var xpath   = {
  'node' : {     // any node i.e. thread or subthread
    'desc' : 'Thread or sub-thread',
      'p'  : {   // key to enter/browse 'Replies' collection
        'desc'   : 'Replies',
        xpath    : function () { return "//tr[@class='reply']" },
        'l' : {  
          'desc'   : 'go to node title links',
          xpath    : function (i) {
                         return <XPath expr selecting links based
                                 on 'Replies' collection index>
          },
        },
      'b' : {
        'desc'   : 'go to node body links',
        xpath    : function (i) { ... },
            },
        },
    }
};

##</code><code>##

  'id-3628'   : {
    'desc' : 'Newest Nodes',
    'p' : { 
      'desc'  : 'Collections of Postings',
      xpath   : function () { return "//html/body/center/table/tbody/tr/td[1]/h3/a" },
      'hl'    : function (t) { return t.parentNode }, // different highlighting
      'l' : { // list of postings - left column
        'desc' : 'posting titles',
        xpath   : function (i) { return "//html/body/center/table/tbody/tr/td[1]/table["+i+"]/tbody/tr/td[1]/a" },
        'sticky': 'u',
      },
      'u' : { // list of users - right column
        'desc'  : 'authors',
        xpath   : function (i) { return "//html/body/center/table/tbody/tr/td[1]/table["+i+"]/tbody/tr/td[2]/a" },
        'sticky': 'l',
      },
    }
  },

##</code><code>##

// $Id: keypress.js,v 0.6 2008/07/27 12:16:05 shmem Exp $
// .
// Key Driven PerlMonks

// For [blazar] and all ye monks

function $ (id) { return document.getElementById(id) }

function xq (query) {
    return document.evaluate(query,document,null,XPathResult.ORDERED_NODE_SNAPSHOT_TYPE,null);
}

function xl (query) {
    var r = xq(query);
    var a = new Array;
    for ( var i=0 ; i < r.snapshotLength; i++ ) a.push(r.snapshotItem(i));
    return a;
}

// globals
var context;                    // current context
var cursnum;                    // current prefix number (as string)
var curchild;                   // current child
var curindex;                   // current index into collection
var hl      = 'border';         // how to highlight
var hc      = '1px solid #F00'; // highlight attributes
var cursor  = new Object;

// all of PerlMonks (well, some day, hopefully...)
var xpath   = {
     'node'      : { // any node i.e. thread or subthread
        'desc' : 'Thread or sub-thread',
        'p' : {
            'desc'   : 'Replies',
            xpath    : function () { return "//tr`[@class='reply']" },
            'hl'     : function (t) { return t.childNodes`[0] },
            'sticky' : 'r',
            'l' : {
                'desc'   : 'go to node title links',
                xpath    : function (i) { var j = i * 2; return "//table`[@id='replies_table']/tbody/tr`["+j+"]/td//a`[@href]" },
            },
            'b' : {
                'desc'   : 'go to node body links',
                xpath    : function (i) { var j = i * 2 + 1; return "//table`[@id='replies_table']/tbody/tr`["+j+"]/td//a`[@href]" },
            },
        },
        'r' : {
            'desc'   : '`[reply] link',
            xpath    : function (i) { return "//table/tbody/tr/td`[1]/form/center`[1]/table`[@id='replies_table']/tbody/tr/td`[2]/font/a" },
            'sticky' : 'p',
                                           //html/body/center/table/tbody/tr/td`[1]/form/center`[1]/table`[@id='replies_table']/tbody/tr`[5]/td`[2]/font/a
        },
        'C' : {
            'desc'   : 'Comment on',
            xpath    : function () { return "//table`[@id='replies_table']/tbody/tr`[1]/th/a" },
        },
     },
     'id-131'    : {
        'desc' : 'The Monastery Gates',
        'p' : {
            'desc'   : 'Front-paged Posts',
            xpath    : function () { return "//tr`[@class='post_head']" },
            'sticky' : 'rl',
            'hl'    : function (t) { return t.childNodes`[1] },
        },
        'r' : {
            'desc'   : 'Offer your reply',
            xpath    : function () { return  "//td`[2]/a/font" },
            'sticky' : 'pl',
        },
        'l' : {
            'desc'   : 'Link to thread',
            xpath    : function () { return "//td/table/tbody/tr/td`[1]/a`[@id]"},
            'sticky' : 'rp',
        },
     },
     'id-479'    : {
        'desc' : 'SoPW, Meditations, PM Discussion, ...',
        'p' : {
            'desc'   : 'Questions',
            xpath    : function () { return "//tr`[@class='post_head']" },
            'sticky' : 'rl',
            'hl'    : function (t) { return t.childNodes`[1] },
        },
        'r' : {
            'desc'   : 'Link `[Offer your reply]',
            xpath    : function () { return  "//td`[2]/a/font" },
            'sticky' : 'pl',
        },
        'l' : {
            'desc'   : 'Link to thread',
            xpath    : function () { return "//td/table/tbody/tr/td`[1]/a`[@id]"},
            'sticky' : 'rp',
        },
     },
     'id-3628'   : {
        'desc' : 'Newest Nodes',
        'p' : {
            'desc'  : 'Collections of Postings',
            xpath   : function () { return "//html/body/center/table/tbody/tr/td`[1]/h3/a" },
            'hl'    : function (t) { return t.parentNode },
            'l' : { // list of postings - left column
                'desc' : 'posting titles',
                xpath   : function (i) { return "//html/body/center/table/tbody/tr/td`[1]/table`["+i+"]/tbody/tr/td`[1]/a" },
                'sticky': 'u',
            },
            'u' : { // list of users - right column
                'desc'  : 'authors',
                xpath   : function (i) { return "//html/body/center/table/tbody/tr/td`[1]/table`["+i+"]/tbody/tr/td`[2]/a" },
                'sticky': 'l',
            },
        }
     },
     'id-9066' : {
        'desc' : 'Best Nodes',
        'p' : {
            'desc'  : 'Collections of Postings',
            xpath   : function () { return "/html/body/center/table/tbody/tr/td/h4" },
            'l'     : {
                'desc'   : 'posting titles',
                xpath    : function (i) { return "/html/body/center/table/tbody/tr/td`[1]/table`["+i+"]/tbody/tr/td`[2]/a" },
                'sticky' : 'u',
            },
            'u'     : {
                'desc'   : 'authors',
                xpath    : function (i) { return "/html/body/center/table/tbody/tr/td`[1]/table`["+i+"]/tbody/tr/td`[3]/a" },
                'sticky' : 'l',
            },
        },
     },
    'n' : { // nodelets
        'desc' : 'Nodelets',
        xpath  : function () { return "//table`[@id='nodelet_container']/tbody/tr`[1]/th" },
        'l'  : {
            'desc'  : 'links in nodelet',
            xpath   :function (i) { return "//table`[@id='nodelet_container']/tbody`["+i+"]/tr/td//a" },
        },
     },
    'T'    : {
        'desc' : 'Title Bar',
        xpath  : function () { return "/html/body/table`[@id='titlebar-top']/tbody/tr/td`[2]/font/span/a" },
     },
     'R'    : {
        'desc' : 'root & parent link (if applicable)',
        xpath  : function () { return "/html/body/center/table/tbody/tr/td`[1]/form/div`[2]/p`[1]/a" },
     },
     'c' : {
        'desc' : 'Chatterbox',
        xpath  : function () { return "//input`[@id='talkbox']" },
        focus  : function () { setFocus(talkbox) }, // chatterbox
     },
     't' : {
        'desc' : 'Composition textbox (if any)',
     // xpath  : function () { return "//table[3]/tbody/tr[2]/td//input[@name='node']" },
        xpath  : function () { return "//textarea[contains(@name,'doctext')]" },
        focus  : function () { setFocus(context`['colls']`[0]) },
     },
};

var bodyid  = xq('//body').snapshotItem(0).id;
// nodes that resemble SoPW (#479), i.e. main sections
var javascriptisstupid = new Array(480,1040,1044,1590,1597,21144,23771);
//for (i in Array(480,1040,1044,1590,1597,21144,23771)) {
for (i in javascriptisstupid) {
    var j = javascriptisstupid`[i];
    if(bodyid == 'id-' + j) xpath`['id-' + j] = xpath`['id-479'];
}
var context = xpath`[bodyid] || xpath`['node'];

// these are present in all nodes...
context`['T'] = xpath`['T']; // Monkbar
context`['R'] = xpath`['R']; // link to root|parent node
context`['n'] = xpath`['n']; // nodelets
context`['c'] = xpath`['c']; // Chatterbox
// ...well, except these
context`['t'] = xpath`['t']; // Composition textbox title
var root = context;        // save context root

// keys for all contexts and subcontexts (where apropriate)
var keys = {
    'j' : {
        'desc' : 'move down',
        value  : 1,
    },
    'k' : {
        'desc' : 'move up',
        value  : -1,
    },
    '+' : {
        'desc' : 'vote ++',
        func   : function () { vote(0) },
    },
    '0' : {
        'desc' : 'reset vote',
        func   : function () { vote(1) },
    },
    '-' : {
        'desc' : 'vote --',
        func   : function () { vote(2) },
    },
    'v' : {
        'desc' : 'jump to "vote!" button',
        func   : function () { document.forms`[1]`['sexisgreat'].focus() },
    },
    'h' : {
        'desc' : 'Hide the body of a post',
        func   : hideBody,
    },
    'm' : {
        'desc' : 'go to page top',
        func   : function () { window.scroll(0,0); if (curchild) curchild.style`[hl] = curchild`['oldstyle']; context = root }
    }
};

// scroll element to top of page
function setScroll (i) {
    var child = context`['coll']`[i];
    if (! child) return;
    var helem = child;
    if (context`['hl']) helem = context`['hl'](child);
    if (curchild) { // unhighlight
        curchild.style`[hl] = curchild`['oldstyle'];
    }
    helem`['oldstyle'] = helem.style`[hl];
    helem.style`[hl] = hc;
    if(child.nodeName == 'A') child.focus();
    else if (child.parentNode.nodeName == 'A') child.parentNode.focus();
    else
    window.scroll(0,getOffset(child));

    curchild = helem;
}

// cast vote on a post in collection
// XXX use xpath proper
function vote(n) {
    var t = curchild;
    var nm; 
    if (! t || context['desc'] == 'Thread or sub-thread') { // HACK
        var id = 'vote__'+bodyid.split('-')[1];
        if(document.forms[1][id])
            document.forms[1][id][n].checked = 'checked';
        return;
    }
    if (t.childNodes[0]) // post + replies
        var nm = t.childNodes[0].name;
    if (! nm) { // section page, e.g. meditations
        try {  
            nm = t.childNodes[1].childNodes[1].href;
            nm = nm.slice(nm.indexOf('=')+1);
        } catch (ex) {
            nm = bodyid.split('-')[1];
            if(! document.forms[1]['vote__'+nm]) nm = '';
        }
        if(! nm) { // HACK
            try {
                nm = curchild.childNodes[1].href.split('=')[1];
            } catch (ex) {}
        }
    }
    var id = 'vote__' + nm;
    if(document.forms[1][id]) 
        document.forms[1][id][n].checked = 'checked';
}


function setFocus (t) {
    if (! t) return;
    document.onkeypress = '';
    t.onblur = function () { document.onkeypress = keyDriven };
    t.focus();
}

// for threads
function hideBody () {
    if (! curchild) return;
    var n = curchild.parentNode.nextSibling.nextSibling;
    var v = n.style.display;
    if (v == 'none') 
        n.style.display = 'table-row';
    else
        n.style.display = 'none';
}
// get textareas, text inputs to disable keyDriven
var talkbox = document.getElementById('talkbox');

// get offset of an element
function getOffset (foo) {
    if (! foo) return;
    var offset = 0;
    if (foo.nodeName != 'A') offset = foo.offsetTop;
    while(foo.parentNode != foo) {
        if(foo.parentNode) {
            var p = foo.parentNode;
            var o = p.offsetTop;
            foo = p;
            if (p.nodeName == 'BODY') break;
            if (p.nodeName == 'CENTER') continue;
            // if (p.nodeName == 'TD') continue;
            if (p.nodeName == 'A') continue;
            if (p.nodeName == 'TR') continue;
            if (p.nodeName == 'TBODY') continue;
            if (p.nodeName == 'FORM') continue;
            offset += p.offsetTop;
        } else break;
    }
    return offset;
}

// Event handler
function keyDriven (evt) {
    evt = evt || window.event;
    // don't mess up with the browser shortcuts
    if (evt.ctrlKey) return;
    if (evt.modifiers)
        if (evt.modifiers == 2) return
    var k = evt.keyCode ? evt.keyCode : evt.charCode ? evt.charCode : evt.which;
    var s = String.fromCharCode(k);
    var num = parseInt(cursnum,10);
    var found = 0;
    if (! num) num = 0;
    if (k > 47 && k < 59) { // 0 - 9
        if ( cursnum || s != '0') {// leading 0 not allowed - used elsewhere.
            cursnum += s;
            return;
        }
    }
    var rel = 0;
    // select context
    if(s == '?') {
        s = 'Current context: '+context`['desc']+"\n\n";
        for (var k in context) {
            if (k.length == 1) {
                s += k +' - '+ context`[k]`['desc'] + "\n";
                if (context`[k]`['sticky']) {
                    ary = context`[k]`['sticky'].split('');
                    s += '   index linked with key(s) ' + ary.join(', ') + "\n";
                }
            }
        }
        if (context.parent) {
            for (var k in context.parent) {
                if (k.length == 1)
                    s += k +' - '+ context.parent`[k]`['desc']+"\n";
            }
        }
        s+= "\nGlobal keys:\n\n";
        for (var k in keys)
            s += k + ' - ' + keys`[k]`['desc'] + "\n";
        s += "\nMovement commands may be preceeded with a number,\n"
          +  "e.g. 12j - go 12 items down\n";
        alert(s);
    } else if (keys`[s]) { // global browsing key pressed
        var n = 0;
        if(keys`[s].value) {
            rel = 1;
            n   = keys`[s].value;
            if(num && n) num *= n;
            else num = n
            found = 1;
        } else {
            try {
                keys`[s].func();
            } catch (ex){
                alert("invocation of\n"+keys`[s]+"\nfailed:\n"+ex);
            }
        }
    } else if (context`[s]) { // sub-context or function
        try {
            context`[s]();
        } catch (ex) {
            context`[s].parent = context;
            var i = 1;
            if (context`['index']) i = context`['index']+1;
            context = context`[s];
            context`['coll'] = xl(context.xpath(i));
            found = 1;
        }
    } else if (context.parent) {
        if (context.parent`[s]) {
            if(context.parent`[s] == context) { // next item in collection
                if(!num) num = 1;
                rel = 1;
            } else { // adjacent collection context.parent
                context.parent`[s].parent = context.parent;
                if (context`['sticky']) {
                    var ary = context`['sticky'].split('');
                    for (var i in ary) {
                        //alert(ary`[i]);
                        if(ary`[i] == s) {
                            context.parent`[s]`['index'] = context`['index'];
                        }
                    }
                }
                var i = 1;
                if (context.parent`['index']) i = context.parent`['index']+1;
                context = context.parent`[s];
                context`['coll'] = xl(context.xpath(i));
            }
            found = 1;
        } else if (context.parent.parent) {
            if (context.parent.parent`[s]) {
                context.parent.parent`[s].parent = context.parent.parent;
                context = context.parent.parent`[s];
                found = 1;
            }
        }
    }
    if (! found)  { // invalid key pressed | key not defined
        if (k < 48 || k > 58) // reset number string
            cursnum = '';
        return;
    }
    if (! context`['index']) context`['index'] = 0;
    if (! context`['coll']) {
        var i = 1;
        if (context.parent) {
            i = context.parent`['index']+1;
            // alert(context.parent`['desc']+' index = '+context.parent`['index']);
        }
        context`['coll'] = xl(context.xpath(i));
    }
    var coll  = context`['coll'];
    var index = context`['index'];
    if (rel) num += index;
    else num = index;
    if (num > context`['coll'].length-1) num = context`['coll'].length-1;
    if (num < 0) num = 0;

    setScroll(num);
    context`['index'] = num;
    if (context.focus) setFocus(curchild);

    if (k < 48 || k > 58) // reset number string
        cursnum = '';
}

// get all textareas and disable keyDriven while they have focus.
// XXX use xpath for that
function setSuspendKeyMode (t) {
    t.onblur  = function () { document.onkeypress = keyDriven };
    t.onfocus = function () { document.onkeypress = '' };
}       

function applyFuncOnTree(e,f,tag,type) {
    if (e.tagName == tag) { 
        if(type != '') {
            if (e.type == type) f(e);
        } else {
            f(e);
        }   
    }
    if (e.childNodes) {
        for(var i = 0; i<e.childNodes.length; i++) {
            applyFuncOnTree(e.childNodes`[i],f,tag,type);
        }
    }
}   

// find all textarea elements and applyFuncOnTree on them
for (var i = 0; i<document.forms.length; i++) {
    f = document.forms`[i];
    applyFuncOnTree(f,setSuspendKeyMode,'TEXTAREA','');
    applyFuncOnTree(f,setSuspendKeyMode,'INPUT','text');
}

document.onkeypress = keyDriven;

##</code><code>##

<script type="text/javascript" src="http://cruft.de/keypress.js"></script>