*: format/pack -> packfile; format/delta -> delta; delete format

1 files changed, 60 insertions, 0 deletions

diff --git a/packfile/ingest/record_delta.go b/packfile/ingest/record_delta.go
new file mode 100644
index 00000000..a28fcabc
--- /dev/null
+++ b/packfile/ingest/record_delta.go
@@ -0,0 +1,60 @@
+package ingest
+
+import (
+	"fmt"
+
+	deltaapply "codeberg.org/lindenii/furgit/delta/apply"
+	"codeberg.org/lindenii/furgit/objecttype"
+)
+
+// applyDeltaRecord applies one delta record onto base content.
+func applyDeltaRecord(state *ingestState, idx int, baseType objecttype.Type, baseContent []byte) (objecttype.Type, []byte, error) {
+	record := state.records[idx]
+	if record.packedType != objecttype.TypeOfsDelta && record.packedType != objecttype.TypeRefDelta {
+		return objecttype.TypeInvalid, nil, fmt.Errorf("packfile/ingest: record %d is not a delta record", idx)
+	}
+
+	deltaPayload, err := inflateRecordPayload(state, idx)
+	if err != nil {
+		return objecttype.TypeInvalid, nil, err
+	}
+
+	if int64(len(deltaPayload)) != record.declaredSize {
+		return objecttype.TypeInvalid, nil, &MalformedPackEntryError{
+			Offset: record.offset,
+			Reason: fmt.Sprintf("delta payload size mismatch got %d want %d", len(deltaPayload), record.declaredSize),
+		}
+	}
+
+	srcSize, dstSize, err := readDeltaHeaderSizes(deltaPayload)
+	if err != nil {
+		return objecttype.TypeInvalid, nil, &MalformedPackEntryError{
+			Offset: record.offset,
+			Reason: fmt.Sprintf("read delta header: %v", err),
+		}
+	}
+
+	if srcSize != len(baseContent) {
+		return objecttype.TypeInvalid, nil, &MalformedPackEntryError{
+			Offset: record.offset,
+			Reason: fmt.Sprintf("delta source size mismatch got %d want %d", srcSize, len(baseContent)),
+		}
+	}
+
+	content, err := deltaapply.Apply(baseContent, deltaPayload)
+	if err != nil {
+		return objecttype.TypeInvalid, nil, &MalformedPackEntryError{
+			Offset: record.offset,
+			Reason: fmt.Sprintf("apply delta: %v", err),
+		}
+	}
+
+	if len(content) != dstSize {
+		return objecttype.TypeInvalid, nil, &MalformedPackEntryError{
+			Offset: record.offset,
+			Reason: fmt.Sprintf("delta result size mismatch got %d want %d", len(content), dstSize),
+		}
+	}
+
+	return baseType, content, nil
+}