1 files changed, 106 insertions, 0 deletions
diff --git a/object/store/packed/store_lookup.go b/object/store/packed/store_lookup.go
new file mode 100644
index 00000000..882a8888
--- /dev/null
+++ b/object/store/packed/store_lookup.go
@@ -0,0 +1,106 @@
+package packed
+
+import (
+	"errors"
+
+	objectid "codeberg.org/lindenii/furgit/object/id"
+	"codeberg.org/lindenii/furgit/object/store"
+)
+
+// lookup resolves one object ID to its pack location.
+func (store *Store) lookup(id objectid.ObjectID) (location, error) {
+	var zero location
+	if id.Algorithm() != store.algo {
+		return zero, errors.New("objectstore/packed: object id algorithm mismatch")
+	}
+
+	snapshot, err := store.ensureCandidates()
+	if err != nil {
+		return zero, err
+	}
+
+	loc, ok, err := store.lookupInCandidates(id, snapshot)
+	if err != nil {
+		return zero, err
+	}
+
+	if ok {
+		return loc, nil
+	}
+
+	if store.refreshPolicy == RefreshPolicyOnMissing { //nolint:nestif
+		err = store.Refresh()
+		if err != nil {
+			return zero, err
+		}
+
+		refreshed := store.candidates.Load()
+		if refreshed != nil && refreshed != snapshot {
+			loc, ok, err = store.lookupInCandidates(id, refreshed)
+			if err != nil {
+				return zero, err
+			}
+
+			if ok {
+				return loc, nil
+			}
+		}
+	}
+
+	return zero, objectstore.ErrObjectNotFound
+}
+
+func (store *Store) lookupInCandidates(
+	id objectid.ObjectID,
+	snapshot *candidateSnapshot,
+) (location, bool, error) {
+	var zero location
+
+	nextPackName := store.firstCandidatePackName(snapshot)
+	for nextPackName != "" {
+		candidate, ok := snapshot.candidateByPack[nextPackName]
+		if !ok {
+			nextPackName = store.firstCandidatePackName(snapshot)
+
+			continue
+		}
+
+		nextPackName = store.nextCandidatePackName(candidate.packName, snapshot)
+
+		index, err := store.openIndex(candidate)
+		if err != nil {
+			return zero, false, err
+		}
+
+		offset, ok, err := index.lookup(id)
+		if err != nil {
+			return zero, false, err
+		}
+
+		if ok {
+			store.touchCandidate(candidate.packName)
+
+			return location{packName: index.packName, offset: offset}, true, nil
+		}
+	}
+
+	for _, candidate := range snapshot.candidates {
+		index, err := store.openIndex(candidate)
+		if err != nil {
+			return zero, false, err
+		}
+
+		offset, ok, err := index.lookup(id)
+		if err != nil {
+			return zero, false, err
+		}
+
+		if ok {
+			store.touchCandidate(candidate.packName)
+
+			return location{packName: index.packName, offset: offset}, true, nil
+		}
+	}
+
+	return zero, false, nil
+}