<?php 
function reda_formats_button($buttons) {
	array_unshift($buttons, 'styleselect');

	return $buttons;
}

add_filter('mce_buttons', 'reda_formats_button');

function reda_mce_before_init_insert_formats($init_array) {

	$style_formats = array(  
		array(  
			'title' => 'Lead header',  
			'inline' => 'span',  
			'styles' => array('line-height' => '1.8em'),
		),
		array(  
			'title' => 'Lead paragraph',  
			'inline' => 'span',  
			'styles' => array('font-size' => '17px', 'line-height' => '2.1em'),
		),
		array(  
			'title' => 'Subheading',  
			'block' => 'p',  
			'classes' => 'reda-header-top',
			'styles' => array('margin-bottom' => '5px'),
		),
		array(  
			'title' => 'Font weight 100',  
			'inline' => 'span',  
			'styles' => array('font-weight' => '100'),
		),
		array(  
			'title' => 'Font weight 200',  
			'inline' => 'span',  
			'styles' => array('font-weight' => '200'),
		),
		array(  
			'title' => 'Font weight 300',  
			'inline' => 'span',  
			'styles' => array('font-weight' => '300'),
		),
		array(  
			'title' => 'Font weight 400',  
			'inline' => 'span',  
			'styles' => array('font-weight' => '400'),
		),
		array(  
			'title' => 'Font weight 500',  
			'inline' => 'span',  
			'styles' => array('font-weight' => '500'),
		),
		array(  
			'title' => 'Font weight 600',  
			'inline' => 'span',  
			'styles' => array('font-weight' => '600'),
		),
		array(  
			'title' => 'Font weight 700',  
			'inline' => 'span',
			'styles' => array('font-weight' => '700'),
		),
		array(  
			'title' => 'Font weight 800',  
			'inline' => 'span',
			'styles' => array('font-weight' => '800'),
		),
		array(  
			'title' => 'Font weight 900',  
			'inline' => 'span',  
			'styles' => array('font-weight' => '900'),
		),
	);
	$init_array['style_formats'] = json_encode( $style_formats );  
	$sizes = '';
	for($size = 10; $size <= 160; $size+=2) {
		$sizes .= ' '.$size.'px';
	}
	$init_array['fontsizeselect'] = true;
	$init_array['fontsize_formats'] = $sizes;
	return $init_array;
}

add_filter('tiny_mce_before_init', 'reda_mce_before_init_insert_formats');

function customize_acf_wysiwyg_toolbar( $toolbars ) {
  if (($key = array_search('fontsizeselect' , $toolbars['Full'][2])) !== true) {
    array_push($toolbars['Full'][2], 'fontsizeselect');
  }

  return $toolbars;
}

if ( ! function_exists( 'wpex_mce_buttons' ) ) {
	function wpex_mce_buttons( $buttons ) {
		array_push( $buttons, 'fontsizeselect' );
		return $buttons;
	}
}
add_filter( 'mce_buttons_2', 'wpex_mce_buttons' );