How to work with bookmarks in Word OpenXML

HandlingBookmarksWithOpenXML.cs

/*** EXTENSTION METHODS START ***/

public static T GetFirstDescendant<T>(this OpenXmlElement parent) where T : OpenXmlElement
{
    var descendants = parent.Descendants<T>();

    if (descendants != null)
        return descendants.FirstOrDefault();
    else
        return null;
}

public static T GetParent<T>(this OpenXmlElement child) where T : OpenXmlElement
{
    while (child != null)
    {
        child = child.Parent;

        if (child is T)
            return (T)child;
    }

    return null;
}

public static bool IsEndBookmark(this OpenXmlElement element, BookmarkStart startBookmark)
{
    return IsEndBookmark(element as BookmarkEnd, startBookmark);
}

public static bool IsEndBookmark(this BookmarkEnd endBookmark, BookmarkStart startBookmark)
{
    if (endBookmark == null)
        return false;

    return endBookmark.Id == startBookmark.Id;
}

/*** EXTENSTION METHODS  END ***/

public IDictionary<string, string> GetDocumentBookmarkValues(bool includeHiddenBookmarks = false)
{
    IDictionary<string, string> bookmarks = new Dictionary<string, string>();

    foreach (var bookmark in GetAllBookmarks())
    {
        if (includeHiddenBookmarks || !IsHiddenBookmark(bookmark.Name))
            bookmarks[bookmark.Name] = GetText(bookmark);
    }
    return bookmarks;
}

public void SetDocumentBookmarkValues(IDictionary<string, string> bookmarkValues)
{
    foreach (var bookmark in GetAllBookmarks())
    {
        SetBookmarkValue(bookmark, bookmarkValues);
    }
}

private IEnumerable<BookmarkStart> GetAllBookmarks()
{
    return Document.MainDocumentPart.RootElement.Descendants<BookmarkStart>();
}

private bool IsHiddenBookmark(string bookmarkName)
{
    return bookmarkName.StartsWith("_");
}

public string GetText(BookmarkStart bookmark)
{
    var text = FindBookmarkText(bookmark);

    if (text != null)
        return text.Text;
    else
        return string.Empty;
}

private void SetBookmarkValue(BookmarkStart bookmark, IDictionary<string, string> bookmarkValues)
{
    string value;

    if (bookmarkValues.TryGetValue(bookmark.Name, out value))
    {
        SetText(bookmark, value);
    }
}

public void SetText(BookmarkStart bookmark, string value)
{
    var text = FindBookmarkText(bookmark);

    if (text != null)
    {
        text.Text = value;
        RemoveOtherTexts(bookmark, text);
    }
    else
        InsertBookmarkText(bookmark, value);
}

private Text FindBookmarkText(BookmarkStart bookmark)
{
    if (bookmark.ColumnFirst != null)
        return FindTextInColumn(bookmark);
    else
    {
        var run = bookmark.NextSibling<Run>();

        if (run != null)
            return run.GetFirstChild<Text>();
        else
        {
            Text text = null;
            var nextSibling = bookmark.NextSibling();
            while (text == null && nextSibling != null)
            {
                if (nextSibling.IsEndBookmark(bookmark))
                    return null;

                text = nextSibling.GetFirstDescendant<Text>();
                nextSibling = nextSibling.NextSibling();
            }

            return text;
        }
    }
}

private Text FindTextInColumn(BookmarkStart bookmark)
{
    var cell = bookmark.GetParent<TableRow>().GetFirstChild<TableCell>();

    for (int i = 0; i < bookmark.ColumnFirst; i++)
    {
        cell = cell.NextSibling<TableCell>();
    }

    return cell.GetFirstDescendant<Text>();
}

private void RemoveOtherTexts(BookmarkStart bookmark, Text keep)
{
    if (bookmark.ColumnFirst != null) return;

    Text text = null;
    var nextSibling = bookmark.NextSibling();
    while (text == null && nextSibling != null)
    {
        if (nextSibling.IsEndBookmark(bookmark))
            break;

        foreach (var item in nextSibling.Descendants<Text>())
        {
            if (item != keep)
                item.Remove();
        }
        nextSibling = nextSibling.NextSibling();
    }
}

private void InsertBookmarkText(BookmarkStart bookmark, string value)
{
    bookmark.Parent.InsertAfter(new Run(new Text(value)), bookmark);
}

Related links:
http://emptycode.blogspot.com/2013/02/handling-bookmarks-in-openxml-word.html
https://msdn.microsoft.com/en-us/library/bb448854.aspx

@paulsm4 - actually the new place for that blog is http://peter.grman.at/handling-bookmarks-in-openxml-word/ - but thx for adding it here

For me the detection of IsEndBookmark does not work (SetText removes too much text). Changed it to this:

return endBookmark.Id.HasValue && startBookmark.Id.HasValue && (endBookmark.Id.Value == startBookmark.Id.Value);

By this problem:
https://github.com/Leviasan/Extensions/tree/master/Leviasan.Extension.DocumentFormat.OpenXml
NuGet:
https://www.nuget.org/packages/Leviasan.Extension.DocumentFormat.OpenXml/1.0.2