negentropy.

- a way to handle custom messages from Relay (NEG-whatever etc)
- negentropy implementation (adapted from that other one)
- nip77 nostr negentropy extension
- QueryEvents method for RelayStore that returns a channel (makes negentropy syncing work more seamlessly)

nip77/example/example.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/fiatjaf/eventstore"
+	"github.com/fiatjaf/eventstore/slicestore"
+	"github.com/nbd-wtf/go-nostr"
+	"github.com/nbd-wtf/go-nostr/nip77"
+)
+
+func main() {
+	ctx := context.Background()
+	db := &slicestore.SliceStore{}
+	db.Init()
+
+	sk := nostr.GeneratePrivateKey()
+	local := eventstore.RelayWrapper{Store: db}
+
+	for {
+		for i := 0; i < 20; i++ {
+			{
+				evt := nostr.Event{
+					Kind:      1,
+					Content:   fmt.Sprintf("same old hello %d", i),
+					CreatedAt: nostr.Timestamp(i),
+					Tags:      nostr.Tags{},
+				}
+				evt.Sign(sk)
+				db.SaveEvent(ctx, &evt)
+			}
+
+			{
+				evt := nostr.Event{
+					Kind:      1,
+					Content:   fmt.Sprintf("custom hello %d", i),
+					CreatedAt: nostr.Now(),
+					Tags:      nostr.Tags{},
+				}
+				evt.Sign(sk)
+				db.SaveEvent(ctx, &evt)
+			}
+		}
+
+		err := nip77.NegentropySync(ctx,
+			local, "ws://localhost:7777", nostr.Filter{})
+		if err != nil {
+			panic(err)
+		}
+
+		data, err := local.QuerySync(ctx, nostr.Filter{})
+		if err != nil {
+			panic(err)
+		}
+
+		fmt.Println("total local events:", len(data))
+		time.Sleep(time.Second * 10)
+	}
+}