From 3209b39488de1f6b172ffbf81fb36980b010909f Mon Sep 17 00:00:00 2001
From: Lea Anthony <lea.anthony@gmail.com>
Date: Sat, 3 Oct 2020 20:46:18 +1000
Subject: [PATCH] Support System calls in Go Runtime

---
 v2/internal/app/desktop.go    |  2 +-
 v2/internal/subsystem/call.go | 29 ++++++++++++++++++++++++++---
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/v2/internal/app/desktop.go b/v2/internal/app/desktop.go
index 39d6c0fb..e28dd2d4 100644
--- a/v2/internal/app/desktop.go
+++ b/v2/internal/app/desktop.go
@@ -119,7 +119,7 @@ func (a *App) Run() error {
 	a.event.Start()
 
 	// Start the call subsystem
-	call, err := subsystem.NewCall(a.servicebus, a.logger, a.bindings.DB())
+	call, err := subsystem.NewCall(a.servicebus, a.logger, a.bindings.DB(), a.runtime.GoRuntime())
 	if err != nil {
 		return err
 	}
diff --git a/v2/internal/subsystem/call.go b/v2/internal/subsystem/call.go
index 1ade33dd..54407117 100644
--- a/v2/internal/subsystem/call.go
+++ b/v2/internal/subsystem/call.go
@@ -3,11 +3,14 @@ package subsystem
 import (
 	"encoding/json"
 	"fmt"
+	"strings"
 
 	"github.com/wailsapp/wails/v2/internal/binding"
 	"github.com/wailsapp/wails/v2/internal/logger"
 	"github.com/wailsapp/wails/v2/internal/messagedispatcher/message"
 	"github.com/wailsapp/wails/v2/internal/servicebus"
+	"github.com/wailsapp/wails/v2/internal/runtime/goruntime"
+
 )
 
 // Call is the Call subsystem. It manages all service bus messages
@@ -25,10 +28,13 @@ type Call struct {
 
 	// logger
 	logger logger.CustomLogger
+
+	// runtime
+	runtime *goruntime.Runtime 
 }
 
-// NewCall creates a new log subsystem
-func NewCall(bus *servicebus.ServiceBus, logger *logger.Logger, DB *binding.DB) (*Call, error) {
+// NewCall creates a new call subsystem
+func NewCall(bus *servicebus.ServiceBus, logger *logger.Logger, DB *binding.DB, runtime *goruntime.Runtime) (*Call, error) {
 
 	// Register quit channel
 	quitChannel, err := bus.Subscribe("quit")
@@ -48,6 +54,7 @@ func NewCall(bus *servicebus.ServiceBus, logger *logger.Logger, DB *binding.DB)
 		logger:      logger.CustomLogger("Call Subsystem"),
 		DB:          DB,
 		bus:         bus,
+		runtime: runtime,
 	}
 
 	return result, nil
@@ -65,7 +72,7 @@ func (c *Call) Start() error {
 			case <-c.quitChannel:
 				c.running = false
 			case callMessage := <-c.callChannel:
-
+				// TODO: Check if this works ok in a goroutine
 				c.processCall(callMessage)
 			}
 		}
@@ -87,6 +94,12 @@ func (c *Call) processCall(callMessage *servicebus.Message) {
 	// Lookup method
 	registeredMethod := c.DB.GetMethod(payload.Name)
 
+	// Check if it's a system call
+	if strings.HasPrefix(payload.Name, ".wails.") {
+		c.processSystemCall(payload, callMessage.Target())
+		return
+	}
+
 	// Check we have it
 	if registeredMethod == nil {
 		c.sendError(fmt.Errorf("Method not registered"), payload, callMessage.Target())
@@ -105,6 +118,16 @@ func (c *Call) processCall(callMessage *servicebus.Message) {
 
 }
 
+func (c *Call) processSystemCall(payload *message.CallMessage, clientID string) {
+	c.logger.Trace("Got internal System call: %+v", payload)
+	callName := strings.TrimPrefix(payload.Name, ".wails.")
+	switch callName {
+	case "IsDarkMode": 
+		darkModeEnabled := c.runtime.System.IsDarkMode()
+		c.sendResult(darkModeEnabled, payload, clientID)
+	}
+}
+
 func (c *Call) sendResult(result interface{}, payload *message.CallMessage, clientID string) {
 	c.logger.Trace("Sending success result with CallbackID '%s' : %+v\n", payload.CallbackID, result)
 	message := &CallbackMessage{