Editor/src/Tables.js

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

var Tables_insertTable;
var Tables_addAdjacentRow;
var Tables_addAdjacentColumn;
var Tables_removeAdjacentRow;
var Tables_removeAdjacentColumn;
var Tables_deleteRegion;
var Tables_clearCells;
var Tables_mergeCells;
var Tables_splitSelection;
var Tables_cloneRegion;
var Tables_analyseStructure;
var Tables_findContainingCell;
var Tables_findContainingTable;
var Tables_regionFromRange;
var Tables_getSelectedTableId;
var Tables_getProperties;
var Tables_setProperties;
var Tables_getColWidths;
var Tables_setColWidths;
var Tables_getGeometry;

var Table_get;
var Table_set;
var Table_setRegion;
var Table_fix;
var Table_fixColumnWidths;
var TableRegion_splitCells;

(function() {

    function Cell(element,row,col)
    {
        this.element = element;
        this.row = row;
        this.col = col;

        if (element.hasAttribute("colspan"))
            this.colspan = parseInt(element.getAttribute("colspan"));
        else
            this.colspan = 1;
        if (element.hasAttribute("rowspan"))
            this.rowspan = parseInt(element.getAttribute("rowspan"));
        else
            this.rowspan = 1;

        if (this.colspan < 1)
            this.colspan = 1;
        if (this.rowspan < 1)
            this.rowspan = 1;

        this.top = this.row;
        this.bottom = this.top + this.rowspan - 1;
        this.left = this.col;
        this.right = this.left + this.colspan - 1;
    }

    function Cell_setRowspan(cell,rowspan)
    {
        if (rowspan < 1)
            rowspan = 1;
        cell.rowspan = rowspan;
        cell.bottom = cell.top + cell.rowspan - 1;
        if (rowspan == 1)
            DOM_removeAttribute(cell.element,"rowspan");
        else
            DOM_setAttribute(cell.element,"rowspan",rowspan);
    }

    function Cell_setColspan(cell,colspan)
    {
        if (colspan < 1)
            colspan = 1;
        cell.colspan = colspan;
        cell.right = cell.left + cell.colspan - 1;
        if (colspan == 1)
            DOM_removeAttribute(cell.element,"colspan");
        else
            DOM_setAttribute(cell.element,"colspan",colspan);
    }

    function Table(element)
    {
        this.element = element;
        this.row = 0;
        this.col = 0;
        this.cells = new Array();
        this.numRows = 0;
        this.numCols = 0;
        this.translated = false;
        this.cellsByElement = new NodeMap();
        Table_processTable(this,element);
    }

    // public
    Table_get = function(table,row,col)
    {
        if (table.cells[row] == null)
            return null;
        return table.cells[row][col];
    }

    // public
    Table_set = function(table,row,col,cell)
    {
        if (table.numRows < row+1)
            table.numRows = row+1;
        if (table.numCols < col+1)
            table.numCols = col+1;
        if (table.cells[row] == null)
            table.cells[row] = new Array();
        table.cells[row][col] = cell;
    }

    // public
    Table_setRegion = function(table,top,left,bottom,right,cell)
    {
        for (var row = top; row <= bottom; row++) {
            for (var col = left; col <= right; col++) {
                var destCell = Table_get(table,row,col);
                DOM_deleteNode(destCell.element);
                Table_set(table,row,col,cell);
            }
        }
    }

    function Table_processTable(table,node)
    {
        var type = node._type;
        switch (node._type) {
        case HTML_TD:
        case HTML_TH: {
            while (Table_get(table,table.row,table.col) != null)
                table.col++;

            var cell = new Cell(node,table.row,table.col);
            table.cellsByElement.put(node,cell);

            for (var r = 0; r < cell.rowspan; r++) {
                for (var c = 0; c < cell.colspan; c++) {
                    Table_set(table,table.row+r,table.col+c,cell);
                }
            }
            table.col += cell.colspan;
            break;
        }
        case HTML_TR:
            for (var child = node.firstChild; child != null; child = child.nextSibling)
                Table_processTable(table,child);
            table.row++;
            table.col = 0;
            break;
        default:
            for (var child = node.firstChild; child != null; child = child.nextSibling)
                Table_processTable(table,child);
            break;
        }
    }

    // public
    Tables_insertTable = function(rows,cols,width,numbered,caption,className)
    {
        UndoManager_newGroup("Insert table");

        if (rows < 1)
            rows = 1;
        if (cols < 1)
            cols = 1;

        var haveCaption = (caption != null) && (caption != "");
        var table = DOM_createElement(document,"TABLE");

        if (width != null)
            DOM_setStyleProperties(table,{"width": width});

        if (className != null)
            DOM_setAttribute(table,"class",className);

        // Caption comes first
        if (haveCaption) {
            var tableCaption = DOM_createElement(document,"CAPTION");
            DOM_appendChild(tableCaption,DOM_createTextNode(document,caption));
            DOM_appendChild(table,tableCaption);
        }

        // Set equal column widths
        var colWidth = Math.round(100/cols)+"%";
        for (var c = 0; c < cols; c++) {
            var col = DOM_createElement(document,"COL");
            DOM_setAttribute(col,"width",colWidth);
            DOM_appendChild(table,col);
        }

        var firstTD = null;

        // Then the rows and columns
        var tbody = DOM_createElement(document,"TBODY");
        DOM_appendChild(table,tbody);
        for (var r = 0; r < rows; r++) {
            var tr = DOM_createElement(document,"TR");
            DOM_appendChild(tbody,tr);
            for (var c = 0; c < cols; c++) {
                var td = DOM_createElement(document,"TD");
                var p = DOM_createElement(document,"P");
                var br = DOM_createElement(document,"BR");
                DOM_appendChild(tr,td);
                DOM_appendChild(td,p);
                DOM_appendChild(p,br);

                if (firstTD == null)
                    firstTD = td;
            }
        }

        Clipboard_pasteNodes([table]);

        // Now that the table has been inserted into the DOM tree, the outline code will
        // have noticed it and added an id attribute, as well as a caption giving the
        // table number.
        Outline_setNumbered(table.getAttribute("id"),numbered);

        // Place the cursor at the start of the first cell on the first row
        var pos = new Position(firstTD,0);
        pos = Position_closestMatchForwards(pos,Position_okForMovement);
        Selection_set(pos.node,pos.offset,pos.node,pos.offset);

        PostponedActions_add(UndoManager_newGroup);
    }

    // private
    function createEmptyTableCell(elementName)
    {
        var br = DOM_createElement(document,"BR");
        var p = DOM_createElement(document,"P");
        var td = DOM_createElement(document,elementName);
        DOM_appendChild(p,br);
        DOM_appendChild(td,p);
        return td;
    }

    // private
    function addEmptyTableCell(newTR,elementName)
    {
        var td = createEmptyTableCell(elementName);
        DOM_appendChild(newTR,td);
        return td;
    }

    // private
    function populateNewRow(structure,newTR,newRow,oldRow)
    {
        var col = 0;
        while (col < structure.numCols) {
            var existingCell = Table_get(structure,oldRow,col);
            if (((newRow > oldRow) && (newRow < existingCell.row + existingCell.rowspan)) ||
                ((newRow < oldRow) && (newRow >= existingCell.row))) {
                Cell_setRowspan(existingCell,existingCell.rowspan+1);
            }
            else {
                var td = addEmptyTableCell(newTR,existingCell.element.nodeName); // check-ok
                if (existingCell.colspan != 1)
                    DOM_setAttribute(td,"colspan",existingCell.colspan);
            }
            col += existingCell.colspan;
        }
    }

    function tableAtRightOfRange(range)
    {
        if (!Range_isEmpty(range))
            return null;

        var pos = Position_preferElementPosition(range.start);
        if ((pos.node.nodeType == Node.ELEMENT_NODE) &&
            (pos.offset < pos.node.childNodes.length) &&
            (pos.node.childNodes[pos.offset]._type == HTML_TABLE)) {
            var element = pos.node.childNodes[pos.offset];
            var table = Tables_analyseStructure(element);
            return table;
        }
        return null;
    }

    function tableAtLeftOfRange(range)
    {
        if (!Range_isEmpty(range))
            return null;

        var pos = Position_preferElementPosition(range.start);
        if ((pos.node.nodeType == Node.ELEMENT_NODE) &&
            (pos.offset > 0) &&
            (pos.node.childNodes[pos.offset-1]._type == HTML_TABLE)) {
            var element = pos.node.childNodes[pos.offset-1];
            var table = Tables_analyseStructure(element);
            return table;
        }
        return null;
    }

    function insertRowAbove(table,row)
    {
        var cell = Table_get(table,row,0);
        var oldTR = cell.element.parentNode;
        var newTR = DOM_createElement(document,"TR");
        DOM_insertBefore(oldTR.parentNode,newTR,oldTR);
        populateNewRow(table,newTR,row-1,row);
    }

    function insertRowBelow(table,row)
    {
        var cell = Table_get(table,row,0);
        var oldTR = cell.element.parentNode;
        var newTR = DOM_createElement(document,"TR");
        DOM_insertBefore(oldTR.parentNode,newTR,oldTR.nextSibling);
        populateNewRow(table,newTR,row+1,row);
    }

    function insertRowAdjacentToRange(range)
    {
        var table;

        table = tableAtLeftOfRange(range);
        if (table != null) {
            insertRowBelow(table,table.numRows-1);
            return;
        }

        table = tableAtRightOfRange(range);
        if (table != null) {
            insertRowAbove(table,0);
            return;
        }
    }

    // public
    Tables_addAdjacentRow = function()
    {
        UndoManager_newGroup("Insert row below");
        Selection_preserveWhileExecuting(function() {
            var range = Selection_get();
            var region = Tables_regionFromRange(range,true);
            if (region != null)
                insertRowBelow(region.structure,region.bottom);
            else
                insertRowAdjacentToRange(range);
        });
        UndoManager_newGroup();
    }

    // private
    function getColElements(table)
    {
        var cols = new Array();
        for (child = table.firstChild; child != null; child = child.nextSibling) {
            switch (child._type) {
            case HTML_COLGROUP:
                for (var gc = child.firstChild; gc != null; gc = gc.nextSibling) {
                    if (gc._type == HTML_COL)
                        cols.push(gc);
                }
                break;
            case HTML_COL:
                cols.push(child);
                break;
            }
        }
        return cols;
    }

    // private
    function getColWidths(colElements,expectedCount)
    {
        // FIXME: also handle the case where the width has been set as a CSS property in the
        // style attribute. There's probably not much we can do if the width comes from a style
        // rule elsewhere in the document though.
        var colWidths = new Array();
        for (var i = 0; i < colElements.length; i++) {
            if (colElements[i].hasAttribute("width"))
                colWidths.push(colElements[i].getAttribute("width"));
            else
                colWidths.push("");
        }
        return colWidths;
    }

    // private
    function addMissingColElements(structure,colElements)
    {
        // If there are fewer COL elements than there are colums, add extra ones, copying the
        // width value from the last one
        // FIXME: handle col elements with colspan > 1, as well as colgroups with width set
        // FIXME: What if there are 0 col elements?
        while (colElements.length < structure.numCols) {
            var newColElement = DOM_createElement(document,"COL");
            var lastColElement = colElements[colElements.length-1];
            DOM_insertBefore(lastColElement.parentNode,newColElement,lastColElement.nextSibling);
            colElements.push(newColElement);
            DOM_setAttribute(newColElement,"width",lastColElement.getAttribute("width"));
        }
    }

    // private
    function fixColPercentages(structure,colElements)
    {
        var colWidths = getColWidths(colElements,structure.numCols);

        var percentages = colWidths.map(getPercentage);
        if (percentages.every(notNull)) {
            var colWidthTotal = 0;
            for (var i = 0; i < percentages.length; i++)
                colWidthTotal += percentages[i];

            for (var i = 0; i < colElements.length; i++) {
                var pct = 100*percentages[i]/colWidthTotal;
                // Store value using at most two decimal places
                pct = Math.round(100*pct)/100;
                DOM_setAttribute(colElements[i],"width",pct+"%");
            }
        }

        function notNull(arg)
        {
            return (arg != null);
        }

        function getPercentage(str)
        {
            if (str.match(/^\s*\d+(\.\d+)?\s*%\s*$/))
                return parseInt(str.replace(/\s*%\s*$/,""));
            else
                return null;
        }
    }

    // private
    function addColElement(structure,oldIndex,right)
    {
        var table = structure.element;

        var colElements = getColElements(table);
        if (colElements.length == 0) {
            // The table doesn't have any COL elements; don't add any
            return;
        }

        addMissingColElements(structure,colElements);

        var prevColElement = colElements[oldIndex];
        var newColElement = DOM_createElement(document,"COL");
        DOM_setAttribute(newColElement,"width",prevColElement.getAttribute("width"));
        if (right)
            DOM_insertBefore(prevColElement.parentNode,newColElement,prevColElement.nextSibling);
        else
            DOM_insertBefore(prevColElement.parentNode,newColElement,prevColElement);

        if (right) {
            colElements.splice(oldIndex+1,0,newColElement);
        }
        else {
            colElements.splice(oldIndex+1,0,newColElement);
        }

        fixColPercentages(structure,colElements);
    }

    // private
    function deleteColElements(structure,left,right)
    {
        var table = structure.element;

        var colElements = getColElements(table);
        if (colElements.length == 0) {
            // The table doesn't have any COL elements
            return;
        }

        addMissingColElements(structure,colElements);

        for (var col = left; col <= right; col++)
            DOM_deleteNode(colElements[col]);
        colElements.splice(left,right-left+1);

        fixColPercentages(structure,colElements);
    }

    // private
    function addColumnCells(structure,oldIndex,right)
    {
        for (var row = 0; row < structure.numRows; row++) {
            var cell = Table_get(structure,row,oldIndex);
            var oldTD = cell.element;
            if (cell.row == row) {

                if (((right && (oldIndex+1 < cell.col + cell.colspan)) ||
                    (!right && (oldIndex-1 >= cell.col))) &&
                    (cell.colspan > 1)) {
                    Cell_setColspan(cell,cell.colspan+1);
                }
                else {
                    var newTD = createEmptyTableCell(oldTD.nodeName); // check-ok
                    if (right)
                        DOM_insertBefore(cell.element.parentNode,newTD,oldTD.nextSibling);
                    else
                        DOM_insertBefore(cell.element.parentNode,newTD,oldTD);
                    if (cell.rowspan != 1)
                        DOM_setAttribute(newTD,"rowspan",cell.rowspan);
                }
            }
        }
    }

    function insertColumnAdjacentToRange(range)
    {
        var table;

        table = tableAtLeftOfRange(range);
        if (table != null) {
            var right = table.numCols-1;
            addColElement(table,right,right+1);
            addColumnCells(table,right,true);
            return;
        }

        table = tableAtRightOfRange(range);
        if (table != null) {
            var left = 0;
            addColElement(table,left,left-1);
            addColumnCells(table,left,false);
            return;
        }
    }

    // public
    Tables_addAdjacentColumn = function()
    {
        UndoManager_newGroup("Insert column at right");
        Selection_preserveWhileExecuting(function() {
            var range = Selection_get();
            var region = Tables_regionFromRange(range,true);
            if (region != null) {
                addColElement(region.structure,region.right,region.right+1);
                addColumnCells(region.structure,region.right,true);
            }
            else {
                insertColumnAdjacentToRange(range);
            }
        });
        UndoManager_newGroup();
    }

    function columnHasContent(table,col)
    {
        for (var row = 0; row < table.numRows; row++) {
            var cell = Table_get(table,row,col);
            if ((cell != null) && (cell.col == col) && nodeHasContent(cell.element))
                return true;
        }
        return false;
    }

    function rowHasContent(table,row)
    {
        for (var col = 0; col < table.numCols; col++) {
            var cell = Table_get(table,row,col);
            if ((cell != null) && (cell.row == row) && nodeHasContent(cell.element))
                return true;
        }
        return false;
    }

    function selectRegion(table,top,bottom,left,right)
    {
        left = clampCol(table,left);
        right = clampCol(table,right);
        top = clampRow(table,top);
        bottom = clampRow(table,bottom);

        var tlCell = Table_get(table,top,left);
        var brCell = Table_get(table,bottom,right);
        if ((tlCell != null) && (brCell != null)) {
            var tlPos = new Position(tlCell.element,0);
            tlPos = Position_closestMatchForwards(tlPos,Position_okForMovement);

            var brPos = new Position(brCell.element,brCell.element.childNodes.length);
            brPos = Position_closestMatchBackwards(brPos,Position_okForMovement);

            Selection_set(tlPos.node,tlPos.offset,brPos.node,brPos.offset);
        }
    }

    function clampCol(table,col)
    {
        if (col > table.numCols-1)
            col = table.numCols-1;
        if (col < 0)
            col = 0;
        return col;
    }

    function clampRow(table,row)
    {
        if (row > table.numRows-1)
            row = table.numRows-1;
        if (row < 0)
            row = 0;
        return row;
    }

    function removeRowAdjacentToRange(range)
    {
        var table;

        table = tableAtLeftOfRange(range);
        if ((table != null) && (table.numRows >= 2)) {
            UndoManager_newGroup("Delete one row");
            var row = table.numRows-1;
            Tables_deleteRegion(new TableRegion(table,row,row,0,table.numCols-1));
            UndoManager_newGroup();
            return;
        }

        table = tableAtRightOfRange(range);
        if ((table != null) && (table.numRows >= 2)) {
            UndoManager_newGroup("Delete one row");
            Tables_deleteRegion(new TableRegion(table,0,0,0,table.numCols-1));
            UndoManager_newGroup();
            return;
        }
    }

    Tables_removeAdjacentRow = function()
    {
        var range = Selection_get();
        var region = Tables_regionFromRange(range,true);

        if (region == null) {
            removeRowAdjacentToRange(range);
            return;
        }

        if (region.structure.numRows <= 1)
            return;

        UndoManager_newGroup("Delete one row");

        var table = region.structure;
        var left = region.left;
        var right = region.right;
        var top = region.top;
        var bottom = region.bottom;

        // Is there an empty row below the selection? If so, delete it
        if ((bottom+1 < table.numRows) && !rowHasContent(table,bottom+1)) {
            Selection_preserveWhileExecuting(function() {
                Tables_deleteRegion(new TableRegion(table,bottom+1,bottom+1,0,table.numCols-1));
            });
        }

        // Is there an empty row above the selection? If so, delete it
        else if ((top-1 >= 0) && !rowHasContent(table,top-1)) {
            Selection_preserveWhileExecuting(function() {
                Tables_deleteRegion(new TableRegion(table,top-1,top-1,0,table.numCols-1));
            });
        }


        // There are no empty rows adjacent to the selection. Delete the right-most row
        // of the selection (which may be the only one)
        else {
            Selection_preserveWhileExecuting(function() {
                Tables_deleteRegion(new TableRegion(table,bottom,bottom,0,table.numCols-1));
            });

            table = Tables_analyseStructure(table.element);
            var multiple = (top != bottom);

            if (multiple) {
                selectRegion(table,top,bottom-1,left,right);
            }
            else {
                var newRow = clampRow(table,bottom);
                var newCell = Table_get(table,newRow,left);
                if (newCell != null) {
                    var pos = new Position(newCell.element,0);
                    pos = Position_closestMatchForwards(pos,Position_okForMovement);
                    Selection_set(pos.node,pos.offset,pos.node,pos.offset);
                }
            }
        }

        UndoManager_newGroup();
    }

    function removeColumnAdjacentToRange(range)
    {
        var table;

        table = tableAtLeftOfRange(range);
        if ((table != null) && (table.numCols >= 2)) {
            UndoManager_newGroup("Delete one column");
            var col = table.numCols-1;
            Tables_deleteRegion(new TableRegion(table,0,table.numRows-1,col,col));
            UndoManager_newGroup();
            return;
        }

        table = tableAtRightOfRange(range);
        if ((table != null) && (table.numCols >= 2)) {
            UndoManager_newGroup("Delete one column");
            Tables_deleteRegion(new TableRegion(table,0,table.numRows-1,0,0));
            UndoManager_newGroup();
            return;
        }
    }

    Tables_removeAdjacentColumn = function()
    {
        var range = Selection_get();
        var region = Tables_regionFromRange(range,true);

        if (region == null) {
            removeColumnAdjacentToRange(range);
            return;
        }

        if (region.structure.numCols <= 1)
            return;

        UndoManager_newGroup("Delete one column");

        var table = region.structure;
        var left = region.left;
        var right = region.right;
        var top = region.top;
        var bottom = region.bottom;

        // Is there an empty column to the right of the selection? If so, delete it
        if ((right+1 < table.numCols) && !columnHasContent(table,right+1)) {
            Selection_preserveWhileExecuting(function() {
                Tables_deleteRegion(new TableRegion(table,0,table.numRows-1,right+1,right+1));
            });
        }

        // Is there an empty column to the left of the selection? If so, delete it
        else if ((left-1 >= 0) && !columnHasContent(table,left-1)) {
            Selection_preserveWhileExecuting(function() {
                Tables_deleteRegion(new TableRegion(table,0,table.numRows-1,left-1,left-1));
            });
        }

        // There are no empty columns adjacent to the selection. Delete the right-most column
        // of the selection (which may be the only one)
        else {
            Selection_preserveWhileExecuting(function() {
                Tables_deleteRegion(new TableRegion(table,0,table.numRows-1,right,right));
            });

            table = Tables_analyseStructure(table.element);
            var multiple = (left != right);

            if (multiple) {
                selectRegion(table,top,bottom,left,right-1);
            }
            else {
                var newCol = clampCol(table,right);
                var newCell = Table_get(table,top,newCol);
                if (newCell != null) {
                    var pos = new Position(newCell.element,0);
                    pos = Position_closestMatchForwards(pos,Position_okForMovement);
                    Selection_set(pos.node,pos.offset,pos.node,pos.offset);
                }
            }
        }

        UndoManager_newGroup();
    }

    // private
    function deleteTable(structure)
    {
        DOM_deleteNode(structure.element);
    }

    // private
    function deleteRows(structure,top,bottom)
    {
        var trElements = new Array();
        getTRs(structure.element,trElements);

        for (var row = top; row <= bottom; row++)
            DOM_deleteNode(trElements[row]);
    }

    // private
    function getTRs(node,result)
    {
        if (node._type == HTML_TR) {
            result.push(node);
        }
        else {
            for (var child = node.firstChild; child != null; child = child.nextSibling)
                getTRs(child,result);
        }
    }

    // private
    function deleteColumns(structure,left,right)
    {
        var nodesToDelete = new NodeSet();
        for (var row = 0; row < structure.numRows; row++) {
            for (var col = left; col <= right; col++) {
                var cell = Table_get(structure,row,col);
                nodesToDelete.add(cell.element);
            }
        }
        nodesToDelete.forEach(DOM_deleteNode);
        deleteColElements(structure,left,right);
    }

    // private
    function deleteCellContents(region)
    {
        var structure = region.structure;
        for (var row = region.top; row <= region.bottom; row++) {
            for (var col = region.left; col <= region.right; col++) {
                var cell = Table_get(structure,row,col);
                DOM_deleteAllChildren(cell.element);
            }
        }
    }

    // public
    Tables_deleteRegion = function(region)
    {
        var structure = region.structure;

        var coversEntireWidth = (region.left == 0) && (region.right == structure.numCols-1);
        var coversEntireHeight = (region.top == 0) && (region.bottom == structure.numRows-1);

        if (coversEntireWidth && coversEntireHeight)
            deleteTable(region.structure);
        else if (coversEntireWidth)
            deleteRows(structure,region.top,region.bottom);
        else if (coversEntireHeight)
            deleteColumns(structure,region.left,region.right);
        else
            deleteCellContents(region);
    }

    // public
    Tables_clearCells = function()
    {
    }

    // public
    Tables_mergeCells = function()
    {
        Selection_preserveWhileExecuting(function() {
            var region = Tables_regionFromRange(Selection_get());
            if (region == null)
                return;

            var structure = region.structure;

            // FIXME: handle the case of missing cells
            // (or even better, add cells where there are some missing)

            for (var row = region.top; row <= region.bottom; row++) {
                for (var col = region.left; col <= region.right; col++) {
                    var cell = Table_get(structure,row,col);
                    var cellFirstRow = cell.row;
                    var cellLastRow = cell.row + cell.rowspan - 1;
                    var cellFirstCol = cell.col;
                    var cellLastCol = cell.col + cell.colspan - 1;

                    if ((cellFirstRow < region.top) || (cellLastRow > region.bottom) ||
                        (cellFirstCol < region.left) || (cellLastCol > region.right)) {
                        debug("Can't merge this table: cell at "+row+","+col+
                              " goes outside bounds of selection");
                        return;
                    }
                }
            }

            var mergedCell = Table_get(structure,region.top,region.left);

            for (var row = region.top; row <= region.bottom; row++) {
                for (var col = region.left; col <= region.right; col++) {
                    var cell = Table_get(structure,row,col);
                    // parentNode will be null if we've already done this cell
                    if ((cell != mergedCell) && (cell.element.parentNode != null)) {
                        while (cell.element.firstChild != null)
                            DOM_appendChild(mergedCell.element,cell.element.firstChild);
                        DOM_deleteNode(cell.element);
                    }
                }
            }

            var totalRows = region.bottom - region.top + 1;
            var totalCols = region.right - region.left + 1;
            if (totalRows == 1)
                DOM_removeAttribute(mergedCell.element,"rowspan");
            else
                DOM_setAttribute(mergedCell.element,"rowspan",totalRows);
            if (totalCols == 1)
                DOM_removeAttribute(mergedCell.element,"colspan");
            else
                DOM_setAttribute(mergedCell.element,"colspan",totalCols);
        });
    }

    // public
    Tables_splitSelection = function()
    {
        Selection_preserveWhileExecuting(function() {
            var range = Selection_get();
            Range_trackWhileExecuting(range,function() {
                var region = Tables_regionFromRange(range,true);
                if (region != null)
                    TableRegion_splitCells(region);
            });
        });
    }

    // public
    TableRegion_splitCells = function(region)
    {
        var structure = region.structure;
        var trElements = new Array();
        getTRs(structure.element,trElements);

        for (var row = region.top; row <= region.bottom; row++) {
            for (var col = region.left; col <= region.right; col++) {
                var cell = Table_get(structure,row,col);
                if ((cell.rowspan > 1) || (cell.colspan > 1)) {

                    var original = cell.element;

                    for (var r = cell.top; r <= cell.bottom; r++) {
                        for (var c = cell.left; c <= cell.right; c++) {
                            if ((r == cell.top) && (c == cell.left))
                                continue;
                            var newTD = createEmptyTableCell(original.nodeName); // check-ok
                            var nextElement = null;

                            var nextCol = cell.right+1;
                            while (nextCol < structure.numCols) {
                                var nextCell = Table_get(structure,r,nextCol);
                                if ((nextCell != null) && (nextCell.row == r)) {
                                    nextElement = nextCell.element;
                                    break;
                                }
                                nextCol++;
                            }

                            DOM_insertBefore(trElements[r],newTD,nextElement);
                            Table_set(structure,r,c,new Cell(newTD,r,c));
                        }
                    }
                    DOM_removeAttribute(original,"rowspan");
                    DOM_removeAttribute(original,"colspan");
                }
            }
        }
    }

    // public
    Tables_cloneRegion = function(region)
    {
        var cellNodesDone = new NodeSet();
        var table = DOM_shallowCopyElement(region.structure.element);
        for (var row = region.top; row <= region.bottom; row++) {
            var tr = DOM_createElement(document,"TR");
            DOM_appendChild(table,tr);
            for (var col = region.left; col <= region.right; col++) {
                var cell = Table_get(region.structure,row,col);
                if (!cellNodesDone.contains(cell.element)) {
                    DOM_appendChild(tr,DOM_cloneNode(cell.element,true));
                    cellNodesDone.add(cell.element);
                }
            }
        }
        return table;
    }

    // private
    function pasteCells(fromTableElement,toRegion)
    {
        // FIXME
        var fromStructure = Tables_analyseStructure(fromTableElement);
    }

    // public
    Table_fix = function(table)
    {
        var changed = false;

        var tbody = null;
        for (var child = table.element.firstChild; child != null; child = child.nextSibling) {
            if (child._type == HTML_TBODY)
                tbody = child;
        }

        if (tbody == null)
            return table; // FIXME: handle presence of THEAD and TFOOT, and also a missing TBODY

        var trs = new Array();
        for (var child = tbody.firstChild; child != null; child = child.nextSibling) {
            if (child._type == HTML_TR)
                trs.push(child);
        }

        while (trs.length < table.numRows) {
            var tr = DOM_createElement(document,"TR");
            DOM_appendChild(tbody,tr);
            trs.push(tr);
        }

        for (var row = 0; row < table.numRows; row++) {
            for (var col = 0; col < table.numCols; col++) {
                var cell = Table_get(table,row,col);
                if (cell == null) {
                    var td = createEmptyTableCell("TD");
                    DOM_appendChild(trs[row],td);
                    changed = true;
                }
            }
        }

        if (changed)
            return new Table(table.element);
        else
            return table;
    }

    // public
    Table_fixColumnWidths = function(structure)
    {
        var colElements = getColElements(structure.element);
        if (colElements.length == 0)
            return;
        addMissingColElements(structure,colElements);

        var widths = Tables_getColWidths(structure);
        fixWidths(widths,structure.numCols);
        colElements = getColElements(structure.element);
        for (var i = 0; i < widths.length; i++)
            DOM_setAttribute(colElements[i],"width",widths[i]+"%");
    }

    // public
    Tables_analyseStructure = function(element)
    {
        // FIXME: we should probably be preserving the selection here, since we are modifying
        // the DOM (though I think it's unlikely it would cause problems, becausing the fixup
        // logic only adds elements). However this method is called (indirectly) from within
        // Selection_update(), which causes unbounded recursion due to the subsequent Selecton_set()
        // that occurs.
        var initial = new Table(element);
        var fixed = Table_fix(initial);
        return fixed;
    }

    // public
    Tables_findContainingCell = function(node)
    {
        for (var ancestor = node; ancestor != null; ancestor = ancestor.parentNode) {
            if (isTableCell(ancestor))
                return ancestor;
        }
        return null;
    }

    // public
    Tables_findContainingTable = function(node)
    {
        for (var ancestor = node; ancestor != null; ancestor = ancestor.parentNode) {
            if (ancestor._type == HTML_TABLE)
                return ancestor;
        }
        return null;
    }

    function TableRegion(structure,top,bottom,left,right)
    {
        this.structure = structure;
        this.top = top;
        this.bottom = bottom;
        this.left = left;
        this.right = right;
    }

    TableRegion.prototype.toString = function()
    {
        return "("+this.top+","+this.left+") - ("+this.bottom+","+this.right+")";
    }

    // public
    Tables_regionFromRange = function(range,allowSameCell)
    {
        var region = null;

        if (range == null)
            return null;

        var start = Position_closestActualNode(range.start,true);
        var end = Position_closestActualNode(range.end,true);

        var startTD = Tables_findContainingCell(start);
        var endTD = Tables_findContainingCell(end);

        if (!isTableCell(start) || !isTableCell(end)) {
            if (!allowSameCell) {
                if (startTD == endTD) // not in cell, or both in same cell
                    return null;
            }
        }

        if ((startTD == null) || (endTD == null))
            return null;

        var startTable = Tables_findContainingTable(startTD);
        var endTable = Tables_findContainingTable(endTD);

        if (startTable != endTable)
            return null;

        var structure = Tables_analyseStructure(startTable);

        var startInfo = structure.cellsByElement.get(startTD);
        var endInfo = structure.cellsByElement.get(endTD);

        var startTopRow = startInfo.row;
        var startBottomRow = startInfo.row + startInfo.rowspan - 1;
        var startLeftCol = startInfo.col;
        var startRightCol = startInfo.col + startInfo.colspan - 1;

        var endTopRow = endInfo.row;
        var endBottomRow = endInfo.row + endInfo.rowspan - 1;
        var endLeftCol = endInfo.col;
        var endRightCol = endInfo.col + endInfo.colspan - 1;

        var top = (startTopRow < endTopRow) ? startTopRow : endTopRow;
        var bottom = (startBottomRow > endBottomRow) ? startBottomRow : endBottomRow;
        var left = (startLeftCol < endLeftCol) ? startLeftCol : endLeftCol;
        var right = (startRightCol > endRightCol) ? startRightCol : endRightCol;

        var region = new TableRegion(structure,top,bottom,left,right);
        adjustRegionForSpannedCells(region);
        return region;
    }

    // private
    function adjustRegionForSpannedCells(region)
    {
        var structure = region.structure;
        var boundariesOk;
        var columnsOk;
        do {
            boundariesOk = true;
            for (var row = region.top; row <= region.bottom; row++) {
                var cell = Table_get(structure,row,region.left);
                if (region.left > cell.left) {
                    region.left = cell.left;
                    boundariesOk = false;
                }
                cell = Table_get(structure,row,region.right);
                if (region.right < cell.right) {
                    region.right = cell.right;
                    boundariesOk = false;
                }
            }

            for (var col = region.left; col <= region.right; col++) {
                var cell = Table_get(structure,region.top,col);
                if (region.top > cell.top) {
                    region.top = cell.top;
                    boundariesOk = false;
                }
                cell = Table_get(structure,region.bottom,col);
                if (region.bottom < cell.bottom) {
                    region.bottom = cell.bottom;
                    boundariesOk = false;
                }
            }
        } while (!boundariesOk);
    }

    Tables_getSelectedTableId = function()
    {
        var element = Cursor_getAdjacentNodeWithType(HTML_TABLE);
        return element ? element.getAttribute("id") : null;
    }

    Tables_getProperties = function(itemId)
    {
        var element = document.getElementById(itemId);
        if ((element == null) || (element._type != HTML_TABLE))
            return null;
        var structure = Tables_analyseStructure(element);
        var width = element.style.width;
        return { width: width, rows: structure.numRows, cols: structure.numCols };
    }

    Tables_setProperties = function(itemId,width)
    {
        var table = document.getElementById(itemId);
        if (table == null)
            return null;
        DOM_setStyleProperties(table,{ width: width });
        Selection_update(); // ensure cursor/selection drawn in correct pos
    }

    // Returns an array of numbers representing the percentage widths (0 - 100) of each
    // column. This works on the assumption that all tables are supposed to have all of
    // their column widths specified, and in all cases as percentages. Any which do not
    // are considered invalid, and have any non-percentage values filled in based on the
    // average values of all valid percentage-based columns.
    Tables_getColWidths = function(structure)
    {
        var colElements = getColElements(structure.element);
        var colWidths = new Array();

        for (var i = 0; i < structure.numCols; i++) {
            var value = null;

            if (i < colElements.length) {
                var widthStr = DOM_getAttribute(colElements[i],"width");
                if (widthStr != null) {
                    value = parsePercentage(widthStr);
                }
            }

            if ((value != null) && (value >= 1.0)) {
                colWidths[i] = value;
            }
            else {
                colWidths[i] = null;
            }
        }

        fixWidths(colWidths,structure.numCols);

        return colWidths;

        function parsePercentage(str)
        {
            if (str.match(/^\s*\d+(\.\d+)?\s*%\s*$/))
                return parseFloat(str.replace(/\s*%\s*$/,""));
            else
                return null;
        }
    }

    function fixWidths(colWidths,numCols)
    {
        var totalWidth = 0;
        var numValidCols = 0;
        for (var i = 0; i < numCols; i++) {
            if (colWidths[i] != null) {
                totalWidth += colWidths[i];
                numValidCols++;
            }
        }

        var averageWidth = (numValidCols > 0) ? totalWidth/numValidCols : 1.0;
        for (var i = 0; i < numCols; i++) {
            if (colWidths[i] == null) {
                colWidths[i] = averageWidth;
                totalWidth += averageWidth;
            }
        }

        // To cater for the case where the column widths do not all add up to 100%,
        // recalculate all of them based on their value relative to the total width
        // of all columns. For example, if there are three columns of 33%, 33%, and 33%,
        // these will get rounded up to 33.33333.....%.
        // If there are no column widths defined, each will have 100/numCols%.
        if (totalWidth > 0) {
            for (var i = 0; i < numCols; i++) {
                colWidths[i] = 100.0*colWidths[i]/totalWidth;
            }
        }
    }

    // public
    Tables_setColWidths = function(itemId,widths)
    {
        var element = document.getElementById(itemId);
        if (element == null)
            return null;

        var structure = Tables_analyseStructure(element);

        fixWidths(widths,structure.numCols);

        var colElements = getColElements(element);
        for (var i = 0; i < widths.length; i++)
            DOM_setAttribute(colElements[i],"width",widths[i]+"%");

        Selection_update();
    }

    // public
    Tables_getGeometry = function(itemId)
    {
        var element = document.getElementById(itemId);
        if ((element == null) || (element.parentNode == null))
            return null;

        var structure = Tables_analyseStructure(element);

        var result = new Object();

        // Calculate the rect based on the cells, not the whole table element;
        // we want to ignore the caption
        var topLeftCell = Table_get(structure,0,0);
        var bottomRightCell = Table_get(structure,structure.numRows-1,structure.numCols-1);

        if (topLeftCell == null)
            throw new Error("No top left cell");
        if (bottomRightCell == null)
            throw new Error("No bottom right cell");

        var topLeftRect = topLeftCell.element.getBoundingClientRect();
        var bottomRightRect = bottomRightCell.element.getBoundingClientRect();

        var left = topLeftRect.left + window.scrollX;
        var right = bottomRightRect.right + window.scrollX;
        var top = topLeftRect.top + window.scrollY;
        var bottom = bottomRightRect.bottom + window.scrollY;

        result.contentRect = { x: left, y: top, width: right - left, height: bottom - top };
        result.fullRect = xywhAbsElementRect(element);
        result.parentRect = xywhAbsElementRect(element.parentNode);

        result.columnWidths = Tables_getColWidths(structure);

        var caption = firstChildOfType(element,HTML_CAPTION);
        result.hasCaption = (caption != null);

        return result;

    }

})();