Show a notice to admin if network activation

Mailpoet seems to be working on network activated multisites but we
don't support it.
[MAILPOET-923]

lib/Config/DeferredAdminNotices.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace MailPoet\Config;
+
+use MailPoet\WP\Notice;
+
+class DeferredAdminNotices {
+
+  const OPTIONS_KEY_NAME = 'mailpoet_deferred_admin_notices';
+
+  /**
+   * @param string $message
+   */
+  public function addNetworkAdminNotice($message) {
+    $notices = get_option(DeferredAdminNotices::OPTIONS_KEY_NAME, array());
+    $notices[] = array(
+      "message" => $message,
+      "networkAdmin" => true,// if we'll need to display the notice to anyone else
+    );
+    update_option(DeferredAdminNotices::OPTIONS_KEY_NAME, $notices);
+  }
+
+  public function flushAll() {
+    $notices = get_option(DeferredAdminNotices::OPTIONS_KEY_NAME, array());
+
+    foreach($notices as $notice) {
+      $notice = new Notice(Notice::TYPE_WARNING, $notice["message"]);
+      add_action('network_admin_notices', array($notice, 'displayWPNotice'));
+    }
+
+    if(!empty($notices)) {
+      delete_option(DeferredAdminNotices::OPTIONS_KEY_NAME);
+    }
+  }
+
+}

lib/Config/Initializer.php

@@ -25,7 +25,6 @@ class Initializer {
   function init() {
     $requirements_check_results = $this->checkRequirements();
 
-    // abort initialization if PDO extension is missing
     if(!$requirements_check_results[RequirementsChecker::TEST_PDO_EXTENSION] ||
       !$requirements_check_results[RequirementsChecker::TEST_VENDOR_SOURCE]
     ) {
@@ -43,6 +42,16 @@ class Initializer {
       )
     );
 
+    add_action('activated_plugin', array(
+      new PluginActivatedHook(new DeferredAdminNotices),
+      'action'
+    ), 10, 2);
+
+    add_action('admin_init', array(
+      new DeferredAdminNotices,
+      'flushAll'
+    ));
+
     add_action('plugins_loaded', array(
       $this,
       'setup'
@@ -62,8 +71,8 @@ class Initializer {
   }
 
   function checkRequirements() {
-    $requrements = new RequirementsChecker();
-    return $requrements->checkAllRequirements();
+    $requirements = new RequirementsChecker();
+    return $requirements->checkAllRequirements();
   }
 
   function setupDB() {

lib/Config/PluginActivatedHook.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace MailPoet\Config;
+
+class PluginActivatedHook {
+
+  /** @var DeferredAdminNotices */
+  private $deferredAdminNotices;
+
+  public function __construct(DeferredAdminNotices $deferredAdminNotices) {
+    $this->deferredAdminNotices = $deferredAdminNotices;
+  }
+
+  public function action($plugin, $networkWide) {
+    if($networkWide) {
+      $this->deferredAdminNotices->addNetworkAdminNotice(__('We noticed that you\'re using an unsupported environment. While MailPoet might work within a MultiSite environment, we don’t support it.', 'mailpoet'));
+    }
+  }
+
+}

tests/unit/Config/PluginActivatedHookTest.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace MailPoet\Config;
+
+use Codeception\Util\Stub;
+
+class PluginActivatedHookTest extends \MailPoetTest {
+
+
+  public function testItAddsANewMessageIfNetworkActivation() {
+    $deferredAdminNotices = Stub::makeEmpty(
+      'MailPoet\Config\DeferredAdminNotices',
+      array(
+        'addNetworkAdminNotice' => Stub::exactly(1, function () {
+        }),
+      ),
+      $this
+    );
+    $hook = new PluginActivatedHook($deferredAdminNotices);
+    $hook->action("mailpoet", true);
+  }
+
+  public function testItDoesntAddsAMessageIfNoNetworkActivation() {
+    $deferredAdminNotices = Stub::makeEmpty(
+      'MailPoet\Config\DeferredAdminNotices',
+      array(
+        'addNetworkAdminNotice' => Stub::never(),
+      ),
+      $this
+    );
+    $hook = new PluginActivatedHook($deferredAdminNotices);
+    $hook->action("mailpoet", false);
+  }
+
+}