// For complete examples and data files, please go to https://github.com/aspose-words/Aspose.Words-for-.NET.git.
/// <summary>
/// Simple implementation of saving a document in the plain text format. Implemented as a Visitor.
/// </summary>
internal class ConvertDocToTxt : DocumentVisitor
{
    public ConvertDocToTxt()
    {
        mIsSkipText = false;
        mBuilder = new StringBuilder();
    }

    /// <summary>
    /// Gets the plain text of the document that was accumulated by the visitor.
    /// </summary>
    public string GetText()
    {
        return mBuilder.ToString();
    }

    /// <summary>
    /// Called when a Run node is encountered in the document.
    /// </summary>
    public override VisitorAction VisitRun(Run run)
    {
        AppendText(run.Text);
        // Let the visitor continue visiting other nodes.
        return VisitorAction.Continue;
    }

    /// <summary>
    /// Called when a FieldStart node is encountered in the document.
    /// </summary>
    public override VisitorAction VisitFieldStart(FieldStart fieldStart)
    {
        // In Microsoft Word, a field code (such as "MERGEFIELD FieldName") follows
        // after a field start character. We want to skip field codes and output field.
        // Result only, therefore we use a flag to suspend the output while inside a field code.
        // Note this is a very simplistic implementation and will not work very well.
        // If you have nested fields in a document.
        mIsSkipText = true;
        return VisitorAction.Continue;
    }

    /// <summary>
    /// Called when a FieldSeparator node is encountered in the document.
    /// </summary>
    public override VisitorAction VisitFieldSeparator(FieldSeparator fieldSeparator)
    {
        // Once reached a field separator node, we enable the output because we are
        // now entering the field result nodes.
        mIsSkipText = false;
        return VisitorAction.Continue;
    }

    /// <summary>
    /// Called when a FieldEnd node is encountered in the document.
    /// </summary>
    public override VisitorAction VisitFieldEnd(FieldEnd fieldEnd)
    {
        // Make sure we enable the output when reached a field end because some fields
        // do not have field separator and do not have field result.
        mIsSkipText = false;
        return VisitorAction.Continue;
    }

    /// <summary>
    /// Called when visiting of a Paragraph node is ended in the document.
    /// </summary>
    public override VisitorAction VisitParagraphEnd(Paragraph paragraph)
    {
        // When outputting to plain text we output Cr+Lf characters.
        AppendText(ControlChar.CrLf);
        return VisitorAction.Continue;
    }

    public override VisitorAction VisitBodyStart(Body body)
    {
        // We can detect beginning and end of all composite nodes such as Section, Body, 
        // Table, Paragraph etc and provide custom handling for them.
        mBuilder.Append("*** Body Started ***\r\n");
        return VisitorAction.Continue;
    }

    public override VisitorAction VisitBodyEnd(Body body)
    {
        mBuilder.Append("*** Body Ended ***\r\n");
        return VisitorAction.Continue;
    }

    /// <summary>
    /// Called when a HeaderFooter node is encountered in the document.
    /// </summary>
    public override VisitorAction VisitHeaderFooterStart(HeaderFooter headerFooter)
    {
        // Returning this value from a visitor method causes visiting of this
        // Node to stop and move on to visiting the next sibling node
        // The net effect in this example is that the text of headers and footers
        // Is not included in the resulting output
        return VisitorAction.SkipThisNode;
    }

    /// <summary>
    /// Adds text to the current output. Honors the enabled/disabled output flag.
    /// </summary>
    private void AppendText(string text)
    {
        if (!mIsSkipText)
            mBuilder.Append(text);
    }

    private readonly StringBuilder mBuilder;
    private bool mIsSkipText;
}