public int AddIssue(Problem issue)
        {
            if (issue == null)
            {
                throw new ArgumentException();
            }

            issue.Id = this.nextIssueId++;
            this.IssueId_Issue.Add(issue.Id, issue);
            this.UserName_Issue.Add(this.CurrentlyLoggedInUser.Name, issue);

            foreach (var tag in issue.Tags)
            {
                this.TagIssue.Add(tag, issue);
            }

            return issue.Id;
        }
        public string CreateIssue(string title, string description, IssuePriority priority, string[] tags)
        {
            if (this.Data.CurrentlyLoggedInUser == null)
            {
                return string.Format("There is no currently logged in user");
            }

            var issue = new Problem(title, description, priority, tags.Distinct().ToList());

            var issueId = this.Data.AddIssue(issue);

            return string.Format("Issue {0} created successfully.", issueId);
        }