// Sometimes encounter cells that have no r attribute, so infer it if possible.
        // These are invalid spreadsheets, but attempt to get the data anyway.
        private static void FixUpCellsThatHaveNoRAtt(XDocument shXDoc)
        {
            // if there are any rows that have all cells with no r attribute, then fix them up
            var invalidRows = shXDoc
                              .Descendants(S.row)
                              .Where(r => !r.Elements(S.c).Any(c => c.Attribute("r") != null))
                              .ToList();

            foreach (var row in invalidRows)
            {
                var rowNumberStr = (string)row.Attribute("r");
                var colNumber    = 0;
                foreach (var cell in row.Elements(S.c))
                {
                    var newCellRef = XlsxTables.IndexToColumnAddress(colNumber) + rowNumberStr;
                    cell.Add(new XAttribute("r", newCellRef));
                }
            }

            // repeat iteratively until no further fixes can be made
            while (true)
            {
                var invalidCells = shXDoc
                                   .Descendants(S.c)
                                   .Where(c => c.Attribute("r") == null)
                                   .ToList();

                bool didFixup = false;
                foreach (var cell in invalidCells)
                {
                    var followingCell = cell.ElementsAfterSelf(S.c).FirstOrDefault();
                    if (followingCell != null)
                    {
                        var followingR = (string)followingCell.Attribute("r");
                        if (followingR != null)
                        {
                            var spl             = XlsxTables.SplitAddress(followingR);
                            var colIdxFollowing = XlsxTables.ColumnAddressToIndex(spl[0]);
                            var newRef          = XlsxTables.IndexToColumnAddress(colIdxFollowing - 1) + spl[1];
                            cell.Add(new XAttribute("r", newRef));
                            didFixup = true;
                        }
                        else
                        {
                            didFixup = FixUpBasedOnPrecedingCell(didFixup, cell);
                        }
                    }
                    else
                    {
                        didFixup = FixUpBasedOnPrecedingCell(didFixup, cell);
                    }
                }
                if (!didFixup)
                {
                    break;
                }
            }
        }
        private static bool FixUpBasedOnPrecedingCell(bool didFixup, XElement cell)
        {
            XElement precedingCell = GetPrevousElement(cell);

            if (precedingCell != null)
            {
                var precedingR = (string)precedingCell.Attribute("r");
                if (precedingR != null)
                {
                    var spl             = XlsxTables.SplitAddress(precedingR);
                    var colIdxFollowing = XlsxTables.ColumnAddressToIndex(spl[0]);
                    var newRef          = XlsxTables.IndexToColumnAddress(colIdxFollowing + 1) + spl[1];
                    cell.Add(new XAttribute("r", newRef));
                    didFixup = true;
                }
            }
            return(didFixup);
        }
        private static XElement GetCellProps_InTable(SpreadsheetDocument sDoc, XDocument styleXDoc, Table table, Cell tc)
        {
            var style = tc.Style;

            if (style == null)
            {
                return(null);
            }

            var         colIdStr = tc.ColumnAddress;
            int         colNbr   = XlsxTables.ColumnAddressToIndex(colIdStr);
            TableColumn column   = table.TableColumns().FirstOrDefault(z => z.ColumnNumber == colNbr);

            if (column == null)
            {
                throw new FileFormatException("Invalid spreadsheet");
            }

            var cellProps = new XElement("CellProps");
            var d         = column.DataDxfId;

            if (d != null)
            {
                var dataDxf = styleXDoc
                              .Root
                              .Elements(S.dxfs)
                              .Elements(S.dxf)
                              .Skip((int)d)
                              .FirstOrDefault();
                if (dataDxf == null)
                {
                    throw new FileFormatException("Invalid spreadsheet");
                }

                var numFmt = dataDxf.Element(S.numFmt);
                if (numFmt != null)
                {
                    var numFmtId = (int?)numFmt.Attribute("numFmtId");
                    if (numFmtId != null)
                    {
                        cellProps.Add(new XAttribute("numFmtId", numFmtId));
                    }
                    var formatCode = (string)numFmt.Attribute("formatCode");
                    if (formatCode != null)
                    {
                        cellProps.Add(new XAttribute("formatCode", formatCode));
                    }
                }
            }

            var xf = styleXDoc.Root
                     .Elements(S.cellXfs)
                     .Elements(S.xf)
                     .Skip((int)style)
                     .FirstOrDefault();

            if (xf == null)
            {
                throw new FileFormatException("Invalid spreadsheet");
            }

            // if xf has different numFmtId, then replace the ones from the table definition
            var numFmtId2 = (int?)xf.Attribute("numFmtId");

            if (numFmtId2 != null)
            {
                AddNumFmtIdAndFormatCode(styleXDoc, cellProps, numFmtId2);
            }

            var masterXfId = (int?)xf.Attribute("xfId");

            if (masterXfId != null)
            {
                var masterXf = styleXDoc
                               .Root
                               .Elements(S.cellStyleXfs)
                               .Elements(S.xf)
                               .Skip((int)masterXfId)
                               .FirstOrDefault();
                if (masterXf != null)
                {
                    AddFormattingToCellProps(styleXDoc, cellProps, masterXf);
                }
            }

            AddFormattingToCellProps(styleXDoc, cellProps, xf);
            AugmentAndCleanUpProps(cellProps);

            if (!cellProps.HasElements && !cellProps.HasAttributes)
            {
                return(null);
            }
            return(cellProps);
        }
        public static XElement RetrieveRange(SpreadsheetDocument sDoc, string sheetName, int leftColumn, int topRow, int rightColumn, int bottomRow)
        {
            var wbXdoc = sDoc.WorkbookPart.GetXDocument();
            var sheet  = wbXdoc
                         .Root
                         .Elements(S.sheets)
                         .Elements(S.sheet)
                         .FirstOrDefault(s => (string)s.Attribute("name") == sheetName);

            if (sheet == null)
            {
                throw new ArgumentException("Invalid sheet name passed to RetrieveRange", "sheetName");
            }
            var rId = (string)sheet.Attribute(R.id);

            if (rId == null)
            {
                throw new FileFormatException("Invalid spreadsheet");
            }
            var sheetPart = sDoc.WorkbookPart.GetPartById(rId);

            if (sheetPart == null)
            {
                throw new FileFormatException("Invalid spreadsheet");
            }
            var shXDoc = sheetPart.GetXDocument();

            if (sDoc.WorkbookPart.WorkbookStylesPart == null)
            {
                throw new FileFormatException("Invalid spreadsheet.  No WorkbookStylesPart.");
            }
            var styleXDoc = sDoc.WorkbookPart.WorkbookStylesPart.GetXDocument();

            // if there is no shared string table, sharedStringTable will be null
            // it will only be used if there is a cell type == "s", in which case, referencing this
            // part would indicate an invalid spreadsheet.
            SharedStringTablePart sharedStringTable = sDoc.WorkbookPart.SharedStringTablePart;

            FixUpCellsThatHaveNoRAtt(shXDoc);

            // assemble the transform
            var sheetData = shXDoc
                            .Root
                            .Elements(S.sheetData)
                            .Elements(S.row)
                            .Select(row =>
            {
                // filter
                string ra = (string)row.Attribute("r");
                if (ra == null)
                {
                    return(null);
                }
                int rowNbr;
                if (!int.TryParse(ra, out rowNbr))
                {
                    return(null);
                }
                if (rowNbr < topRow)
                {
                    return(null);
                }
                if (rowNbr > bottomRow)
                {
                    return(null);
                }

                var cells = row
                            .Elements(S.c)
                            .Select(cell =>
                {
                    var cellAddress = (string)cell.Attribute("r");
                    if (cellAddress == null)
                    {
                        throw new FileFormatException("Invalid spreadsheet - cell does not have r attribute.");
                    }
                    var splitCellAddress = XlsxTables.SplitAddress(cellAddress);
                    var columnAddress    = splitCellAddress[0];
                    var columnIndex      = XlsxTables.ColumnAddressToIndex(columnAddress);

                    // filter
                    if (columnIndex < leftColumn || columnIndex > rightColumn)
                    {
                        return(null);
                    }

                    var cellType        = (string)cell.Attribute("t");
                    string sharedString = null;
                    if (cellType == "s")
                    {
                        int sharedStringIndex;
                        string sharedStringBeforeParsing = (string)cell.Element(S.v);
                        if (sharedStringBeforeParsing == null)
                        {
                            sharedStringBeforeParsing = (string)cell.Elements(S._is).Elements(S.t).FirstOrDefault();
                        }
                        if (sharedStringBeforeParsing == null)
                        {
                            throw new FileFormatException("Invalid document");
                        }
                        if (!int.TryParse(sharedStringBeforeParsing, out sharedStringIndex))
                        {
                            throw new FileFormatException("Invalid document");
                        }
                        XElement sharedStringElement = null;
                        if (sharedStringTable == null)
                        {
                            throw new FileFormatException("Invalid spreadsheet.  Shared string, but no Shared String Part.");
                        }
                        sharedStringElement =
                            sharedStringTable
                            .GetXDocument()
                            .Root
                            .Elements(S.si)
                            .Skip(sharedStringIndex)
                            .FirstOrDefault();
                        if (sharedStringElement == null)
                        {
                            throw new FileFormatException("Invalid spreadsheet.  Shared string reference not valid.");
                        }
                        sharedString =
                            sharedStringElement
                            .Descendants(S.t)
                            .StringConcatenate(e => (string)e);
                    }

                    if (sharedString != null)
                    {
                        XElement cellProps = GetCellProps_NotInTable(sDoc, styleXDoc, cell);
                        string value       = sharedString;
                        string displayValue;
                        string color = null;
                        if (cellProps != null)
                        {
                            displayValue = SmlCellFormatter.FormatCell(
                                (string)cellProps.Attribute("formatCode"),
                                value,
                                out color);
                        }
                        else
                        {
                            displayValue = value;
                        }
                        XElement newCell1 = new XElement("Cell",
                                                         new XAttribute("Ref", (string)cell.Attribute("r")),
                                                         new XAttribute("ColumnId", columnAddress),
                                                         new XAttribute("ColumnNumber", columnIndex),
                                                         cell.Attribute("f") != null ? new XAttribute("Formula", (string)cell.Attribute("f")) : null,
                                                         cell.Attribute("s") != null ? new XAttribute("Style", (string)cell.Attribute("s")) : null,
                                                         cell.Attribute("t") != null ? new XAttribute("Type", (string)cell.Attribute("t")) : null,
                                                         cellProps,
                                                         new XElement("Value", value),
                                                         new XElement("DisplayValue", displayValue),
                                                         color != null ? new XElement("DisplayColor", color) : null
                                                         );
                        return(newCell1);
                    }
                    else
                    {
                        var type       = (string)cell.Attribute("t");
                        XElement value = new XElement("Value", cell.Value);
                        if (type != null && type == "inlineStr")
                        {
                            type = "s";
                        }
                        XAttribute typeAttr = null;
                        if (type != null)
                        {
                            typeAttr = new XAttribute("Type", type);
                        }

                        XElement cellProps = GetCellProps_NotInTable(sDoc, styleXDoc, cell);
                        string displayValue;
                        string color = null;
                        if (cellProps != null)
                        {
                            displayValue = SmlCellFormatter.FormatCell(
                                (string)cellProps.Attribute("formatCode"),
                                cell.Value,
                                out color);
                        }
                        else
                        {
                            displayValue = displayValue = SmlCellFormatter.FormatCell(
                                (string)"General",
                                cell.Value,
                                out color);
                        }
                        XElement newCell2 = new XElement("Cell",
                                                         new XAttribute("Ref", (string)cell.Attribute("r")),
                                                         new XAttribute("ColumnId", columnAddress),
                                                         new XAttribute("ColumnNumber", columnIndex),
                                                         typeAttr,
                                                         cell.Attribute("f") != null ? new XAttribute("Formula", (string)cell.Attribute("f")) : null,
                                                         cell.Attribute("s") != null ? new XAttribute("Style", (string)cell.Attribute("s")) : null,
                                                         cellProps,
                                                         value,
                                                         new XElement("DisplayValue", displayValue),
                                                         color != null ? new XElement("DisplayColor", color) : null);
                        return(newCell2);
                    }
                });
                XElement dataRow = new XElement("Row",
                                                row.Attribute("r") != null ? new XAttribute("RowNumber", (int)row.Attribute("r")) : null,
                                                cells);
                return(dataRow);
            });

            var      dataProps = GetDataProps(shXDoc);
            XElement data      = new XElement("Data",
                                              dataProps,
                                              sheetData);

            return(data);
        }