up

internal/services/wifi_service/service.go

@@ -0,0 +1,43 @@
+// Package wifi_service reads the collector's latest snapshot without LAN access.
+package wifi_service
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"os"
+	"time"
+
+	"evening_detective_server/internal/modules/cudy"
+)
+
+type Service struct {
+	path string
+	now  func() time.Time
+}
+
+func New(path string) *Service { return &Service{path: path, now: time.Now} }
+
+func (s *Service) Get(ctx context.Context) (cudy.Snapshot, bool) {
+	if s == nil || s.path == "" {
+		return cudy.Snapshot{}, false
+	}
+	snapshot := cudy.Snapshot{Enabled: true, HasError: true}
+	if ctx.Err() != nil {
+		return snapshot, true
+	}
+	file, err := os.Open(s.path)
+	if err != nil {
+		return snapshot, true
+	}
+	defer file.Close()
+	data, err := io.ReadAll(io.LimitReader(file, 2<<20+1))
+	if err != nil || len(data) > 2<<20 || json.Unmarshal(data, &snapshot) != nil {
+		return cudy.Snapshot{Enabled: true, HasError: true}, true
+	}
+	if !snapshot.Enabled {
+		return snapshot, false
+	}
+	stale := snapshot.HasError || snapshot.CollectedAt.IsZero() || s.now().Sub(snapshot.CollectedAt) >= 30*time.Second || snapshot.CollectedAt.After(s.now())
+	return snapshot, stale
+}