Added abstract AdminPage

Author: grzegorz-jamroz

src/CustomAdminPage/AdminPage.php

@@ -0,0 +1,154 @@
+<?php
+declare(strict_types=1);
+
+namespace Grzechu\CustomAdminPage;
+
+abstract class AdminPage
+{
+    private static $instances;
+
+    /**
+     * @var string
+     */
+    protected $pageTitle;
+
+    /**
+     * @var string
+     */
+    protected $menuTitle;
+
+    /**
+     * @var string
+     */
+    protected $capability;
+
+    /**
+     * @var string
+     */
+    protected $menuSlug;
+
+    /**
+     * @var string
+     */
+    private $iconUrl;
+
+    /**
+     * @var int
+     */
+    private $position;
+
+    /**
+     * @var string|null
+     */
+    private $parentSlug;
+
+    final public static function getInstance(): self
+    {
+        $className = get_called_class();
+
+        if (isset(self::$instances[$className]) === false) {
+            self::$instances[$className] = new static();
+        }
+
+        return self::$instances[$className];
+    }
+
+    public function __toString()
+    {
+        return self::class;
+    }
+
+    final private function __construct()
+    {
+        $this->pageTitle = $this->getPageTitle();
+        $this->menuTitle = $this->getMenuTitle();
+        $this->capability = $this->getCapability();
+        $this->menuSlug = $this->getMenuSlug();
+        $this->iconUrl = $this->getIconUrl();
+        $this->position = $this->getPosition();
+        $this->parentSlug = $this->getParentSlug();
+
+        add_action(
+            'in_admin_header',
+            [$this, 'dismissAllNotices'],
+            1000
+        );
+        $this->registerMenu();
+
+    }
+
+    abstract public function getPageTitle(): string;
+    abstract public function getMenuTitle(): string;
+    abstract public function getCapability(): string;
+    abstract public function getMenuSlug(): string;
+    abstract public function callableFunction();
+
+    public function getPosition(): int
+    {
+        return 1;
+    }
+
+    public function getIconUrl(): string
+    {
+        return '';
+    }
+
+    public function getParentSlug()
+    {
+        return '';
+    }
+
+    public function adminMenu()
+    {
+        add_menu_page(
+            $this->pageTitle,
+            $this->menuTitle,
+            $this->capability,
+            $this->menuSlug,
+            [$this, 'callableFunction'],
+            $this->iconUrl,
+            $this->position
+        );
+    }
+
+    public function adminSubMenu()
+    {
+        add_submenu_page(
+            $this->parentSlug,
+            $this->pageTitle,
+            $this->menuTitle,
+            $this->capability,
+            $this->menuSlug,
+            [$this, 'callableFunction']
+        );
+    }
+
+    public function dismissAllNotices()
+    {
+        if (!isset($_GET['page']) || $_GET['page'] !== $this->menuSlug) {
+            return;
+        }
+
+        remove_all_actions('admin_notices');
+        remove_all_actions('all_admin_notices');
+    }
+
+    private function registerMenu()
+    {
+        if ($this->parentSlug !== '') {
+            add_action('admin_menu', [$this, 'adminSubMenu']);
+
+            return;
+        }
+
+        add_action('admin_menu', [$this, 'adminMenu']);
+    }
+
+    final private function __clone()
+    {
+    }
+
+    final private function __wakeup()
+    {
+    }
+}