Handling of OutlookSynchronizer alias.

Wino.Core/Extensions/OutlookIntegratorExtensions.cs

@@ -1,5 +1,9 @@
 using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
 using Microsoft.Graph.Models;
+using MimeKit;
 using Wino.Core.Domain.Entities;
 using Wino.Core.Domain.Enums;
 
@@ -61,5 +65,143 @@ namespace Wino.Core.Extensions
 
             return mailCopy;
         }
+
+        public static Message AsOutlookMessage(this MimeMessage mime, string threadId)
+        {
+            var fromAddress = GetRecipients(mime.From).ElementAt(0);
+            var toAddresses = GetRecipients(mime.To).ToList();
+            var ccAddresses = GetRecipients(mime.Cc).ToList();
+            var bccAddresses = GetRecipients(mime.Bcc).ToList();
+            var replyToAddresses = GetRecipients(mime.ReplyTo).ToList();
+
+            var message = new Message()
+            {
+                Subject = mime.Subject,
+                Importance = GetImportance(mime.Importance),
+                Body = new ItemBody() { ContentType = BodyType.Html, Content = mime.HtmlBody },
+                IsDraft = false,
+                IsRead = true, // Sent messages are always read.
+                ToRecipients = toAddresses,
+                CcRecipients = ccAddresses,
+                BccRecipients = bccAddresses,
+                From = fromAddress,
+                InternetMessageId = GetMessageIdHeader(mime.MessageId),
+                ConversationId = threadId,
+                InternetMessageHeaders = GetHeaderList(mime),
+                ReplyTo = replyToAddresses,
+                Attachments = []
+            };
+
+            foreach (var part in mime.BodyParts)
+            {
+                if (part.IsAttachment)
+                {
+                    // File attachment.
+
+                    using var memory = new MemoryStream();
+                    ((MimePart)part).Content.DecodeTo(memory);
+
+                    var bytes = memory.ToArray();
+
+                    var fileAttachment = new FileAttachment()
+                    {
+                        ContentId = part.ContentId,
+                        Name = part.ContentDisposition?.FileName ?? part.ContentType.Name,
+                        ContentBytes = bytes,
+                    };
+
+                    message.Attachments.Add(fileAttachment);
+                }
+                else if (part.ContentDisposition != null && part.ContentDisposition.Disposition == "inline")
+                {
+                    // Inline attachment.
+
+                    using var memory = new MemoryStream();
+                    ((MimePart)part).Content.DecodeTo(memory);
+
+                    var bytes = memory.ToArray();
+                    var inlineAttachment = new FileAttachment()
+                    {
+                        IsInline = true,
+                        ContentId = part.ContentId,
+                        Name = part.ContentDisposition?.FileName ?? part.ContentType.Name,
+                        ContentBytes = bytes
+                    };
+
+                    message.Attachments.Add(inlineAttachment);
+                }
+            }
+
+            return message;
+        }
+
+        #region Mime to Outlook Message Helpers
+
+        private static IEnumerable<Recipient> GetRecipients(this InternetAddressList internetAddresses)
+        {
+            foreach (var address in internetAddresses)
+            {
+                if (address is MailboxAddress mailboxAddress)
+                    yield return new Recipient() { EmailAddress = new EmailAddress() { Address = mailboxAddress.Address, Name = mailboxAddress.Name } };
+                else if (address is GroupAddress groupAddress)
+                {
+                    // TODO: Group addresses are not directly supported.
+                    // It'll be individually added.
+
+                    foreach (var mailbox in groupAddress.Members)
+                        if (mailbox is MailboxAddress groupMemberMailAddress)
+                            yield return new Recipient() { EmailAddress = new EmailAddress() { Address = groupMemberMailAddress.Address, Name = groupMemberMailAddress.Name } };
+                }
+            }
+        }
+
+        private static Importance? GetImportance(MessageImportance importance)
+        {
+            return importance switch
+            {
+                MessageImportance.Low => Importance.Low,
+                MessageImportance.Normal => Importance.Normal,
+                MessageImportance.High => Importance.High,
+                _ => null
+            };
+        }
+
+        private static List<InternetMessageHeader> GetHeaderList(this MimeMessage mime)
+        {
+            // Graph API only allows max of 5 headers.
+            // Here we'll try to ignore some headers that are not neccessary.
+            // Outlook API will generate them automatically.
+
+            string[] headersToIgnore = ["Date", "To", "MIME-Version", "From", "Subject", "Message-Id"];
+
+            var headers = new List<InternetMessageHeader>();
+
+            int includedHeaderCount = 0;
+
+            foreach (var header in mime.Headers)
+            {
+                if (!headersToIgnore.Contains(header.Field))
+                {
+                    headers.Add(new InternetMessageHeader() { Name = header.Field, Value = header.Value });
+                    includedHeaderCount++;
+                }
+
+                if (includedHeaderCount >= 5) break;
+            }
+
+            return headers;
+        }
+
+        private static string GetMessageIdHeader(string messageId)
+        {
+            // Message-Id header must always start with "X-" or "x-".
+            if (string.IsNullOrEmpty(messageId)) return string.Empty;
+
+            if (!messageId.StartsWith("x-") || !messageId.StartsWith("X-"))
+                return $"X-{messageId}";
+
+            return messageId;
+        }
+        #endregion
     }
 }