feat(sub): expose last subscription fetch time (#6217)

* feat(sub): expose last subscription fetch time

Record successful GET subscription fetches per client and surface the timestamp in the client API and UI.

* fix(frontend): include last subscription fetch in client traffic

* Update sub_fetch_test.go

---------

Co-authored-by: Hermes Agent <hermes-agent@localhost>

internal/sub/sub_fetch_test.go

@@ -0,0 +1,99 @@
+package sub
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/gin-gonic/gin"
+
+	"github.com/mhsanaei/3x-ui/v3/internal/database"
+	"github.com/mhsanaei/3x-ui/v3/internal/database/model"
+	"github.com/mhsanaei/3x-ui/v3/internal/xray"
+)
+
+func TestRecordSubscriptionFetch(t *testing.T) {
+	initSubDB(t)
+	db := database.GetDB()
+
+	clients := []model.ClientRecord{
+		{Email: "alpha@example.com", SubID: "sub-alpha", Enable: true},
+		{Email: "bravo@example.com", SubID: "sub-bravo", Enable: true},
+	}
+	for i := range clients {
+		if err := db.Create(&clients[i]).Error; err != nil {
+			t.Fatalf("create client %s: %v", clients[i].Email, err)
+		}
+		if err := db.Create(&xray.ClientTraffic{Email: clients[i].Email}).Error; err != nil {
+			t.Fatalf("create traffic %s: %v", clients[i].Email, err)
+		}
+	}
+
+	before := time.Now().UnixMilli()
+	if err := (&SubService{}).RecordSubscriptionFetch("sub-alpha"); err != nil {
+		t.Fatalf("RecordSubscriptionFetch: %v", err)
+	}
+
+	var alpha, bravo xray.ClientTraffic
+	if err := db.Where("email = ?", "alpha@example.com").First(&alpha).Error; err != nil {
+		t.Fatalf("load alpha traffic: %v", err)
+	}
+	if err := db.Where("email = ?", "bravo@example.com").First(&bravo).Error; err != nil {
+		t.Fatalf("load bravo traffic: %v", err)
+	}
+	if alpha.LastSubFetch < before {
+		t.Fatalf("alpha lastSubFetch = %d, want >= %d", alpha.LastSubFetch, before)
+	}
+	if bravo.LastSubFetch != 0 {
+		t.Fatalf("bravo lastSubFetch = %d, want 0", bravo.LastSubFetch)
+	}
+
+	if err := (&SubService{}).RecordSubscriptionFetch("unknown"); err != nil {
+		t.Fatalf("unknown subId: %v", err)
+	}
+	if err := (&SubService{}).RecordSubscriptionFetch(""); err != nil {
+		t.Fatalf("empty subId: %v", err)
+	}
+}
+
+func TestRecordSubscriptionFetchStatusGate(t *testing.T) {
+	initSubDB(t)
+	db := database.GetDB()
+	client := &model.ClientRecord{Email: "alpha@example.com", SubID: "sub-alpha", Enable: true}
+	if err := db.Create(client).Error; err != nil {
+		t.Fatalf("create client: %v", err)
+	}
+	if err := db.Create(&xray.ClientTraffic{Email: client.Email}).Error; err != nil {
+		t.Fatalf("create traffic: %v", err)
+	}
+
+	controller := &SUBController{subService: &SubService{}}
+	notFoundRecorder := httptest.NewRecorder()
+	notFound, _ := gin.CreateTestContext(notFoundRecorder)
+	notFound.Request = httptest.NewRequest(http.MethodGet, "/sub/sub-alpha", nil)
+	notFound.Params = gin.Params{{Key: "subid", Value: "sub-alpha"}}
+	notFound.Status(http.StatusNotFound)
+	controller.recordSubscriptionFetch(notFound)
+
+	var traffic xray.ClientTraffic
+	if err := db.Where("email = ?", client.Email).First(&traffic).Error; err != nil {
+		t.Fatalf("load traffic after 404: %v", err)
+	}
+	if traffic.LastSubFetch != 0 {
+		t.Fatalf("404 updated lastSubFetch to %d", traffic.LastSubFetch)
+	}
+
+	okRecorder := httptest.NewRecorder()
+	ok, _ := gin.CreateTestContext(okRecorder)
+	ok.Request = httptest.NewRequest(http.MethodGet, "/sub/sub-alpha", nil)
+	ok.Params = gin.Params{{Key: "subid", Value: "sub-alpha"}}
+	ok.Status(http.StatusOK)
+	controller.recordSubscriptionFetch(ok)
+	if err := db.Where("email = ?", client.Email).First(&traffic).Error; err != nil {
+		t.Fatalf("load traffic after 200: %v", err)
+	}
+	if traffic.LastSubFetch == 0 {
+		t.Fatal("200 did not update lastSubFetch")
+	}
+}