Added helper class for ezselection types

This class makes it easy to add/set or remove entries in
ezselection attributes.
SelectionType::set will add/set and SelectionType::unset will
remove.

Aplia/Content/AttributeHelpers/SelectionType.php

@@ -0,0 +1,108 @@
+<?php
+namespace Aplia\Content\AttributeHelpers;
+
+use Aplia\Content\ContentType;
+use Aplia\Content\Exceptions\TypeError;
+
+/**
+ * Helper class for working with `ezselection` data types.
+ *
+ * Makes it easy to add or remove selections entries.
+ */
+class SelectionType
+{
+    /**
+     * Add or update ezselection entry using ID and name.
+     * If the ID already exists it changes the name, otherwise it is added as a new entry.
+     * If the ID is null it creates a new unique ID.
+     *
+     * @param ContentType $contentType The content-type object
+     * @param string $identifier Identifier for content class attribute
+     * @param int|null $id The unique ID of the selection
+     * @param string $name Name of selection
+     * @return void 
+     */
+    public static function set(ContentType $contentType, string $identifier, $id, string $name)
+    {
+        $attribute = $contentType->getAttribute($identifier);
+        if ($attribute->type !== 'ezselection') {
+            throw new TypeError("The content class attribute {$attribute->identifier} is not an ezselection, got: {$attribute->type}");
+        }
+        $value = $attribute->value;
+        if (!$value) {
+            $value = array('options');
+        }
+        $found = false;
+        if ($id !== null) {
+            foreach ($value['options'] as $idx => $selection) {
+                if ($selection['id'] == $id) {
+                    $value['options'][$idx]['name'] = $name;
+                    $found = true;
+                    break;
+                }
+            }
+        } else {
+            $ids = array();
+            foreach ($value['options'] as $idx => $selection) {
+                $ids = $selection['id'];
+            }
+            $id = ($ids ? max($ids) : 0) + 1;
+        }
+        if (!$found) {
+            $value['options'][] = array('id' => (string)$id, 'name' => $name);
+            $value['options'] = array_values($value['options']);
+        }
+        $attribute->value = $value;
+        // Write back the attribute, this will add it to the change-list
+        $contentType->setAttribute($identifier, $attribute);
+    }
+
+    /**
+     * Remove ezselection entry using ID or name.
+     * If the ID is null it uses the name to locate the entry.
+     * If there is no match the attribute is left as-is.
+     *
+     * @param ContentType $contentType The content-type object
+     * @param string $identifier Identifier for content class attribute
+     * @param int|null $id The unique ID of the selection to remove or null to use name matching
+     * @param string $name Name of selection to remove
+     * @return void 
+     */
+    public static function unset(ContentType $contentType, string $identifier, $id=null, string $name=null)
+    {
+        $attribute = $contentType->getAttribute($identifier);
+        if ($attribute->type !== 'ezselection') {
+            throw new TypeError("The content class attribute {$attribute->identifier} is not an ezselection, got: {$attribute->type}");
+        }
+        if ($id === null && $name === null) {
+            throw new TypeError("Cannot unset ezselection entry without id or name");
+        }
+        $value = $attribute->value;
+        if (!$value) {
+            $value = array('options');
+        }
+        $found = false;
+        if ($id !== null) {
+            foreach ($value['options'] as $idx => $selection) {
+                if ($selection['id'] == $id) {
+                    unset($value['options'][$idx]);
+                    $found = true;
+                }
+            }
+        } else {
+            foreach ($value['options'] as $idx => $selection) {
+                if ($selection['name'] == $name) {
+                    unset($value['options'][$idx]);
+                    $found = true;
+                }
+            }
+        }
+        if (!$found) {
+            return;
+        }
+        $value['options'] = array_values($value['options']);
+        $attribute->value = $value;
+        // Write back the attribute, this will add it to the change-list
+        $contentType->setAttribute($identifier, $attribute);
+    }
+}