// ==UserScript==
// @name         imgur scroll to gallery images keyboard shortcuts
// @namespace    http://porath.org/
// @version      0.12
// @description  use ./, to scroll to the next/previous image within an imgur gallery
// @author       porath
// @match        http://imgur.com/*
// @grant        none
// @downloadURL none
// ==/UserScript==

// thanks to moiph and CBenni and Brybry

var current = 0;
var elems = $('div.image');
var numElems = elems.length;

$(document).on('keydown', function (key) {
    if (key.which == 40) {
        key.preventDefault();
        
        if (current + 1 == numElems) {
            if ($('div#album-truncated')) {
                $('div#album-truncated > a').click();
                
                elems = $('div.image');
                numElems = elems.length;
            }
            
            return;
        }
        
        elems[current + 1].scrollIntoView();
        $('body').scrollTop($('body').scrollTop() - 28);
        current = current + 1;
    }
    
    if (key.which == 38) {
        key.preventDefault();
        
        if (current == 0) {
            return;
        }
        
        elems[current - 1].scrollIntoView();
        $('body').scrollTop($('body').scrollTop() - 28);
        current = current - 1;
    }
    
    if (key.which == 36) { // "home" puts you at the top of the gallery
        current = 0;
    }
    
    if (key.which == 35) { // "end" puts you at the bottom of the gallery
        current = numElems;
    }
    
    if (key.which == 37 || key.which == 39) { // when a user presses left or right to go to the prev/next page
        current = 0;
        elems = $('div.image');
        numElems = elems.length;
    }
});