initial draft of neo4j database driver

pkg/neo4j/markers.go

@@ -0,0 +1,91 @@
+package neo4j
+
+import (
+	"context"
+	"fmt"
+
+	"next.orly.dev/pkg/encoders/hex"
+)
+
+// Markers provide metadata key-value storage using Neo4j Marker nodes
+// We store markers as special nodes with label "Marker"
+
+// SetMarker sets a metadata marker
+func (n *N) SetMarker(key string, value []byte) error {
+	valueHex := hex.Enc(value)
+
+	cypher := `
+MERGE (m:Marker {key: $key})
+SET m.value = $value`
+
+	params := map[string]any{
+		"key":   key,
+		"value": valueHex,
+	}
+
+	_, err := n.ExecuteWrite(context.Background(), cypher, params)
+	if err != nil {
+		return fmt.Errorf("failed to set marker: %w", err)
+	}
+
+	return nil
+}
+
+// GetMarker retrieves a metadata marker
+func (n *N) GetMarker(key string) (value []byte, err error) {
+	cypher := "MATCH (m:Marker {key: $key}) RETURN m.value AS value"
+	params := map[string]any{"key": key}
+
+	result, err := n.ExecuteRead(context.Background(), cypher, params)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get marker: %w", err)
+	}
+
+	ctx := context.Background()
+	neo4jResult, ok := result.(interface {
+		Next(context.Context) bool
+		Record() *interface{}
+		Err() error
+	})
+	if !ok {
+		return nil, fmt.Errorf("invalid result type")
+	}
+
+	if neo4jResult.Next(ctx) {
+		record := neo4jResult.Record()
+		if record != nil {
+			recordMap, ok := (*record).(map[string]any)
+			if ok {
+				if valueStr, ok := recordMap["value"].(string); ok {
+					// Decode hex value
+					value, err = hex.Dec(valueStr)
+					if err != nil {
+						return nil, fmt.Errorf("failed to decode marker value: %w", err)
+					}
+					return value, nil
+				}
+			}
+		}
+	}
+
+	return nil, fmt.Errorf("marker not found: %s", key)
+}
+
+// HasMarker checks if a marker exists
+func (n *N) HasMarker(key string) bool {
+	_, err := n.GetMarker(key)
+	return err == nil
+}
+
+// DeleteMarker removes a metadata marker
+func (n *N) DeleteMarker(key string) error {
+	cypher := "MATCH (m:Marker {key: $key}) DELETE m"
+	params := map[string]any{"key": key}
+
+	_, err := n.ExecuteWrite(context.Background(), cypher, params)
+	if err != nil {
+		return fmt.Errorf("failed to delete marker: %w", err)
+	}
+
+	return nil
+}