HtmlPreviewVisitor handle text/calender separately

[TimBo93]

Hi @jstedfast ,

thank you for your awesome library!

I use it this library to convert mails to html to display them in a browser.
Today we found e-mails with a Content-Type: text/calendar; charset="utf-8"; method=REQUEST section before a text/html section.

At this point:

MimeKit/UnitTests/HtmlPreviewVisitor.cs

Line 177 in f2404c0

if (body != null) {

we fill a body with an .ics file content instead of the actual html content.

My first patch would look like this:

protected override void VisitTextPart(TextPart entity)
{
    TextConverter converter;

    if (body != null)
    {
        // since we've already found the body, treat this as an attachment
        attachments.Add(entity);
        return;
    }

    // we want to treat text/calendar as an attachment, not as a regular text part.
    if (entity.ContentType.IsMimeType("text", "calendar"))
    {
        calenderAttachments.Add(entity);
        return;
    }

    if (entity.IsHtml)
    {
...

where calenderAttachments is just a new list of readonly List<MimeEntity> calenderAttachments = new List<MimeEntity>();

I would love to know what your thoughts about this calender stuff are.

Kind regards
Tim

[jstedfast]

Yea, your modification is probably the best way to handle it.

[TimBo93]

nice! Thank you for your fast reply.

Do you think it makes sense that I create a PR for the calendar case? Or is it a special edge case that doesn't necessarily need attention?

[jstedfast]

Sure, go ahead and submit a PR