function getCw()
{
    return document.getElementById("crossword");
}

function getCwHead()
{
    return getCw().getElementsByTagName("thead")[0];
}

function getCwHeadRow()
{
    return getCwHead().getElementsByTagName("tr")[0];
}

function getCwBody()
{
    return getCw().getElementsByTagName("tbody")[0];
}

function getCwBodyRows()
{
    return getCwBody().getElementsByTagName("tr");
}

function getQuestionsOrderedList()
{
    return document.getElementById("questions");
}

function getQuestions()
{
    return getQuestionsOrderedList().getElementsByTagName("li");
}


function getNextElement(o)
{
    o=o.nextSibling;
    while (o)
    {
        if (o.nodeType==1)
        {
            return o;
        }
        else
        {
            o=o.nextSibling;
        }
    }
    return false;
}

function getPreviousElement(o)
{
    o=o.previousSibling;
    while (o)
    {
        if (o.nodeType==1)
        {
            return o;
        }
        else
        {
            o=o.previousSibling;
        }
    }
    return false;
}


function getNextField(o)
{
    if (getNextElement(o.parentNode) && getNextElement(o.parentNode).getElementsByTagName("input")[0])
    {
        // return next input in this row
        return getNextElement(o.parentNode).getElementsByTagName("input")[0];
    }
    else
    {
        if (getNextElement(o.parentNode.parentNode))
        {
            // retur first input in next row
            return getNextElement(o.parentNode.parentNode).getElementsByTagName("input")[0];
        }
        else
        {
            // return first input in first row
            return getCwBody().getElementsByTagName("input")[0];
        }
    }
}

function getPreviousField(o)
{
    if (getPreviousElement(getPreviousElement(o.parentNode)))
    {
        // return previous input in this row
        return getPreviousElement(o.parentNode).getElementsByTagName("input")[0];
    }
    else
    {
        if (getPreviousElement(o.parentNode.parentNode))
        {
            // return last input in previous row
            var inputs=getPreviousElement(o.parentNode.parentNode).getElementsByTagName("input");
            return inputs[inputs.length-1];
        }
        else
        {
            // return last input in last row
            var inputs=getCwBody().getElementsByTagName("input");
            return inputs[inputs.length-1];
        }
    }
}


function getUpperField(o)
{
    var position=getPositionInList(o, o.parentNode.parentNode.getElementsByTagName("input"));
    
    if (getPreviousElement(o.parentNode.parentNode))
    {
        return getPreviousElement(o.parentNode.parentNode).getElementsByTagName("input")[position];
    }
    else
    {
        var rows=getCwBodyRows();
        return rows[rows.length-1].getElementsByTagName("input")[position];
    }
}


function getLowerField(o)
{
    var position=getPositionInList(o, o.parentNode.parentNode.getElementsByTagName("input"));

    if (getNextElement(o.parentNode.parentNode))
    {
        return getNextElement(o.parentNode.parentNode).getElementsByTagName("input")[position];
    }
    else
    {
        return getCwBodyRows()[0].getElementsByTagName("input")[position];
    }
}

    
function KeyCheck(e) 
{ 
    var evnt; 
    var elmnt; 

    if (window.event)
    {
        evnt = event;
        elmnt = evnt.srcElement;
    } 
    else
    {
        evnt = e;
        elmnt = evnt.target;
    } 
    var keyID = evnt.keyCode; 
    
    if (elmnt.type && elmnt.name && elmnt.type=="text" && elmnt.name=="t")
    {
        if (keyID>=32)
        {
            var field;
            switch (keyID)
            {
                case 37: //left
                    field=getPreviousField(elmnt);
                break;
                case 38: //up
                    field=getUpperField(elmnt);
                break;
                case 40: //down
                    field=getLowerField(elmnt);
                break;
                case 39: //right
                default:
                    field=getNextField(elmnt);
            }
            field.focus();
            field.select();
        }
    }

}

function createFieldCell()
{
    var newTd=document.createElement("td");
    var newInput=newTd.appendChild(document.createElement("input"));
    newInput.type="text";
    newInput.name="t";
    return newTd;
}

function createQuestion()
{
    var newLi=document.createElement("li");
    var newInput=newLi.appendChild(document.createElement("input"));
    newInput.type="text";
    newInput.name="q";
    return newLi;
}

function createRowLike(refRow)
{
    var newRow=document.createElement("tr");
    
    var nextRowNumber=parseInt(refRow.getElementsByTagName("th")[0].firstChild.nodeValue)+1;
    var newTh=newRow.appendChild(document.createElement("th"));
    newTh.appendChild(document.createTextNode(nextRowNumber+"."));
    
    var refRowTds=refRow.getElementsByTagName("td");
    var nrOfFields=refRowTds.length;
    
    
    for (var i=0; i<nrOfFields; i++)
    {
        newTd=newRow.appendChild(createFieldCell());
        if (refRowTds[i].className=="solution"){
            newTd.className="solution";
        }
    }
    
    return newRow;
}

function renumberElements(eList)
{
    for (var i=0;i<eList.length; i++)
    {
        eList[i].firstChild.nodeValue=(i+1)+".";
    }
}


function insertFirstRow()
{
    var cwBody=getCwBody();
    var cwBodyRows=cwBody.getElementsByTagName("tr");
    
    cwBody.insertBefore(createRowLike(cwBodyRows[0]),cwBodyRows[0]);
    
    renumberElements(cwBody.getElementsByTagName("th"));
    
    var QuestionsOL=getQuestionsOrderedList();
    QuestionsOL.insertBefore(createQuestion(), QuestionsOL.getElementsByTagName("li")[0]);
}


function insertLastRow()
{
    var cwBody=getCwBody();
    var cwBodyRows=cwBody.getElementsByTagName("tr");

    cwBody.appendChild(createRowLike(cwBodyRows[cwBodyRows.length-1]));
    
    getQuestionsOrderedList().appendChild(createQuestion());
}


function removeFirstRow()
{
    var cwBody=getCwBody();
    var cwBodyRows=cwBody.getElementsByTagName("tr");
    
    if (cwBodyRows.length>1)
    {
        cwBody.removeChild(cwBodyRows[0]);
        renumberElements(cwBody.getElementsByTagName("th"));
        
        getQuestionsOrderedList().removeChild(getQuestions()[0]);
    }
}

function removeLastRow()
{
    var cwBody=getCwBody();
    var cwBodyRows=cwBody.getElementsByTagName("tr");
    var questions=getQuestions()

    if (cwBodyRows.length>1)
    {
        cwBody.removeChild(cwBodyRows[cwBodyRows.length-1]);

        getQuestionsOrderedList().removeChild(questions[questions.length-1]);
    }
}


function insertLastCol()
{
    
    var cwHeadRow=getCwHeadRow();
    
    var cwHeadAnchors=cwHeadRow.getElementsByTagName("a");
    var lastNr=parseInt(cwHeadAnchors[cwHeadAnchors.length-1].firstChild.nodeValue);
    
    var newA=cwHeadRow.appendChild(document.createElement("th")).appendChild(document.createElement("a"));
    newA.href="#";
    newA.onclick=function(){setAsSolution(this); return 0;};
    newA.appendChild(document.createTextNode( ( lastNr + 1 ) + "."));
    
    var cwBodyRows=getCwBodyRows();
    
    for (var i=0; i<cwBodyRows.length; i++)
    {
        cwBodyRows[i].appendChild(createFieldCell())
    }
}


function insertFirstCol()
{
    var cwHeadRow=getCwHeadRow();
    
    var newA=cwHeadRow.insertBefore(document.createElement("th"), cwHeadRow.getElementsByTagName("th")[0])
              .appendChild(document.createElement("a"));
    
    newA.href="#";
    newA.onclick=function(){setAsSolution(this); return 0;};
    newA.appendChild(document.createTextNode( "0."));
    
    var cwBodyRows=getCwBodyRows();
    
    for (var i=0; i<cwBodyRows.length; i++)
    {
        cwBodyRows[i].insertBefore(createFieldCell(), cwBodyRows[i].getElementsByTagName("td")[0])
    }
    
    renumberElements(cwHeadRow.getElementsByTagName("a"));
}

function removeFirstCol()
{
    var cwHeadRow=getCwHeadRow();
    var cwHeadRowHeadings=cwHeadRow.getElementsByTagName("th");
    if (cwHeadRowHeadings.length>1)
    {
        if (cwHeadRowHeadings[0].className=="solution")
        {
            cwHeadRowHeadings[1].className="solution";
        }
        cwHeadRow.removeChild(cwHeadRowHeadings[0]);
        
        var cwBodyRows=getCwBodyRows();
        for (var i=0; i<cwBodyRows.length; i++)
        {
            var removable=cwBodyRows[i].getElementsByTagName("td")[0];
            
            if (removable.className=="solution")
            {
                cwBodyRows[i].getElementsByTagName("td")[1].className="solution";
            }
            
            cwBodyRows[i].removeChild(removable);
        }
        
        renumberElements(cwHeadRow.getElementsByTagName("a"));
    }
}

function removeLastCol()
{
    var cwHeadRow=getCwHeadRow();
    var cwHeadRowHeadings=cwHeadRow.getElementsByTagName("th")
    if (cwHeadRowHeadings.length>1)
    {
        if (cwHeadRowHeadings[cwHeadRowHeadings.length-1].className=="solution")
        {
            cwHeadRowHeadings[cwHeadRowHeadings.length-2].className="solution";
        }
        cwHeadRow.removeChild(cwHeadRowHeadings[cwHeadRowHeadings.length-1]);

        var cwBodyRows=getCwBodyRows();
        for (var i=0; i<cwBodyRows.length; i++)
        {
            var cwBodyRowsCells=cwBodyRows[i].getElementsByTagName("td");
            var removable=cwBodyRowsCells[cwBodyRowsCells.length-1];

            if (removable.className=="solution")
            {
                cwBodyRows[i].getElementsByTagName("td")[cwBodyRowsCells.length-2].className="solution";
            }

            cwBodyRows[i].removeChild(cwBodyRowsCells[cwBodyRowsCells.length-1]);
        }
    }
}


function getSolutionColumnNr()
{
    var cwHeadCells=getCwHeadRow().getElementsByTagName("th");
    for (var i=0;i<cwHeadCells.length; i++)
    {
        if (cwHeadCells[i].className=="solution")
        {
            return i;
        }
    }
}


function getPositionInList(o, list)
{
    for (var i=0; i<list.length; i++)
    {
        if (list[i]==o)
        {
            return i;
        }
    }
}



function setAsSolution(o)
{
    if (o.parentNode.className!="solution")
    {
        var oldSolution=getSolutionColumnNr();
        var newSolution=getPositionInList(o, getCwHeadRow().getElementsByTagName("a"));
        
        var cwHeadCells=getCwHeadRow().getElementsByTagName("th");
        cwHeadCells[oldSolution].className="";
        cwHeadCells[newSolution].className="solution";
        
        var cwBodyRows=getCwBodyRows();
        for (var i=0; i<cwBodyRows.length; i++)
        {
            var cells=cwBodyRows[i].getElementsByTagName("td");
            cells[oldSolution].className="";
            cells[newSolution].className="solution";
        }
    }
}

function fillHiddenFields()
{
    var cwBodyRows=getCwBodyRows();
    document.getElementById("y").value=cwBodyRows.length;
    document.getElementById("x").value=cwBodyRows[0].getElementsByTagName("input").length;
    document.getElementById("solution-col").value=getSolutionColumnNr();

    return true;
}


document.onkeyup = KeyCheck;        

window.onload=function()
{
    var cwHeadAnchors=getCwHeadRow().getElementsByTagName("a");
    for (var i=0; i<cwHeadAnchors.length; i++)
    {
        cwHeadAnchors[i].onclick=function(){setAsSolution(this); return 0;};
    }
    
    document.getElementsByTagName("form")[0].onsubmit=function(){return fillHiddenFields();};
};