feat: add go daily metric writer

go/vehicle-gateway/internal/stats/daily_metric.go

@@ -0,0 +1,159 @@
+package stats
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"strconv"
+	"strings"
+	"time"
+
+	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
+)
+
+const (
+	MetricDailyMileageKM      = "daily_mileage_km"
+	MetricDailyTotalMileageKM = "daily_total_mileage_km"
+)
+
+type Execer interface {
+	ExecContext(context.Context, string, ...any) (sql.Result, error)
+}
+
+type Writer struct {
+	exec Execer
+	loc  *time.Location
+}
+
+type MetricSample struct {
+	VIN            string
+	Protocol       envelope.Protocol
+	StatDate       string
+	MetricKey      string
+	MetricValue    float64
+	TotalMileageKM float64
+}
+
+func NewWriter(exec Execer, loc *time.Location) *Writer {
+	if exec == nil {
+		panic("stats execer must not be nil")
+	}
+	if loc == nil {
+		loc = time.FixedZone("Asia/Shanghai", 8*3600)
+	}
+	return &Writer{exec: exec, loc: loc}
+}
+
+func (w *Writer) EnsureSchema(ctx context.Context) error {
+	_, err := w.exec.ExecContext(ctx, DailyMetricTableSQL)
+	return err
+}
+
+func (w *Writer) Append(ctx context.Context, env envelope.FrameEnvelope) error {
+	samples, err := SamplesFromEnvelope(env, w.loc)
+	if err != nil {
+		return err
+	}
+	for _, sample := range samples {
+		if _, err := w.exec.ExecContext(ctx, upsertDailyMetricSQL,
+			sample.VIN,
+			sample.StatDate,
+			string(sample.Protocol),
+			sample.MetricKey,
+			sample.MetricValue,
+			sample.TotalMileageKM,
+			sample.TotalMileageKM); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func SamplesFromEnvelope(env envelope.FrameEnvelope, loc *time.Location) ([]MetricSample, error) {
+	vin := strings.TrimSpace(env.VIN)
+	if vin == "" {
+		return nil, nil
+	}
+	totalMileage, ok := floatField(env, envelope.FieldTotalMileageKM)
+	if !ok {
+		return nil, nil
+	}
+	if loc == nil {
+		loc = time.FixedZone("Asia/Shanghai", 8*3600)
+	}
+	eventMS := env.EventTimeMS
+	if eventMS <= 0 {
+		eventMS = env.ReceivedAtMS
+	}
+	if eventMS <= 0 {
+		return nil, errors.New("event or received time is required")
+	}
+	statDate := time.UnixMilli(eventMS).In(loc).Format("2006-01-02")
+	return []MetricSample{
+		{
+			VIN:            vin,
+			Protocol:       env.Protocol,
+			StatDate:       statDate,
+			MetricKey:      MetricDailyMileageKM,
+			MetricValue:    0,
+			TotalMileageKM: totalMileage,
+		},
+		{
+			VIN:            vin,
+			Protocol:       env.Protocol,
+			StatDate:       statDate,
+			MetricKey:      MetricDailyTotalMileageKM,
+			MetricValue:    totalMileage,
+			TotalMileageKM: totalMileage,
+		},
+	}, nil
+}
+
+const upsertDailyMetricSQL = `
+INSERT INTO vehicle_daily_metric
+  (vin, stat_date, protocol, metric_key, metric_value, metric_unit,
+   first_total_mileage_km, latest_total_mileage_km, sample_count, calculation_method)
+VALUES (?, ?, ?, ?, ?, 'km', ?, ?, 1, 'TOTAL_MILEAGE_DIFF')
+ON DUPLICATE KEY UPDATE
+  first_total_mileage_km = LEAST(first_total_mileage_km, VALUES(first_total_mileage_km)),
+  latest_total_mileage_km = GREATEST(latest_total_mileage_km, VALUES(latest_total_mileage_km)),
+  metric_value = CASE
+    WHEN metric_key = 'daily_mileage_km'
+      THEN GREATEST(latest_total_mileage_km, VALUES(latest_total_mileage_km))
+           - LEAST(first_total_mileage_km, VALUES(first_total_mileage_km))
+    WHEN metric_key = 'daily_total_mileage_km'
+      THEN GREATEST(latest_total_mileage_km, VALUES(latest_total_mileage_km))
+    ELSE VALUES(metric_value)
+  END,
+  sample_count = sample_count + 1,
+  updated_at = CURRENT_TIMESTAMP
+`
+
+func floatField(env envelope.FrameEnvelope, key string) (float64, bool) {
+	if env.Fields == nil {
+		return 0, false
+	}
+	value, ok := env.Fields[key]
+	if !ok || value == nil {
+		return 0, false
+	}
+	switch typed := value.(type) {
+	case float64:
+		return typed, true
+	case float32:
+		return float64(typed), true
+	case int:
+		return float64(typed), true
+	case int64:
+		return float64(typed), true
+	case uint16:
+		return float64(typed), true
+	case uint32:
+		return float64(typed), true
+	case string:
+		parsed, err := strconv.ParseFloat(strings.TrimSpace(typed), 64)
+		return parsed, err == nil
+	default:
+		return 0, false
+	}
+}

go/vehicle-gateway/internal/stats/daily_metric_test.go

@@ -0,0 +1,107 @@
+package stats
+
+import (
+	"context"
+	"database/sql"
+	"strings"
+	"testing"
+	"time"
+
+	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
+)
+
+func TestSamplesFromEnvelopeDerivesDailyMileageAndTotal(t *testing.T) {
+	loc := time.FixedZone("Asia/Shanghai", 8*3600)
+	env := envelope.FrameEnvelope{
+		Protocol:    envelope.ProtocolJT808,
+		VIN:         "LNBVIN00000000001",
+		EventTimeMS: time.Date(2026, 7, 1, 8, 30, 0, 0, loc).UnixMilli(),
+		Fields: map[string]any{
+			envelope.FieldTotalMileageKM: 10241.2,
+		},
+	}
+
+	samples, err := SamplesFromEnvelope(env, loc)
+	if err != nil {
+		t.Fatalf("SamplesFromEnvelope() error = %v", err)
+	}
+	if len(samples) != 2 {
+		t.Fatalf("sample count = %d", len(samples))
+	}
+	if samples[0].MetricKey != MetricDailyMileageKM || samples[0].MetricValue != 0 {
+		t.Fatalf("unexpected daily mileage sample: %#v", samples[0])
+	}
+	if samples[1].MetricKey != MetricDailyTotalMileageKM || samples[1].MetricValue != 10241.2 {
+		t.Fatalf("unexpected daily total sample: %#v", samples[1])
+	}
+	if samples[0].StatDate != "2026-07-01" {
+		t.Fatalf("stat date = %q", samples[0].StatDate)
+	}
+}
+
+func TestSamplesFromEnvelopeSkipsMissingVINOrMileage(t *testing.T) {
+	samples, err := SamplesFromEnvelope(envelope.FrameEnvelope{
+		Protocol: envelope.ProtocolJT808,
+		Fields:   map[string]any{envelope.FieldTotalMileageKM: 1.2},
+	}, nil)
+	if err != nil {
+		t.Fatalf("SamplesFromEnvelope() error = %v", err)
+	}
+	if len(samples) != 0 {
+		t.Fatalf("expected no samples without vin, got %#v", samples)
+	}
+
+	samples, err = SamplesFromEnvelope(envelope.FrameEnvelope{
+		Protocol: envelope.ProtocolGB32960,
+		VIN:      "LNBVIN00000000002",
+		Fields:   map[string]any{},
+	}, nil)
+	if err != nil {
+		t.Fatalf("SamplesFromEnvelope() error = %v", err)
+	}
+	if len(samples) != 0 {
+		t.Fatalf("expected no samples without mileage, got %#v", samples)
+	}
+}
+
+func TestWriterEnsuresSchemaAndUpsertsTwoMetrics(t *testing.T) {
+	exec := &recordingExec{}
+	writer := NewWriter(exec, time.FixedZone("Asia/Shanghai", 8*3600))
+	if err := writer.EnsureSchema(context.Background()); err != nil {
+		t.Fatalf("EnsureSchema() error = %v", err)
+	}
+	if err := writer.Append(context.Background(), envelope.FrameEnvelope{
+		Protocol:    envelope.ProtocolGB32960,
+		VIN:         "LNBVIN00000000002",
+		EventTimeMS: time.Date(2026, 7, 1, 9, 0, 0, 0, time.FixedZone("Asia/Shanghai", 8*3600)).UnixMilli(),
+		Fields: map[string]any{
+			envelope.FieldTotalMileageKM: "10000.0",
+		},
+	}); err != nil {
+		t.Fatalf("Append() error = %v", err)
+	}
+
+	if !strings.Contains(exec.calls[0].query, "CREATE TABLE IF NOT EXISTS vehicle_daily_metric") {
+		t.Fatalf("unexpected schema sql: %s", exec.calls[0].query)
+	}
+	if len(exec.calls) != 3 {
+		t.Fatalf("exec calls = %d", len(exec.calls))
+	}
+	if !strings.Contains(exec.calls[1].query, "ON DUPLICATE KEY UPDATE") {
+		t.Fatalf("unexpected upsert sql: %s", exec.calls[1].query)
+	}
+}
+
+type execCall struct {
+	query string
+	args  []any
+}
+
+type recordingExec struct {
+	calls []execCall
+}
+
+func (e *recordingExec) ExecContext(_ context.Context, query string, args ...any) (sql.Result, error) {
+	e.calls = append(e.calls, execCall{query: query, args: args})
+	return nil, nil
+}

go/vehicle-gateway/internal/stats/schema.go

@@ -0,0 +1,20 @@
+package stats
+
+const DailyMetricTableSQL = `CREATE TABLE IF NOT EXISTS vehicle_daily_metric (
+  id BIGINT PRIMARY KEY AUTO_INCREMENT,
+  vin VARCHAR(32) NOT NULL,
+  stat_date DATE NOT NULL,
+  protocol VARCHAR(32) NOT NULL,
+  metric_key VARCHAR(64) NOT NULL,
+  metric_value DECIMAL(18,3) NOT NULL,
+  metric_unit VARCHAR(16) NOT NULL,
+  first_total_mileage_km DECIMAL(18,3) NULL,
+  latest_total_mileage_km DECIMAL(18,3) NULL,
+  sample_count BIGINT NOT NULL DEFAULT 0,
+  calculation_method VARCHAR(64) NOT NULL,
+  created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+  UNIQUE KEY uk_daily_metric (vin, stat_date, protocol, metric_key),
+  KEY idx_stat_date (stat_date),
+  KEY idx_protocol_metric (protocol, metric_key)
+)`