Addsheet May Leave Active Sheet Uninitialized

Fix PHPOffice#4112. Direct cause is that `applyStylesFromArray` tries to save and restore `activeSheetIndex`. However, if activeSheetIndex is -1, indicating no active sheet, the restore should not be attempted. Code is changed to test before attempting to restore.

The actual problem, however, is that user specified a sheet number for `addSheet`. That method will set activeSheetIndex most of the time, but this was a gap - when the supplied sheet number (0 in this case) is greater than activeSheetIndex (-1 in this case), it was leaving activeSheetIndex as -1. It is changed to set activeSheetIndex to 0 when activeSheetIndex is negative.

CHANGELOG.md

@@ -25,7 +25,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 
 ### Fixed
 
-- Nothing
+- Add Sheet may leave Active Sheet uninitialized. [Issue #4112](https://github.com/PHPOffice/PhpSpreadsheet/issues/4112) [PR #4113](https://github.com/PHPOffice/PhpSpreadsheet/pull/4113)
 
 ## 2024-07-24 - 2.2.0
 

src/PhpSpreadsheet/Spreadsheet.php

@@ -558,6 +558,9 @@ public function addSheet(Worksheet $worksheet, ?int $sheetIndex = null): Workshe
             if ($this->activeSheetIndex >= $sheetIndex) {
                 ++$this->activeSheetIndex;
             }
+            if ($this->activeSheetIndex < 0) {
+                $this->activeSheetIndex = 0;
+            }
         }
 
         if ($worksheet->getParent() === null) {

src/PhpSpreadsheet/Worksheet/Worksheet.php

@@ -3684,7 +3684,9 @@ public function applyStylesFromArray(string $coordinate, array $styleArray): boo
         $originalSelected = $this->selectedCells;
         $this->getStyle($coordinate)->applyFromArray($styleArray);
         $this->selectedCells = $originalSelected;
-        $spreadsheet->setActiveSheetIndex($activeSheetIndex);
+        if ($activeSheetIndex >= 0) {
+            $spreadsheet->setActiveSheetIndex($activeSheetIndex);
+        }
 
         return true;
     }

tests/PhpSpreadsheetTests/Worksheet/Issue4112Test.php

@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpOffice\PhpSpreadsheetTests\Worksheet;
+
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
+use PhpOffice\PhpSpreadsheetTests\Functional\AbstractFunctional;
+
+class Issue4112Test extends AbstractFunctional
+{
+    /**
+     * Problem deleting all sheets then adding one.
+     *
+     * @dataProvider providerSheetNumber
+     */
+    public function testIssue4112(?int $sheetNumber): void
+    {
+        $mySpreadsheet = new Spreadsheet();
+        $mySpreadsheet->removeSheetByIndex(0);
+        $worksheet = new Worksheet($mySpreadsheet, 'addedsheet');
+        self::assertSame(-1, $mySpreadsheet->getActiveSheetIndex());
+        $mySpreadsheet->addSheet($worksheet, 0);
+        self::assertSame('addedsheet', $mySpreadsheet->getActiveSheet()->getTitle());
+        $row = 1;
+        $col = 1;
+        $worksheet->getCell([$col, $row])->setValue('id_uti');
+        self::assertSame('id_uti', $worksheet->getCell([$col, $row])->getValue());
+        $mySpreadsheet->disconnectWorksheets();
+    }
+
+    public static function providerSheetNumber(): array
+    {
+        return [
+            'problem case' => [0],
+            'normal case' => [null],
+            'negative 1 (as if there were no sheets)' => [-1],
+            'diffeent negative number' => [-4],
+            'positive number' => [4],
+        ];
+    }
+}