<?php

namespace TotalTheme\Updates;

defined( 'ABSPATH' ) || exit;

/**
 * Displays plugin update notifications for some bundled theme plugins to make it easier for the end user.
 */
final class Plugin_Updater {

	/**
	 * Instance.
	 */
	private static $instance = null;

	/**
	 * Create or retrieve the instance of Plugin_Updater.
	 */
	public static function instance() {
		if ( null === static::$instance ) {
			static::$instance = new self();
		}
		return static::$instance;
	}

	/**
	 * Private constructor.
	 */
	private function __construct() {
		if ( ! $this->is_enabled() ) {
			return;
		}

		// For testing purposes only !!!
		// delete_site_transient( 'update_plugins' );

		add_filter( 'pre_set_site_transient_update_plugins', [ $this, 'check_for_updates' ], 99 );
	}

	/**
	 * Checks if auto updates are enabled.
	 */
	public function is_enabled() {
		$check = apply_filters( 'wpex_has_bundled_plugin_update_notices', true ); // @deprecated
		return (bool) apply_filters( 'totaltheme/updates/plugin_updater/is_enabled', $check );
	}

	/**
	 * Returns list of plugins to check
	 */
	public function get_plugins_to_check(): array {
		$recommended_plugins = totaltheme_call_static( 'Admin\Recommended_Plugins', 'get_list' );
		if ( empty( $recommended_plugins ) || ! is_array( $recommended_plugins ) ) {
			return [];
		}
		$list = [];
		foreach ( $recommended_plugins as $k => $plugin ) {
			if ( ! isset( $plugin['auto_updates'] ) || ! (bool) $plugin['auto_updates'] ) {
				continue;
			}
			if ( empty( $plugin['package' ] ) && isset( $plugin['source' ] ) ) {
				$plugin['package'] = $plugin['source' ];
				unset( $plugin['source' ] );
			}
			if ( ! empty( $plugin['package'] ) ) {
				$plugin['id' ]    = $this->get_plugin_base( $plugin );
				$plugin['plugin'] = $plugin['id'];
				$list[ $k ]       = $plugin;
			}
		}
		return $list;
	}

	/**
	 * Check transients
	 */
	public function check_for_updates( $transient ) {
		if ( empty( $transient->checked ) ) {
			return $transient;
		}

		$plugins_to_check = $this->get_plugins_to_check();

		if ( empty( $plugins_to_check ) ) {
			return $transient;
		}

		$installed_plugins = $this->get_installed_plugins();

		if ( empty( $installed_plugins ) || ! is_array( $installed_plugins ) ) {
			return $transient;
		}

		foreach ( $plugins_to_check as $plugin ) {
			if ( ! $this->is_plugin_installed( $plugin, $installed_plugins ) ) {
				continue;
			}

			$has_update = $this->has_update( $plugin, $installed_plugins );

			if ( $has_update ) {
				$response = (object) [
					'id'            => $plugin['id'],
					'slug'          => $plugin['slug'],
					'plugin'        => $plugin['plugin'],
					'new_version'   => $plugin['version'],
					'package'       => $plugin['package'],
					'url'           => '',
					'icons'         => [],
					'banners'       => [],
					'banners_rtl'   => [],
					'tested'        => '',
					'requires_php'  => '',
					'compatibility' => '',

				];
				$transient->response[ $plugin['id' ] ] = $response;
			} elseif ( isset( $transient->no_update ) ) {
				$item = (object) [
					'id'            => $plugin['id'],
					'slug'          => $plugin['slug'],
					'plugin'        => $plugin['plugin'],
					'new_version'   => $plugin['version'],
					'package'       => '',
					'url'           => '',
					'icons'         => [],
					'banners'       => [],
					'banners_rtl'   => [],
					'tested'        => '',
					'requires_php'  => '',
					'compatibility' => '',
				];
				$transient->no_update[ $plugin['id' ] ] = $item;
			}

		}

		return $transient;
	}

	/**
	 * Get list of installed plugins.
	 */
	public function get_installed_plugins( $plugin_folder = '' ) {
		if ( ! function_exists( 'get_plugins' ) ) {
			require_once ABSPATH . 'wp-admin/includes/plugin.php';
		}
		return get_plugins( $plugin_folder );
	}

	/**
	 * Check if a specific plugin is installed.
	 */
	public function is_plugin_installed( $plugin, $installed_plugins ) {
		return array_key_exists( $this->get_plugin_base( $plugin ), $installed_plugins );
	}

	/**
	 * Check if a plugin has an update available
	 */
	private function has_update( $plugin, $installed_plugins ) {
		$base = $this->get_plugin_base( $plugin );
		if ( ! empty( $installed_plugins[ $base ]['Version'] ) ) {
			return version_compare( $plugin['version'], $installed_plugins[ $base ]['Version'], '>' );
		}
	}

	/**
	 * Returns plugin base from slug
	 */
	private function get_plugin_base( $plugin ) {
		return "{$plugin['slug']}/{$plugin['slug']}.php";
	}

	/**
	 * Prevent cloning.
	 */
	private function __clone() {}

	/**
	 * Prevent unserializing.
	 */
	public function __wakeup() {
		trigger_error( 'Cannot unserialize a Singleton.', E_USER_WARNING);
	}

}