From 4d1774264affd097dceaa0b1719c0a53e78bc344 Mon Sep 17 00:00:00 2001
From: fiatjaf <fiatjaf@gmail.com>
Date: Sun, 12 Oct 2025 13:55:44 +0000
Subject: [PATCH] mmm: add debug helpers for fixing an inconsistent db.

---
 eventstore/mmm/debug.go | 89 +++++++++++++++++++++++++++++++++++++++++
 eventstore/mmm/query.go |  2 +-
 2 files changed, 90 insertions(+), 1 deletion(-)
 create mode 100644 eventstore/mmm/debug.go

diff --git a/eventstore/mmm/debug.go b/eventstore/mmm/debug.go
new file mode 100644
index 0000000..b671443
--- /dev/null
+++ b/eventstore/mmm/debug.go
@@ -0,0 +1,89 @@
+package mmm
+
+import (
+	"encoding/binary"
+
+	"fiatjaf.com/nostr"
+	"github.com/PowerDNS/lmdb-go/lmdb"
+)
+
+func (b *MultiMmapManager) DebugAtPosition(offset uint64) (idPrefix []byte, layers []*IndexingLayer) {
+	b.lmdbEnv.View(func(txn *lmdb.Txn) error {
+		txn.RawRead = true
+
+		cursor, err := txn.OpenCursor(b.indexId)
+		if err != nil {
+			panic(err)
+		}
+		defer cursor.Close()
+
+		for key, val, err := cursor.Get(nil, nil, lmdb.First); err == nil; key, val, err = cursor.Get(key, val, lmdb.Next) {
+			pos := positionFromBytes(val[0:12])
+
+			if pos.start == offset {
+				idPrefix = key
+				layers = make([]*IndexingLayer, 0, (len(val)-12)/2)
+
+				for s := 12; s < len(val); s += 2 {
+					layer := b.layers.ByID(binary.BigEndian.Uint16(val[s : s+2]))
+					layers = append(layers, layer)
+				}
+
+				return nil
+			}
+		}
+
+		return nil
+	})
+
+	return
+}
+
+func (il *IndexingLayer) HasAtPosition(offset uint64) (
+	exists bool,
+	createdAt nostr.Timestamp,
+	kind nostr.Kind,
+) {
+	il.lmdbEnv.View(func(txn *lmdb.Txn) error {
+		txn.RawRead = true
+
+		{
+			cursor, err := txn.OpenCursor(il.indexCreatedAt)
+			if err != nil {
+				panic(err)
+			}
+			defer cursor.Close()
+
+			for key, val, err := cursor.Get(nil, nil, lmdb.First); err == nil; key, val, err = cursor.Get(key, val, lmdb.Next) {
+				pos := positionFromBytes(val[0:12])
+
+				if pos.start == offset {
+					exists = true
+					createdAt = nostr.Timestamp(binary.BigEndian.Uint32(key))
+					break
+				}
+			}
+		}
+
+		{
+			cursor, err := txn.OpenCursor(il.indexKind)
+			if err != nil {
+				panic(err)
+			}
+			defer cursor.Close()
+
+			for key, val, err := cursor.Get(nil, nil, lmdb.First); err == nil; key, val, err = cursor.Get(key, val, lmdb.Next) {
+				pos := positionFromBytes(val[0:12])
+				if pos.start == offset {
+					exists = true
+					kind = nostr.Kind(binary.BigEndian.Uint16(key))
+					break
+				}
+			}
+		}
+
+		return nil
+	})
+
+	return
+}
diff --git a/eventstore/mmm/query.go b/eventstore/mmm/query.go
index 899c51e..ae40d34 100644
--- a/eventstore/mmm/query.go
+++ b/eventstore/mmm/query.go
@@ -49,7 +49,7 @@ func (b *MultiMmapManager) queryByIDs(
 				pos := positionFromBytes(val[0:12])
 				evt := nostr.Event{}
 				if err := b.loadEvent(pos, &evt); err != nil {
-					panic(fmt.Errorf("failed to decode event from %v: %w", pos, err))
+					panic(fmt.Errorf("failed to decode event %s from %v: %w", id, pos, err))
 				}
 
 				restrictionSatisfied := restrictToLayer == nil