media", required = TRUE , label = @Translation("media"))
+ *   }
+ * )
+ */
+class MediaIsIslandoraMedia extends ConditionPluginBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function evaluate() {
+    $media = $this->getContextValue('media');
+    if (!$media) {
+      return FALSE;
+    }
+    // Islandora Media have these two fields.
+    if ($media->hasField('field_media_use') && $media->hasField('field_media_of')) {
+      return TRUE;
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function summary() {
+    if (!empty($this->configuration['negate'])) {
+      return $this->t('The media is not an Islandora media.');
+    }
+    else {
+      return $this->t('The media is an Islandora media.');
+    }
+  }
+
+}

src/Plugin/Condition/NodeIsIslandoraObject.php

@@ -0,0 +1,59 @@
+<?php
+
+namespace Drupal\islandora\Plugin\Condition;
+
+use Drupal\Core\Condition\ConditionPluginBase;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Checks whether node has fields that qualify it as an "Islandora" node.
+ *
+ * @Condition(
+ *   id = "node_is_islandora_object",
+ *   label = @Translation("Node is an Islandora object"),
+ *   context_definitions = {
+ *     "node" = @ContextDefinition("entity:node", required = TRUE , label = @Translation("node"))
+ *   }
+ * )
+ */
+class NodeIsIslandoraObject extends ConditionPluginBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function evaluate() {
+    $node = $this->getContextValue('node');
+    if (!$node) {
+      return FALSE;
+    }
+    // Islandora objects have these two fields.
+    if ($node->hasField('field_model') && $node->hasField('field_member_of')) {
+      return TRUE;
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function summary() {
+    if (!empty($this->configuration['negate'])) {
+      return $this->t('The node is not an Islandora object.');
+    }
+    else {
+      return $this->t('The node is an Islandora object.');
+    }
+  }
+
+}