sdk: make it so replaceable stuff is automatically reloaded from time to time.

sdk/loader_helpers.go

@@ -0,0 +1,36 @@
+package sdk
+
+import (
+	"encoding/binary"
+	"encoding/hex"
+
+	"github.com/nbd-wtf/go-nostr"
+)
+
+var kvStoreLastFetchPrefix = byte('f')
+
+func makeLastFetchKey(kind int, pubkey string) []byte {
+	buf := make([]byte, 1+5+32)
+	buf[0] = kvStoreLastFetchPrefix
+	binary.LittleEndian.PutUint32(buf[1:], uint32(kind))
+	hex.Decode(buf[5:], []byte(pubkey))
+	return buf
+}
+
+// encodeTimestamp encodes a unix timestamp as 4 bytes
+func encodeTimestamp(t nostr.Timestamp) []byte {
+	b := make([]byte, 4)
+	binary.BigEndian.PutUint32(b, uint32(t))
+	return b
+}
+
+// decodeTimestamp decodes a 4-byte timestamp into unix seconds
+func decodeTimestamp(b []byte) nostr.Timestamp {
+	return nostr.Timestamp(binary.BigEndian.Uint32(b))
+}
+
+// shouldRefreshFromNetwork checks if we should try fetching from network
+func shouldRefreshFromNetwork(lastFetchData []byte) bool {
+	lastFetch := decodeTimestamp(lastFetchData)
+	return nostr.Now()-lastFetch > 7*24*60*60
+}