public async Task <List <ISequential> > SortBySequence(IEnumerable <ISequential> enumerable, ISequential origin, ISequential target)
{
var list = enumerable.ToList();
using (var db = _context.Database.BeginTransaction())
{
// normalize
foreach (var a in list)
{
a.Sequence = list.IndexOf(a) + 1;
}
var start = list.IndexOf(target);
if (origin.Sequence > target.Sequence)
{
for (var i = start; i < list.Count - 1; i++)
{
list[i].Sequence = list[i].Sequence + 1;
}
origin.Sequence = target.Sequence - 1;
}
else
{
for (var i = start; i >= origin.Sequence; i--)
{
list[i].Sequence = list[i].Sequence - 1;
}
origin.Sequence = target.Sequence + 1;
}
await _context.SaveChangesAsync();
db.Commit();
return(list.OrderBy(a => a.Sequence).ToList());
}
}
public async Task CompleteAsync()
{
await _context.SaveChangesAsync();
}