// ==UserScript==
// @name           PlayLanguage
// @include        https://play.google.com/*
// @include        https://play.google.com/store/*
// @include        https://play.google.com/store/apps/*
// @include        http://play.google.com/*
// ==/UserScript==

window.addEventListener('load', function () {
    var newP = document.createElement('p'),
        url = window.location.href,
        regex = /([?&]hl=)\w*/,
        langInUrl = regex.test(url),
        paramInUrl = /\?\w+=/.test(url),
        position = document.querySelector('.document-title'),
        tmpA, langs, i;

    function handle_click(event) {
        event.preventDefault();
        event.stopPropagation();
        window.top.location.href = event.target.href;
    }

    // Make sure the page is not in a frame
    if (window.self !== window.top || !position) { return; }

    // define languages here
    langs = [
        {name : 'English', abbrev : 'en'},
        {name : 'German', abbrev : 'de'}
    ];

    for (i = 0; i < langs.length; i += 1) {
        tmpA = document.createElement('a');
        tmpA.href = langInUrl ? url.replace(regex, '$1' + langs[i].abbrev) : url + (paramInUrl ? '&' : '?') + 'hl=' + langs[i].abbrev;
        tmpA.appendChild( document.createTextNode( langs[i].name ) );
        tmpA.addEventListener('click', handle_click, false);
        newP.appendChild(tmpA);
        if ( (i + 1) < langs.length) {
            newP.appendChild( document.createTextNode(' | ') );
        }
    }

    newP.setAttribute('style', 'float: right; clear: right; font-size: 13px;');
    position.appendChild(newP);
}, false);