Integration of Wordpress Polylang and the Customizer

customizer.php

add_action( 'customize_register' , 'my_options' );

function home_page_options( $wp_customize ) {

	// get current lang
	$language = (empty($_REQUEST['lang'])) ? 'en_' : $_REQUEST['lang'] . '_';

	$wp_customize->add_setting( $language . 'my_field',
    	array(
      		'default' => ''
    	)
  	);

  	$wp_customize->add_control( $language . 'my_field',
    	array(
      		'label'    => __( 'Title', 'mytheme' ),
      		'settings' => $language . 'my_field',
      		'type' => 'text'
    	)
  	);

  	$wp_customize->get_setting( $language . 'my_field' )->transport = 'postMessage';

}

/*
$language = (function_exists('pll_current_language')) ? pll_current_language() . '_' : 'en_';
get_theme_mod( $language . 'my_field', '' );
*/

polylang-customizer.js

/**
 * Code from https://github.com/xwp/wp-customizer-blank-slate
 *
 * Learn more at: https://make.xwp.co/2016/09/11/resetting-the-customizer-to-a-blank-slate/
 * Copyright (c) 2016 XWP (https://make.xwp.co/)
 */
/* global wp, jQuery */
/* exported PluginCustomizer */
var PSPolyLang = (function( api, $ ) {
	'use strict';

	var component = {
		data: {
			url: null
		}
	};

	/**
	 * Initialize functionality.
	 *
	 * @param {object} args Args.
	 * @param {string} args.url  Preview URL.
	 * @returns {void}
	 */
	component.init = function init( home ) {
		_.extend( component.data, home );
		if ( ! home || ! home.url  ) {
			throw new Error( 'Missing args' );
		}

		api.bind( 'ready', function(){
			// console.log( home.url );
			api.previewer.previewUrl.set( home.url );
		});
	};
	return component;
} ( wp.customize, jQuery ) );

(function( api, $ ) {

	function updateQueryStringParameter(uri, key, value) {
	  	var re = new RegExp("([?&])" + key + "=.*?(&|$)", "i");
	  	var separator = uri.indexOf('?') !== -1 ? "&" : "?";
	  	if (uri.match(re)) {
	    	return uri.replace(re, '$1' + key + "=" + value + '$2');
	  	} else {
	    	return uri + separator + key + "=" + value;
	  	}
	}

	api.bind( 'ready', function(){

		var pll = pll_object;
		var languages = pll['languages'];
		var current_language = pll['current_language'];
		var current_language_name = '';

		var html = '<li class="accordion-section control-section control-section-themes">';
		html += '<h3 class="accordion-section-title"><span class="customize-action">Active language</span>Select language';
		html += '<select id="pll-language-select" style="position: absolute; right: 10px; top: 50%; margin-top: -14px;">';
		for (var i = 0; i < languages.length; i++) {
			var language = languages[i];
			var selected = (language.slug === current_language) ? 'selected=""' : '';
			current_language_name = (language.slug === current_language) ? language.name : 'English';
			html += '<option ' + selected + ' value="' + language.slug + '">' + language.name + '</option>';
		}
		html += '</select>';
		html += '</h3>';
		html += '</li>';

		$('<span style="float: right;">Language: ' + current_language_name + '</span>').insertAfter('#customize-header-actions .spinner');

		$(html).insertAfter('#accordion-section-themes');

		$('body').on('change', '#pll-language-select', function() {
			var language = $(this).val();
			window.location.href = updateQueryStringParameter(window.location.href, 'lang', language);
		});

	});

} ( wp.customize, jQuery ) );

polylang-customizer.php

add_action( 'customize_controls_enqueue_scripts', 'add_lang_to_customizer_previewer' );
/**
 * If Polylang activated, set the preview url
 *
 * @author soderlind
 * @version 1.0.0
 */
function add_lang_to_customizer_previewer() {
	if ( function_exists( 'pll_current_language' ) ) {
		$src = get_stylesheet_directory_uri() . '/js/polylang-customizer.js';
		$deps = array( 'customize-controls' );
		$version = rand();
		$in_footer = 1;
		// get current lang
		$language = (empty($_REQUEST['lang'])) ? 'en' : $_REQUEST['lang'];
		wp_enqueue_script( 'dss-add-lang-to-template', $src, $deps, $version , $in_footer );
		wp_localize_script( 'dss-add-lang-to-template', 'pll_object', array( 'languages' => get_option('_transient_pll_languages_list'), 'current_language' => $language ) );
		$lang = pll_current_language();
		if ( empty( $lang ) ) {
			$lang = pll_default_language();
		}
		$url = add_query_arg( 'lang', $lang, pll_home_url( $lang ) );
		add_lang_to_template( $url);
	}
}
/**
 * Set the previewer url
 *
 * @author soderlind
 * @version 1.0.0
 */
function add_lang_to_template( $url ) {
	wp_add_inline_script(
		'dss-add-lang-to-template',
		sprintf( 'PSPolyLang.init( %s );', wp_json_encode( array( 'url' => $url ) ) ),
		'after'
	);
}

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