core/app/Models/ContentHistory.php

<?php

namespace App\Models;

use App\Handlers\Contracts\AppHandler;
use App\Handlers\Contracts\HistoryHandler;
use App\Handlers\Handler;
use App\Helpers\Differ;
use Illuminate\Database\Eloquent\Model;

/**
 * Class ContentHistory
 */
class ContentHistory extends Model
{
    protected $table = 'content_history';
    // this table does not have created_at and updated_at fields
    public $timestamps = false;
    protected $fillable = [
        'user_id',
        'content_id',
        'edit_batch',
        'column',
        'new_value',
        'old_value'
    ];
    protected $guarded = [];

    /**
     * Returns history grouped by revisions (edit_batches)
     *
     * @param Content $content
     *
     * @return array
     */
    public function getStructuredHistoryOf(Content $content)
    {
        $data = $content->history()
                        ->select('content_history.*', 'contents.module_handler', 'users.email AS user_email', 'users.name AS user_name')
                        ->join('users', 'users.id', '=', 'content_history.user_id')
                        ->join('contents', 'contents.id', '=', 'content_history.content_id')
                        ->orderBy('changed_at', 'DESC')
                        ->get();

        $info = [];
        $history = [];
        foreach ($data as $change) {
            $info[$change->edit_batch] = [
                'changed_at' => $change->changed_at,
                'user'       => [
                    'id'    => $change->user_id,
                    'name'  => $change->user_name,
                    'email' => $change->user_email
                ]
            ];

            $change = $this->handleChangeset($change);

            $history[$change->edit_batch][] = $change;
        }

        return [
            'changesets' => $history,
            'info'       => $info
        ];
    }

    /**
     * @param $change
     *
     * @return HistoryHandler
     */
    protected function getHistoryHandler($change)
    {
        /**
         * @var $handler        AppHandler
         * @var $historyHandler HistoryHandler
         */

        // get handler of given content page
        if ($change->column == 'module_settings') {
            $handler = $handler = $change->module_handler;
        } else {
            $handler = Handler::class;
        }

        return $handler::getHistoryHandler();
    }

    public function handleChangeset($change)
    {
        $historyHandler = $this->getHistoryHandler($change);

        $change->column_trans = $historyHandler::parseColumnName($change->column);
        $change->diff = $historyHandler::parseChangedValue($change);

        return $change;
    }

    public function getDiff($change)
    {
        return Differ::htmlDiff($change->old_value, $change->new_value);
    }
}