Urgh I made some wrong amends and I'm too tired to separate the commits out this time

ancestor: Split out of reachability
mergebase: Add merge base routines
internal/commitquery: Add commit query context engine thingy
internal/peel: Shared tag peeling
errors: Shared object query errors
internal/testgit: Add rooted repo helpers; remove raw path access
objectstore/memory: Add in-memory object store
objectid: Add Compare helper

1 files changed, 95 insertions, 0 deletions

diff --git a/internal/commitquery/oid.go b/internal/commitquery/oid.go
new file mode 100644
index 00000000..7ba05eb5
--- /dev/null
+++ b/internal/commitquery/oid.go
@@ -0,0 +1,95 @@
+package commitquery
+
+import (
+	stderrors "errors"
+
+	giterrors "codeberg.org/lindenii/furgit/errors"
+	commitgraphread "codeberg.org/lindenii/furgit/format/commitgraph/read"
+	"codeberg.org/lindenii/furgit/object"
+	"codeberg.org/lindenii/furgit/objectid"
+	"codeberg.org/lindenii/furgit/objectstore"
+	"codeberg.org/lindenii/furgit/objecttype"
+)
+
+// ID returns the canonical object ID of one internal node.
+func (ctx *Context) ID(idx NodeIndex) objectid.ObjectID {
+	return ctx.nodes[idx].id
+}
+
+// CommitTime returns the committer timestamp used for one internal node.
+func (ctx *Context) CommitTime(idx NodeIndex) int64 {
+	return ctx.nodes[idx].commitTime
+}
+
+// ResolveOID resolves one commit object ID to one internal query node.
+func (ctx *Context) ResolveOID(id objectid.ObjectID) (NodeIndex, error) {
+	idx, ok := ctx.byOID[id]
+	if ok {
+		err := ctx.ensureLoaded(idx)
+		if err != nil {
+			return 0, err
+		}
+
+		return idx, nil
+	}
+
+	idx = ctx.newNode(id)
+	ctx.byOID[id] = idx
+
+	err := ctx.loadByOID(idx)
+	if err != nil {
+		delete(ctx.byOID, id)
+
+		return 0, err
+	}
+
+	return idx, nil
+}
+
+// loadByOID populates one node from an object ID.
+func (ctx *Context) loadByOID(idx NodeIndex) error {
+	id := ctx.nodes[idx].id
+
+	if ctx.graph != nil {
+		pos, err := ctx.graph.Lookup(id)
+		if err != nil {
+			var notFound *commitgraphread.NotFoundError
+			if !stderrors.As(err, &notFound) {
+				return err
+			}
+		} else {
+			return ctx.loadCommitAtGraphPos(idx, pos)
+		}
+	}
+
+	ty, content, err := ctx.store.ReadBytesContent(id)
+	if err != nil {
+		if stderrors.Is(err, objectstore.ErrObjectNotFound) {
+			return &giterrors.ObjectMissingError{OID: id}
+		}
+
+		return err
+	}
+
+	if ty != objecttype.TypeCommit {
+		return &giterrors.ObjectTypeError{OID: id, Got: ty, Want: objecttype.TypeCommit}
+	}
+
+	commitObj, err := object.ParseCommit(content, id.Algorithm())
+	if err != nil {
+		return err
+	}
+
+	parents := make([]Parent, 0, len(commitObj.Parents))
+	for _, parentID := range commitObj.Parents {
+		parents = append(parents, Parent{ID: parentID})
+	}
+
+	commit := Commit{
+		ID:         id,
+		Parents:    parents,
+		CommitTime: commitObj.Committer.WhenUnix,
+	}
+
+	return ctx.populateNode(idx, commit)
+}