refactor: refactor the code for qol.go

internal/qol/results/writer.go

@@ -0,0 +1,51 @@
+package results
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"time"
+)
+
+type DNSMetric struct {
+	Domain       string    `json:"domain"`
+	QueryType    string    `json:"query_type"`
+	Protocol     string    `json:"protocol"`
+	DNSSEC       bool      `json:"dnssec"`
+	DNSServer    string    `json:"dns_server"`
+	Timestamp    time.Time `json:"timestamp"`
+	Duration     int64     `json:"duration_ns"`
+	DurationMs   float64   `json:"duration_ms"`
+	RequestSize  int       `json:"request_size_bytes"`
+	ResponseSize int       `json:"response_size_bytes"`
+	ResponseCode string    `json:"response_code"`
+	Error        string    `json:"error,omitempty"`
+}
+
+type MetricsWriter struct {
+	encoder *json.Encoder
+	file    *os.File
+}
+
+func NewMetricsWriter(path string) (*MetricsWriter, error) {
+	file, err := os.Create(path)
+	if err != nil {
+		return nil, fmt.Errorf("create json output: %w", err)
+	}
+
+	return &MetricsWriter{
+		encoder: json.NewEncoder(file),
+		file:    file,
+	}, nil
+}
+
+func (mw *MetricsWriter) WriteMetric(metric DNSMetric) error {
+	return mw.encoder.Encode(metric)
+}
+
+func (mw *MetricsWriter) Close() error {
+	if mw.file != nil {
+		return mw.file.Close()
+	}
+	return nil
+}