Better matching of image URLs to migrate to handle for example Markdown in HTML field

[svdoever]

We use the HTML field to store Markdown. in Markdown images are referenced using [The src image](https://dev.azure.com/DEV-01/19f380ba-c69f-4496-9c8f-68eed9767b86/_apis/wit/attachments/7872efe7-7343-4412-931c-e98a9f93df8a?fileName=srcimg.png =200x400). Image migration did not work for us, so made the image migration algorithm a bit more robust. Might be useful for others as well.

In the file: azure-devops-migration-tools\src\MigrationTools.Clients.TfsObjectModel\Tools\TfsEmbededImagesTool.cs we modifed the function FixEmbededImages(WorkItemData wi, string oldTfsurl, string newTfsurl, string sourcePersonalAccessToken = "") to the following code:

        protected override void FixEmbededImages(WorkItemData wi, string oldTfsurl, string newTfsurl, string sourcePersonalAccessToken = "")
        {
            Log.LogInformation("EmbededImagesRepairEnricher: Fixing HTML field attachments for work item {Id} from {OldTfsurl} to {NewTfsUrl}", wi.Id, oldTfsurl, newTfsurl);

            var oldTfsurlOppositeSchema = GetUrlWithOppositeSchema(oldTfsurl);

            foreach (Field field in wi.ToWorkItem().Fields)
            {
                if (field.FieldDefinition.FieldType != FieldType.Html && field.FieldDefinition.FieldType != FieldType.History)
                    continue;

                try
                {
                    // The RegexPatternForImageUrl pattern is too restrictive, only matches:
                    // < img src="https://dev.azure.com/DEV-01/19f380ba-c69f-4496-9c8f-68eed9767b86/_apis/wit/attachments/7872efe7-7343-4412-931c-e98a9f93df8a?fileName=srcimg.png">
                    // But not:
                    // ! [The src image](https://dev.azure.com/DEV-01/19f380ba-c69f-4496-9c8f-68eed9767b86/_apis/wit/attachments/7872efe7-7343-4412-931c-e98a9f93df8a?fileName=srcimg.png =200x400)
                    // When HTML field is used as a Markdown field.
                    // MatchCollection matches = Regex.Matches((string)field.Value, RegexPatternForImageUrl);
                    var collection = this._processor.Source.InternalCollection; // something like https://dev.azure.com/DEV-01
                    string escapedCollection = Regex.Escape(collection.ToString().TrimEnd('/')); // Escape the collection URL for regex
                    // If the escaped collection ends "/", remove it

                    string imageUrlPattern = $@"{escapedCollection}/[a-f0-9]{{8}}-[a-f0-9]{{4}}-[a-f0-9]{{4}}-[a-f0-9]{{4}}-[a-f0-9]{{12}}/_apis/wit/attachments/[^""\s)]+";
                    MatchCollection matches = Regex.Matches((string)field.Value, imageUrlPattern, RegexOptions.IgnoreCase);
                    foreach (Match match in matches)
                    {
                        if (!match.Value.ToLower().Contains(oldTfsurl.ToLower()) && !match.Value.ToLower().Contains(oldTfsurlOppositeSchema.ToLower()))
                            continue;

                        string newImageLink = "";
                        if (_cachedUploadedUrisBySourceValue.ContainsKey(match.Value))
                        {
                            newImageLink = _cachedUploadedUrisBySourceValue[match.Value];
                        }
                        else
                        {
                            // go upload and get newImageLink
                            newImageLink = UploadedAndRetrieveAttachmentLinkUrl(match.Value, field.Name, wi, sourcePersonalAccessToken);

                            // if unable to store/upload the link, should we cache that result? so the next revision will either just ignore it or try again
                            //   for now, i think the best option is to set it to null so we don't retry an upload, with the assumption being that the next
                            //   upload will most likely fail and just cause the revision process to take longer
                            _cachedUploadedUrisBySourceValue[match.Value] = newImageLink;
                        }

                        if (!string.IsNullOrWhiteSpace(newImageLink))
                        {
                            // the match.Value was either just uploaded or uploaded most likely because of a previous revision. we can replace it
                            field.Value = field.Value.ToString().Replace(match.Value, newImageLink);
                        }
                    }
                }
                catch (Exception ex)
                {
                    Log.LogError(ex, "EmbededImagesRepairEnricher: Unable to fix HTML field attachments for work item {wiId} from {oldTfsurl} to {newTfsurl}", wi.Id, oldTfsurl, newTfsurl);
                    Telemetry.TrackException(ex, null);
                }
            }
        }

Code is in my fork https://github.com/svdoever/azure-devops-migration-tools

[MrHinsh]

Please submit a PR: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/creating-a-pull-request-from-a-fork