// ==UserScript==
// @name        RuTracker - magnet links in search pages
// @namespace   RuTracker-Micdu70
// @version     2019.4.19.2
// @description Adds magnet links in RuTracker search pages
// @author      Micdu70
// @license     MIT
// @include     /^(https?:)?\/\/rutracker\.org\/forum\/search_cse\.php.*$/
// @grant       none
// @downloadURL none
// ==/UserScript==

function INIT(){

    window.setTimeout(function(){ // wait for the results to display

        var element = 'gsc-results gsc-webResult';
        var results = document.getElementsByClassName(element)[0];

        if (results) {
            var magnetClass = document.getElementsByClassName('xhrMagnetLink')[0];
            if (!magnetClass) {
                addMagnet();
                var xhrMagnetLinks = document.querySelectorAll('.xhrMagnetLink');
                addMouseoverListeners(xhrMagnetLinks, 'ml' );
            }
        } else {
            INIT();
        }

    }, 500);

}

function addMagnet(){

    var noResults = document.getElementsByClassName('gs-webResult gs-result gs-no-results-result') [0]; // check if there are results or not

    if (noResults) {
        return;
    }

    var result = document.getElementsByClassName('gs-webResult gs-result');

    for (let i=0; i < result.length-1; i++) {

        let title = result[i].getElementsByTagName('div') [0];
        let _href = result[i].getElementsByTagName('div') [2];
        let href = _href.getElementsByTagName('div') [1].textContent;
        if (href.substring(0, 8) != 'https://') {
            href = 'https://'+href;
        }

        title.innerHTML += '<a class="xhrMagnetLink" data-href="' + href + '" href="#DL-ML"><img src="https://cdn0.iconfinder.com/data/icons/48_px_web_icons/48/Magnet.png""></>';
        title.lastChild.title = 'ML via XHR';

    }

    addMagnetOnPageChange();

}

function addMagnetOnPageChange(){

    var optionClass = document.getElementsByClassName('gsc-option');
    var pageClass = document.getElementsByClassName('gsc-cursor-page');

    for (let i=0; i < optionClass.length; i++) {

        optionClass[i].addEventListener('click', function optionClick(){

            INIT();

        }, false);

    }

    for (let j=0; j < pageClass.length; j++) {

        if (pageClass[j].className !== 'gsc-cursor-page gsc-cursor-current-page') {

            pageClass[j].addEventListener('click', function pageClick(){

                INIT();

            }, false);

        }

    }

}

function addMouseoverListeners(links, type){

    for(let i=0; i < links.length; i++) {

        links[i].addEventListener('mouseover', function(event){

            event.preventDefault();
            let href = this.getAttribute('href');
            if (href === '#DL-ML') {
                let tLink = this.getAttribute('data-href');

                var xhr = new XMLHttpRequest();
                xhr.open('GET', tLink, false);	// XMLHttpRequest.open(method, url, async)
                xhr.onload = function () {

                    let container = document.implementation.createHTMLDocument().documentElement;
                    container.innerHTML = xhr.responseText;

                    let retrievedLink;

                    retrievedLink = container.querySelector('.magnet-link');		// the 'magnet link' element in the retrieved page

                    if (retrievedLink) {
                        links[i].setAttribute('href', retrievedLink.href);
                    }

                };
                xhr.send();

            }

        }, false);

    }

}

INIT();