Edit Header/Footer of Word Document programmatically using Office Open XML

Scenario- My Client wants to publish policy document(Word Document) to multiple departments with department specific header and footer.

Design-
System.IO.Packing API provides strongly typed classes to manipulate office documents that adhere to office open XML file format specification. An open XML document like Word Document is stored as a package. The package has multiple parts like main document, header, footer etc. with relationship between them. The header part is included in the document by header reference tag. Changing the header information of a Word Document is to delete the existing header part and add a new header part.

Solution-

       public SPFile ProcessHeaderFooter(string targetFilePath, string department)
       {
            string headerInfo = GetHeaderInfo(department);
            string footerInfo = GetFooterInfo(department);
    
            Stream headerStream = new MemoryStream(System.Text.Encoding.UTF8.GetBytes(headerContent));
            Stream footerStream = new MemoryStream(System.Text.Encoding.UTF8.GetBytes  (footerContent));

           SPWeb web = SpContext.Current.Web;
           SPFile targetFile = web.GetFile(targetFilePath);
           MemoryStream fileStream = new MemoryStream();
           fileStream.Write(targetFile.OpenBinary(), 0, (int)targetFile.TotalLength);
           AddHeader(headerStream, fileStream);
           AddFooter(footerStream, fileStream);
           targetFile.SaveBinary(fileStream);
           fileStream.Close();
           return targetFile;
         }

        public void AddHeader(Stream headerContent, Stream fileContent)
        {
            const string documentRelationshipType = "http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument";
            const string wordmlNamespace = "http://schemas.openxmlformats.org/wordprocessingml/2006/main";
            const string headerContentType = "application/vnd.openxmlformats-officedocument.wordprocessingml.header+xml";
            const string headerRelationshipType = "http://schemas.openxmlformats.org/officeDocument/2006/relationships/header";
            const string relationshipNamespace = "http://schemas.openxmlformats.org/officeDocument/2006/relationships";
            PackagePart documentPart = null;
            using (Package wdPackage = Package.Open(fileContent, FileMode.Open, FileAccess.ReadWrite))
            {
                //  Get the main document part (document.xml).
                foreach (System.IO.Packaging.PackageRelationship relationship in wdPackage.GetRelationshipsByType(documentRelationshipType))
                {
                    Uri documentUri = PackUriHelper.ResolvePartUri(new Uri("/", UriKind.Relative), relationship.TargetUri);
                    documentPart = wdPackage.GetPart(documentUri);
                    //  There is only one officeDocument.
                    break;
                }

                Uri uriHeader = new Uri("/word/header1.xml", UriKind.Relative);
                
if (wdPackage.PartExists(uriHeader))
                {                    
                    wdPackage.DeletePart(uriHeader);
                }

                //  Create the header part.
                PackagePart headerPart = wdPackage.CreatePart(uriHeader, headerContentType);                
                XmlDocument headerDoc = new XmlDocument();
                headerContent.Position = 0;
                headerDoc.Load(headerContent);

                //  Write the header out to its part.
                headerDoc.Save(headerPart.GetStream());

                //  Create the document's relationship to the new part.
                PackageRelationship rel = documentPart.CreateRelationship(uriHeader, TargetMode.Internal, headerRelationshipType);
                string relID = rel.Id;

                //  Manage namespaces to perform Xml XPath queries.
                NameTable nt = new NameTable();
                XmlNamespaceManager nsManager = new XmlNamespaceManager(nt);
                nsManager.AddNamespace("w", wordmlNamespace);

                //  Get the document part from the package.
                //  Load the XML in the part into an XmlDocument instance.
                XmlDocument xdoc = new XmlDocument(nt);
                xdoc.Load(documentPart.GetStream());

                //  Find the node containing the document layout.
                XmlNode targetNode = xdoc.SelectSingleNode("//w:sectPr", nsManager);
                if (targetNode != null)
                {
                    //  Delete any existing references to headers.
                    XmlNodeList headerNodes = targetNode.SelectNodes("./w:headerReference", nsManager);
                    foreach (System.Xml.XmlNode headerNode in headerNodes)
                    {
                        targetNode.RemoveChild(headerNode);
                    }

                    //  Create the new header reference node.
                    XmlElement node = xdoc.CreateElement("w:headerReference", wordmlNamespace);
                    XmlAttribute attr = node.Attributes.Append(xdoc.CreateAttribute("r:id", relationshipNamespace));
                    attr.Value = relID;
                    node.Attributes.Append(attr);
                    targetNode.InsertBefore(node, targetNode.FirstChild);
                }

                //  Save the document XML back to its part.
                xdoc.Save(documentPart.GetStream(FileMode.Create, FileAccess.Write));
            }
        }


        public void AddFooter(Stream footerContent, Stream fileContent)
        {
            const string documentRelationshipType = "http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument";
            const string wordmlNamespace = "http://schemas.openxmlformats.org/wordprocessingml/2006/main";
            const string footerContentType = "application/vnd.openxmlformats-officedocument.wordprocessingml.footer+xml";
            const string footerRelationshipType = "http://schemas.openxmlformats.org/officeDocument/2006/relationships/footer";
            const string relationshipNamespace = "http://schemas.openxmlformats.org/officeDocument/2006/relationships";
            PackagePart documentPart = null;
            using (Package wdPackage = Package.Open(fileContent, FileMode.Open, FileAccess.ReadWrite))
            {
                //  Get the main document part (document.xml).
                foreach (System.IO.Packaging.PackageRelationship relationship in wdPackage.GetRelationshipsByType(documentRelationshipType))
                {
                    Uri documentUri = PackUriHelper.ResolvePartUri(new Uri("/", UriKind.Relative), relationship.TargetUri);
                    documentPart = wdPackage.GetPart(documentUri);
                    //  There is only one officeDocument.
                    break;
                }

                Uri uriFooter = new Uri("/word/footer1.xml", UriKind.Relative);
                if (wdPackage.PartExists(uriFooter))
                {
                    //  Although you can delete the relationship
                    //  to the existing node, the next time you save
                    //  the document after making changes, Word
                    //  will delete the relationship.
                    wdPackage.DeletePart(uriFooter);
                }
                //  Create the footer part.
                PackagePart footerPart = wdPackage.CreatePart(uriFooter, footerContentType);

                XmlDocument footerDoc = new XmlDocument();
                footerContent.Position = 0;
                footerDoc.Load(footerContent);
                //  Write the footer out to its part.
                footerDoc.Save(footerPart.GetStream());
                //  Create the document's relationship to the new part.
                PackageRelationship rel = documentPart.CreateRelationship(uriFooter, TargetMode.Internal, footerRelationshipType);
                string relID = rel.Id;

                //  Manage namespaces to perform Xml XPath queries.
                NameTable nt = new NameTable();
                XmlNamespaceManager nsManager = new XmlNamespaceManager(nt);
                nsManager.AddNamespace("w", wordmlNamespace);

                //  Get the document part from the package.
                //  Load the XML in the part into an XmlDocument instance.
                XmlDocument xdoc = new XmlDocument(nt);
                xdoc.Load(documentPart.GetStream());

                //  Find the node containing the document layout.
                XmlNode targetNode = xdoc.SelectSingleNode("//w:sectPr", nsManager);
                if (targetNode != null)
                {
                    //  Delete any existing references to footers.
                    XmlNodeList footerNodes = targetNode.SelectNodes("./w:footerReference", nsManager);
                    foreach (System.Xml.XmlNode footerNode in footerNodes)
                    {
                        targetNode.RemoveChild(footerNode);
                    }

                    //  Create the new footer reference node.
                    XmlElement node = xdoc.CreateElement("w:footerReference", wordmlNamespace);
                    XmlAttribute attr = node.Attributes.Append(xdoc.CreateAttribute("r:id", relationshipNamespace));
                    attr.Value = relID;
                    node.Attributes.Append(attr);
                    targetNode.InsertBefore(node, targetNode.FirstChild);
                }

                //  Save the document XML back to its part.
                xdoc.Save(documentPart.GetStream(FileMode.Create, FileAccess.Write));
            }
        }

References
http://msdn.microsoft.com/en-us/library/bb491088(v=office.12).aspx