platform: modularize api/gui, add docs-tests-web foundation, and refresh root config

selective-vpn-api/app/dns_smartdns_handlers_runtime.go

@@ -0,0 +1,70 @@
+package app
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+)
+
+func handleSmartdnsRuntime(w http.ResponseWriter, r *http.Request) {
+	switch r.Method {
+	case http.MethodGet:
+		writeJSON(w, http.StatusOK, smartDNSRuntimeSnapshot())
+	case http.MethodPost:
+		var body SmartDNSRuntimeRequest
+		if r.Body != nil {
+			defer r.Body.Close()
+			if err := json.NewDecoder(io.LimitReader(r.Body, 1<<20)).Decode(&body); err != nil && err != io.EOF {
+				http.Error(w, "bad json", http.StatusBadRequest)
+				return
+			}
+		}
+		if body.Enabled == nil {
+			http.Error(w, "enabled is required", http.StatusBadRequest)
+			return
+		}
+
+		prev := loadSmartDNSRuntimeState(nil)
+		next := prev
+		next.Enabled = *body.Enabled
+		if err := saveSmartDNSRuntimeState(next); err != nil {
+			http.Error(w, "runtime state write error", http.StatusInternalServerError)
+			return
+		}
+
+		changed, err := applySmartDNSRuntimeConfig(next.Enabled)
+		if err != nil {
+			_ = saveSmartDNSRuntimeState(prev)
+			http.Error(w, "runtime config apply error: "+err.Error(), http.StatusInternalServerError)
+			return
+		}
+
+		restart := true
+		if body.Restart != nil {
+			restart = *body.Restart
+		}
+		restarted := false
+		msg := ""
+		if restart && smartdnsUnitState() == "active" {
+			res := runSmartdnsUnitAction("restart")
+			restarted = res.OK
+			if !res.OK {
+				msg = "runtime config changed, but smartdns restart failed: " + strings.TrimSpace(res.Message)
+			}
+		}
+		if msg == "" {
+			msg = fmt.Sprintf("smartdns runtime set: enabled=%t changed=%t restarted=%t", next.Enabled, changed, restarted)
+		}
+		appendTraceLineTo(smartdnsLogPath, "smartdns", msg)
+
+		resp := smartDNSRuntimeSnapshot()
+		resp.Changed = changed
+		resp.Restarted = restarted
+		resp.Message = msg
+		writeJSON(w, http.StatusOK, resp)
+	default:
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+	}
+}