<?php
/**
 * This source file is part of the open source project
 * ExpressionEngine (https://expressionengine.com)
 *
 * @link      https://expressionengine.com/
 * @copyright Copyright (c) 2003-2022, Packet Tide, LLC (https://www.packettide.com)
 * @license   https://expressionengine.com/license Licensed under Apache License, Version 2.0
 */

namespace ExpressionEngine\Service\Model;

use ExpressionEngine\Library\Filesystem\Filesystem;

/**
 * File Synced Model
 *
 * A parent model that allows some of the model data to be stored and edited
 * on disk, for example to store templates as files.
 */
abstract class FileSyncedModel extends Model
{
    protected $_skip_next_write = false;

    protected static $_events = array(
        'afterLoad',
        'afterDelete',
        'afterSave',
        'afterUpdate'
    );

    /**
     * Get the full server path to the file
     *
     * @return String Full file path
     */
    abstract public function getFilePath();

    /**
     * Get modification time as the database believes to be true.
     *
     * The value returned here is compared to the file mtime on load and
     * the database value is updated from the file if the file mtime is newer.
     *
     * @return Int Last modificaiton time of the model
     */
    abstract public function getModificationTime();

    /**
    * Set modification time in the database.
    *
    * This is called if the model has to automatically do a sync.
    *
    * @param Int $mtime The new last modified time
    * @return void
    */
    abstract public function setModificationTime($mtime);

    /**
     * Given an array of old model data, get that file path. Used to
     * sync renames.
     *
     * @param Array $previous Assoc array of old model data
     * @return String Full file path
     */
    abstract protected function getPreviousFilePath($previous);

    /**
     * Take the current model information and return a string of whatever
     * it is that should be synced to the file.
     *
     * @return String File data
     */
    abstract protected function serializeFileData();

    /**
     * Given the file data, set any fields that need to be set.
     *
     * @param String $str The current file data
     */
    abstract protected function unserializeFileData($str);

    /**
     * After loading the row from the database, ensure that the file exists and
     * that the two data points are up to date.
     */
    public function onAfterLoad()
    {
        $path = $this->getFilePath();
   
        if (! isset($path)) {
            return;
        }

        if (! ee('Filesystem')->exists($path)) {
            $this->writeToFile();

            return;
        }

        $mtime = ee('Filesystem')->mtime($path);

        if ($mtime > $this->getModificationTime()) {
            $this->unserializeFileData(ee('Filesystem')->read($path));
            $this->setModificationTime($mtime);

            $this->_skip_next_write = true;
            $this->save();
        }
    }

    /**
     * For all saves, write the template file. Unless specifically told not to.
     *
     * Technically we could make this afterInsert and do more checks
     * in afterUpdate to make sure things actually changed, but this
     * lets us be fieldname agnostic and gives devs a little more control.
     */
    public function onAfterSave()
    {
        if ($this->_skip_next_write === true) {
            $this->_skip_next_write = false;

            return;
        }

        $this->writeToFile();
    }

    /**
     * If the template is updated, we need to make sure things like
     * renames or changes in template group are reflected in the
     * filesystem. We do this by simply deleting the old file, since
     * our afterSave event will always write a new one.
     *
     * @param Array Old values that were changed by this save
     */
    public function onAfterUpdate($previous)
    {
        $path = $this->getFilePath();
        $old_path = $this->getPreviousFilePath($previous);

        if ($path != $old_path && $old_path && ee('Filesystem')->exists($old_path)) {
            ee('Filesystem')->delete($old_path);
        }
    }

    /**
     * If the template is deleted, remove the template file
     */
    public function onAfterDelete()
    {
        $path = $this->getFilePath();

        if (isset($path) && ee('Filesystem')->exists($path)) {
            ee('Filesystem')->delete($path);
        }
    }

    /**
     * Helper to write the template to the file
     */
    protected function writeToFile()
    {
        $path = $this->getFilePath();

        if (isset($path) && ee('Filesystem')->exists(ee('Filesystem')->dirname($path))) {
            ee('Filesystem')->write($path, $this->serializeFileData(), true);
        }
    }
}

// EOF
