install_plugin_install_status( array|object $api, bool $loop = false )

function install_plugin_install_status($api, $loop = false) {
	// This function is called recursively, $loop prevents further loops.
	if ( is_array($api) )
		$api = (object) $api;

	// Default to a "new" plugin
	$status = 'install';
	$url = false;
	$update_file = false;
	$version     = '';

	/*
	 * Check to see if this plugin is known to be installed,
	 * and has an update awaiting it.
	 */
	$update_plugins = get_site_transient('update_plugins');
	if ( isset( $update_plugins->response ) ) {
		foreach ( (array)$update_plugins->response as $file => $plugin ) {
			if ( $plugin->slug === $api->slug ) {
				$status = 'update_available';
				$update_file = $file;
				$version = $plugin->new_version;
				if ( current_user_can('update_plugins') )
					$url = wp_nonce_url(self_admin_url('update.php?action=upgrade-plugin&plugin=' . $update_file), 'upgrade-plugin_' . $update_file);
				break;
			}
		}
	}

	if ( 'install' == $status ) {
		if ( is_dir( WP_PLUGIN_DIR . '/' . $api->slug ) ) {
			$installed_plugin = get_plugins('/' . $api->slug);
			if ( empty($installed_plugin) ) {
				if ( current_user_can('install_plugins') )
					$url = wp_nonce_url(self_admin_url('update.php?action=install-plugin&plugin=' . $api->slug), 'install-plugin_' . $api->slug);
			} else {
				$key = array_keys( $installed_plugin );
				$key = reset( $key ); //Use the first plugin regardless of the name, Could have issues for multiple-plugins in one directory if they share different version numbers
				$update_file = $api->slug . '/' . $key;
				if ( version_compare($api->version, $installed_plugin[ $key ]['Version'], '=') ){
					$status = 'latest_installed';
				} elseif ( version_compare($api->version, $installed_plugin[ $key ]['Version'], '<') ) {
					$status = 'newer_installed';
					$version = $installed_plugin[ $key ]['Version'];
				} else {
					//If the above update check failed, Then that probably means that the update checker has out-of-date information, force a refresh
					if ( ! $loop ) {
						delete_site_transient('update_plugins');
						wp_update_plugins();
						return install_plugin_install_status($api, true);
					}
				}
			}
		} else {
			// "install" & no directory with that slug
			if ( current_user_can('install_plugins') )
				$url = wp_nonce_url(self_admin_url('update.php?action=install-plugin&plugin=' . $api->slug), 'install-plugin_' . $api->slug);
		}
	}
	if ( isset($_GET['from']) )
		$url .= '&amp;from=' . urlencode( wp_unslash( $_GET['from'] ) );

	$file = $update_file;
	return compact( 'status', 'url', 'version', 'file' );
}