// drupal replayer. 
// by M.W.Park 2008-06-03
// 
// main features:
// 1. shows articles by time.
// 2. shows new article(s) quickly.
//
// key bindings:
//     n - next
//     p - prev
//     , - top
//     . - bottom
//     (if a key above pressed with shift, navigates NEW article(s) only).
//     k - tracker page
//
// some code refs:
// mozilla example (http://developer.mozilla.org/en/docs/Whitespace_in_the_DOM) for node manipulation.
// me2DAY Shortcut 0.5 (http://jeongsw.springnote.com/pages/1227312) - for keydown event handler.
//
// ==UserScript==
// @name          drupal-replayer
// @namespace     http://kldp.org/
// @description   replays drupal comments for readablity
// @include       http://kldp.org/node/*
// @exclude       
// ==/UserScript==

// some code import from the document http://developer.mozilla.org/en/docs/Whitespace_in_the_DOM
/**
 * Throughout, whitespace is defined as one of the characters
 *  "\t" TAB \u0009
 *  "\n" LF  \u000A
 *  "\r" CR  \u000D
 *  " "  SPC \u0020
 *
 * This does not use Javascript's "\s" because that includes non-breaking
 * spaces (and also some other characters).
 */


/**
 * Determine whether a node's text content is entirely whitespace.
 *
 * @param nod  A node implementing the |CharacterData| interface (i.e.,
 *             a |Text|, |Comment|, or |CDATASection| node
 * @return     True if all of the text content of |nod| is whitespace,
 *             otherwise false.
 */
function is_all_ws( nod )
{
  // Use ECMA-262 Edition 3 String and RegExp features
  return !(/[^\t\n\r ]/.test(nod.data));
}


/**
 * Determine if a node should be ignored by the iterator functions.
 *
 * @param nod  An object implementing the DOM1 |Node| interface.
 * @return     true if the node is:
 *                1) A |Text| node that is all whitespace
 *                2) A |Comment| node
 *             and otherwise false.
 */

function is_ignorable( nod )
{
  return ( nod.nodeType == 8) || // A comment node
         ( (nod.nodeType == 3) && is_all_ws(nod) ); // a text node, all ws
}

/**
 * Version of |previousSibling| that skips nodes that are entirely
 * whitespace or comments.  (Normally |previousSibling| is a property
 * of all DOM nodes that gives the sibling node, the node that is
 * a child of the same parent, that occurs immediately before the
 * reference node.)
 *
 * @param sib  The reference node.
 * @return     Either:
 *               1) The closest previous sibling to |sib| that is not
 *                  ignorable according to |is_ignorable|, or
 *               2) null if no such node exists.
 */
function node_before( sib )
{
  while ((sib = sib.previousSibling)) {
    if (!is_ignorable(sib)) return sib;
  }
  return null;
}

/**
 * Version of |nextSibling| that skips nodes that are entirely
 * whitespace or comments.
 *
 * @param sib  The reference node.
 * @return     Either:
 *               1) The closest next sibling to |sib| that is not
 *                  ignorable according to |is_ignorable|, or
 *               2) null if no such node exists.
 */
function node_after( sib )
{
  while ((sib = sib.nextSibling)) {
    if (!is_ignorable(sib)) return sib;
  }
  return null;
}

/**
 * Version of |lastChild| that skips nodes that are entirely
 * whitespace or comments.  (Normally |lastChild| is a property
 * of all DOM nodes that gives the last of the nodes contained
 * directly in the reference node.)
 *
 * @param sib  The reference node.
 * @return     Either:
 *               1) The last child of |sib| that is not
 *                  ignorable according to |is_ignorable|, or
 *               2) null if no such node exists.
 */
function last_child( par )
{
  var res=par.lastChild;
  while (res) {
    if (!is_ignorable(res)) return res;
    res = res.previousSibling;
  }
  return null;
}

/**
 * Version of |firstChild| that skips nodes that are entirely
 * whitespace and comments.
 *
 * @param sib  The reference node.
 * @return     Either:
 *               1) The first child of |sib| that is not
 *                  ignorable according to |is_ignorable|, or
 *               2) null if no such node exists.
 */
function first_child( par )
{
  var res=par.firstChild;
  while (res) {
    if (!is_ignorable(res)) return res;
    res = res.nextSibling;
  }
  return null;
}

/**
 * Version of |data| that doesn't include whitespace at the beginning
 * and end and normalizes all whitespace to a single space.  (Normally
 * |data| is a property of text nodes that gives the text of the node.)
 *
 * @param txt  The text node whose data should be returned
 * @return     A string giving the contents of the text node with
 *             whitespace collapsed.
 */
function data_of( txt )
{
  var data = txt.data;
  // Use ECMA-262 Edition 3 String and RegExp features
  data = data.replace(/[\t\n\r ]+/g, " ");
  if (data.charAt(0) == " ")
    data = data.substring(1, data.length);
  if (data.charAt(data.length - 1) == " ")
    data = data.substring(0, data.length - 1);
  return data;
}
// END of import (from the document http://developer.mozilla.org/en/docs/Whitespace_in_the_DOM)

Array.find = function(a, element){
    for(var i = 0; i < a.length; i++){
        if(a[i] == element){
            return i;
        }
    }
    return -1;
}

var comments = document.evaluate('//div[@class=\"comment\"]',
				   document, null, XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE, null);
var newComment = document.evaluate('//a[@id=\"new\"]',
				   document, null, XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE, null);
// sets page URL.
var URL = document.URL;
if (URL.split('#').length > 1)
    URL = URL.split('#')[0];

var pos = -1;
var ids = new Array();
var newPos = -1;
var NEW_HEAD = -1;

if (comments.snapshotLength > 0) {
    for (var i = 0; i < comments.snapshotLength; i++) {
	var node = comments.snapshotItem(i);
	var a = node_before(node);
	if (a) {
	    var id = a.getAttribute("id");
	    ids[i] = id;
	} else {
	    alert(i + " is null");
	}
	
    }
    ids.sort(function (a, b) {
	    aNum = a.split('-')[1];
	    bNum = b.split('-')[1];
	    return aNum - bNum;
	});
    //alert(ids);
}

if (newComment.snapshotLength > 0) { // should be 0 or 1.
    var base = newComment.snapshotItem(0);
    var a = node_after(base);
    var newId = a.getAttribute("id");
    var i = Array.find(ids, newId);
    NEW_HEAD = i;
    newPos = i - 1;

    if (document.URL.split('#').length > 1 && "new" == document.URL.split('#')[1]) { // clicked 'new'?
	pos = i;
    }
    else {
	pos = i - 1;
    }
}

function previous() {
    if (pos > 0) {
	pos--;
	window.location.href = URL + "#" + ids[pos];
    } else {
	top();
    }
}

function next() {
    if (pos < ids.length -1) {
	pos++;
	window.location.href = URL + "#" + ids[pos];
    } else {
	bottom();
    }
}

function top() {
    pos = -1;
    window.location.href = URL;
}

// NOTE: not the physical bottom, just the last comment.
function bottom() {
    pos = ids.length -1;
    window.location.href = URL + "#" + ids[pos];
}

function newPrevious() {
    if (newPos > NEW_HEAD) {
	newPos--;
	window.location.href = URL + "#" + ids[newPos];
    } else {
	newTop();
    }
}

function newNext() {
    if (newPos < ids.length -1) {
	newPos++;
	window.location.href = URL + "#" + ids[newPos];
    } else {
	newBottom();
    }
}

function newTop() {
    newPos = NEW_HEAD;
    window.location.href = URL + "#" + ids[newPos];
}

// NOTE: not the physical bottom, just the last comment.
function newBottom() {
    newPos = ids.length -1;
    window.location.href = URL + "#" + ids[newPos];
}

// registers key bindings (emacs-like binding).
// shortcuts didn't work with GM_registerMenuCommand. only menu selection.
// ref: http://greasemonkey.mozdev.org/authoring.html
function registerKeyBindings() {
    GM_registerMenuCommand("previous", previous, "p", "shift", "p");
    GM_registerMenuCommand("next", next, "n", "shift", "n");
    GM_registerMenuCommand("top", top, ",", "control shift", ",");
    GM_registerMenuCommand("bottom", bottom, ".", "control shift", ".");
}

registerKeyBindings();

// keydown event handler.
function shortcut(event) {
    var target = event.target || event.srcElement;

    if (target.tagName === 'INPUT' || target.tagName === 'TEXTAREA') {
	return;
    }

    if (!event.altKey && !event.ctrlKey) {
	var invokeNew = false;
	if (NEW_HEAD > -1 && event.shiftKey)
	    invokeNew = true;
	switch (event.keyCode) {
	case 80: // P
	    if (invokeNew)
		newPrevious();
	    else
		previous();
	    break;
	case 78: // N
	    if (invokeNew)
		newNext();
	    else
		next();
	    break;
	case 188: // ,
	    if (invokeNew)
		newTop();
	    else
		top();
	    break;
	case 190: // .
	    if (invokeNew)
		newBottom();
	    else
		bottom();
	    break;
	case 75: // K 
	    window.location.href = "http://kldp.org/ktracker2"
	    break;
	}
    }
}

document.addEventListener('keydown', shortcut, false);