// ==UserScript==
// @name         prime-switch
// @namespace    http://tampermonkey.net/
// @version      0.5
// @description  add quick filter for Prime included content
// @author       EifelDriver
// @match        https://www.amazon.de/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    // pv shortcut means "prime video"
    var _debug              = 0;
    var version             = '0.5';
    var version_file        = 'https://raw.githubusercontent.com/eifeldriver/prime-switch/master/version';
    var pv_timer            = null;
    var watcher             = null;
    var is_loading          = null;
    var selector_vidthumb   = '.DigitalVideoWebNodeStorefront_Card__CardWrapper';
    var selector_spinner    = '.DigitalVideoUI_Spinner__spinner';
    
    
    /**
     * debug function
     */
    function pv_debug(txt) {
        if (_debug) {
            var d = new Date();
            var now = [d.getHours(), d.getMinutes(), d.getSeconds(), d.getMilliseconds()].join(':');
            console.log(now + ': ' + txt);
        }
    }
    
    
    /**
     * insert custom CSS
     *
     */
    function insertCss() {
        var css     =   '' +
            '#pv-switch-wrapper { position: fixed; z-index: 999; top: 5px; left: 1px; } ' +
            '#pv-switch { background: #999; color: #333; } ' +
            '#pv-switch.active { background: green; color: white; } ' +
            '#prime-switch-update { position: absolute; top: 0; right:0; transform: translate(50%, -50%);  } ' +
            '#prime-switch-update span { ' +
            '  line-height: 20px; width: 75px; border-radius: 50%; padding: 0; ' +
            '  font-size: 0px; padding: 4px; border: 1px solid lightgreen; background: red; ' +
            '} ' +
            '.flashit {  color:#f2f; animation: flash linear 3s 3; } ' +
            '  @keyframes flash { 0% { opacity: 1; } 70% { opacity: .1; } 100% { opacity: 1; } }' +
            '.card-on  { display: inline-block; }' +
            '.card-off { display: none !important; } ' +
            '.cat-off { display: none !important; } ';
        var style   = document.createElement('STYLE');
        style.innerHTML = css;
        document.querySelector('head').appendChild(style);
    }
    
    /**
     * hide all thumbnails
     *
     */
    function disableAllPvThumbs() {
        var pv_thumbs = document.querySelectorAll(selector_vidthumb);
        if (pv_thumbs) {
            for(var idx=0; idx<pv_thumbs.length; idx++) {
                pv_thumbs[idx].className = pv_thumbs[idx].className.replace(' card-on', '') + ' card-off';
            }
        }
        enableAllCategories();
    }
    
    /**
     * show all thumbnails
     *
     */
    function enableAllPvThumbs() {
        var pv_thumbs = document.querySelectorAll(selector_vidthumb);
        if (pv_thumbs) {
            for(var idx=0; idx<pv_thumbs.length; idx++) {
                pv_thumbs[idx].className = pv_thumbs[idx].className.replace(' card-on', '').replace(' card-off', '') + ' card-on';
            }
        }
        enableAllCategories();
    }
    
    /**
     * enable only thumbnails on Prime included items
     *
     */
    function enableOnlyPvThumbs() {
        var pv_thumbs = document.querySelectorAll(selector_vidthumb + ' .DigitalVideoUI_Logo__primeSash, ' + selector_vidthumb + ' .DigitalVideoWebNodeStorefront_Card__primeBadge');
        if (pv_thumbs) {
            for (var idx=0; idx<pv_thumbs.length; idx++) {
                var vid = pv_thumbs[idx].closest(selector_vidthumb);
                vid.className = vid.className.replace(' card-off', ' card-on');
            }
        }
        hideEmptyCategories();
    }
    
    /**
     * disable all empty categories (means without any Prime included video)
     */
    function hideEmptyCategories() {
        var cats = document.querySelectorAll('.DigitalVideoWebNodeStorefront_Collection__Collection');
        for (var idx=0; idx<cats.length; idx++) {
            var cat = cats[idx];
            if (cat.querySelectorAll('.card-on').length == 0) {
                // no visible thumb found
                cat.className += ' cat-off';
            }
        }
    }
    
    /**
     * makes any category visible
     */
    function enableAllCategories() {
        var cats = document.querySelectorAll('.DigitalVideoWebNodeStorefront_Collection__Collection');
        for (var idx=0; idx<cats.length; idx++) {
            var cat = cats[idx];
            cat.className = cat.className.replace(' cat-off', '');
        }
    }
    
    /**
     * toggle filter on / off
     *
     */
    function togglePvOnly() {
        var btn = document.querySelector('#pv-switch');
        if (btn) {
            if (btn.className.indexOf(' active') >= 0) {
                // show all thumbs
                btn.className = btn.className.replace(' active', ''); //?
                enableAllPvThumbs();
                
            } else {
                // show only Prime Thumbs
                disableAllPvThumbs();
                enableOnlyPvThumbs();
                btn.className += ' active';
            }
        }
    }
    
    /**
     * check Github version with local version
     */
    function checkForUpdates() {
        var xhr = new XMLHttpRequest();
        xhr.open('GET', version_file);
        xhr.onload = function() {
            if (xhr.status == 200) {
                var repo_version = xhr.responseText;
                if (version.trim() != repo_version.trim()) {
                    // other version available
                    var info        = document.createElement('DIV');
                    info.id         = 'prime-switch-update';
                    info.className  = 'flashit';
                    info.innerHTML  = '<span title="Your version = ' + version + ' | New version = ' + repo_version + '">*</span>';
                    var btn = document.querySelector('#pv-switch');
                    btn.appendChild(info);
                }
            } else {
                return null;
            }
        };
        xhr.send();
    }
    
    /**
     * add filter button to top navigation
     *
     */
    function createPvButton() {
        var div         = document.createElement('DIV');
        div.id          = 'pv-switch-wrapper';
        div.innerHTML   = '<button id="pv-switch">Prime only</button>';
        document.querySelector('#navbar').appendChild(div);
        document.querySelector('#pv-switch').addEventListener('click', togglePvOnly);
    }
    
    /**
     * update filtered view
     *
     */
    function refreshPvFilter() {
        // update view after scrolling and dynamic loads
        disableAllPvThumbs();
        enableOnlyPvThumbs();
    }
    
    /**
     * simple check for dynamic reload is running
     */
    function isDynLoading() {
        // DOM element only exists on running reload
        return document.querySelectorAll(selector_spinner).length;
    }
    
    function watchDynReloading() {
        pv_debug('is_loading = ' + is_loading ? '1' : '0');
        if (isDynLoading()) {
            is_loading = 1;
            pv_debug('re-loading running');
    
        } else {
            if (is_loading) {
                // reload finished
                is_loading = 0;
                pv_debug('loading finished');
                refreshPvFilter();
                initWatcher();
            } else {
                pv_debug('still watching');
            }
        }
    }
    
    function initWatcher() {
        window.clearInterval(watcher);
        pv_debug('watcher cleared');
        watcher = window.setInterval(watchDynReloading, 1000);
        pv_debug('watcher installed');
    }
    
    /**
     * watch for new loaded items after scrolling
     *
     */
    function initDomObserver() {
        var div = document.querySelector('#Storefront .DigitalVideoWebNodeStorefront_FiltersNav__FiltersNav + div');
        if (div) {
            var observer = new MutationObserver(
                function(mutations) {
                    var btn = document.querySelector('#pv-switch');
                    if (btn.style.backgroundColor == 'green') {
                        mutations.forEach(
                            function(mutation) {
                                if (mutation.type == 'childList') {
                                    window.clearTimeout(pv_timer);
                                    pv_timer = window.setTimeout(refreshPvFilter, 1000);
                                }
                            }
                        );
                    }
                }
            );
            observer.observe(div,
                {
                  attributes: true,
                  characterData: true,
                  childList: true,
                  subtree: true,
                  attributeOldValue: true,
                  characterDataOldValue: true
                }
            );
        }
    }
    
    
    /**
     * init the script
     *
     */
    insertCss();
    createPvButton();
    // check for updates
    checkForUpdates();
    
    // ineable dyn. loading observer or watcher
    // initDomObserver();
    initWatcher();
    
    // start with filtered view
    togglePvOnly();
    
    console.log('Prime-switch started.');
})();