(abandoned) multiple json save points plugin.php

<?php

/**
 * Plugin Name: MJSP 2019-10-17 12:30 GMT by @Brugman
 * Description: Multiple JSON Save Points plugin, work in progress.
 *
 * Notes:
 * 2019-12-20
 * Use at own risk. I've integrated parts of this code in
 * https://github.com/Brugman/acf-agency-workflow and will be working
 * on that instead.
 */

new acf_custom_json_save_path_setting();

class acf_custom_json_save_path_setting {
    // This will store the preferred save path for the group for later retrieval.
    private $preferred_save_path;

    public function __construct() {
        // Add the "JSON Save Path" setting to all field groups.
        add_action('acf/render_field_group_settings', [$this, 'add_json_save_path_setting']);

        // Call an early bird (priority 1) action before saving the field group.
        add_action('acf/update_field_group', [$this, 'set_up_save_path'], 1, 1);
    }

    public function add_json_save_path_setting($field_group) {
        $load_dir_current = false;
        $choices = [];

        $load_dirs = acf_get_setting('load_json');

        $path_to_plugins = dirname( dirname( __FILE__ ) );
        $path_to_themes = dirname( get_stylesheet_directory() );

        foreach ( $load_dirs as $load_dir )
        {
            $display_title = $load_dir;
            if ( strpos( $load_dir, $path_to_plugins ) !== false )
                $display_title = 'Plugin: '.substr( str_replace( $path_to_plugins, '', $load_dir ), 1 );
            if ( strpos( $load_dir, $path_to_themes ) !== false )
                $display_title = 'Theme: '.substr( str_replace( $path_to_themes, '', $load_dir ), 1 );
            $choices[ $load_dir ] = $display_title;

            if ( file_exists( $load_dir.'/'.$field_group['key'].'.json' ) )
                $load_dir_current = $load_dir;
        }

        $load_dir_selected = false;

        if ( isset( $load_dirs[0] ) )
            $load_dir_selected = $load_dirs[0];

        if ( $load_dir_current )
            $load_dir_selected = $load_dir_current;

        if ( !$load_dir_selected )
            return;

        acf_render_field_wrap([
            'label'        => 'JSON Save Path',
            'instructions' => 'Determines where the field group\'s JSON file will be saved.',
            'type'         => 'select',
            'name'         => 'json_save_path',
            'prefix'       => 'acf_field_group',
            'value'        => $load_dir_selected,
            'choices'      => $choices,
        ]);
    }

    public function set_up_save_path($group) {
        // Get the preferred save path, if set.
        $preferred_save_path = $group['json_save_path'] ?? null;

        // If not set (or set to an empty string), do nothing.
        if (!$preferred_save_path) {
            return $group;
        }

        // Set aside the preferred path and add an override action.
        $this->preferred_save_path = $preferred_save_path;
        add_action('acf/settings/save_json', [$this, 'save_to_preferred_save_path'], 9999);

        // Return the group for updating as usual.
        return $group;
    }

    public function save_to_preferred_save_path($path) {
        // Ensure this field group is saved to the preferred save path.
        $path = $this->preferred_save_path;

        return $path;
    }
}