<?php

class MC4WP_Update_Optin
{

    /**
     * @const string
     */
    const CAPABILITY = 'install_plugins';

    /**
     * @var string
     */
    protected $plugin_file = '';

    /**
     * @var string
     */
    protected $to_version;

    /**
     * @var string
     */
    protected $view_file;

    /**
     * @var string
     */
    protected $option_enable;

    /**
     * @var string
     */
    protected $option_notice;

    /**
     * @var bool
     */
    protected $active = false;

    /**
     * @param string $to_version
     * @param string $plugin_file
     * @param string $view_file
     */
    public function __construct($to_version, $plugin_file, $view_file)
    {
        $this->to_version = $to_version;
        $this->plugin_file = $plugin_file;
        $this->view_file = $view_file;

        $this->option_enable = 'mc4wp_enable_' . sanitize_key($this->to_version);
        $this->option_notice = 'mc4wp_notice_' . sanitize_key($this->to_version);
    }

    /**
     * Add hooks
     */
    public function add_hooks()
    {
        add_filter('pre_set_site_transient_update_plugins', array( $this, 'maybe_hide_update' ));
        add_action('init', array( $this, 'listen' ));

        global $pagenow;
        $on_settings_page = isset($_GET['page']) && stristr($_GET['page'], dirname($this->plugin_file)) !== false;
        if ($pagenow === 'plugins.php' || $pagenow === 'update-core.php' || $on_settings_page) {
            add_action('admin_notices', array( $this, 'show_update_optin' ));
        }
    }
    /**
     * Listen for actions
     */
    public function listen()
    {

        // only show to users with required capability
        if (! current_user_can(self::CAPABILITY)) {
            return;
        }

        if (isset($_GET[ $this->option_enable ])) {
            $this->enable_major_updates();
        }
    }
    /**
     * Prevents updates from showing
     *
     * @param array $data
     * @return array
     */
    public function maybe_hide_update($data)
    {
        if (empty($data->response)) {
            return $data;
        }

        // do nothing if the specified version is not out there yet..
        if (empty($data->response[ $this->plugin_file ]->new_version)
            || version_compare($data->response[ $this->plugin_file ]->new_version, $this->to_version, '<')) {

            // reset flags here in case we revert the update
            if (! $this->active) {
                delete_option($this->option_notice);
                delete_option($this->option_enable);
            }

            return $data;
        }

        // return unmodified data if already opted-in
        $opted_in = get_option($this->option_enable, false);
        if ($opted_in) {
            return $data;
        }

        // set a flag to start showing "update to x.x" notice
        update_option($this->option_notice, 1);

        // unset update data
        unset($data->response[ $this->plugin_file ]);

        // set flag because this filter runs multiple times..
        $this->active = true;

        return $data;
    }

    /**
     * Enables major updates (opts-in to 3.x update)
     */
    public function enable_major_updates()
    {

        // update option
        update_option($this->option_enable, 1);

        // delete site transient so wp core will fetch latest version
        delete_site_transient('update_plugins');

        // redirect to updates page
        wp_safe_redirect(admin_url('update-core.php'));
        exit;
    }

    /**
     * Shows update opt-in
     */
    public function show_update_optin()
    {
        if (! $this->should_show_update_optin()) {
            return;
        }

        // prepare link URL
        $update_link = add_query_arg(array( $this->option_enable => 1 ));

        // show!
        include $this->view_file;
    }

    /**
     * @return bool
     */
    public function should_show_update_optin()
    {

        // don't show if flag is not set
        if (! get_option($this->option_notice, false)) {
            return false;
        }

        // stop showing if opted-in already
        if (get_option($this->option_enable, false)) {
            return false;
        }

        // only show to users with required capability
        if (! current_user_can(self::CAPABILITY)) {
            return false;
        }

        return true;
    }
}
