bring in mysql backend from relayer.

mysql/save.go

@@ -0,0 +1,76 @@
+package mysql
+
+import (
+	"context"
+	"encoding/json"
+
+	"github.com/fiatjaf/eventstore"
+	"github.com/nbd-wtf/go-nostr"
+)
+
+func (b *MySQLBackend) SaveEvent(ctx context.Context, evt *nostr.Event) error {
+	deleteQuery, deleteParams, shouldDelete := deleteBeforeSaveSql(evt)
+	if shouldDelete {
+		_, _ = b.DB.ExecContext(ctx, deleteQuery, deleteParams...)
+	}
+
+	sql, params, _ := saveEventSql(evt)
+	res, err := b.DB.ExecContext(ctx, sql, params...)
+	if err != nil {
+		return err
+	}
+
+	nr, err := res.RowsAffected()
+	if err != nil {
+		return err
+	}
+
+	if nr == 0 {
+		return eventstore.ErrDupEvent
+	}
+
+	return nil
+}
+
+func deleteBeforeSaveSql(evt *nostr.Event) (string, []any, bool) {
+	// react to different kinds of events
+	var (
+		query        = ""
+		params       []any
+		shouldDelete bool
+	)
+	if evt.Kind == nostr.KindSetMetadata || evt.Kind == nostr.KindContactList || (10000 <= evt.Kind && evt.Kind < 20000) {
+		// delete past events from this user
+		query = `DELETE FROM event WHERE pubkey = ? AND kind = ?`
+		params = []any{evt.PubKey, evt.Kind}
+		shouldDelete = true
+	} else if evt.Kind == nostr.KindRecommendServer {
+		// delete past recommend_server events equal to this one
+		query = `DELETE FROM event WHERE pubkey = ? AND kind = ? AND content = ?`
+		params = []any{evt.PubKey, evt.Kind, evt.Content}
+		shouldDelete = true
+	} else if evt.Kind >= 30000 && evt.Kind < 40000 {
+		// NIP-33
+		d := evt.Tags.GetFirst([]string{"d"})
+		if d != nil {
+			query = `DELETE FROM event WHERE pubkey = ? AND kind = ? AND tags LIKE ?`
+			params = []any{evt.PubKey, evt.Kind, d.Value()}
+			shouldDelete = true
+		}
+	}
+
+	return query, params, shouldDelete
+}
+
+func saveEventSql(evt *nostr.Event) (string, []any, error) {
+	const query = `INSERT INTO event (
+	id, pubkey, created_at, kind, tags, content, sig)
+	VALUES (?, ?, ?, ?, ?, ?, ?)`
+
+	var (
+		tagsj, _ = json.Marshal(evt.Tags)
+		params   = []any{evt.ID, evt.PubKey, evt.CreatedAt, evt.Kind, tagsj, evt.Content, evt.Sig}
+	)
+
+	return query, params, nil
+}