Add support for message-text and delete-identifier

The delete-identifier allows to delete all exiting comments of this identifier in the PR. So the identifier does only exist once.

message.go

@@ -2,20 +2,29 @@ package main
 
 import (
 	"code.gitea.io/sdk/gitea"
+	"fmt"
+	log "github.com/sirupsen/logrus"
+	"strings"
 )
 
 type messageClient struct {
-	Client  *gitea.Client
-	Owner   string
-	Repo    string
-	Index   int64
-	Title   string
-	Message string
+	Client           *gitea.Client
+	Owner            string
+	Repo             string
+	Index            int64
+	Title            string
+	Message          string
+	DeleteIdentifier string
 }
 
 func (mc *messageClient) sendMessage() (*gitea.Comment, *gitea.Response, error) {
+	var body = mc.Message
+	if mc.DeleteIdentifier != "" {
+		body = mc._getDeleteIdentifierMd() + "\n" + body
+	}
+
 	opt := gitea.CreateIssueCommentOption{
-		Body: mc.Message,
+		Body: body,
 	}
 
 	return mc.Client.CreateIssueComment(
@@ -25,3 +34,57 @@ func (mc *messageClient) sendMessage() (*gitea.Comment, *gitea.Response, error)
 		opt,
 	)
 }
+
+// Deletes all comments in the PR that include the DeleteIdentifier.
+// If the DeleteIdentifier is "", the search will not be performed.
+//
+// Returns the number of deleted comments or an error.
+func (mc *messageClient) deletePreviousMessages() (int, error) {
+	if mc.DeleteIdentifier == "" {
+		log.Info("No DeleteIdentifier specified... skipping comment deletion")
+		return 0, nil
+	}
+
+	identifier := mc._getDeleteIdentifierMd()
+	log.WithField("deleteIdentifier", mc.DeleteIdentifier).Info("Start deletion of PR comments")
+	matchingComments, err := mc._searchCommentsForIdentifier(identifier)
+	log.Info("Found comments with identifier: ", len(matchingComments))
+
+	if err != nil {
+		return 0, fmt.Errorf("failed to search for comments. %s", err)
+	}
+
+	for i, comment := range matchingComments {
+		_, err := mc.Client.DeleteIssueComment(mc.Owner, mc.Repo, comment.ID)
+		if err != nil {
+			return i, fmt.Errorf("error deleting comment: %w", err)
+		}
+		log.WithField("id", comment.ID).Info("Deleted comment")
+	}
+
+	log.WithField("numberOfComments", len(matchingComments)).Info("Deletion of old comment(s) completed")
+	return len(matchingComments), nil
+}
+
+// searchCommentsForIdentifier searches for comments containing a specific identifier within a pull request
+func (mc *messageClient) _searchCommentsForIdentifier(identifier string) ([]*gitea.Comment, error) {
+	// Fetch all comments on the specified pull request
+	comments, _, err := mc.Client.ListIssueComments(mc.Owner, mc.Repo, mc.Index, gitea.ListIssueCommentOptions{})
+	if err != nil {
+		return nil, fmt.Errorf("error fetching comments: %w", err)
+	}
+
+	// Filter comments to find those that contain the identifier
+	var matchingComments []*gitea.Comment
+	for _, comment := range comments {
+		if strings.Contains(comment.Body, identifier) {
+			matchingComments = append(matchingComments, comment)
+		}
+	}
+
+	return matchingComments, nil
+}
+
+func (mc *messageClient) _getDeleteIdentifierMd() string {
+	return "<!-- delete-identifier=\"" + mc.DeleteIdentifier + "\" -->"
+}