using DevExpress.XtraRichEdit;
using DevExpress.XtraRichEdit.API.Native;

MemoryStream InsertFields(Stream stream, IEnumerable<string> fieldNames, DocumentFormat targetFormat) {
    using var wordProcessor = new RichEditDocumentServer();
    wordProcessor.LoadDocument(stream);
    Document document = wordProcessor.Document;
    Table table = document.Tables.First();
    document.CalculateDocumentVariable += CalculateDocumentVariable;
    foreach (var fieldType in fieldNames) {
        var row = table.Rows.Append();
        var firstCell = row.FirstCell;
        var secondCell = row.LastCell;
        switch (fieldType) {
            case "DATE":
                document.InsertText(firstCell.Range.Start, "New Date Field");
                document.Fields.Create(secondCell.Range.Start, "DATE");
                break;
            case "TIME":
                document.InsertText(firstCell.Range.Start, "New Time Field");
                document.Fields.Create(secondCell.Range.Start, "TIME");
                break;
            case "PAGE":
                document.InsertText(firstCell.Range.Start, "New Page Field");
                document.Fields.Create(secondCell.Range.Start, "PAGE");
                break;
            case "NUMPAGES":
                document.InsertText(firstCell.Range.Start, "New NumPages Field");
                document.Fields.Create(secondCell.Range.Start, "NUMPAGES");
                break;
            case "DocVariable":
                document.InsertText(firstCell.Range.Start, "New DocVariable Field");
                document.Fields.Create(secondCell.Range.Start, "DocVariable MyVariable");
                break;
            case "AUTHOR":
                document.InsertText(firstCell.Range.Start, "New Author Field");
                document.DocumentProperties.Author = "Test Author";
                document.Fields.Create(secondCell.Range.Start, "AUTHOR");
                break;
            case "TITLE":
                document.InsertText(firstCell.Range.Start, "New Title Field");
                document.DocumentProperties.Title = "Test Title";
                document.Fields.Create(secondCell.Range.Start, "TITLE");
                break;
            case "DOCPROPERTY":
                document.InsertText(firstCell.Range.Start, "New DocProperty Field");
                document.CustomProperties.Add("MyProperty", "Custom Property Value");
                document.Fields.Create(secondCell.Range.Start, "DOCPROPERTY MyProperty");
                break;
        }
    }
    document.UpdateAllFields();
    var outputStream = new MemoryStream();
    wordProcessor.SaveDocument(outputStream, targetFormat);
    outputStream.Position = 0;
    return outputStream;
}

MemoryStream UpdateFields(Stream stream, DocumentFormat targetFormat) {
    using var wordProcessor = new RichEditDocumentServer();
    wordProcessor.CalculateDocumentVariable += CalculateDocumentVariable;
    wordProcessor.LoadDocument(stream);
    Document document = wordProcessor.Document;
    document.UpdateAllFields();
    var outputStream = new MemoryStream();
    wordProcessor.SaveDocument(outputStream, targetFormat);
    outputStream.Position = 0;
    return outputStream;
}

MemoryStream LockFields(Stream stream, IEnumerable<string> fieldNames, DocumentFormat targetFormat) {
    using var wordProcessor = new RichEditDocumentServer();
    wordProcessor.LoadDocument(stream);
    Document document = wordProcessor.Document;
    document.CalculateDocumentVariable += CalculateDocumentVariable;
    document.UpdateAllFields();
    foreach (Field field in document.Fields) {
        field.ShowCodes = true;
        string fieldCode = document.GetText(field.CodeRange).ToUpper().TrimStart();
        if (fieldNames.Any(fn => fieldCode.StartsWith(fn, StringComparison.InvariantCultureIgnoreCase)))
            field.Locked = true;
    }
    var outputStream = new MemoryStream();
    wordProcessor.SaveDocument(outputStream, targetFormat);
    outputStream.Position = 0;
    return outputStream;
}

MemoryStream UnlinkFields(Stream stream, IEnumerable<string> fieldNames, DocumentFormat targetFormat) {
    using var wordProcessor = new RichEditDocumentServer();
    wordProcessor.LoadDocument(stream);
    Document document = wordProcessor.Document;
    document.CalculateDocumentVariable += CalculateDocumentVariable;
    document.UpdateAllFields();
    for (int i = document.Fields.Count - 1; i >= 0; i--) {
        Field field = document.Fields[i];
        field.ShowCodes = true;
        string fieldCode = document.GetText(field.CodeRange).ToUpper().TrimStart();
        if (fieldNames.Any(fn => fieldCode.StartsWith(fn, StringComparison.InvariantCultureIgnoreCase)))
            field.Unlink();
    }
    var outputStream = new MemoryStream();
    wordProcessor.SaveDocument(outputStream, targetFormat);
    outputStream.Position = 0;
    return outputStream;
}

MemoryStream DeleteFields(Stream stream, IEnumerable<string> fieldNames, DocumentFormat targetFormat) {
    using var wordProcessor = new RichEditDocumentServer();
    wordProcessor.LoadDocument(stream);
    Document document = wordProcessor.Document;
    document.CalculateDocumentVariable += CalculateDocumentVariable;
    document.UpdateAllFields();
    for (int i = document.Fields.Count - 1; i >= 0; i--) {
        Field field = document.Fields[i];
        field.ShowCodes = true;
        string fieldCode = document.GetText(field.CodeRange).ToUpper().TrimStart();
        if (fieldNames.Any(fn => fieldCode.StartsWith(fn, StringComparison.InvariantCultureIgnoreCase)))
            document.Delete(field.Range);
    }
    var outputStream = new MemoryStream();
    wordProcessor.SaveDocument(outputStream, targetFormat);
    outputStream.Position = 0;
    return outputStream;
}

void CalculateDocumentVariable(object sender, CalculateDocumentVariableEventArgs e) {
    if (e.VariableName == "MyVariable") {
        e.Value = "My Test Variable " + DateTime.Now.ToString("MMMM dd, yyyy");
        e.Handled = true;
    }
    if (e.VariableName == "Test") {
        var tempWordProcessor = new RichEditDocumentServer();
        tempWordProcessor.Unit = DevExpress.Office.DocumentUnit.Inch;
        Document tempDoc = tempWordProcessor.Document;
        Shape picture = tempDoc.Shapes.InsertPicture(tempDoc.Range.Start, DocumentImageSource.FromFile(DemoDocumentPaths.DevExpressLogo));
        picture.TextWrapping = TextWrappingType.InLineWithText;
        picture.LockAspectRatio = true;
        picture.Width = 2f;
        e.Value = tempWordProcessor;
        e.Handled = true;
    }
}