SIL.Cog.Application.ViewModels.MultipleWordAlignmentViewModel.AlignWords C# (CSharp) Method

        private void AlignWords()
        {
            if (_selectedMeaning == null || !_projectService.AreAllVarietiesCompared)
                return;

            _busyService.ShowBusyIndicatorUntilFinishDrawing();

            var words = new HashSet<Word>();
            foreach (VarietyPair vp in _projectService.Project.VarietyPairs)
            {
                WordPair wp;
                if (vp.WordPairs.TryGetValue(_selectedMeaning.DomainMeaning, out wp))
                {
                    words.Add(wp.Word1);
                    words.Add(wp.Word2);
                }
            }
            if (words.Count == 0)
            {
                _words.Clear();
                return;
            }

            IWordAligner aligner = _projectService.Project.WordAligners[ComponentIdentifiers.PrimaryWordAligner];
            Alignment<Word, ShapeNode> alignment;
            if (words.Count == 1)
            {
                Word word = words.First();
                Annotation<ShapeNode> prefixAnn = word.Prefix;
                var prefix = new AlignmentCell<ShapeNode>(prefixAnn != null ? word.Shape.GetNodes(prefixAnn.Span).Where(NodeFilter) : Enumerable.Empty<ShapeNode>());
                IEnumerable<AlignmentCell<ShapeNode>> columns = word.Shape.GetNodes(word.Stem.Span).Where(NodeFilter).Select(n => new AlignmentCell<ShapeNode>(n));
                Annotation<ShapeNode> suffixAnn = word.Suffix;
                var suffix = new AlignmentCell<ShapeNode>(suffixAnn != null ? word.Shape.GetNodes(suffixAnn.Span).Where(NodeFilter) : Enumerable.Empty<ShapeNode>());
                alignment = new Alignment<Word, ShapeNode>(0, 0, Tuple.Create(word, prefix, columns, suffix));
            }
            else
            {
                IWordAlignerResult result = aligner.Compute(words);
                alignment = result.GetAlignments().First();
            }

            List<Cluster<Word>> cognateSets = _projectService.Project.GenerateCognateSets(_selectedMeaning.DomainMeaning).OrderBy(c => c.Noise).ThenByDescending(c => c.DataObjects.Count).ToList();
            ColumnCount = alignment.ColumnCount;
            using (_words.BulkUpdate())
            {
                _words.Clear();
                for (int i = 0; i < alignment.SequenceCount; i++)
                {
                    AlignmentCell<ShapeNode> prefix = alignment.Prefixes[i];
                    Word word = alignment.Sequences[i];
                    IEnumerable<AlignmentCell<ShapeNode>> columns = Enumerable.Range(0, alignment.ColumnCount).Select(col => alignment[i, col]);
                    AlignmentCell<ShapeNode> suffix = alignment.Suffixes[i];
                    int cognateSetIndex = cognateSets.FindIndex(set => set.DataObjects.Contains(word));
                    _words.Add(new MultipleWordAlignmentWordViewModel(this, word, prefix, columns, suffix, cognateSetIndex == cognateSets.Count - 1 ? int.MaxValue : cognateSetIndex + 1));
                }
            }
            IsEmpty = false;
        }