support macOS

autoload/lumen/platforms.vim

@@ -1,6 +1,8 @@
 let s:platform = ''
 if has('linux')
 	let s:platform = 'linux'
+elseif has('osx')
+	let s:platform = 'macos'
 endif
 
 func lumen#platforms#call(func, ...)

autoload/lumen/platforms/macos.vim

@@ -0,0 +1,17 @@
+func lumen#platforms#macos#watch_cmd()
+	let path = fnamemodify(resolve(expand('<sfile>:p')), ':h')
+	return [path . "/autoload/lumen/platforms/macos/watcher.swift"]
+endfunc
+
+func lumen#platforms#macos#parse_line(line)
+	if a:line == "Dark"
+		call lumen#dark_hook()
+	else
+		call lumen#light_hook()
+	endif
+endfunc
+
+func lumen#platforms#macos#oneshot()
+	let out = system(join(lumen#platforms#macos#watch_cmd() + ["get"]))
+	call lumen#platforms#macos#parse_line(out)
+endfunc

autoload/lumen/platforms/macos/watcher.swift

@@ -0,0 +1,35 @@
+#!/usr/bin/env swift
+
+// Based on https://github.com/bouk/dark-mode-notify/blob/main/dark-mode-notify.swift (MIT license)
+// Which itself is based on https://github.com/mnewt/dotemacs/blob/master/bin/dark-mode-notifier.swift (Unlicense license)
+
+import Cocoa
+import Darwin
+
+var isAppearanceDark: Bool {
+	if #available(macOS 11.0, *) {
+		return NSAppearance.currentDrawing().bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+	} else {
+		return NSAppearance.current.bestMatch(from: [.darkAqua, .aqua]) == .darkAqua
+	}
+}
+
+func printAppearance() {
+	let string = isAppearanceDark ? "Dark" : "Light"
+	try! FileHandle.standardOutput.write(contentsOf: Data((string + "\n").utf8))
+	// print(string) // doesn't work for some strange reason?!
+}
+
+if CommandLine.arguments.dropFirst(1).first == "get" {
+	printAppearance()
+	exit(0)
+}
+
+DistributedNotificationCenter.default.addObserver(
+		forName: Notification.Name("AppleInterfaceThemeChangedNotification"),
+		object: nil,
+		queue: nil) { _ in
+	printAppearance()
+}
+
+NSApplication.shared.run()