Burak Kaan Köse
122 lines
3.5 KiB
C#
122 lines
3.5 KiB
C#
using System;
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using System.IO;
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using System.Linq;
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using System.Text;
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using MimeKit;
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namespace Wino.Core.Extensions;
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public static class CalendarInvitationExtensions
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{
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public static string ExtractInvitationUid(this MimeMessage message)
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{
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if (message == null)
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{
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return null;
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}
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var icsContent = GetCalendarContent(message);
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if (string.IsNullOrWhiteSpace(icsContent))
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{
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return null;
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}
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var unfolded = UnfoldIcs(icsContent);
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var veventSection = ExtractFirstVEventSection(unfolded);
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if (string.IsNullOrWhiteSpace(veventSection))
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{
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return null;
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}
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return TryReadIcsProperty(veventSection, "UID", out var uid)
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? uid
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: null;
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}
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private static string GetCalendarContent(MimeMessage message)
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{
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var textPart = message.BodyParts
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.OfType<TextPart>()
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.FirstOrDefault(p => p.ContentType?.MimeType?.Equals("text/calendar", StringComparison.OrdinalIgnoreCase) == true);
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if (textPart != null)
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{
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return textPart.Text;
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}
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var mimePart = message.BodyParts
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.OfType<MimePart>()
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.FirstOrDefault(p => p.ContentType?.MimeType?.Equals("text/calendar", StringComparison.OrdinalIgnoreCase) == true);
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if (mimePart == null)
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{
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return null;
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}
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using var stream = new MemoryStream();
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mimePart.Content.DecodeTo(stream);
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var bytes = stream.ToArray();
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if (bytes.Length == 0)
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{
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return null;
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}
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var charset = mimePart.ContentType?.Charset;
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var encoding = string.IsNullOrWhiteSpace(charset) ? Encoding.UTF8 : Encoding.GetEncoding(charset);
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return encoding.GetString(bytes);
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}
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private static string UnfoldIcs(string content)
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=> content
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.Replace("\r\n ", string.Empty, StringComparison.Ordinal)
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.Replace("\r\n\t", string.Empty, StringComparison.Ordinal)
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.Replace("\n ", string.Empty, StringComparison.Ordinal)
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.Replace("\n\t", string.Empty, StringComparison.Ordinal);
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private static string ExtractFirstVEventSection(string ics)
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{
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const string beginVevent = "BEGIN:VEVENT";
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const string endVevent = "END:VEVENT";
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var beginIndex = ics.IndexOf(beginVevent, StringComparison.OrdinalIgnoreCase);
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if (beginIndex < 0)
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{
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return string.Empty;
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}
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var endIndex = ics.IndexOf(endVevent, beginIndex, StringComparison.OrdinalIgnoreCase);
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if (endIndex < 0)
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{
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return ics[beginIndex..];
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}
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return ics.Substring(beginIndex, endIndex - beginIndex + endVevent.Length);
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}
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private static bool TryReadIcsProperty(string icsSection, string propertyName, out string value)
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{
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value = string.Empty;
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var lines = icsSection.Split(["\r\n", "\n"], StringSplitOptions.RemoveEmptyEntries);
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foreach (var rawLine in lines)
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{
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var line = rawLine.Trim();
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if (!line.StartsWith(propertyName, StringComparison.OrdinalIgnoreCase))
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{
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continue;
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}
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var colonIndex = line.IndexOf(':');
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if (colonIndex <= 0 || colonIndex >= line.Length - 1)
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{
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continue;
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}
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value = line[(colonIndex + 1)..].Trim();
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return !string.IsNullOrWhiteSpace(value);
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}
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return false;
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}
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}
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