amp.php

<?php
/**
 * AMP functionality
 *
 * @package      EAStarter
 * @author       Bill Erickson
 * @since        1.0.0
 * @license      GPL-2.0+
**/

/**
 * Is AMP?
 * Conditional tag
 */
function ea_is_amp() {
	return function_exists( 'is_amp_endpoint' ) && is_amp_endpoint();
}

/**
 * Generate a class attribute and an AMP class attribute binding.
 *
 * @param string $default Default class value.
 * @param string $active  Value when the state enabled.
 * @param string $state   State variable to toggle based on.
 * @return string HTML attributes.
 */
function ea_amp_class( $default, $active, $state ) {
	$output = '';
	if( ea_is_amp() ) {
		$output .= sprintf(
			' [class]="%s"',
			esc_attr(
				sprintf(
					'%s ? \'%s\' : \'%s\'',
					$state,
					$default . ' ' . $active,
					$default
				)
			)
		);
	}
	$output .= sprintf( ' class="%s"', esc_attr( $default ) );
	return $output;
}

/**
 * Add the AMP toggle 'on' attribute.
 *
 * @param string $state State to toggle.
 * @param array $disable, list of states to disable
 * @return string The 'on' attribute.
 */
function ea_amp_toggle( $state = '', $disable = array() ) {
	if( ! ea_is_amp() )
		return;

	$settings = sprintf(
		'%1$s: ! %1$s',
		esc_js( $state )
	);

	if( !empty( $disable ) ) {
		foreach( $disable as $disableState ) {
			$settings .= sprintf(
				', %s: false',
				esc_js( $disableState )
			);
		}
	}

	return sprintf(
		' on="tap:AMP.setState({%s})"',
		$settings
	);

}

/**
 * AMP Nav Dropdown toggle and class attributes.
 *
 * @param string $theme_location Theme location.
 * @param int    $depth          Depth.
 * @return string The class and on attributes.
 */
function ea_amp_nav_dropdown( $theme_location = false, $depth = 0 ) {

	$key = 'nav';
	if( !empty( $theme_location ) )
		$key .= ucwords( $theme_location );

	global $submenu_index;
	$submenu_index++;
	$key .= 'SubmenuExpanded' . $submenu_index;

	if( 1 < $depth )
		$key .= 'Depth' . $depth;

	return ea_amp_toggle( $key ) . ea_amp_class( 'submenu-expand', 'expanded', $key );
}