WordPress Plugins Dependency Manger

deps-manager.class

<?php

require_once ABSPATH . '/wp-admin/includes/file.php';
require_once ABSPATH . '/wp-admin/includes/plugin.php';
require_once ABSPATH . '/wp-admin/includes/plugin-install.php';
require_once ABSPATH . '/wp-admin/includes/class-wp-upgrader.php';

/**
 * Main Deps Manager Class
 */
class DepManager {
    /**
     * Plugins we depend on
     */
    static $deps = array();
    
    /**
     * Static constructor
     */
    function init() {
        if ( self::check_fs() )
            self::check_packages();
        else
            set_transient( 'depman_fs_error', true );
        add_action( 'admin_notices', array( __CLASS__, 'notifications' ) );
    }
    
    function check_fs() {
        $method = get_filesystem_method( false, false );
        $creds = array_filter( get_option( 'ftp_credentials', array() ) );
        
        if ( !$method || $method != 'direct' )
            return false;
        
        return true;
    }
    
    /**
     * Bring some notifications if any errors occur
     */
    function notifications() {
        $errors = get_transient( 'depman_deps_errors' );
        if ( get_transient( 'depman_fs_error' ) ) {
            $errors[] = __( 'Current settings do not allow automatic installation of plugins.', 'depman' );
            $errors[] = __( 'Please visit theme options page for further instructions.', 'depman' );
        }
        
        if ( !current_user_can( 'update_plugins' ) )
            $errors[] = __( 'Current theme requires some plugins installed, please ask an administrator to log in.', 'depman' );
        
        if ( !empty( $errors ) )
            echo '<div class="error">' . self::walk_errors( $errors ) . '</div>';
        
        delete_transient( 'depman_deps_errors' );
        delete_transient( 'depman_fs_error' );
    }
    
    /**
     * Walk through error messages
     *
     * @param $messages, Mixed array of messages
     */
    function walk_errors( $messages ) {
        $ps = '';
        foreach ( $messages as $m ) {
            $ps .= "<p>{$m}</p>";
        }
        return $ps;
    }
    
    /**
     * check_packages()
     * Checks available installed packages for active dependencies
     * On failure fires __CLASS__::install_dep( $dep )
     */
    function check_packages() {
        if ( !current_user_can( 'update_plugins' ) )
            return;
        
        $available = get_plugins();
        
        foreach( self::$deps as $dep ) {
            $dep_data = plugins_api( 'plugin_information',
                array(
                    'slug' => $dep,
                    'fields' => array( 'sections' => false )
                )
            );
            
            if ( !is_wp_error( $dep_data ) )
                foreach ( $available as $av_dep ) {
                    if ( $av_dep['Name'] == $dep_data->name )
                        $dep_data->dep_installed = true;
                }
            
            if ( !isset( $dep_data->dep_installed ) || !$dep_data->dep_installed ) {
                $result = self::install_dep( $dep_data );
                if ( $result != true ) {
                    set_transient( 'depman_deps_errors', $result );
                    update_option( 'depman_deps_welcomed', false );
                    break;
                }
            }
            // Plugins installed
            update_option( 'depman_deps_welcomed', true );
        }
    }
    
    /**
     * load_deps_info()
     * Load all the dependencies details from WordPress.org API
     *
     * @return Mixed, deps data
     */
    function load_deps_info() {
        $plugins = array();
        foreach( self::$deps as $dep ) {
            $dep_data = plugins_api( 'plugin_information',
                array(
                    'slug' => $dep,
                    'fields' => array(
                        'sections' => false,
                        'description' => true
                    )
                )
            );
            
            if ( !is_wp_error( $dep_data ) )
                $plugins[] = $dep_data;
        }
        return $plugins;
    }
    
    /**
     * install_dep( $dep )
     * Installs a dependency
     *
     * @param Mixed, $dep, the dependency information object
     * @return Bool, true on success, Mixed an array of error informations on failure
     */
    function install_dep( $dep = null ) {
        $errors = array();
        $plugin = false;
        
        if ( !$dep )
            return true;
        
        $result = install_plugin_install_status( $dep );
        
        if ( isset( $result['status'] ) && $result['status'] == 'install' ) {
            $installer = new Plugin_Upgrader(
                new DepManagerSkin (
                    array (
                        'plugin' => $dep->slug,
                        'api' => $dep
                    )
                )
            );
            
            $installer->install( $dep->download_link );
            $plugin = $installer->plugin_info();
            
            if ( !empty( $installer->error ) )
                $errors[] = $installer->error;
        }
        
        if ( empty( $errors ) ) {
            // To flush installed plugins cache
            wp_cache_flush();
            $errors[] = activate_plugin( $plugin );
            return true;
        }
        
        return array_filter( $errors );
    }
}

/**
 * Helpers/Wrappers
 */
class DepManagerSkin extends Plugin_Installer_Skin {
    function header() {}
    function error( $errors ) {}
    function feedback( $string ) {}
    function before() {}
    function after() {}
}

?>

functions.php

<?php
/**
 * Example usage of dependency manager
 * Link to /?install_deps to fire the dep-manager
 */
function load_depman() {
    // Check if deps were installed
    $deps_welcomed = get_option( 'depman_deps_welcomed', false );
    if ( !$deps_welcomed && isset( $_GET['install_deps'] ) ) {
        // Try to install the deps
        require_once dirname( __FILE__ ) . '/deps-manager.class.php';
        // Set deps
        DepManager::$deps = array(
            'sharedaddy',
            'post-types-calendar'
        );
        DepManager::init();
    }
}
add_action( 'admin_init', 'load_depman' );