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pkg/data/dedupestor/metadata.go

@@ -0,0 +1,123 @@
+// Package dedupestor provides a key-value store with deduplication based on content hashing
+package dedupestor
+
+import (
+	"encoding/binary"
+)
+
+// Metadata represents a stored value with its ID and references
+type Metadata struct {
+	ID         uint32      // ID of the stored data in the database
+	References []Reference // List of references to this data
+}
+
+// Reference represents a reference to stored data
+type Reference struct {
+	Owner uint16 // Owner identifier
+	ID    uint32 // Reference identifier
+}
+
+// ToBytes converts Metadata to bytes for storage
+func (m Metadata) ToBytes() []byte {
+	// Calculate size: 4 bytes for ID + 6 bytes per reference
+	size := 4 + (len(m.References) * 6)
+	result := make([]byte, size)
+
+	// Write ID (4 bytes)
+	binary.LittleEndian.PutUint32(result[0:4], m.ID)
+
+	// Write references (6 bytes each)
+	offset := 4
+	for _, ref := range m.References {
+		refBytes := ref.ToBytes()
+		copy(result[offset:offset+6], refBytes)
+		offset += 6
+	}
+
+	return result
+}
+
+// BytesToMetadata converts bytes back to Metadata
+func BytesToMetadata(b []byte) Metadata {
+	if len(b) < 4 {
+		return Metadata{
+			ID:         0,
+			References: []Reference{},
+		}
+	}
+
+	id := binary.LittleEndian.Uint32(b[0:4])
+	refs := []Reference{}
+
+	// Parse references (each reference is 6 bytes)
+	for i := 4; i < len(b); i += 6 {
+		if i+6 <= len(b) {
+			refs = append(refs, BytesToReference(b[i:i+6]))
+		}
+	}
+
+	return Metadata{
+		ID:         id,
+		References: refs,
+	}
+}
+
+// AddReference adds a new reference if it doesn't already exist
+func (m Metadata) AddReference(ref Reference) (Metadata, error) {
+	// Check if reference already exists
+	for _, existing := range m.References {
+		if existing.Owner == ref.Owner && existing.ID == ref.ID {
+			return m, nil
+		}
+	}
+
+	// Add the new reference
+	newRefs := append(m.References, ref)
+	return Metadata{
+		ID:         m.ID,
+		References: newRefs,
+	}, nil
+}
+
+// RemoveReference removes a reference if it exists
+func (m Metadata) RemoveReference(ref Reference) (Metadata, error) {
+	newRefs := []Reference{}
+	for _, existing := range m.References {
+		if existing.Owner != ref.Owner || existing.ID != ref.ID {
+			newRefs = append(newRefs, existing)
+		}
+	}
+
+	return Metadata{
+		ID:         m.ID,
+		References: newRefs,
+	}, nil
+}
+
+// ToBytes converts Reference to bytes
+func (r Reference) ToBytes() []byte {
+	result := make([]byte, 6)
+	
+	// Write owner (2 bytes)
+	binary.LittleEndian.PutUint16(result[0:2], r.Owner)
+	
+	// Write ID (4 bytes)
+	binary.LittleEndian.PutUint32(result[2:6], r.ID)
+	
+	return result
+}
+
+// BytesToReference converts bytes to Reference
+func BytesToReference(b []byte) Reference {
+	if len(b) < 6 {
+		return Reference{}
+	}
+	
+	owner := binary.LittleEndian.Uint16(b[0:2])
+	id := binary.LittleEndian.Uint32(b[2:6])
+	
+	return Reference{
+		Owner: owner,
+		ID:    id,
+	}
+}