bring in khatru and eventstore.

eventstore/mmm/count.go

@@ -0,0 +1,91 @@
+package mmm
+
+import (
+	"bytes"
+	"context"
+	"encoding/binary"
+	"slices"
+
+	"github.com/PowerDNS/lmdb-go/lmdb"
+	"github.com/fiatjaf/eventstore/mmm/betterbinary"
+	"github.com/nbd-wtf/go-nostr"
+)
+
+func (il *IndexingLayer) CountEvents(ctx context.Context, filter nostr.Filter) (int64, error) {
+	var count int64 = 0
+
+	queries, extraAuthors, extraKinds, extraTagKey, extraTagValues, since, err := il.prepareQueries(filter)
+	if err != nil {
+		return 0, err
+	}
+
+	err = il.lmdbEnv.View(func(txn *lmdb.Txn) error {
+		// actually iterate
+		for _, q := range queries {
+			cursor, err := txn.OpenCursor(q.dbi)
+			if err != nil {
+				continue
+			}
+
+			it := &iterator{cursor: cursor}
+			it.seek(q.startingPoint)
+
+			for {
+				// we already have a k and a v and an err from the cursor setup, so check and use these
+				if it.err != nil ||
+					len(it.key) != q.keySize ||
+					!bytes.HasPrefix(it.key, q.prefix) {
+					// either iteration has errored or we reached the end of this prefix
+					break // stop this cursor and move to the next one
+				}
+
+				// "id" indexes don't contain a timestamp
+				if q.timestampSize == 4 {
+					createdAt := binary.BigEndian.Uint32(it.key[len(it.key)-4:])
+					if createdAt < since {
+						break
+					}
+				}
+
+				if extraAuthors == nil && extraKinds == nil && extraTagValues == nil {
+					count++
+				} else {
+					// fetch actual event
+					pos := positionFromBytes(it.posb)
+					bin := il.mmmm.mmapf[pos.start : pos.start+uint64(pos.size)]
+
+					// check it against pubkeys without decoding the entire thing
+					if extraAuthors != nil && !slices.Contains(extraAuthors, [32]byte(bin[39:71])) {
+						it.next()
+						continue
+					}
+
+					// check it against kinds without decoding the entire thing
+					if extraKinds != nil && !slices.Contains(extraKinds, [2]byte(bin[1:3])) {
+						it.next()
+						continue
+					}
+
+					// decode the entire thing (TODO: do a conditional decode while also checking the extra tag)
+					event := &nostr.Event{}
+					if err := betterbinary.Unmarshal(bin, event); err != nil {
+						it.next()
+						continue
+					}
+
+					// if there is still a tag to be checked, do it now
+					if !event.Tags.ContainsAny(extraTagKey, extraTagValues) {
+						it.next()
+						continue
+					}
+
+					count++
+				}
+			}
+		}
+
+		return nil
+	})
+
+	return count, err
+}