/**
 * When the CDN support option is enabled the IMG elements src attibutes are replaced with data attributes in the server
 * side. Then, in the client side, as soon as the DOM is ready, the IMG src attributes are restored with their original
 * values and an added url parameter with the resolution cookie. This is necessary in cases of CDNs and caching servers
 * because, without the url parameter, they would cache only one version of each requested image.
 */

document.addEventListener( 'DOMContentLoaded', function ( event ) {

    // Make sure there is a String trim function. 

    if ( ! String.prototype.trim ) {

        String.prototype.trim = function () {

            return this.replace( /^[\s\uFEFF\xA0]+|[\s\uFEFF\xA0]+$/g, '' );

        };

    }

    

    // When the DOM is ready.

    var cookies = document.cookie.split( ';' );

    for ( var k in cookies ) {

        // Get the plugin resolution cookie.

        var cookie = cookies[k].trim();

        if ( cookie.indexOf( 'resolution' ) === 0 ) {

            // Restore all images src attribute with the resolution cookie value.

            var imgs = document.querySelectorAll( 'img[data-adaptive-images-src]' );

            for ( var k = 0; k < imgs.length; k++ ) {

                var img = imgs[k];

                var data_src = img.getAttribute( 'data-adaptive-images-src' );
                var new_src  = data_src.indexOf( '?' ) >= 0 ? data_src + '&' + cookie : data_src + '?' + cookie;

                img.setAttribute( 'src', new_src );

            }



            // Do the same for the srcset attribute of images and pictures.

            var pictures = document.querySelectorAll( 'img[data-adaptive-images-srcset], picture source[data-adaptive-images-srcset]' );

            for ( var k = 0; k < pictures.length; k++ ) {

                var picture     = pictures[k];
                var data_srcset = picture.getAttribute( 'data-adaptive-images-srcset' );
                var srcsets =     data_srcset.split( ',' );

                var new_srcset = [];

                for ( var m = 0; m < srcsets.length; m++ ) {

                    var srcset = srcsets[m].trim().split( ' ' );

                    if ( srcset.length > 0 ) {
                        
                        new_srcset.push( srcset[0].indexOf( '?' ) >= 0 ? srcset[0] + '&' + cookie : srcset[0] + '?' + cookie + ' ' + (srcset.length > 1 ? srcset[1] : '') );

                    }

                }

                picture.setAttribute( 'srcset', new_srcset.join( ', ' ) );
                
            }

            break;

        }

    }

});