Switched to Index brand random Snowflakes instead of SharpIds.

If you were still handling message ids as integers in an environment that can't handle signed 64-bit integers you're going to be having a fun time after this update!

SharpChatCommon/Snowflake/SnowflakeGenerator.cs

@@ -0,0 +1,35 @@
+namespace SharpChat.Snowflake {
+    public class SnowflakeGenerator {
+        public const long MASK = 0x7FFFFFFFFFFFFFFF;
+        // previous default epoch was 1588377600000, but snowflakes are much larger than SharpIds
+        public const long EPOCH = 1356998400000;
+        public const byte SHIFT = 16;
+
+        public readonly long Epoch;
+        public readonly byte Shift;
+        public readonly long TimestampMask;
+        public readonly long SequenceMask;
+
+        public SnowflakeGenerator(long epoch = EPOCH, byte shift = SHIFT) {
+            if(epoch is < 0 or > MASK)
+                throw new ArgumentException("Epoch must be a positive int64.", nameof(epoch));
+            if(shift is < 1 or > 63)
+                throw new ArgumentException("Shift must be between or equal to 1 and 63", nameof(shift));
+
+            Epoch = epoch;
+            Shift = shift;
+
+            // i think Index only does this as a hack for how integers work in PHP but its gonna run Once per application instance lol
+            TimestampMask = ~(~0L << (63 - shift));
+            SequenceMask = ~(~0L << shift);
+        }
+
+        public long Now(DateTimeOffset? at = null) {
+            return Math.Max(0, (at ?? DateTimeOffset.UtcNow).ToUnixTimeMilliseconds() - Epoch);
+        }
+
+        public long Next(long sequence, DateTimeOffset? at = null) {
+            return ((Now(at) & TimestampMask) << Shift) | (sequence & SequenceMask);
+        }
+    }
+}