A few various changes

- Fixed the '-local' flag to accept host and port
- Added a '-debug' flag to accept a file to write debug log messages
- Added some logic which will force the dark background flag on if MacOS is in dark mode

internal/common/ui/osstyle/osstyle.go

@@ -0,0 +1,18 @@
+package osstyle
+
+type ColorScheme int
+
+const (
+	ColorSchemeUnknown ColorScheme = iota
+	ColorSchemeLightMode
+	ColorSchemeDarkMode
+)
+
+var getOSColorScheme func() ColorScheme = nil
+
+func CurrentColorScheme() ColorScheme {
+	if getOSColorScheme == nil {
+		return ColorSchemeUnknown
+	}
+	return getOSColorScheme()
+}

internal/common/ui/osstyle/osstyle_darwin.go

@@ -0,0 +1,27 @@
+package osstyle
+
+import (
+	"log"
+	"os/exec"
+)
+
+// Usage: https://stefan.sofa-rockers.org/2018/10/23/macos-dark-mode-terminal-vim/
+func darwinGetOSColorScheme() ColorScheme {
+	d, err := exec.Command("defaults", "read", "-g", "AppleInterfaceStyle").Output()
+	if err != nil {
+		log.Printf("cannot get current OS color scheme: %v", err)
+		return ColorSchemeUnknown
+	}
+
+	switch string(d) {
+	case "Dark\n":
+		return ColorSchemeDarkMode
+	case "Light\n":
+		return ColorSchemeLightMode
+	}
+	return ColorSchemeUnknown
+}
+
+func init() {
+	getOSColorScheme = darwinGetOSColorScheme
+}