public Reachability Merge(IEnumerable<UniqueAddress> allowed, Reachability other)
{
var recordBuilder = ImmutableList.CreateBuilder<Record>();
//TODO: Size hint somehow?
var newVersions = _versions;
foreach (var observer in allowed)
{
var observerVersion1 = CurrentVersion(observer);
var observerVersion2 = other.CurrentVersion(observer);
var rows1 = ObserverRows(observer);
var rows2 = other.ObserverRows(observer);
if (rows1 != null && rows2 != null)
{
var rows = observerVersion1 > observerVersion2 ? rows1 : rows2;
foreach(var record in rows.Values.Where(r => allowed.Contains(r.Subject)))
recordBuilder.Add(record);
}
if (rows1 != null && rows2 == null)
{
if(observerVersion1 > observerVersion2)
foreach (var record in rows1.Values.Where(r => allowed.Contains(r.Subject)))
recordBuilder.Add(record);
}
if (rows1 == null && rows2 != null)
{
if (observerVersion2 > observerVersion1)
foreach (var record in rows2.Values.Where(r => allowed.Contains(r.Subject)))
recordBuilder.Add(record);
}
if (observerVersion2 > observerVersion1)
newVersions = newVersions.SetItem(observer, observerVersion2);
}
newVersions = ImmutableDictionary.CreateRange(newVersions.Where(p => allowed.Contains(p.Key)));
return new Reachability(recordBuilder.ToImmutable(), newVersions);
}