// ==UserScript==
// @name         Last.fm Extra
// @namespace    https://malachisoord.com/
// @version      0.1.3
// @description  Provide missing extra functionality to Last.fm
// @author       Malachi Soord
// @match        http://www.last.fm/*
// @require      https://code.jquery.com/jquery-2.2.0.min.js
// @run-at       document-idle
// ==/UserScript==

'use strict';


$(document).on('ready', function() {    

    var url = window.location.href;

    console.log('xx: ' + url);
    
    if (!url.match(/^http:\/\/www\.last.fm\/([a-z]{2}\/)?music\/[^\/]+$/)) {
        return;
    }

    console.log('xx: running');


    var users = getUsers();

    var libraryUrl = 'http://www.last.fm/user/{user}/library/music/{artist}';

    var artist = url.substring(url.lastIndexOf('/') + 1);

    libraryUrl = libraryUrl.replace('{artist}', artist);

    var template = '<div id="listening" class="kerve widget widget_listeningnow"><div class="nowwrap noselect"></div></div>';

    $(template).insertAfter('#mobile_pos_4');
    
    var found = false;

    $.each(users, function(index, user) {
        var requestUrl = libraryUrl.replace('{user}', user);
        $.ajax(requestUrl, {
            success: function(data) {
                var $data = $(data);
                var scrobbles = $data.find('#mantle_skin > div.container.page-content > div > div.col-main > ul > li:nth-child(1) > p').html() || 0;
                if (scrobbles !== 0) {
                    found = true;
                    var pictureUrl = $data.find('div.header-avatar > div > a > img').prop('src');
                    var userTemplate = $('<div style="padding-bottom:5px;"><a href="' + requestUrl + '"><img src="' + pictureUrl + '" class="avatar" style="width:40px;margin-right:10px;" title ="' + user +'"/>' + scrobbles + ' scrobbles</a></div>');
                    $('#listening').append(userTemplate);
                } else if (index === (users.length-1) && !found) {
                     $('#listening').append('None of your friends listen to this artist :(');
                }
            }
        });
    });


   
    function getUsers() {
        var users = GM_getValue('users', []);
        if (users.length === 0) {
            var user = $('#mantle_skin > div.container.page-content > div > div.col-sidebar > div.kerve.widget.widget_trends').attr('data-user');
            var followingUrl = 'http://www.last.fm/user/{user}/following?page='.replace('{user}', user);
            loadUsers(followingUrl, users, 1);
            GM_setValue('users', users);
        }

        return users;
    }

    function loadUsers(followingUrl, users, page) {

        var response = $.ajax({
            type: 'GET',
            url: followingUrl + page++,
            async: false
        }).responseText;

        var $response = $(response);

        var $users = $(response).find('div.username > a');

        $.each($users, function() {
            users.push($.trim($(this).text()));
        });

        var $next = $response.find('li.next > a');
        if ($next.length === 1) {
            loadUsers(followingUrl, users, page);
        }
    }
});