Understanding File Paths

<?php
class File_demo extends Trongate {

    /**
     * Display the upload form
     */
    public function index() {
        $data['view_module'] = 'file_demo';
        $data['view_file'] = 'upload_form';
        $this->view('upload_form', $data);
    }

    /**
     * Process the file upload and store in database
     * 
     * Responsibility: Validate, upload file, store metadata, then redirect
     * Uses POST-Redirect-GET pattern to prevent duplicate submissions
     */
    public function submit_upload() {
        // Set validation rules
        $this->validation->set_rules(
            'userfile',
            'File',
            'required|allowed_types[pdf,txt,md]|max_size[5000]'
        );

        if ($this->validation->run() === true) {

            // Configure file upload options
            $config = [
                'destination' => 'uploads', 
                'upload_to_module' => true,
                'make_rand_name' => true
            ];
            
            // Upload file and get all metadata
            $file_info = $this->file->upload($config);
            
            // Store ALL data returned by upload() in database
            $data = [
                'file_name' => $file_info['file_name'],
                'file_path' => $file_info['file_path'],
                'file_type' => $file_info['file_type'],
                'file_size' => $file_info['file_size']
            ];
            
            $insert_id = $this->db->insert($data, 'documents');
            
            set_flashdata('File uploaded successfully!');
            
            // Redirect to display page with database ID
            redirect('file_demo/display/' . $insert_id);
        } else {
            // Validation failed - show form again with errors
            $this->index();
        }
    }

    /**
     * Display file metadata from database
     * 
     * Responsibility: Retrieve file info from database and display it
     */
    public function display() {
        // Fetch the record ID from the URL.
        $id = segment(3, 'int');

        // Get file metadata from database
        $doc = $this->db->get_where($id, 'documents');
        
        if ($doc === false) {
            // Record not found - send the user elsewhere.
            redirect('file_demo/file_not_found');
        }
        
        // Prepare data for view using database values
        $data = [
            'file_name' => $doc->file_name,
            'file_path' => $doc->file_path,
            'file_type' => $doc->file_type,
            'file_size' => $doc->file_size,
            'formatted_size' => $this->format_size($doc->file_size),
            'download_url' => $this->convert_to_url($doc->file_path)
        ];
        
        $data['view_module'] = 'file_demo';
        $data['view_file'] = 'display_file';
        $this->view('display_file', $data);
    }

    /**
     * Helper function to format file size (in controller, not view)
     */
    private function format_size($bytes) {
        $units = ['B', 'KB', 'MB', 'GB'];
        $bytes = max($bytes, 0);
        $pow = floor(($bytes ? log($bytes) : 0) / log(1024));
        $pow = min($pow, count($units) - 1);
        $bytes /= pow(1024, $pow);
        return round($bytes, 2) . ' ' . $units[$pow];
    }

    /**
     * Convert module file path to URL (in controller, not view)
     */
    private function convert_to_url($file_path) {
        if (strpos($file_path, '../modules/') === 0) {
            $path_parts = explode('/', $file_path);
            $module_name = $path_parts[2];
            return str_replace("../modules/{$module_name}/", "{$module_name}_module/", $file_path);
        }
        return $file_path;
    }

}

<h2>File Information</h2>

<p><strong>Stored Filename:</strong> <?= out($file_name) ?></p>
<p><strong>File Type:</strong> <?= out($file_type) ?></p>
<p><strong>Size:</strong> <?= out($formatted_size) ?></p>
<p><strong>Relative Path:</strong> <code><?= out($file_path) ?></code></p>
<p><strong>Download Link:</strong> <?= anchor($download_url, 'Download') ?></p>
<p><?= anchor('file_demo', 'Upload Another File') ?></p>