Move Sheet to Common/Entity (#438)

... and introduce a SheetManager

src/Spout/Writer/Common/Creator/EntityFactory.php

@@ -2,7 +2,7 @@
 
 namespace Box\Spout\Writer\Common\Creator;
 
-use Box\Spout\Writer\Common\Sheet;
+use Box\Spout\Writer\Common\Entity\Sheet;
 use Box\Spout\Writer\Common\Entity\Workbook;
 use Box\Spout\Writer\Common\Entity\Worksheet;
 
@@ -14,6 +14,19 @@ use Box\Spout\Writer\Common\Entity\Worksheet;
  */
 class EntityFactory
 {
+    /** @var ManagerFactory */
+    private $managerFactory;
+
+    /**
+     * EntityFactory constructor.
+     *
+     * @param ManagerFactory $managerFactory
+     */
+    public function __construct(ManagerFactory $managerFactory)
+    {
+        $this->managerFactory = $managerFactory;
+    }
+
     /**
      * @return Workbook
      */
@@ -31,4 +44,15 @@ class EntityFactory
     {
         return new Worksheet($worksheetFilePath, $externalSheet);
     }
+
+    /**
+     * @param int $sheetIndex Index of the sheet, based on order in the workbook (zero-based)
+     * @param string $associatedWorkbookId ID of the sheet's associated workbook
+     * @return Sheet
+     */
+    public function createSheet($sheetIndex, $associatedWorkbookId)
+    {
+        $sheetManager = $this->managerFactory->createSheetManager();
+        return new Sheet($sheetIndex, $associatedWorkbookId, $sheetManager);
+    }
 }