<?php
/**
 * @package     Joomla.Plugin
 * @subpackage  Installer.override
 *
 * @copyright   (C) 2018 Open Source Matters, Inc. <https://www.joomla.org>
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */

defined('_JEXEC') or die;

use Joomla\CMS\Application\CMSApplicationInterface;
use Joomla\CMS\Date\Date;
use Joomla\CMS\Language\Text;
use Joomla\CMS\Plugin\CMSPlugin;
use Joomla\Database\ParameterType;

/**
 * Override Plugin
 *
 * @since  4.0.0
 */
class PlgInstallerOverride extends CMSPlugin
{
	/**
	 * Application object.
	 *
	 * @var    CMSApplicationInterface
	 */
	protected $app;

	/**
	 * Load the language file on instantiation.
	 *
	 * @var    boolean
	 *
	 * @since  4.0.0
	 */
	protected $autoloadLanguage = true;

	/**
	 * Database object
	 *
	 * @var    \Joomla\Database\DatabaseInterface
	 * @since  4.0.0
	 */
	protected $db;

	/**
	 * Method to get com_templates model instance.
	 *
	 * @param   string  $name    The model name. Optional
	 * @param   string  $prefix  The class prefix. Optional
	 *
	 * @return  \Joomla\Component\Templates\Administrator\Model\TemplateModel
	 *
	 * @since   4.0.0
	 *
	 * @throws \Exception
	 */
	public function getModel($name = 'Template', $prefix = 'Administrator')
	{
		/** @var \Joomla\Component\Templates\Administrator\Extension\TemplatesComponent $templateProvider */
		$templateProvider = $this->app->bootComponent('com_templates');

		/** @var \Joomla\Component\Templates\Administrator\Model\TemplateModel $model */
		$model = $templateProvider->getMVCFactory()->createModel($name, $prefix);

		return $model;
	}

	/**
	 * Purges session array.
	 *
	 * @return  void
	 *
	 * @since   4.0.0
	 */
	public function purge()
	{
		// Delete stored session value.
		$session = $this->app->getSession();
		$session->remove('override.beforeEventFiles');
		$session->remove('override.afterEventFiles');
	}

	/**
	 * Method to store files before event.
	 *
	 * @return  void
	 *
	 * @since   4.0.0
	 */
	public function storeBeforeEventFiles()
	{
		// Delete stored session value.
		$this->purge();

		// Get list and store in session.
		$list = $this->getOverrideCoreList();
		$this->app->getSession()->set('override.beforeEventFiles', $list);
	}

	/**
	 * Method to store files after event.
	 *
	 * @return  void
	 *
	 * @since   4.0.0
	 */
	public function storeAfterEventFiles()
	{
		// Get list and store in session.
		$list = $this->getOverrideCoreList();
		$this->app->getSession()->set('override.afterEventFiles', $list);
	}

	/**
	 * Method to prepare changed or updated core file.
	 *
	 * @param   string  $action  The name of the action.
	 *
	 * @return   array   A list of changed files.
	 *
	 * @since   4.0.0
	 */
	public function getUpdatedFiles($action)
	{
		$session = $this->app->getSession();

		$after  = $session->get('override.afterEventFiles');
		$before = $session->get('override.beforeEventFiles');
		$result = array();

		if (!is_array($after) || !is_array($before))
		{
			return $result;
		}

		$size1  = count($after);
		$size2  = count($before);

		if ($size1 === $size2)
		{
			for ($i = 0; $i < $size1; $i++)
			{
				if ($after[$i]->coreFile !== $before[$i]->coreFile)
				{
					$after[$i]->action = $action;
					$result[] = $after[$i];
				}
			}
		}

		return $result;
	}

	/**
	 * Method to get core list of override files.
	 *
	 * @return   array  The list of core files.
	 *
	 * @since   4.0.0
	 */
	public function getOverrideCoreList()
	{
		try
		{
			/** @var \Joomla\Component\Templates\Administrator\Model\TemplateModel $templateModel */
			$templateModel = $this->getModel();
		}
		catch (\Exception $e)
		{
			return [];
		}

		return $templateModel->getCoreList();
	}

	/**
	 * Last process of this plugin.
	 *
	 * @param   array  $result  Result array.
	 *
	 * @return  void
	 *
	 * @since   4.0.0
	 */
	public function finalize($result)
	{
		$num = count($result);

		if ($num != 0)
		{
			$this->app->enqueueMessage(Text::plural('PLG_INSTALLER_OVERRIDE_N_FILE_UPDATED', $num), 'notice');
			$this->saveOverrides($result);
		}

		// Delete stored session value.
		$this->purge();
	}

	/**
	 * Event before extension update.
	 *
	 * @return   void
	 *
	 * @since   4.0.0
	 */
	public function onExtensionBeforeUpdate()
	{
		$this->storeBeforeEventFiles();
	}

	/**
	 * Event after extension update.
	 *
	 * @return   void
	 *
	 * @since   4.0.0
	 */
	public function onExtensionAfterUpdate()
	{
		$this->storeAfterEventFiles();
		$result = $this->getUpdatedFiles('Extension Update');
		$this->finalize($result);
	}

	/**
	 * Event before joomla update.
	 *
	 * @return   void
	 *
	 * @since   4.0.0
	 */
	public function onJoomlaBeforeUpdate()
	{
		$this->storeBeforeEventFiles();
	}

	/**
	 * Event after joomla update.
	 *
	 * @return   void
	 *
	 * @since   4.0.0
	 */
	public function onJoomlaAfterUpdate()
	{
		$this->storeAfterEventFiles();
		$result = $this->getUpdatedFiles('Joomla Update');
		$this->finalize($result);
	}

	/**
	 * Event before install.
	 *
	 * @return   void
	 *
	 * @since   4.0.0
	 */
	public function onInstallerBeforeInstaller()
	{
		$this->storeBeforeEventFiles();
	}

	/**
	 * Event after install.
	 *
	 * @return   void
	 *
	 * @since   4.0.0
	 */
	public function onInstallerAfterInstaller()
	{
		$this->storeAfterEventFiles();
		$result = $this->getUpdatedFiles('Extension Install');
		$this->finalize($result);
	}

	/**
	 * Check for existing id.
	 *
	 * @param   string   $id    Hash id of file.
	 * @param   integer  $exid  Extension id of file.
	 *
	 * @return   boolean  True/False
	 *
	 * @since   4.0.0
	 */
	public function load($id, $exid)
	{
		$db = $this->db;

		// Create a new query object.
		$query = $db->getQuery(true);

		$query
			->select($db->quoteName('hash_id'))
			->from($db->quoteName('#__template_overrides'))
			->where($db->quoteName('hash_id') . ' = :id')
			->where($db->quoteName('extension_id') . ' = :exid')
			->bind(':id', $id)
			->bind(':exid', $exid, ParameterType::INTEGER);

		$db->setQuery($query);
		$results = $db->loadObjectList();

		if (count($results) === 1)
		{
			return true;
		}

		return false;
	}

	/**
	 * Save the updated files.
	 *
	 * @param   array  $pks  Updated files.
	 *
	 * @return  void
	 *
	 * @since   4.0.0
	 * @throws   \Joomla\Database\Exception\ExecutionFailureException|\Joomla\Database\Exception\ConnectionFailureException
	 */
	private function saveOverrides($pks)
	{
		// Insert columns.
		$columns = [
			'template',
			'hash_id',
			'action',
			'created_date',
			'modified_date',
			'extension_id',
			'state',
			'client_id',
		];

		// Create an insert query.
		$insertQuery = $this->db->getQuery(true)
			->insert($this->db->quoteName('#__template_overrides'))
			->columns($this->db->quoteName($columns));

		foreach ($pks as $pk)
		{
			$date = new Date('now');
			$createdDate = $date->toSql();

			if (empty($pk->coreFile))
			{
				$modifiedDate = null;
			}
			else
			{
				$modifiedDate = $createdDate;
			}

			if ($this->load($pk->id, $pk->extension_id))
			{
				$updateQuery = $this->db->getQuery(true)
					->update($this->db->quoteName('#__template_overrides'))
					->set(
						[
							$this->db->quoteName('modified_date') . ' = :modifiedDate',
							$this->db->quoteName('action') . ' = :pkAction',
							$this->db->quoteName('state') . ' = 0',
						]
					)
					->where($this->db->quoteName('hash_id') . ' = :pkId')
					->where($this->db->quoteName('extension_id') . ' = :exId')
					->bind(':modifiedDate', $modifiedDate)
					->bind(':pkAction', $pk->action)
					->bind(':pkId', $pk->id)
					->bind(':exId', $pk->extension_id, ParameterType::INTEGER);

				// Set the query using our newly populated query object and execute it.
				$this->db->setQuery($updateQuery);
				$this->db->execute();

				continue;
			}

			// Insert values, preserve order
			$bindArray = $insertQuery->bindArray(
				[
					$pk->template,
					$pk->id,
					$pk->action,
					$createdDate,
					$modifiedDate,
				],
				ParameterType::STRING
			);
			$bindArray = array_merge(
				$bindArray,
				$insertQuery->bindArray(
					[
						$pk->extension_id,
						0,
						(int) $pk->client,
					]
				)
			);

			$insertQuery->values(implode(',', $bindArray));
		}

		$this->db->setQuery($insertQuery);
		$this->db->execute();
	}
}

• [F] override.php
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• [F] override.xml
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